http://solarcities.blogspot.com/
This blog describes the activities of global nomads T.H. Culhane and Sybille Culhane as they work on the Solar C3.I.T.I.E.S. mission: "Connecting Community Catalysts Integrating Technologies for Industrial Ecology Systems"
Those technologies mentioned in the video clip are “home scale” energy solutions made by local people from local materials. We don’t want to reinvent the wheel or try to create something new out of whole cloth. Like Aydogan Ozcan’s use of cell phones as microscopes and Ken Banks use of existing cell phone networks for vital SMS empowerment we also try to repurpose local, “found” materials, and off the shelf, ubiquitous technologies, both real and virtual, analog and digital, to solve the problems of sustainable development and education. We know we can solve many our energy, waste, water and food problems using simple solar and biofuel technologies. In this slide we see technologies we developed in Egypt that use recycled materials we knew would be available in Alaska.
To bring this to scale we need to use our new media technologies and social networking tools, things like google earth and google sketchup, open source 3d animation and multimedia production software to make learning the energy systems easy for people. We use the ipod touch with a handheld projector to erase literacy and language barriers, projecting the animations on walls and rooftop satellite dishes as screens. And we compose songs to spread the message which we take around the world with solar powered music groups to environmental festivals like this one in India.
And the thing is, we can’t just use all this great multimedia technology and educational materials to talk about environmental issues if we aren’t teaching people how to actually solve the problems themselves. This is why we have this two pronged approach -- work collectively to develop safe energy technologies and then use social media to broadcast the solutions.
So in this presentation I’m going to weave together two threads - one is the very simple low cost technologies we are developing and implementing to reduce our consumption of fossil fuels and forest resources,
The other is how we go about spreading the message the these technologies are in fact so simple that you CAN try them at home.
This year I have been blessed to receive, with fellow Emerging Explorer Dr. Katey Walter, the first National Geographic Blackstone Ranch Innovation Challenge Grant for combining our different projects into an application to help the world. Katey is an arctic biologist working on newly discovered microbes that are producing greenhouse gases at freezing temperatures and I’ve been using microbes to clean water and produce biogas for cooking and electricity, heat and fertilizer. We decided to team up, kind of like Wonder Woman and, I dunno, Captain America? ... to see if we can harness these microbes to make garbage to biogas systems more efficient and then use social networking and media technologies as well as airplanes, to take the results from household to household and community to community, around the globe.
This is because when we met last year here we figured that if technology and globalization gave individuals disproportionate power to do bad things and form terrorist networks than by the same logic it could amplify our power to do great things for the world, if we found a way to pool our different talents.
The Blackstone Ranch Foundation Innovation Challenge has given us a way to formally create those synergies. Certainly this motley crew of cartoon action figures makes a formidable league of superheroes. The question is how to bring us all together. What would the first unifying project be for what we call "the Nat Geo E-Team"?
At Solar CITIES the word “CITIES” with a C cubed stands for Connecting Community Catalysts Integrating Technologies for Industrial Ecology Solutions, and we operate with a belief in Collective Intelligence, Crowd Sourcing, Cloud Computing and Citizen Science. We believe the intelligence is in the network and once we pick a project that has rhizomal links to issues we all face in common, our special abilities will start to complement each other. We picked household waste to biogas solutions for our Blackstone project because it provides a possible solution to the challenges of clean renewable energy, public health, waste management, fertilizer and food production, water conservation, wildlife conservation, poverty alleviation and climate change. Not bad for a single simple technology. But how to spread the message so everybody could pitch in with their piece of the puzzle?
In 1966 at the age of 4 I read my first Dr. Seuss Beginners Books, “Come over to My House” and learned about the power of social networking to bring peace and understanding between different cultures. The message was clear -- make friends from around the world, from different walks of life and then invite each other to live at each other’s homes for a time and share ideas and perspectives. This way you get to know firsthand the problems and solutions sets available in each environment. As the Irish say “If you want to know me, come and live with me”.
So we decided to go and live in homes in rural villages and urban slums and work together on collective problem solving.
My wife and I moved into the slums of Cairo and built a solar hot water system with our garbage recycler friends but later went back to Europe when our baby was born. But we were able to continue improving the system remotely by making simple animations and sharing them on facebook and youtube with our friends in Cairo.
Sunday, June 13, 2010
Saturday, June 12, 2010
best source of energy for the future
By Russell Lowes, February 27, 2010
The real choice is not nuclear versus coal, but nukes & coal versus the reasonable alternatives.
There is massive opposition to coal now, which comprises about 45% of U.S. electricity. You can see smoke from the stacks or read about its CO2 emissions.
Opposition to nuclear energy is also amassing. Nuclear also produces CO2 emissions, which are growing ever-greater. It emits invisible radioactivity, uses even more water, and is much pricier. Here are some of the problems with nuclear energy.
Safety Issues Persist: The world has 436 reactors. In order to have a significant contribution to world energy, 1000 reactors are projected. Even if future reactor accidents improve by a factor of 10, the chance of a reactor meltdown would be roughly one more Chernobyl-like “sacrifice zone” by 2050.
Terrorist Issues: Shortly after the 9/11 New York jetliner crashes, the NRC corrected itself saying that airliners could destroy U.S. reactors. There is an even greater threat at the adjacent spent fuel cooling pools, housed in non-hardened buildings which, if breached, could create a meltdown.
Poor Economics/Subsidies Required: Nuclear electricity would run about 25 cents per kilowatt-hour to your meter. Current Tucson electricity is about 11 cents. New coal would be about 16 cents, wind at 12, solar photovoltaic at 24, gas at 13. The best option, however, is reducing energy with better lighting, architecture, insulation, A/C efficiency, etc. Energy efficiency averages about 3 cents. Numerous nuclear industry officials have said they will build no new reactors without taxpayer loan guarantees.
Two Ways to Worsen Global Warming: Investing 1 dollar in nuclear rather than energy efficiency, you forgo saving 8 times the electricity. In other words, you can invest 1 dollar in nuclear and get 4 kilowatt-hours – or you can invest in energy savings and get 33 KWH. Investing in nuclear energy will dominate energy dollars, setting back the real options.
Second, nukes produce about 110 grams of CO2 per kilowatt-hour. This is 11 times the CO2 of wind, double that of solar, and many times that of energy savings/efficiency. It gets worse if you include 1 million years of waste storage.
Water Consumption Is Highest: Water lost to the environment at Palo Verde is about 0.8 gallons per kilowatt-hour. Coal consumes 0.5 gallons. With solar PV, wind and energy savings, water use is negligible.
National Security Is Diminished: We import 80-92% of our U.S. nuclear fuel. Energy independence is set back with nuclear.
Waste Legacy: The U.S. courts have ruled that nuclear waste much be safeguarded for 1 million years, 25,000 times the 40-year operating life of a reactor.
Russell Lowes is Research Director for www.SafeEnergyAnalyst.org. He was the primary author of a book on the Palo Verde Nuclear Power Plant, the largest U.S. nuclear plant upwind of Tucson about 125 miles. This book was used in a campaign to successfully stop two reactors at this now three-reactor complex. You can contact Russell Lowes for presentations or for questions at russlowes@gmail.com Documentation to this article can be found at www.SafeEnergyAnalyst.org
The real choice is not nuclear versus coal, but nukes & coal versus the reasonable alternatives.
There is massive opposition to coal now, which comprises about 45% of U.S. electricity. You can see smoke from the stacks or read about its CO2 emissions.
Opposition to nuclear energy is also amassing. Nuclear also produces CO2 emissions, which are growing ever-greater. It emits invisible radioactivity, uses even more water, and is much pricier. Here are some of the problems with nuclear energy.
Safety Issues Persist: The world has 436 reactors. In order to have a significant contribution to world energy, 1000 reactors are projected. Even if future reactor accidents improve by a factor of 10, the chance of a reactor meltdown would be roughly one more Chernobyl-like “sacrifice zone” by 2050.
Terrorist Issues: Shortly after the 9/11 New York jetliner crashes, the NRC corrected itself saying that airliners could destroy U.S. reactors. There is an even greater threat at the adjacent spent fuel cooling pools, housed in non-hardened buildings which, if breached, could create a meltdown.
Poor Economics/Subsidies Required: Nuclear electricity would run about 25 cents per kilowatt-hour to your meter. Current Tucson electricity is about 11 cents. New coal would be about 16 cents, wind at 12, solar photovoltaic at 24, gas at 13. The best option, however, is reducing energy with better lighting, architecture, insulation, A/C efficiency, etc. Energy efficiency averages about 3 cents. Numerous nuclear industry officials have said they will build no new reactors without taxpayer loan guarantees.
Two Ways to Worsen Global Warming: Investing 1 dollar in nuclear rather than energy efficiency, you forgo saving 8 times the electricity. In other words, you can invest 1 dollar in nuclear and get 4 kilowatt-hours – or you can invest in energy savings and get 33 KWH. Investing in nuclear energy will dominate energy dollars, setting back the real options.
Second, nukes produce about 110 grams of CO2 per kilowatt-hour. This is 11 times the CO2 of wind, double that of solar, and many times that of energy savings/efficiency. It gets worse if you include 1 million years of waste storage.
Water Consumption Is Highest: Water lost to the environment at Palo Verde is about 0.8 gallons per kilowatt-hour. Coal consumes 0.5 gallons. With solar PV, wind and energy savings, water use is negligible.
National Security Is Diminished: We import 80-92% of our U.S. nuclear fuel. Energy independence is set back with nuclear.
Waste Legacy: The U.S. courts have ruled that nuclear waste much be safeguarded for 1 million years, 25,000 times the 40-year operating life of a reactor.
Russell Lowes is Research Director for www.SafeEnergyAnalyst.org. He was the primary author of a book on the Palo Verde Nuclear Power Plant, the largest U.S. nuclear plant upwind of Tucson about 125 miles. This book was used in a campaign to successfully stop two reactors at this now three-reactor complex. You can contact Russell Lowes for presentations or for questions at russlowes@gmail.com Documentation to this article can be found at www.SafeEnergyAnalyst.org
Beating the Heat: Evaporative Coolers vs. Refrigeration
Beating the Heat: Evaporative Coolers vs. Refrigeration
by Roy Emrick and Russell Lowes
An earlier version of this article appeared in the April-June 2010 Sierra Club Rincon Group Newsletter.
Which cooling system is best for energy use? Which is best for water use? Which is best for reducing CO2 output of electrical plants?
For several years, a business columnist at the Arizona Daily Star regularly berated evaporative coolers as water wasters and outmoded technology. He said refrigeration was the way to go in the modern world. Many readers disagreed with him but they gave only qualitative arguments. We decided to see if we could find some quantitative data to compare the two systems. We put together our data on our own rooftop systems. One of us (Roy) has had only evaporative coolers since he came to Tucson in 1960. The second author (Russell) has a combined evap/air conditioner/heat pump unit.
Russell's combo "piggyback" evap cooler/A/C Heatpump system Photo by Russell Lowes
Although evaporative coolers used to be the standard cooling device for Tucson homes, they are less common today, so a brief description of how they work is in order. You’ve probably noticed that even on a very hot summer day, when you come out of swimming pool you find yourself shivering. This is because it takes energy to evaporate water (or any liquid for that matter). This energy, called the latent heat of evaporation, comes from your body and cools it. The evap cooler uses the same principle. It is a box with a tank of water, pads of aspen fiber, corrugated paper, or composite (MasterCool), a pump to distribute water to wet the pads, and a blower fan to pull air in through the pads and force it into your house. The air is cooled as it flows through the pads by the evaporating water. On a hot, dry summer day, this method of cooling is very effective; however, because less water evaporates when the air is more humid, these coolers are admittedly not as effective during the humid monsoon season.
Also, as you probably know, Tucson’s water contains lots of dissolved minerals. These minerals precipitate out on the cooler pads eventually making them useless. To combat this problem, the more modern coolers have pumps that empty out the water tank every eight or twelve hours of operation, thereby purging the salty water. This is good for cooler pad life but uses more water. Because this latter type of cooler is more common today, we included the use of this pump in our experiment.
Refrigeration or “air conditioning” systems are based on the Joule-Thomson effect: a gas cools when it expands. For example, when you let air out of a tire, it is cool. Here a mechanical pump compresses a gas (usually Freon), which warms it. It then goes through a copper coil where air cools it until it condenses. The resulting liquid then flows through a small opening and expands, causing it to cool, and chill your house.
In the table above, we summarize the energy and water consumption of the two types of coolers. Since our electric bills are usually the first concern, we start there. Our data in column 2 are taken from a number of research papers. There is an amazing spread of water usage, almost a factor of ten, in usage for similar houses, so we have used mid-range values that would apply to Tucson. The $0.113/kWh (kilowatt hours)used in Column 3 for calculating the energy cost comes from dividing Roy’s last July bill of $42.91 by the 380 kWh used.
Next we determined the cost of the water used by the evap cooler. Tucson water has a lower rate ($1.39/ccf) for less than 15 ccf (hundred cubic feet – 748 gallons) and much more ($5.14/ccf) for over 15 ccf. We assumed that folks would use some amount of water that fell into the higher category, so estimated $3/ccf as a reasonable average. This results in the total cost for the two systems in Column 9.
The trickier part was figuring the total water usage, Columns 4, 6 and 9. It may come as a surprise, but air conditioning or heat pump refrigeration is not a water-free process. Water—lots of it— is used in the generation of electricity. You may have noted clouds of steam coming from the cooling towers at power plants. Much of the cooling water is recycled, but even so about 0.5 gallon of water is used to generate one kWh of electrical energy at the Tucson Electric power plants.
Hydropower is even more water consumptive, as a huge amount of water evaporates from the reservoir behind the power dam. Lakes Meade and Powell lose almost a million acre feet per year and although some of this must be budgeted to irrigation, recreation, and flood control, at least 4 gallons/kWh could be attributed to hydropower. Nuclear power is even more water intensive than coal plants. Since we are on the Western Power Grid, it is difficult to say what fraction of our local power comes from which source. Once again, we used an average, and calculated 0.8gal/kWh as a reasonable estimate.
There are also indirect water consumption and environmental factors associated with electricity that must be taken into account. Electricity production uses water in the coal and uranium mining process. Extraction of water at these mines often devastates the local environment around the mines. Another area of environmental impact is that of CO2 production. We address this in the last column of the Table. Here you can see that the evap uses so much less electricity that the CO2 impact is 75% lower than refrigeration.
The Table reflects these assumptions on energy and water consumption. It also compares the total energy and water consumption for a typical home in the Southwestern deserts. Depending on the assumptions, the results are quite variable. For example, if you predict that the energy costs per kilowatt-hour in this area are going to increase, which many energy analysts project, then the evap cooler gains favor. If you plan to buy a super-efficient A/C, then this option gains favor. We did assume a high efficiency A/C, but there are even higher efficiency units becoming available.
There are also other factors not considered in this analysis. For example, some people do better, health-wise, with an evaporative cooler, while others do better with A/C. All air contains bacteria, mold and fungi. These microorganisms can even be beneficial for your health, but some people have problems with the very dry air an A/C produces, while others have problems with the moister air an evap produces. To most people it does not seem to make that much difference, except that in the driest conditions, many people say they like the moisture of the evap for their skin, hair and overall health.
Ultimately, the data seem to suggest that environmentally evaporative is the better choice, but using A/C during the most humid times, and using the evap the rest of the time is still a responsible option. Perhaps the most important lesson is not to use either unnecessarily – turn down the thermostat. That didn’t used to be an option for the old evaportative coolers—they were either on or off—with a high or low option. The modern evaps, however, offer affordable thermostats which pre-wet your pads, turn the system on and off like an A/C thermostat, and allow you to program the hours of startup and shutdown. These thermostats let you further reduce your water and energy consumption.
As for initial cost of system, and of repairs, refrigeration systems are much higher in cost than evaps. Evaps take more maintenance, but the routine maintenance is significantly lower in cost than the infrequent maintenance needs for refrigeration units.
What Can Homeownders Do to Reduce Energy and Water Consumption in Cooling Their Homes and Businesses?
Homeowners have several options if they want to reduce energy and water consumption and still cool their
homes during our hot summer months. If you are willing, like Roy, to weather the humidity, then the lowest cost option is the good ol’ evaporative cooler. If you aren’t quite that tough, you can do what Russell has done and install a “piggyback” unit, or cooler/heat-pump-A/C combo. This allows you to use the evaporative cooler during the drier months of April through June and September through October. It also allows you to use the evap during the drier parts of the days July through August. However, when the humidity increases and evap is no longer cooling efficiently, you can turn it off and the A/C on. If you do get a piggyback,
it is important to get a “barometric damper” which swings freely to open to whichever system you turn on. These allow you to not do anything but shut one system off and the other on. If you have a piggyback, you never want to run both systems at once (see picture of piggyback).
Home insulation is also important, especially with refrigeration. Some of the wide variations in experimental results for cooler energy use are no doubt due to the quality of the insulation of the house. Finally, note that in this article we are discussing retrofitting existing buildings. If you are building new, there are many ways to reduce your heating costs to nearly zero and greatly lower your refrigeration or evap consumption. But, that is another story—or at least another article!
References:
For evaporative cooler water use:
Public Service of New Mexico, PNM, has a study at www.pnm.com/environment/cooling.htm
MM Karpiscak, et. al, Evaporative Cooler Water Use in Phoenix, Journal AWWA, Vol. 90, Issue 4, April 1998, pp. 121-130, at: http://apps.awwa.org/WaterLibrary/showabstract.aspx?an=JAW_0048135 (for a fee)
For general info on how evaps work:
http://ag.arizona.edu/pubs/consumer/az9145.pdf
For water consumption at coal mines:
Black Mesa Project Final EIS, Vol. I Report, DOI FES 08-49, OSM-EIS-33, p. 11, November 2008
http://www.netl.doe.gov/technologies/oil-gas/publications/AP/IssuesforFEandWater.pdf
http://www.newton.dep.anl.gov/askasci/phy00/phy00211.htm
http://www.bhpbilliton.com/bbContentRepository/Reports/
NorwichParkHSECReport2005.pdf
http://www.csrm.uq.edu.au/docs/MCA_SOTA.pdf
Posted by Russell Lowes on May 03, 2010 in End Use of Energy, Energy Efficiency | Permalink | Comments (0) | TrackBack (0)
Digg This | Save to del.icio.us
Re-Think Nuclear
Presented as a one-page primer for the Sustainable Tucson Newsletter
by Roy Emrick and Russell Lowes
An earlier version of this article appeared in the April-June 2010 Sierra Club Rincon Group Newsletter.
Which cooling system is best for energy use? Which is best for water use? Which is best for reducing CO2 output of electrical plants?
For several years, a business columnist at the Arizona Daily Star regularly berated evaporative coolers as water wasters and outmoded technology. He said refrigeration was the way to go in the modern world. Many readers disagreed with him but they gave only qualitative arguments. We decided to see if we could find some quantitative data to compare the two systems. We put together our data on our own rooftop systems. One of us (Roy) has had only evaporative coolers since he came to Tucson in 1960. The second author (Russell) has a combined evap/air conditioner/heat pump unit.
Russell's combo "piggyback" evap cooler/A/C Heatpump system Photo by Russell Lowes
Although evaporative coolers used to be the standard cooling device for Tucson homes, they are less common today, so a brief description of how they work is in order. You’ve probably noticed that even on a very hot summer day, when you come out of swimming pool you find yourself shivering. This is because it takes energy to evaporate water (or any liquid for that matter). This energy, called the latent heat of evaporation, comes from your body and cools it. The evap cooler uses the same principle. It is a box with a tank of water, pads of aspen fiber, corrugated paper, or composite (MasterCool), a pump to distribute water to wet the pads, and a blower fan to pull air in through the pads and force it into your house. The air is cooled as it flows through the pads by the evaporating water. On a hot, dry summer day, this method of cooling is very effective; however, because less water evaporates when the air is more humid, these coolers are admittedly not as effective during the humid monsoon season.
Also, as you probably know, Tucson’s water contains lots of dissolved minerals. These minerals precipitate out on the cooler pads eventually making them useless. To combat this problem, the more modern coolers have pumps that empty out the water tank every eight or twelve hours of operation, thereby purging the salty water. This is good for cooler pad life but uses more water. Because this latter type of cooler is more common today, we included the use of this pump in our experiment.
Refrigeration or “air conditioning” systems are based on the Joule-Thomson effect: a gas cools when it expands. For example, when you let air out of a tire, it is cool. Here a mechanical pump compresses a gas (usually Freon), which warms it. It then goes through a copper coil where air cools it until it condenses. The resulting liquid then flows through a small opening and expands, causing it to cool, and chill your house.
In the table above, we summarize the energy and water consumption of the two types of coolers. Since our electric bills are usually the first concern, we start there. Our data in column 2 are taken from a number of research papers. There is an amazing spread of water usage, almost a factor of ten, in usage for similar houses, so we have used mid-range values that would apply to Tucson. The $0.113/kWh (kilowatt hours)used in Column 3 for calculating the energy cost comes from dividing Roy’s last July bill of $42.91 by the 380 kWh used.
Next we determined the cost of the water used by the evap cooler. Tucson water has a lower rate ($1.39/ccf) for less than 15 ccf (hundred cubic feet – 748 gallons) and much more ($5.14/ccf) for over 15 ccf. We assumed that folks would use some amount of water that fell into the higher category, so estimated $3/ccf as a reasonable average. This results in the total cost for the two systems in Column 9.
The trickier part was figuring the total water usage, Columns 4, 6 and 9. It may come as a surprise, but air conditioning or heat pump refrigeration is not a water-free process. Water—lots of it— is used in the generation of electricity. You may have noted clouds of steam coming from the cooling towers at power plants. Much of the cooling water is recycled, but even so about 0.5 gallon of water is used to generate one kWh of electrical energy at the Tucson Electric power plants.
Hydropower is even more water consumptive, as a huge amount of water evaporates from the reservoir behind the power dam. Lakes Meade and Powell lose almost a million acre feet per year and although some of this must be budgeted to irrigation, recreation, and flood control, at least 4 gallons/kWh could be attributed to hydropower. Nuclear power is even more water intensive than coal plants. Since we are on the Western Power Grid, it is difficult to say what fraction of our local power comes from which source. Once again, we used an average, and calculated 0.8gal/kWh as a reasonable estimate.
There are also indirect water consumption and environmental factors associated with electricity that must be taken into account. Electricity production uses water in the coal and uranium mining process. Extraction of water at these mines often devastates the local environment around the mines. Another area of environmental impact is that of CO2 production. We address this in the last column of the Table. Here you can see that the evap uses so much less electricity that the CO2 impact is 75% lower than refrigeration.
The Table reflects these assumptions on energy and water consumption. It also compares the total energy and water consumption for a typical home in the Southwestern deserts. Depending on the assumptions, the results are quite variable. For example, if you predict that the energy costs per kilowatt-hour in this area are going to increase, which many energy analysts project, then the evap cooler gains favor. If you plan to buy a super-efficient A/C, then this option gains favor. We did assume a high efficiency A/C, but there are even higher efficiency units becoming available.
There are also other factors not considered in this analysis. For example, some people do better, health-wise, with an evaporative cooler, while others do better with A/C. All air contains bacteria, mold and fungi. These microorganisms can even be beneficial for your health, but some people have problems with the very dry air an A/C produces, while others have problems with the moister air an evap produces. To most people it does not seem to make that much difference, except that in the driest conditions, many people say they like the moisture of the evap for their skin, hair and overall health.
Ultimately, the data seem to suggest that environmentally evaporative is the better choice, but using A/C during the most humid times, and using the evap the rest of the time is still a responsible option. Perhaps the most important lesson is not to use either unnecessarily – turn down the thermostat. That didn’t used to be an option for the old evaportative coolers—they were either on or off—with a high or low option. The modern evaps, however, offer affordable thermostats which pre-wet your pads, turn the system on and off like an A/C thermostat, and allow you to program the hours of startup and shutdown. These thermostats let you further reduce your water and energy consumption.
As for initial cost of system, and of repairs, refrigeration systems are much higher in cost than evaps. Evaps take more maintenance, but the routine maintenance is significantly lower in cost than the infrequent maintenance needs for refrigeration units.
What Can Homeownders Do to Reduce Energy and Water Consumption in Cooling Their Homes and Businesses?
Homeowners have several options if they want to reduce energy and water consumption and still cool their
homes during our hot summer months. If you are willing, like Roy, to weather the humidity, then the lowest cost option is the good ol’ evaporative cooler. If you aren’t quite that tough, you can do what Russell has done and install a “piggyback” unit, or cooler/heat-pump-A/C combo. This allows you to use the evaporative cooler during the drier months of April through June and September through October. It also allows you to use the evap during the drier parts of the days July through August. However, when the humidity increases and evap is no longer cooling efficiently, you can turn it off and the A/C on. If you do get a piggyback,
it is important to get a “barometric damper” which swings freely to open to whichever system you turn on. These allow you to not do anything but shut one system off and the other on. If you have a piggyback, you never want to run both systems at once (see picture of piggyback).
Home insulation is also important, especially with refrigeration. Some of the wide variations in experimental results for cooler energy use are no doubt due to the quality of the insulation of the house. Finally, note that in this article we are discussing retrofitting existing buildings. If you are building new, there are many ways to reduce your heating costs to nearly zero and greatly lower your refrigeration or evap consumption. But, that is another story—or at least another article!
References:
For evaporative cooler water use:
Public Service of New Mexico, PNM, has a study at www.pnm.com/environment/cooling.htm
MM Karpiscak, et. al, Evaporative Cooler Water Use in Phoenix, Journal AWWA, Vol. 90, Issue 4, April 1998, pp. 121-130, at: http://apps.awwa.org/WaterLibrary/showabstract.aspx?an=JAW_0048135 (for a fee)
For general info on how evaps work:
http://ag.arizona.edu/pubs/consumer/az9145.pdf
For water consumption at coal mines:
Black Mesa Project Final EIS, Vol. I Report, DOI FES 08-49, OSM-EIS-33, p. 11, November 2008
http://www.netl.doe.gov/technologies/oil-gas/publications/AP/IssuesforFEandWater.pdf
http://www.newton.dep.anl.gov/askasci/phy00/phy00211.htm
http://www.bhpbilliton.com/bbContentRepository/Reports/
NorwichParkHSECReport2005.pdf
http://www.csrm.uq.edu.au/docs/MCA_SOTA.pdf
Posted by Russell Lowes on May 03, 2010 in End Use of Energy, Energy Efficiency | Permalink | Comments (0) | TrackBack (0)
Digg This | Save to del.icio.us
Re-Think Nuclear
Presented as a one-page primer for the Sustainable Tucson Newsletter
Thursday, June 10, 2010
Solar chimney to improve natural cooling
Solar chimney article in wikipedia:
illustrations are missing, it shows an earthtube to cool incoming air, and an exhaust via a pipe with southfacing glass enclosure
This solar chimney draws air through a geothermal heat exchange to provide passive home cooling.[2]
Air conditioning and mechanical ventilation have been for decades the standard method of environmental control in many building types, especially offices, in developed countries. Pollution and reallocating energy supplies have led to a new environmental approach in building design. Innovative technologies along with bioclimatic principles and traditional design strategies are often combined to create new and potentially successful design solutions. The solar chimney is one of these concepts currently explored by scientists as well as designers, mostly through research and experimentation.
A Solar chimney can serve many purposes. Direct gain warms air inside the chimney causing it to rise out the top and drawing air in from the bottom. This drawing of air can be used to ventilate a home or office, to draw air through a geothermal heat exchange, or to ventilate only a specific area such as a composting toilet.
Natural ventilation can be created by providing vents in the upper level of a building to allow warm air to rise by convection and escape to the outside. At the same time cooler air can be drawn in through vents at the lower level. Trees may be planted on that side of the building to provide shade for cooler outside air.
This natural ventilation process can be augmented by a solar chimney. The chimney has to be higher than the roof level, and has to be constructed on the wall facing the direction of the sun. Absorption of heat from the sun can be increased by using a glazed surface on the side facing the sun. Heat absorbing material can be used on the opposing side. The size of the heat-absorbing surface is more important than the diameter of the chimney. A large surface area allows for more effective heat exchange with the air necessary for heating by solar radiation. Heating of the air within the chimney will enhance convection, and hence airflow through the chimney. Openings of the vents in the chimney should face away from the direction of the prevailing wind.
To further maximize the cooling effect, the incoming air may be led through underground ducts before it is allowed to enter the building. The solar chimney can be improved by integrating it with a trombe wall. The added advantage of this design is that the system may be reversed during the cold season, providing solar heating instead.
A variation of the solar chimney concept is the solar attic. In a hot sunny climate the attic space is often blazingly hot in the summer. In a conventional building this presents a problem as it leads to the need for increased air conditioning. By integrating the attic space with a solar chimney, the hot air in the attic can be put to work. It can help the convection in the chimney, improving ventilation.[3]
The use of a solar chimney may benefit natural ventilation and passive cooling strategies of buildings thus help reduce energy use, CO2 emissions and pollution in general. Potential benefits regarding natural ventilation and use of solar chimneys are:
CAD(TAS) Solar Chimney model
Improved ventilation rates on still, hot days
Reduced reliance on wind and wind driven ventilation
Improved control of air flow though a building
Greater choice of air intake (i.e. leeward side of building)
Improved air quality and reduced noise levels in urban areas
Increased night time ventilation rates
Allow ventilation of narrow, small spaces with minimal exposure to external elements
Potential benefits regarding passive cooling may include:
Improved passive cooling during warm season (mostly on still, hot days)
Improved night cooling rates
Enhanced performance of thermal mass (cooling, cool storage)
Improved thermal comfort (improved air flow control, reduced draughts)
[edit]Precedent Study: The Environmental Building
The Building Research Establishment (BRE) office building in Garston, incorporates solar assisted passive ventilation stacks as part of its ventilation strategy.
Designed by architects Feilden Clegg Bradley, the BRE offices aim to reduce energy consumption and CO2 emissions by 30% from current best practice guidelines and sustain comfortable environmental conditions without the use of air conditioning. The passive ventilation stacks, solar shading, and hollow concrete slabs with embedded under floor cooling are key features of this building. Ventilation and heating systems are controlled by the building management system (BMS) while a degree of user override is provided to adjust conditions to occupants' needs.
The building utilizes five vertical shafts as an integral part of the ventilation and cooling strategy. The main components of theses stacks are a south facing glass-block wall, thermal mass walls and stainless steel round exhausts rising a few meters above roof level. The chimneys are connected to the curved hollow concrete floor slabs which are cooled via night ventilation. Pipes embedded in the floor can provide additional cooling utilizing groundwater.
On warm windy days air is drawn in through passages in the curved hollow concrete floor slabs. Stack ventilation naturally rising out through the stainless steel chimneys enhances the air flow through the building. The movement of air across the chimney tops enhances the stack effect. During warm, still days, the building relies mostly on the stack effect while air is taken from the shady north side of the building. Low-energy fans in the tops of the stacks can also be used to improve airflow.
Overnight, control systems enable ventilation paths through the hollow concrete slab removing the heat stored during the day and storing coolth for the following day. The exposed curved ceiling gives more surface area than a flat ceiling would, acting as a cool ‘radiator’, again providing summer cooling. Research based on actual performance measurements of the passive stacks found that they enhanced the cooling ventilation of the space during warm and still days and may also have the potential to assist night-time cooling due to their thermally massive structure.[4]
[edit]Passive down-draft cooltower
Cool tower at Zion National Park's Visitor Center provides cool air.
A technology closely related to the solar chimney is the evaporative down-draft cooltower. In areas with a hot, arid climate this approach may contribute to a sustainable way to provide air conditioning for buildings.
Evaporation of moisture from the pads on top of the Toguna buildings built by the Dogon people of Mali, Africa contribute to the coolness felt by the men who rest underneath. The women's buildings on the outskirts of town are functional as more conventional solar chimneys.
The principle is to allow water to evaporate at the top of a tower, either by using evaporative cooling pads or by spraying water. Evaporation cools the incoming air, causing a downdraft of cool air that will bring down the temperature inside the building.[5] Airflow can be increased by using a solar chimney on the opposite side of the building to help in venting hot air to the outside.[6] This concept has been used for the Visitor Center of Zion National Park. The Visitor Center was designed by the High Performance Buildings Research of the National Renewable Energy Laboratory (NREL).
The principle of the downdraft cooltower has been proposed for solar power generation as well. (See Energy tower for more information.)
you can find the source of this story on wikipedia
illustrations are missing, it shows an earthtube to cool incoming air, and an exhaust via a pipe with southfacing glass enclosure
This solar chimney draws air through a geothermal heat exchange to provide passive home cooling.[2]
Air conditioning and mechanical ventilation have been for decades the standard method of environmental control in many building types, especially offices, in developed countries. Pollution and reallocating energy supplies have led to a new environmental approach in building design. Innovative technologies along with bioclimatic principles and traditional design strategies are often combined to create new and potentially successful design solutions. The solar chimney is one of these concepts currently explored by scientists as well as designers, mostly through research and experimentation.
A Solar chimney can serve many purposes. Direct gain warms air inside the chimney causing it to rise out the top and drawing air in from the bottom. This drawing of air can be used to ventilate a home or office, to draw air through a geothermal heat exchange, or to ventilate only a specific area such as a composting toilet.
Natural ventilation can be created by providing vents in the upper level of a building to allow warm air to rise by convection and escape to the outside. At the same time cooler air can be drawn in through vents at the lower level. Trees may be planted on that side of the building to provide shade for cooler outside air.
This natural ventilation process can be augmented by a solar chimney. The chimney has to be higher than the roof level, and has to be constructed on the wall facing the direction of the sun. Absorption of heat from the sun can be increased by using a glazed surface on the side facing the sun. Heat absorbing material can be used on the opposing side. The size of the heat-absorbing surface is more important than the diameter of the chimney. A large surface area allows for more effective heat exchange with the air necessary for heating by solar radiation. Heating of the air within the chimney will enhance convection, and hence airflow through the chimney. Openings of the vents in the chimney should face away from the direction of the prevailing wind.
To further maximize the cooling effect, the incoming air may be led through underground ducts before it is allowed to enter the building. The solar chimney can be improved by integrating it with a trombe wall. The added advantage of this design is that the system may be reversed during the cold season, providing solar heating instead.
A variation of the solar chimney concept is the solar attic. In a hot sunny climate the attic space is often blazingly hot in the summer. In a conventional building this presents a problem as it leads to the need for increased air conditioning. By integrating the attic space with a solar chimney, the hot air in the attic can be put to work. It can help the convection in the chimney, improving ventilation.[3]
The use of a solar chimney may benefit natural ventilation and passive cooling strategies of buildings thus help reduce energy use, CO2 emissions and pollution in general. Potential benefits regarding natural ventilation and use of solar chimneys are:
CAD(TAS) Solar Chimney model
Improved ventilation rates on still, hot days
Reduced reliance on wind and wind driven ventilation
Improved control of air flow though a building
Greater choice of air intake (i.e. leeward side of building)
Improved air quality and reduced noise levels in urban areas
Increased night time ventilation rates
Allow ventilation of narrow, small spaces with minimal exposure to external elements
Potential benefits regarding passive cooling may include:
Improved passive cooling during warm season (mostly on still, hot days)
Improved night cooling rates
Enhanced performance of thermal mass (cooling, cool storage)
Improved thermal comfort (improved air flow control, reduced draughts)
[edit]Precedent Study: The Environmental Building
The Building Research Establishment (BRE) office building in Garston, incorporates solar assisted passive ventilation stacks as part of its ventilation strategy.
Designed by architects Feilden Clegg Bradley, the BRE offices aim to reduce energy consumption and CO2 emissions by 30% from current best practice guidelines and sustain comfortable environmental conditions without the use of air conditioning. The passive ventilation stacks, solar shading, and hollow concrete slabs with embedded under floor cooling are key features of this building. Ventilation and heating systems are controlled by the building management system (BMS) while a degree of user override is provided to adjust conditions to occupants' needs.
The building utilizes five vertical shafts as an integral part of the ventilation and cooling strategy. The main components of theses stacks are a south facing glass-block wall, thermal mass walls and stainless steel round exhausts rising a few meters above roof level. The chimneys are connected to the curved hollow concrete floor slabs which are cooled via night ventilation. Pipes embedded in the floor can provide additional cooling utilizing groundwater.
On warm windy days air is drawn in through passages in the curved hollow concrete floor slabs. Stack ventilation naturally rising out through the stainless steel chimneys enhances the air flow through the building. The movement of air across the chimney tops enhances the stack effect. During warm, still days, the building relies mostly on the stack effect while air is taken from the shady north side of the building. Low-energy fans in the tops of the stacks can also be used to improve airflow.
Overnight, control systems enable ventilation paths through the hollow concrete slab removing the heat stored during the day and storing coolth for the following day. The exposed curved ceiling gives more surface area than a flat ceiling would, acting as a cool ‘radiator’, again providing summer cooling. Research based on actual performance measurements of the passive stacks found that they enhanced the cooling ventilation of the space during warm and still days and may also have the potential to assist night-time cooling due to their thermally massive structure.[4]
[edit]Passive down-draft cooltower
Cool tower at Zion National Park's Visitor Center provides cool air.
A technology closely related to the solar chimney is the evaporative down-draft cooltower. In areas with a hot, arid climate this approach may contribute to a sustainable way to provide air conditioning for buildings.
Evaporation of moisture from the pads on top of the Toguna buildings built by the Dogon people of Mali, Africa contribute to the coolness felt by the men who rest underneath. The women's buildings on the outskirts of town are functional as more conventional solar chimneys.
The principle is to allow water to evaporate at the top of a tower, either by using evaporative cooling pads or by spraying water. Evaporation cools the incoming air, causing a downdraft of cool air that will bring down the temperature inside the building.[5] Airflow can be increased by using a solar chimney on the opposite side of the building to help in venting hot air to the outside.[6] This concept has been used for the Visitor Center of Zion National Park. The Visitor Center was designed by the High Performance Buildings Research of the National Renewable Energy Laboratory (NREL).
The principle of the downdraft cooltower has been proposed for solar power generation as well. (See Energy tower for more information.)
you can find the source of this story on wikipedia
Iranian report on ancient natural cooling with windtower ventilation
International Conference “Passive and Low Energy Cooling 71
for the Built Environment”, May 2005, Santorini, Greece
Wind tower a natural cooling system in Iranian traditional architecture
P.S. Ghaemmaghami
Iran University of Science and Technology
M. Mahmoudi
Qazwin Islamic Azad University
ABSTRACT
This paper is a synopsis of the results of a research
on form of wind towers. Wind tower is
an architectural element in traditional architecture
of Iran. It can be seen in cities with hot-dry
and hot-humid climates. This analysis demonstrates
wind towers' characteristics with emphasis
on their morphology.
1. INTRODUCTION
Wind tower is a key element in traditional architecture
of Iran. It is seen in settlements in hot,
hot-dry and hot-humid climates. They look like
big chimneys in the sky line of ancient cities of
Iran. They are vertical shafts with vents on top
to lead desired wind to the interior spaces and
provide thermal comfort. This architectural
element shows the compatibility of architectural
design with natural environment. It conserves
energy and functions on the basis of sustainability
principles.
The result of this research shows that traditional
architecture can give ideas to enrich modern
architecture. In traditional architecture of
Iran, climate, local materials and renewable energy
resources have been used. Wind tower
shows the harmony of human built environment
with nature. Traditional building techniques
were normally well adapted to the climate.
However, the modern way of life and imported
western technologies have often replaced the
established traditions in the design of the buildings.
There examples which reflect the way
people organize their environment in various
forms. This paper shows different forms of wind
towers adopted by people in different situations.
Wind towers are described in terms of their
function, structure, details, components, ornaments
and form.
2. HISTORY AND DEFINITION OF WIND
TOWER
Wind is one of the important elements for
studying the climate. One of its important users
is the provision of comfort in hot region. This is
because the wind current creates a difference in
pressure on the exterior walls that has an effect
on the natural ventilation and interior air temperature
of a building. For architects, the wind
is an important factor in the design of a building.
They consider the wind's effect on the
thermal comfort through convection or ventilation
and the penetration of air in interior spaces.
Wind has been given much attention in urban
design, and in particular in cities with hot
weather such as Yazd, it is to be seen clearly
from the images of the city. The effect of the
wind on building forms is recognized through
the use of formal features such as wind towerwhich
provides for the best use of the wind for
the comfort of the occupant. Thus, along the
northern shores of the Persian Gulf and the sea
of Oman, architects have known how to make
effective use of the sea breeze. They have
achieved this by designing the wind towerwith
an opening towards the breeze for the maximum
use of natural ventilation.
Wind towers as their name implies, are
ventilation tools used for obtaining natural
cooling. They have been used for centuries in
countries with hot-arid climates, particularly in
Iran. Wind towers in the central cities of Iran are
known as "badgir" which literary means wind
72 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
catcher. Wind towers not only appear on top of
ordinary houses but also can be seen on top of
water cisterns, mosques. The first historical evidence
of wind towers dates back to the fourth
millennium BC. An example of a simple wind
tower was found in Iran by a Japanese expedition
in a house from the site of Tappeh chackmaq
some eight kilometres north of Shahrood
and the southern slopes of Alborz Mountains in
north eastern Iran. Wind tower comprises a
tower with one end in summer living quarter of
the house and the other end rising from the roof.
Wind tower is divided into several vertical
air passages by internal partitions or shafts. The
shafts on top terminate in to opening on the
sides of the tower head. The flow in side the
wind tower is in two directions, up and down.
Namely, when the wind blows from one direction
the windward opening will be the inlets and
the leeward opening will be the outlet and vice
versa.
3. ORIENTATION AND FUNCTION OF
WIND TOWER
The orientation of wind tower generally means
the positions of the wind tower flank based on
the four main geographical directions. It is determined
in view of function, use of wind power
and the desired direction in which the wind
blows. There are one-directional wind towers in
Meibod, they are facing to the desired wind and
in some cases one directional wind towers act as
air suctioning and the air flow turned its back to
the wind to locate itself in a negative pressure
region to cause warm air in interior to blow out
of the house. The desired wind currents in Yazd
blow from the north-west. The long sides of
wind towers are, therefore, oriented towards the
north-west for maximum usage of the wind to
provide cooling for buildings. In coastal regions
like Bandar Lengeh, buildings have an east-west
orientation. Sea breeze that blows during both
days and nights but the most desirable wind
blows from the east to the west.
Wind towers are therefore, built with a fourdirectional
orientation in order to use all of the
desirable winds from north to south and from
east to west (Figs. 1 and 2). Orientations of
wind towers are different according to the blow
of main desired wind.
A Wind tower is a formal structural element
in Iranian architecture that is used to convey the
wind current to the interior spaces of buildings
in order to provide living comfort for occupants.
In Iranian architecture a wind tower is a combination
of inlet and outlet openings.
The tunnel provides cool air for the building
while serving as a conduit through which the
stuffiness within the building is conveyed
through its shaft. There were wind towers in
Bam which were destroyed by earthquakes; they
weren't directly connected to the living hall.
They were built away from the house. An additional
underground tunnel links the base of the
wind tower to the basement.
In most wind towers, especially the four
sided types, the tower is divided by partitions.
One of the shafts operates all the time to receive
the breeze and the other three shafts work as
outlet air passages. They convey the stuffiness
out of the living space through the “flue”
(chimney) effect. The chimney effect is based
on the principle that the air density increases
with the increase in temperature. The difference
in temperature between the interior and exterior
parts of a building and between different regions
creates different pressures and result in air currents.
The average relative humidity in moisture in
hot and dry regions is low and it is necessary
more humidity there for wind towers are used to
provide living comfort through the use of the air
current and evaporation. Through the wind
tower, the air current first passes over a stone
pond and fountain after entering a building,
thereby bringing humidity to the other spaces in
the building (Fig. 4).
In some places, mats or thorns are placed
within the wind tower, and users pour water on
them in order to increase the humidity and the
coolness of the air flow. The hot weather in
Yazd has the potential effect of causing water to
evaporate easily to develop cooling in the living
spaces and relative humidity in the air, thereby
reducing the heat and dryness.
It is clear that there is usually high humidity
in hot and humid regions because of their being
in vicinity of the sea. In these regions, wind
towers reduce the temperature of the weather
only through the movement of the air they facilitate,
not through increased humidity (Fig. 3).
The level of humidity in this region is already
high and an increase in the humidity would
make living conditions troublesome.
A wind tower in a hot and dry region brings
about comfort by evaporation and air motion but
a wind tower in a hot humid region only moves
the air and conveys the wind into spaces. Different
function and shapes were designed for
different climates (Figs. 5 & 6).
4. CATEGORIES BASED ON FUNCTIONS
The tower head may have vents on one, two or
four sides that face the predominant wind direction
to accommodate wind in suitable directions.
Wind towers are often described by the number
of directions in which they face; such as one
directional (yek-tarafe), two directional (dotarafe),
four directional (char-tarafe), and eight
directional (hash-tarafe).
4.1 The one directional towers (yek- tarafeh)
These towers generally face north-west or north.
They have a sloping roof and one or two vents
only. Otherwise they are commonly described
by the direction in which they face such as
“shomali” or north facing. The survey of wind
towers Roaf (1988) reveals that 3% of the wind
towers were unidirectional in Yazd.
4.2 The two directional towers (do- tarafe)
The tower, in a simple example, is divided in to
two shafts by a vertical brick partition. It has
only two vents. They are often called by direction,
such as north-south towers. Roaf’s survey
indicates that 17% of the towers are in this kind
and all are made on the ordinary houses.
4.3 The four directional towers (chahar- tarafe)
Studies indicate that this is the most popular
wind tower. They have four main vertical shafts
divided by partitions. More than half of the
wind towers in hot and dry region have been of
this kind, as reported. They are so common locally
called Yazdi. All of wind tower in hot humid
region are four sided type.
4.4 The eight directional towers (hasht- tarafe)
According to the Roaf survey (1988) only 2% of
the wind towers of Yazd are in this kind. They
are most common on water cistern. The greatest
Figure 3: Function of tower in hot and humid.
Figure 4: Function of tower in Yazd.
Figure 5: Wind tower in
Abarghoo.
Figure 6: A wind tower in
Yazd.
74 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
wind tower on top of bagh-e dolatabad has an
octagonal plan.
5. CATEGORIES BASED ON FORMS OF
PLANS
Forms of the plan were reported square, rectangular
and octagonal. The square form is the type
used in the four directional wind towers in
Yazd. (Fig. 9) The rectangular forms consist of
one, two, four directional wind towers. Eight
directional wind towers are those with an octagonal
plan. There are enormous range of size
and dimension from 0.40 x 0.80 m to 5 x 5 m. in
plan and the ratio between widths to length is
1:2 of which, is reported.
Partitions are component in wind towers to
divide it in to several shafts. They are built of
mud brick. These partitions form a plane grid of
vents ending to a heavy masonry roof on top of
the tower. Partitions can be classified in to
group: main partition and secondary partitions.
Main partitions continue to the center of the
tower, forming a separate shaft behind the vents.
These partitions often start between 1.5-2.5 m
above the ground floor level. The patterns of the
partitions vary from tower to tower, but the
most commons are in forms of I, H and diagonal.
Secondary partitions remain as wide as the
external wall, about 20-25 cm. A shaft can be
subdivided by a number additional partitions
performing either structural or thermal role.
These can separate the tower, respectively in
two or four shafts. Wind towers could be categorized
according to forms of the plan and patterns
of the partitions (Table 1).
Partitions divide tower to small shafts to increase
air motion according to “Bernoly effect”.
It express that air rate will be increased when air
pass from narrow section. Such an arrangement
provides more surfaces in contact with the flowing
air, so that the air can interact thermally
with the heat stored in the mass of these partitions.
They act climatically in spite of aesthetic
aspects. They work as fins of cooler window or
fins of radiator because mud brick partitions
give back stored heat during night and they are
prepare to absorb heat. Warm wind contact with
mud brick partitions there for its heat transfer to
partitions after that wind with less heat enter to
space.
6. MATERIAL, COLOUR, TEXTURE AND
HEIGHT
The construction materials used for wind towers
depend on climate. The choice of materials is
made to ensure that the wind tower operates effectively
as a passive cooling system. Wind
towers in hot dry are built either of mud brick or
more commonly of baked brick covered with
mud plaster. Mud brick (adobe) passes heat at
long time, because soil has got uncompressed
volume and mud makes from water and soil.
After evaporating, there is made empty pit. It
causes that heat and cool can not arrive in molecules
of soil and mud brick or adobe. Mud plaster
(kah_gel) is mixture of wet earth with fine or
chopped coarse straw. These construction materials
give the wind tower a coarse texture. The
mud plaster covering the facade of a wind tower
has a light colour and there for reflects rays
well.
Wind towers in hot humid are covered with
(gach) plaster and (sarooj) this type of covering
Figure 7: Typical plan of one directional wind towers.
Figure 8: Typical plan of two directional wind towers.
Figure 9: Typical plan of four directional wind towers.
Table 1: Categories of wind towers based on plan.
International Conference “Passive and Low Energy Cooling 75
for the Built Environment”, May 2005, Santorini, Greece
resists moisture. Vapor in the air in this region
sits on the surface with temperature less that
dew point in the environment. If there are high
penetration on walls and surfaces of building,
these drops penetrate in wall for the osmosis
pressure or absorption of materials. It causes
demolition of surfaces. It pushes salts of materials
out of surfaces. The texture of wind towers
is polished with a white colour, which also ensures
that the wind towers do not absorb rays. It
provides more operation in climatic function.
Wind towers trap the desired wind currents
and transport these to interior spaces. To fulfil
this purpose, a wind tower is designed to raise
above roof the building. To enable its serve its
function effectively through the appropriate
utilization of wind currents, the ratio of its
length and its width to height is important.
Height of Wind tower in hot dry and hot humid
is different. Height of wind towers in hot dry
regions is more than hot humid regions. When
the air current is closer to the land surface, it is
warm because of the effect of the sunshine on
the ground. Thus in a hot and dry region, because
of the low temperature and a higher wind
velocity at greater heights, wind towers are built
higher to enable them to trap such currents. The
residential regions in hot humid are built near to
the beach. In the hot and humid regions, the
temperature on the land surface is low and desired
wind and breeze or current is at a lower
level thus wind towers in such areas do not rise
very high at their highest, they rise only one
level above the roof. Since building levels in
central plateau of Iran are also below the ground
level, wind towers are designed to service two
interior spaces in different levels: the basement
space and the reception hall on the ground floor
used in summer. Water surface in Bandar
Lengeh is higher because of the proximity of the
sea. Thus there are no basements in the buildings
in this region. (Fig. 11) Here the transportation
of wind currents at their minimum temperature
is an important design objective for wind
towers.
Survey shows that over 60% of all wind towers
are less than 3 meters high above the roof
parapet level and only 15% rise above 5 meters
high. The higher towers carry the potential for
structural failure, particularly in the head of the
towers, which are weakened by a number of
vents.
Shafts of wind tower in hot dry regions are
longer than shafts in hot and humid regions.
Firstly, because wind towers in hot dry areas
serve to basement floor, and this service is not
needed in hot humid regions. Secondly, the
height of wind from the earth has also a role in
determining the height of wind towers. If desired
wind current is in low levels, wind towers
must receive it in low height. Longer shaft also
increases wind speed during the shaft.
7. STRUCTURE AND ORNAMENT
Body of wind towers soar to receive winds in
the height. Open vents reduce resistance in front
of horizontal forces there for it is clear importance
of structural elements. Mud brick and
timbers are used in the construction of wind
towers (Fig. 13). Since a wind tower rises above
a building, it needs elements to support it. The
wind towers are built of mud brick or more
commonly of baked brick and timbers. The
main structure of a typical wind tower consists
of a tower, several vents and partitions (Fig. 14).
Timber beams are used to support partitions
at various levels and to fasten the structure together
in order to increase the shear resistance
of the tower. The beams are left to project out of
Figure 10: Typical plan of eight directional wind towers.
Figure 11: Section of a house in Bandar Length.
Figure 12: Section of a house in Yazd.
76 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
the structure to provide a ladder and scaffolding
for building the tower and for use during subsequent
maintenance. Main and subordinate partitions
are accounted as an element to support
wind towers more.
There are two kinds of ornamental features in
wind towers, which may be considered notable
among Iranian ornamental architecture. The first
comprises ornamental elements that are added
to the body of the wind tower for aesthetic reasons.
The second consists of ornamental elements
that serve as functional elements. Features
of the wind towers of Yazd that may be
referred to as ornamental elements include the
gach feature placed at the end of the fins in different
shapes in a variety of arches. Each architect
used a different type of arch according to
his personal preference; it can thus be said that
this type of ornamentation was his signature
(Fig. 15). Such features are just for decoration
and serve no other function. For example, brick
rows are sometimes placed on the top and bottom
part of the head of a wind tower, thereby
probably creating a shadow effect on the body
of the wind tower. These differences in ornamental
elements are in now way connected with
the climatic conditions and functional problems
existing in these areas, but are rather a reflection
of cultural features and effects.
8. CONCLUSION
In respect to the growing need for environmentally
responsive architecture from one side, and
from another side, the shortcoming in provision
of electricity in many small cities and villages in
Iran, the use of traditional wind towers are recommended.
In large cities, in low and medium
rise buildings, with new mechanism and some
skills, the natural cooling systems can be renewed.
REFERENCES
Battle McCarthy Consulting Engineers, 2002. Wind towers,
Ahmadinezhad (translator), page 29.
Ghiabaklou, Z., 1996. Passive cooling system, Ph.D. thesis,
New South Wales University, 1996, p. 1, quoted
from Rapaport, 1969.
Ghobadian, V., 1995. Climatic analysis of the traditional
Iranian buildings, Tehran, Tehran University press,
p13.
Kasmaee, M., 1999. Climate and architecture, page 344,
400.
Mahyari, A., 1997. Wind catchers, Ph.D thesis, Sydney
University, page 58-62.
Zomorshidy, H., 1999. Iranian architecture, Tehran Amir
Kabir, page15.
Figure 13: Wind tower in Yazd.
Figure 14: Structures of wind towers.
Figure 15: Examples of vent head details (Roaf, 1988).
for the Built Environment”, May 2005, Santorini, Greece
Wind tower a natural cooling system in Iranian traditional architecture
P.S. Ghaemmaghami
Iran University of Science and Technology
M. Mahmoudi
Qazwin Islamic Azad University
ABSTRACT
This paper is a synopsis of the results of a research
on form of wind towers. Wind tower is
an architectural element in traditional architecture
of Iran. It can be seen in cities with hot-dry
and hot-humid climates. This analysis demonstrates
wind towers' characteristics with emphasis
on their morphology.
1. INTRODUCTION
Wind tower is a key element in traditional architecture
of Iran. It is seen in settlements in hot,
hot-dry and hot-humid climates. They look like
big chimneys in the sky line of ancient cities of
Iran. They are vertical shafts with vents on top
to lead desired wind to the interior spaces and
provide thermal comfort. This architectural
element shows the compatibility of architectural
design with natural environment. It conserves
energy and functions on the basis of sustainability
principles.
The result of this research shows that traditional
architecture can give ideas to enrich modern
architecture. In traditional architecture of
Iran, climate, local materials and renewable energy
resources have been used. Wind tower
shows the harmony of human built environment
with nature. Traditional building techniques
were normally well adapted to the climate.
However, the modern way of life and imported
western technologies have often replaced the
established traditions in the design of the buildings.
There examples which reflect the way
people organize their environment in various
forms. This paper shows different forms of wind
towers adopted by people in different situations.
Wind towers are described in terms of their
function, structure, details, components, ornaments
and form.
2. HISTORY AND DEFINITION OF WIND
TOWER
Wind is one of the important elements for
studying the climate. One of its important users
is the provision of comfort in hot region. This is
because the wind current creates a difference in
pressure on the exterior walls that has an effect
on the natural ventilation and interior air temperature
of a building. For architects, the wind
is an important factor in the design of a building.
They consider the wind's effect on the
thermal comfort through convection or ventilation
and the penetration of air in interior spaces.
Wind has been given much attention in urban
design, and in particular in cities with hot
weather such as Yazd, it is to be seen clearly
from the images of the city. The effect of the
wind on building forms is recognized through
the use of formal features such as wind towerwhich
provides for the best use of the wind for
the comfort of the occupant. Thus, along the
northern shores of the Persian Gulf and the sea
of Oman, architects have known how to make
effective use of the sea breeze. They have
achieved this by designing the wind towerwith
an opening towards the breeze for the maximum
use of natural ventilation.
Wind towers as their name implies, are
ventilation tools used for obtaining natural
cooling. They have been used for centuries in
countries with hot-arid climates, particularly in
Iran. Wind towers in the central cities of Iran are
known as "badgir" which literary means wind
72 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
catcher. Wind towers not only appear on top of
ordinary houses but also can be seen on top of
water cisterns, mosques. The first historical evidence
of wind towers dates back to the fourth
millennium BC. An example of a simple wind
tower was found in Iran by a Japanese expedition
in a house from the site of Tappeh chackmaq
some eight kilometres north of Shahrood
and the southern slopes of Alborz Mountains in
north eastern Iran. Wind tower comprises a
tower with one end in summer living quarter of
the house and the other end rising from the roof.
Wind tower is divided into several vertical
air passages by internal partitions or shafts. The
shafts on top terminate in to opening on the
sides of the tower head. The flow in side the
wind tower is in two directions, up and down.
Namely, when the wind blows from one direction
the windward opening will be the inlets and
the leeward opening will be the outlet and vice
versa.
3. ORIENTATION AND FUNCTION OF
WIND TOWER
The orientation of wind tower generally means
the positions of the wind tower flank based on
the four main geographical directions. It is determined
in view of function, use of wind power
and the desired direction in which the wind
blows. There are one-directional wind towers in
Meibod, they are facing to the desired wind and
in some cases one directional wind towers act as
air suctioning and the air flow turned its back to
the wind to locate itself in a negative pressure
region to cause warm air in interior to blow out
of the house. The desired wind currents in Yazd
blow from the north-west. The long sides of
wind towers are, therefore, oriented towards the
north-west for maximum usage of the wind to
provide cooling for buildings. In coastal regions
like Bandar Lengeh, buildings have an east-west
orientation. Sea breeze that blows during both
days and nights but the most desirable wind
blows from the east to the west.
Wind towers are therefore, built with a fourdirectional
orientation in order to use all of the
desirable winds from north to south and from
east to west (Figs. 1 and 2). Orientations of
wind towers are different according to the blow
of main desired wind.
A Wind tower is a formal structural element
in Iranian architecture that is used to convey the
wind current to the interior spaces of buildings
in order to provide living comfort for occupants.
In Iranian architecture a wind tower is a combination
of inlet and outlet openings.
The tunnel provides cool air for the building
while serving as a conduit through which the
stuffiness within the building is conveyed
through its shaft. There were wind towers in
Bam which were destroyed by earthquakes; they
weren't directly connected to the living hall.
They were built away from the house. An additional
underground tunnel links the base of the
wind tower to the basement.
In most wind towers, especially the four
sided types, the tower is divided by partitions.
One of the shafts operates all the time to receive
the breeze and the other three shafts work as
outlet air passages. They convey the stuffiness
out of the living space through the “flue”
(chimney) effect. The chimney effect is based
on the principle that the air density increases
with the increase in temperature. The difference
in temperature between the interior and exterior
parts of a building and between different regions
creates different pressures and result in air currents.
The average relative humidity in moisture in
hot and dry regions is low and it is necessary
more humidity there for wind towers are used to
provide living comfort through the use of the air
current and evaporation. Through the wind
tower, the air current first passes over a stone
pond and fountain after entering a building,
thereby bringing humidity to the other spaces in
the building (Fig. 4).
In some places, mats or thorns are placed
within the wind tower, and users pour water on
them in order to increase the humidity and the
coolness of the air flow. The hot weather in
Yazd has the potential effect of causing water to
evaporate easily to develop cooling in the living
spaces and relative humidity in the air, thereby
reducing the heat and dryness.
It is clear that there is usually high humidity
in hot and humid regions because of their being
in vicinity of the sea. In these regions, wind
towers reduce the temperature of the weather
only through the movement of the air they facilitate,
not through increased humidity (Fig. 3).
The level of humidity in this region is already
high and an increase in the humidity would
make living conditions troublesome.
A wind tower in a hot and dry region brings
about comfort by evaporation and air motion but
a wind tower in a hot humid region only moves
the air and conveys the wind into spaces. Different
function and shapes were designed for
different climates (Figs. 5 & 6).
4. CATEGORIES BASED ON FUNCTIONS
The tower head may have vents on one, two or
four sides that face the predominant wind direction
to accommodate wind in suitable directions.
Wind towers are often described by the number
of directions in which they face; such as one
directional (yek-tarafe), two directional (dotarafe),
four directional (char-tarafe), and eight
directional (hash-tarafe).
4.1 The one directional towers (yek- tarafeh)
These towers generally face north-west or north.
They have a sloping roof and one or two vents
only. Otherwise they are commonly described
by the direction in which they face such as
“shomali” or north facing. The survey of wind
towers Roaf (1988) reveals that 3% of the wind
towers were unidirectional in Yazd.
4.2 The two directional towers (do- tarafe)
The tower, in a simple example, is divided in to
two shafts by a vertical brick partition. It has
only two vents. They are often called by direction,
such as north-south towers. Roaf’s survey
indicates that 17% of the towers are in this kind
and all are made on the ordinary houses.
4.3 The four directional towers (chahar- tarafe)
Studies indicate that this is the most popular
wind tower. They have four main vertical shafts
divided by partitions. More than half of the
wind towers in hot and dry region have been of
this kind, as reported. They are so common locally
called Yazdi. All of wind tower in hot humid
region are four sided type.
4.4 The eight directional towers (hasht- tarafe)
According to the Roaf survey (1988) only 2% of
the wind towers of Yazd are in this kind. They
are most common on water cistern. The greatest
Figure 3: Function of tower in hot and humid.
Figure 4: Function of tower in Yazd.
Figure 5: Wind tower in
Abarghoo.
Figure 6: A wind tower in
Yazd.
74 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
wind tower on top of bagh-e dolatabad has an
octagonal plan.
5. CATEGORIES BASED ON FORMS OF
PLANS
Forms of the plan were reported square, rectangular
and octagonal. The square form is the type
used in the four directional wind towers in
Yazd. (Fig. 9) The rectangular forms consist of
one, two, four directional wind towers. Eight
directional wind towers are those with an octagonal
plan. There are enormous range of size
and dimension from 0.40 x 0.80 m to 5 x 5 m. in
plan and the ratio between widths to length is
1:2 of which, is reported.
Partitions are component in wind towers to
divide it in to several shafts. They are built of
mud brick. These partitions form a plane grid of
vents ending to a heavy masonry roof on top of
the tower. Partitions can be classified in to
group: main partition and secondary partitions.
Main partitions continue to the center of the
tower, forming a separate shaft behind the vents.
These partitions often start between 1.5-2.5 m
above the ground floor level. The patterns of the
partitions vary from tower to tower, but the
most commons are in forms of I, H and diagonal.
Secondary partitions remain as wide as the
external wall, about 20-25 cm. A shaft can be
subdivided by a number additional partitions
performing either structural or thermal role.
These can separate the tower, respectively in
two or four shafts. Wind towers could be categorized
according to forms of the plan and patterns
of the partitions (Table 1).
Partitions divide tower to small shafts to increase
air motion according to “Bernoly effect”.
It express that air rate will be increased when air
pass from narrow section. Such an arrangement
provides more surfaces in contact with the flowing
air, so that the air can interact thermally
with the heat stored in the mass of these partitions.
They act climatically in spite of aesthetic
aspects. They work as fins of cooler window or
fins of radiator because mud brick partitions
give back stored heat during night and they are
prepare to absorb heat. Warm wind contact with
mud brick partitions there for its heat transfer to
partitions after that wind with less heat enter to
space.
6. MATERIAL, COLOUR, TEXTURE AND
HEIGHT
The construction materials used for wind towers
depend on climate. The choice of materials is
made to ensure that the wind tower operates effectively
as a passive cooling system. Wind
towers in hot dry are built either of mud brick or
more commonly of baked brick covered with
mud plaster. Mud brick (adobe) passes heat at
long time, because soil has got uncompressed
volume and mud makes from water and soil.
After evaporating, there is made empty pit. It
causes that heat and cool can not arrive in molecules
of soil and mud brick or adobe. Mud plaster
(kah_gel) is mixture of wet earth with fine or
chopped coarse straw. These construction materials
give the wind tower a coarse texture. The
mud plaster covering the facade of a wind tower
has a light colour and there for reflects rays
well.
Wind towers in hot humid are covered with
(gach) plaster and (sarooj) this type of covering
Figure 7: Typical plan of one directional wind towers.
Figure 8: Typical plan of two directional wind towers.
Figure 9: Typical plan of four directional wind towers.
Table 1: Categories of wind towers based on plan.
International Conference “Passive and Low Energy Cooling 75
for the Built Environment”, May 2005, Santorini, Greece
resists moisture. Vapor in the air in this region
sits on the surface with temperature less that
dew point in the environment. If there are high
penetration on walls and surfaces of building,
these drops penetrate in wall for the osmosis
pressure or absorption of materials. It causes
demolition of surfaces. It pushes salts of materials
out of surfaces. The texture of wind towers
is polished with a white colour, which also ensures
that the wind towers do not absorb rays. It
provides more operation in climatic function.
Wind towers trap the desired wind currents
and transport these to interior spaces. To fulfil
this purpose, a wind tower is designed to raise
above roof the building. To enable its serve its
function effectively through the appropriate
utilization of wind currents, the ratio of its
length and its width to height is important.
Height of Wind tower in hot dry and hot humid
is different. Height of wind towers in hot dry
regions is more than hot humid regions. When
the air current is closer to the land surface, it is
warm because of the effect of the sunshine on
the ground. Thus in a hot and dry region, because
of the low temperature and a higher wind
velocity at greater heights, wind towers are built
higher to enable them to trap such currents. The
residential regions in hot humid are built near to
the beach. In the hot and humid regions, the
temperature on the land surface is low and desired
wind and breeze or current is at a lower
level thus wind towers in such areas do not rise
very high at their highest, they rise only one
level above the roof. Since building levels in
central plateau of Iran are also below the ground
level, wind towers are designed to service two
interior spaces in different levels: the basement
space and the reception hall on the ground floor
used in summer. Water surface in Bandar
Lengeh is higher because of the proximity of the
sea. Thus there are no basements in the buildings
in this region. (Fig. 11) Here the transportation
of wind currents at their minimum temperature
is an important design objective for wind
towers.
Survey shows that over 60% of all wind towers
are less than 3 meters high above the roof
parapet level and only 15% rise above 5 meters
high. The higher towers carry the potential for
structural failure, particularly in the head of the
towers, which are weakened by a number of
vents.
Shafts of wind tower in hot dry regions are
longer than shafts in hot and humid regions.
Firstly, because wind towers in hot dry areas
serve to basement floor, and this service is not
needed in hot humid regions. Secondly, the
height of wind from the earth has also a role in
determining the height of wind towers. If desired
wind current is in low levels, wind towers
must receive it in low height. Longer shaft also
increases wind speed during the shaft.
7. STRUCTURE AND ORNAMENT
Body of wind towers soar to receive winds in
the height. Open vents reduce resistance in front
of horizontal forces there for it is clear importance
of structural elements. Mud brick and
timbers are used in the construction of wind
towers (Fig. 13). Since a wind tower rises above
a building, it needs elements to support it. The
wind towers are built of mud brick or more
commonly of baked brick and timbers. The
main structure of a typical wind tower consists
of a tower, several vents and partitions (Fig. 14).
Timber beams are used to support partitions
at various levels and to fasten the structure together
in order to increase the shear resistance
of the tower. The beams are left to project out of
Figure 10: Typical plan of eight directional wind towers.
Figure 11: Section of a house in Bandar Length.
Figure 12: Section of a house in Yazd.
76 International Conference “Passive and Low Energy Cooling
for the Built Environment”, May 2005, Santorini, Greece
the structure to provide a ladder and scaffolding
for building the tower and for use during subsequent
maintenance. Main and subordinate partitions
are accounted as an element to support
wind towers more.
There are two kinds of ornamental features in
wind towers, which may be considered notable
among Iranian ornamental architecture. The first
comprises ornamental elements that are added
to the body of the wind tower for aesthetic reasons.
The second consists of ornamental elements
that serve as functional elements. Features
of the wind towers of Yazd that may be
referred to as ornamental elements include the
gach feature placed at the end of the fins in different
shapes in a variety of arches. Each architect
used a different type of arch according to
his personal preference; it can thus be said that
this type of ornamentation was his signature
(Fig. 15). Such features are just for decoration
and serve no other function. For example, brick
rows are sometimes placed on the top and bottom
part of the head of a wind tower, thereby
probably creating a shadow effect on the body
of the wind tower. These differences in ornamental
elements are in now way connected with
the climatic conditions and functional problems
existing in these areas, but are rather a reflection
of cultural features and effects.
8. CONCLUSION
In respect to the growing need for environmentally
responsive architecture from one side, and
from another side, the shortcoming in provision
of electricity in many small cities and villages in
Iran, the use of traditional wind towers are recommended.
In large cities, in low and medium
rise buildings, with new mechanism and some
skills, the natural cooling systems can be renewed.
REFERENCES
Battle McCarthy Consulting Engineers, 2002. Wind towers,
Ahmadinezhad (translator), page 29.
Ghiabaklou, Z., 1996. Passive cooling system, Ph.D. thesis,
New South Wales University, 1996, p. 1, quoted
from Rapaport, 1969.
Ghobadian, V., 1995. Climatic analysis of the traditional
Iranian buildings, Tehran, Tehran University press,
p13.
Kasmaee, M., 1999. Climate and architecture, page 344,
400.
Mahyari, A., 1997. Wind catchers, Ph.D thesis, Sydney
University, page 58-62.
Zomorshidy, H., 1999. Iranian architecture, Tehran Amir
Kabir, page15.
Figure 13: Wind tower in Yazd.
Figure 14: Structures of wind towers.
Figure 15: Examples of vent head details (Roaf, 1988).
Natural ventilation is a centuries old fact of life in Iran!
A windcatcher or malqaf used in traditional persian / arabic architecture.
The windcatcher or malqaf can function by several methods:
One of the most common uses of the malqaf is as an architectural feature to cool the inside of the dwelling, and is often used in combination with courtyards and domes as an overall ventilation / heat management strategy. The malqaf is essentially a tall, capped tower with one face open at the top. This open side faces the prevailing wind, thus 'catching' it, and bringing it down the tower into the heart of the building to maintain air flow, thus cooling the interior of the building. This is the most direct way of drawing air into the building, but importantly it does not necessarily cool the air, but relies on a rate of air flow to provide a cooling effect. This use of the malqaf or windcatcher has been employed in this manner for thousands of years, as detailed by contemporary Egyptian architect Hassan Fathy.
A windcatcher and qanat used for cooling.
The second usage is in combination with a qanat, or underground canal. In this method however, the open side of the tower faces away from the direction of the prevailing wind. (This can be adjusted by having directional ports at the top). By closing all but the one facing away from the incoming wind, air is drawn upwards using the Coandă effect, similar to how opening the one facing towards the wind would pull air down into the shaft.
As there is now a pressure differential on one side of the building, air is drawn down into the passage on the other side. This hot air is brought down into the qanat tunnel, and is cooled by the combination of coming into contact with the cold earth (as it is several meters below ground, the earth stays continuously cool) as well as the cold water running through the qanat. The air is therefore cooled significantly, and is then drawn up through the windcatcher by the same Coandă effect. This therefore brings cool air up through the building, cooling the structure overall, with the additionally benefit that the water vapour from the qanat has an added cooling effect.
Finally, in a windless environment or waterless house, a windcatcher functions as a solar chimney. It creates a pressure gradient which allows less dense hot air to travel upwards and escape out the top. This is also compounded significantly by the day-night cycle mentioned above, trapping cool air below. The temperature in such an environment cannot drop below the nightly low temperature. These last two functions have gained some ground in Western architecture, and there are several commercial products using the name windcatcher.
When coupled with thick adobe that exhibits high heat transmission resistance qualities, the windcatcher is able to chill lower level spaces in mosques and houses (e.g. shabestan) in the middle of the day to frigid temperatures.
So effective has been the windcatcher in Persian architecture that it has been routinely used as a refrigerating device (yakhchal) for ages. Many traditional water reservoirs (ab anbars) are built with windcatchers that are capable of storing water at near freezing temperatures for months in summer. The evaporative cooling effect is strongest in the driest climates, such as on the Iranian plateau, hence the ubiquitous use of these devices in drier areas such as Yazd, Kashan, Nain, and Bam. This is especially visible in ab anbars that use windcatchers.
A small windcatcher (badgir) is called a "shish-khan" in traditional Persian architecture. Shish-khans can still be seen on top of ab anbars in Qazvin, and other northern cities in Iran. These seem to be more designed as a pure ventilating device, as opposed to temperature regulators as are their larger cousins in the central deserts of Iran.
i found this here;
http://en.wikipedia.org/wiki/Windcatcher
The windcatcher or malqaf can function by several methods:
One of the most common uses of the malqaf is as an architectural feature to cool the inside of the dwelling, and is often used in combination with courtyards and domes as an overall ventilation / heat management strategy. The malqaf is essentially a tall, capped tower with one face open at the top. This open side faces the prevailing wind, thus 'catching' it, and bringing it down the tower into the heart of the building to maintain air flow, thus cooling the interior of the building. This is the most direct way of drawing air into the building, but importantly it does not necessarily cool the air, but relies on a rate of air flow to provide a cooling effect. This use of the malqaf or windcatcher has been employed in this manner for thousands of years, as detailed by contemporary Egyptian architect Hassan Fathy.
A windcatcher and qanat used for cooling.
The second usage is in combination with a qanat, or underground canal. In this method however, the open side of the tower faces away from the direction of the prevailing wind. (This can be adjusted by having directional ports at the top). By closing all but the one facing away from the incoming wind, air is drawn upwards using the Coandă effect, similar to how opening the one facing towards the wind would pull air down into the shaft.
As there is now a pressure differential on one side of the building, air is drawn down into the passage on the other side. This hot air is brought down into the qanat tunnel, and is cooled by the combination of coming into contact with the cold earth (as it is several meters below ground, the earth stays continuously cool) as well as the cold water running through the qanat. The air is therefore cooled significantly, and is then drawn up through the windcatcher by the same Coandă effect. This therefore brings cool air up through the building, cooling the structure overall, with the additionally benefit that the water vapour from the qanat has an added cooling effect.
Finally, in a windless environment or waterless house, a windcatcher functions as a solar chimney. It creates a pressure gradient which allows less dense hot air to travel upwards and escape out the top. This is also compounded significantly by the day-night cycle mentioned above, trapping cool air below. The temperature in such an environment cannot drop below the nightly low temperature. These last two functions have gained some ground in Western architecture, and there are several commercial products using the name windcatcher.
When coupled with thick adobe that exhibits high heat transmission resistance qualities, the windcatcher is able to chill lower level spaces in mosques and houses (e.g. shabestan) in the middle of the day to frigid temperatures.
So effective has been the windcatcher in Persian architecture that it has been routinely used as a refrigerating device (yakhchal) for ages. Many traditional water reservoirs (ab anbars) are built with windcatchers that are capable of storing water at near freezing temperatures for months in summer. The evaporative cooling effect is strongest in the driest climates, such as on the Iranian plateau, hence the ubiquitous use of these devices in drier areas such as Yazd, Kashan, Nain, and Bam. This is especially visible in ab anbars that use windcatchers.
A small windcatcher (badgir) is called a "shish-khan" in traditional Persian architecture. Shish-khans can still be seen on top of ab anbars in Qazvin, and other northern cities in Iran. These seem to be more designed as a pure ventilating device, as opposed to temperature regulators as are their larger cousins in the central deserts of Iran.
i found this here;
http://en.wikipedia.org/wiki/Windcatcher
Tuesday, June 8, 2010
more on space pods, and the appeal of home rooftop farming
The Engineering Challenge
Not all roofs can support the hundreds or thousands of pounds of soil and water that a farm needs. That was a major obstacle in Viraj Puri's hunt for a rooftop to cultivate. Puri runs Gotham Greens, a startup that's trying to become New York City's first commercial rooftop farming operation. Finding the appropriate site is the first thing he mentions when listing the challenges. "You have to look at the structural composition of the building and line that up with what your operations are going to be," he says.
Jeremijenko's design sidesteps this issue with legs. The steel stilts splayed out underneath distribute the structure's weight to the building's load-bearing walls. And the farms weigh less because they grow in hydroponic, soil-free trays.
The curved shape of the farms optimizes sun exposure and doesn't require moving parts or grow lights, unlike many greenhouse designs. "The building doesn't have to rotate to follow the sun," says Jeremy Edmiston, principal at SYSTEMarchitects in Manhattan and co-designer of the Urban Space Station, as Jeremijenko calls the design. "There's enough change within the shape of the building to allow for variations."
The streamlined form also fares well on windy rooftops. A series of computer models show that decreasing wind resistance helps keep the farm intact. "The wind wants to blow the thing off the roof," Edmiston says. "So, much of the structure is about holding it down rather than holding it up." To get a streamlined shape, Jeremijenko's design incorporates a skin of Ethylene tetrafluoroethylene (ETFE) stretched over curved ribs of steel. ETFE is a supertough, translucent polymer used to cover stadiums and other big spaces.
Beneath its skin, the greenhouse is linked to the building below, sharing energy, air and water. Imagine homes and offices where garden-fresh breezes waft through the vents. The breezes may do more than improve the scent. Plants cull carbon dioxide and increase the oxygen content in air, and some species can filter other harmful gases, such as formaldehyde, as well.
Besides the air, the farms would also recycle and purify gray water, which is wastewater from sinks, bathtubs and drinking fountains. Jeremijenko is experimenting with retrofits of a building's upper two stories. They would circulate water and air through the farm and back again for people to use.
Vertical Farms, the Other Urban Farm
The Urban Space Station has so far taken a back seat to another urban farming concept: the vertical farm. In this approach, an entire skyscraper is dedicated to agriculture, and it doubles as a water-treatment and waste-recycling facility.
Vertical farms are designed to produce a higher volume of food than rooftop farms, but it's not clear if they would do it cheaply. The premium on the building space, Jeremijenko says, is why vertical farms do not have a viable business model. "It takes a stock market to build a high-rise," she says. In other words, it may be tough to recoup the rent through crop sales, especially since high-rise crops would compete on the shelf with food that grows on cheap, building-free flatland farms.
Jeremijenko has nothing against farming upward—in fact, she has designed a vertical farm herself. But hers is built around a fire escape on an otherwise occupied building (it's still code-compliant, she says).
Dickson Despommier, a Columbia University professor who has championed the vertical farm design, has a different economic argument. He has said that costs could change as priorities change. Populations are rising, and so might both food prices and the cost of farmland. And future generations may prefer to pay more for vertically grown crops if they free up land for wildlife, he says.
Despommier likes most aspects of Jeremijenko's rooftop design. "It's a greenhouse that can be built on the roof; that's a great idea," he says. He points out that they can trap heat in the winter, and, he says, the retrofits required for water recycling would not have to be very sophisticated.
To Jeremijenko, a key difference between her concepts and others is that the farm is integrated: It can make life more pleasant for the people who live below it. The principles of mutualism is rare in modern architecture, but it can tackle unsexy problems like efficiency and cost. In other words, the extraordinary curves in this rooftop design are not paying homage to Frank Gehry. Likes ants living in acacias, they serve a purpose.
via http://www.popularmechanics.com/technology/engineering/infrastructure/future-urban-rooftop-agriculture
Not all roofs can support the hundreds or thousands of pounds of soil and water that a farm needs. That was a major obstacle in Viraj Puri's hunt for a rooftop to cultivate. Puri runs Gotham Greens, a startup that's trying to become New York City's first commercial rooftop farming operation. Finding the appropriate site is the first thing he mentions when listing the challenges. "You have to look at the structural composition of the building and line that up with what your operations are going to be," he says.
Jeremijenko's design sidesteps this issue with legs. The steel stilts splayed out underneath distribute the structure's weight to the building's load-bearing walls. And the farms weigh less because they grow in hydroponic, soil-free trays.
The curved shape of the farms optimizes sun exposure and doesn't require moving parts or grow lights, unlike many greenhouse designs. "The building doesn't have to rotate to follow the sun," says Jeremy Edmiston, principal at SYSTEMarchitects in Manhattan and co-designer of the Urban Space Station, as Jeremijenko calls the design. "There's enough change within the shape of the building to allow for variations."
The streamlined form also fares well on windy rooftops. A series of computer models show that decreasing wind resistance helps keep the farm intact. "The wind wants to blow the thing off the roof," Edmiston says. "So, much of the structure is about holding it down rather than holding it up." To get a streamlined shape, Jeremijenko's design incorporates a skin of Ethylene tetrafluoroethylene (ETFE) stretched over curved ribs of steel. ETFE is a supertough, translucent polymer used to cover stadiums and other big spaces.
Beneath its skin, the greenhouse is linked to the building below, sharing energy, air and water. Imagine homes and offices where garden-fresh breezes waft through the vents. The breezes may do more than improve the scent. Plants cull carbon dioxide and increase the oxygen content in air, and some species can filter other harmful gases, such as formaldehyde, as well.
Besides the air, the farms would also recycle and purify gray water, which is wastewater from sinks, bathtubs and drinking fountains. Jeremijenko is experimenting with retrofits of a building's upper two stories. They would circulate water and air through the farm and back again for people to use.
Vertical Farms, the Other Urban Farm
The Urban Space Station has so far taken a back seat to another urban farming concept: the vertical farm. In this approach, an entire skyscraper is dedicated to agriculture, and it doubles as a water-treatment and waste-recycling facility.
Vertical farms are designed to produce a higher volume of food than rooftop farms, but it's not clear if they would do it cheaply. The premium on the building space, Jeremijenko says, is why vertical farms do not have a viable business model. "It takes a stock market to build a high-rise," she says. In other words, it may be tough to recoup the rent through crop sales, especially since high-rise crops would compete on the shelf with food that grows on cheap, building-free flatland farms.
Jeremijenko has nothing against farming upward—in fact, she has designed a vertical farm herself. But hers is built around a fire escape on an otherwise occupied building (it's still code-compliant, she says).
Dickson Despommier, a Columbia University professor who has championed the vertical farm design, has a different economic argument. He has said that costs could change as priorities change. Populations are rising, and so might both food prices and the cost of farmland. And future generations may prefer to pay more for vertically grown crops if they free up land for wildlife, he says.
Despommier likes most aspects of Jeremijenko's rooftop design. "It's a greenhouse that can be built on the roof; that's a great idea," he says. He points out that they can trap heat in the winter, and, he says, the retrofits required for water recycling would not have to be very sophisticated.
To Jeremijenko, a key difference between her concepts and others is that the farm is integrated: It can make life more pleasant for the people who live below it. The principles of mutualism is rare in modern architecture, but it can tackle unsexy problems like efficiency and cost. In other words, the extraordinary curves in this rooftop design are not paying homage to Frank Gehry. Likes ants living in acacias, they serve a purpose.
via http://www.popularmechanics.com/technology/engineering/infrastructure/future-urban-rooftop-agriculture
urban farming moves up the roof and into space pods!
more talk about growing food under cover on the roof, via NYT:
Urban rooftop farming sounds great and all, until you consider the heaps of soil and water required just to sprout a few heads of lettuce. Not many buildings can handle it -- never mind that skyscrapers make for some of the priciest cropland around.
As Popular Mechanics reports, the artist and scientist Natalie Jeremijenko has an idea: growing farms in greenhouse pods that wouldn't look out of place in planetary orbit. Modeled off space stations, they crouch, insect-like, along roofs, absorbing sun through an plastic skin, recycling air and water from the building below, and incubating plants in hydroponic, soil-free trays. The idea here is that the pods will produce fruits, vegetables, and herbs that would otherwise have to travel hundreds or thousands of miles to reach the dinner table. Jeremijenko and her co-designer Jeremy Edmiston call them Urban Space Stations.
Growing food on buildings isn't a new concept. (See some of our past coverage here,
,http://www.fastcompany.com/blog/ariel-schwartz/sustainability/dragonfly-vertical-farm-concept-rethinks-urban-food-production
and here
http://www.fastcompany.com/magazine/145/fast-cities-urban-farms-new-york.html
.) What's new is the idea of something that can be mass marketed. Cost and space, the twin scourges of the urban existence, have scuttled some of the splashier proposals (namely entire towers dedicated to agriculture) -- a problem Jeremijenko's Urban Space Stations seem to avoid.
Or do they? Economically, they might be a better bet than throwing up a skyscraper in Manhattan that does nothing but grow tomatoes, but are they cheaper than transporting food from out of state? And even if they are, will Urban Space Stations on every building in every metropolis provide enough produce to feed the masses, or will cities still have to turn to rural farms?
Maybe we'll never have precise answers. As we told you last year, even the most outlandish ideas on urban farming pay dividends, because they lean on others to propagate their ideas and learnings. At minimum, they can mutate into something more realistic -- something that brings great ideas out of the stars and back down to earth. It's not so hard to imagine a day when greenhouses stud the backyards of suburban homes and sprout from haute restaurants.
Urban rooftop farming sounds great and all, until you consider the heaps of soil and water required just to sprout a few heads of lettuce. Not many buildings can handle it -- never mind that skyscrapers make for some of the priciest cropland around.
As Popular Mechanics reports, the artist and scientist Natalie Jeremijenko has an idea: growing farms in greenhouse pods that wouldn't look out of place in planetary orbit. Modeled off space stations, they crouch, insect-like, along roofs, absorbing sun through an plastic skin, recycling air and water from the building below, and incubating plants in hydroponic, soil-free trays. The idea here is that the pods will produce fruits, vegetables, and herbs that would otherwise have to travel hundreds or thousands of miles to reach the dinner table. Jeremijenko and her co-designer Jeremy Edmiston call them Urban Space Stations.
Growing food on buildings isn't a new concept. (See some of our past coverage here,
,http://www.fastcompany.com/blog/ariel-schwartz/sustainability/dragonfly-vertical-farm-concept-rethinks-urban-food-production
and here
http://www.fastcompany.com/magazine/145/fast-cities-urban-farms-new-york.html
.) What's new is the idea of something that can be mass marketed. Cost and space, the twin scourges of the urban existence, have scuttled some of the splashier proposals (namely entire towers dedicated to agriculture) -- a problem Jeremijenko's Urban Space Stations seem to avoid.
Or do they? Economically, they might be a better bet than throwing up a skyscraper in Manhattan that does nothing but grow tomatoes, but are they cheaper than transporting food from out of state? And even if they are, will Urban Space Stations on every building in every metropolis provide enough produce to feed the masses, or will cities still have to turn to rural farms?
Maybe we'll never have precise answers. As we told you last year, even the most outlandish ideas on urban farming pay dividends, because they lean on others to propagate their ideas and learnings. At minimum, they can mutate into something more realistic -- something that brings great ideas out of the stars and back down to earth. It's not so hard to imagine a day when greenhouses stud the backyards of suburban homes and sprout from haute restaurants.
PHPP design process in detail
Why is PHPP more accurate for energy efficient buildings than other tools?
PHPP was systematically developed by aligning the utilization rate function with the results of dynamic simulation models [AkkP 13]. For this development only such models were used as had been validated against monitoring results of built passive houses (see fig. 2 in the left column). By this method was the standard for Passive Houses aligned, as well as a standard for buildings with low, but not as low, energy requirement for heating. However, for such buildings the calculation differs slightly from what is given in the European standard EN 832 (ISO 13 790). But the difference is not important for conventional buildings - it is only of influence for buildings with very long time constants. In this class of buildings the ISO 13 790 tourns out to be a little bit too optimistic.
The results from PHPP-calculation have been repeatedly compared with monitoring results of sufficiently large samples of built Passive Houses (see fig. 4 on the left side). These comparisons have always shown a very good correlation.
The PHPP clearly uses boundary conditions that are significantly different from the calculation process used for the German Energy Conservation Ordinance (EnEV). There are important reasons for this - these are discussed in detail in [Feist 2001] and given in short here:
For internal heat sources in residential buildings using efficient appliances, during the heating season values of some 2.1 W/m² (±0.3) are realistic (and not 5 W/m², as frequently assumed). In the PHPP, there is an additional calculation sheet to determine the internal heat sources of given building projects. However, if internal heat gains are assumed to be higher than realistic, this will result in significantly lower heating energy requirements and may even lead to the illusion that a "zero heating house" can be built with a building envelope of mediocre quality. Practice shows this to be untrue.
The average indoor design temperature in German dwellings can be assumed to be 20°C. This is more realistic than the 19 °C given in the German ordinance. The PHPP user can adjust this indoor design temperature to his or her specifications.
To calculate solar gains it is important to take into account realistic shading factors (the environment, balconies, etc.) and also to account for ever-present dirt and dust on surfaces.
Temperature-correction-factors (F-factors) very often were chosen too optimistically for super-insulated buildings. E.g. for insulated ceilings under uninsulated roofing, the F-factor values are not in the range of 0.8, but nearer to 1.0.
The assumption to add an "additional air exchange rate" due to user-opening of windows is given by EnEV to be 0.15 h-1 for exhaust systems; 0.2 for balanced ventilation systems with heat recovery. Those values are assumed far too high. To be correct, one needs to base values on achieved air-tightness; which means based on actual measured n50-value, as in the PHPP and DIN EN 832 / ISO 13 790.
These and additional topics result in differences in calculation results, which are significant for energy efficient buildings.
More than just an Energy Calculator
The PHPP was not primarily developed just to calculate energy requirement verifications. Much more, the PHPP is a design-tool, which can be used by the architect and the engineers to design and optimize their Passive House project. In the PHPP they will find dimensioning tools for the windows (with attention to optimal comfort), for the heat recovery ventilation system (with attention to good indoor air quality and sufficient relative humidity), for the mechanical systems and for summer comfort. Within PHPP, the building and the mechanical equipment are treated as one overall system.
The PHPP-handbook is not restricted to explaining the use of the spreadsheets and the compilation of the input data. Rather, the handbook gives advice on how to optimize the design (e.g. how to build very air-tight, how to avoid thermal bridges, how to minimize construction costs). All this is very useful during the planning phase and for quality control work as well.
This link leads to the main site of the Introduction to Passive Houses.
http://www.passivhaustagung.de/Passive_House_E/passivehouse.html
PHPP was systematically developed by aligning the utilization rate function with the results of dynamic simulation models [AkkP 13]. For this development only such models were used as had been validated against monitoring results of built passive houses (see fig. 2 in the left column). By this method was the standard for Passive Houses aligned, as well as a standard for buildings with low, but not as low, energy requirement for heating. However, for such buildings the calculation differs slightly from what is given in the European standard EN 832 (ISO 13 790). But the difference is not important for conventional buildings - it is only of influence for buildings with very long time constants. In this class of buildings the ISO 13 790 tourns out to be a little bit too optimistic.
The results from PHPP-calculation have been repeatedly compared with monitoring results of sufficiently large samples of built Passive Houses (see fig. 4 on the left side). These comparisons have always shown a very good correlation.
The PHPP clearly uses boundary conditions that are significantly different from the calculation process used for the German Energy Conservation Ordinance (EnEV). There are important reasons for this - these are discussed in detail in [Feist 2001] and given in short here:
For internal heat sources in residential buildings using efficient appliances, during the heating season values of some 2.1 W/m² (±0.3) are realistic (and not 5 W/m², as frequently assumed). In the PHPP, there is an additional calculation sheet to determine the internal heat sources of given building projects. However, if internal heat gains are assumed to be higher than realistic, this will result in significantly lower heating energy requirements and may even lead to the illusion that a "zero heating house" can be built with a building envelope of mediocre quality. Practice shows this to be untrue.
The average indoor design temperature in German dwellings can be assumed to be 20°C. This is more realistic than the 19 °C given in the German ordinance. The PHPP user can adjust this indoor design temperature to his or her specifications.
To calculate solar gains it is important to take into account realistic shading factors (the environment, balconies, etc.) and also to account for ever-present dirt and dust on surfaces.
Temperature-correction-factors (F-factors) very often were chosen too optimistically for super-insulated buildings. E.g. for insulated ceilings under uninsulated roofing, the F-factor values are not in the range of 0.8, but nearer to 1.0.
The assumption to add an "additional air exchange rate" due to user-opening of windows is given by EnEV to be 0.15 h-1 for exhaust systems; 0.2 for balanced ventilation systems with heat recovery. Those values are assumed far too high. To be correct, one needs to base values on achieved air-tightness; which means based on actual measured n50-value, as in the PHPP and DIN EN 832 / ISO 13 790.
These and additional topics result in differences in calculation results, which are significant for energy efficient buildings.
More than just an Energy Calculator
The PHPP was not primarily developed just to calculate energy requirement verifications. Much more, the PHPP is a design-tool, which can be used by the architect and the engineers to design and optimize their Passive House project. In the PHPP they will find dimensioning tools for the windows (with attention to optimal comfort), for the heat recovery ventilation system (with attention to good indoor air quality and sufficient relative humidity), for the mechanical systems and for summer comfort. Within PHPP, the building and the mechanical equipment are treated as one overall system.
The PHPP-handbook is not restricted to explaining the use of the spreadsheets and the compilation of the input data. Rather, the handbook gives advice on how to optimize the design (e.g. how to build very air-tight, how to avoid thermal bridges, how to minimize construction costs). All this is very useful during the planning phase and for quality control work as well.
This link leads to the main site of the Introduction to Passive Houses.
http://www.passivhaustagung.de/Passive_House_E/passivehouse.html
Good description of proper passive design process
Passive house utilizes integrated HVAC, solar system
Jun 2, 2010 1:04 PM, BY CANDACE ROULO Of CONTRACTOR’s staff
MILLCREEK TOWNSHIP, UTAH — The Breezeway House, a passive 2,800-sq.ft. home located here, near Salt Lake City, was completed last December, taking approximately eight months to build. Since energy efficiency is at the heart of passive houses, many energy-efficient technologies and systems were used, including an efficient HVAC system with an energy recovery ventilator and a photovoltaic system.
HVAC systems can be minimized in passive houses because these houses focus on conservation first, employing the strategy of minimizing losses and maximizing gains through super insulation, air tightness, high performance doors and windows, and ventilation with highly-efficient heat recovery, according Katrin Klingenberg, executive director of the Passive House Institute of the U.S.
“The remaining peak loads are around 1-1.5 Watts/sq.ft.,” explained Klingenberg. (1W equals 3.412 Btuh). “A very tiny HVAC system can take care of that. Most of the year the building is fine ‘passively,’ not needing any conditioning.
“Ideally, all space conditioning would be transported through a ventilation system that is needed for indoor air quality anyway,” added Klingenberg. “Passive home balanced ventilation systems provide usually continuous air supply at very low-flow rates, between 50-80 cfm. That requirement limits the heating and cooling that can be transported through the system significantly. The envelope has to be designed to reduce the losses to a point that the peak heating load is very small and doesn't exceed 1 Watt per square foot. For cooling that number is even smaller, around about 0.8 Watt/sq.ft.”
According to Mark Fisher of Fisher Custom Building, based in Salt Lake City, the project’s general contractor, the Breezeway House’s mechanical system was the biggest challenge.
“Our heating load was only 12,000 Btuh, less than a tenth of a code built house,” said Fisher. “A passive house is very specific on the amount of energy the house uses per square meter. You can meet these criteria by adjusting the amount of insulation type, of glass type and of the heating system.”
“Air-tight construction is a crucial component of a passive house system,” said Dave Brach, owner of Brach Design Architecture, based in Salt Lake City, the project’s architecture firm. “The standard is less than 0.6 air changes per hour at 50 pascals of pressure. This is very difficult to achieve, but Fisher Custom Building was instrumental in their dedication to realizing this goal and was able to ultimately get the house down to 0.46 air changes per hour.”
*HVAC, solar system*
**
Heliocentric, an energy and environmental engineering firm based in Salt Lake City, was a key member of the project team during the construction documents phase. The firm designed and installed the HVAC system. Installing the system took approximately three months.
“They [Heliocentric] were the only mechanical contractor in the whole state of Utah that was able to cost effectively design and install the integrated HVAC and renewable energy system — a system that utilizes the mechanical ventilation system to efficiently deliver the small amount of space heat required by a passive house,” said Brach.
When designing the HVAC system, a thorough energy analysis was done by running a 3-D model of the house in a simulated climate for the Salt Lake City area. Heliocentric used EnergyPlus to look at all of the dynamic aspects of the building, including mountain shading, seasonal tree shading, mass thermal storage, natural ventilation and detailed thermal loss analysis, according to Troy Harvey, principal engineer, Heliocentric.
The HVAC system consists of a 2 kW photovoltaic system; solar thermal panels and a 120-gal. solar tank; a water-to-air heat exchanger; an energy recovery ventilation system; radiant floor tubing in the basement and entry of the home to provide a heat boost in these areas if required; motorized dampers; a CO2 sensor and a digital controller, and an indirect-direct evaporative cooler. The solar system should provide approximately 75% of the house’s energy needs per year.
“The solar thermal panels provide heat for domestic hot water and for space heat by heating the liquid in the storage tank,” explained Brach. “The remaining space heat demand is provided by an electric resistance element in the storage tank (and only indirectly by the PV panels). The excess energy created by the PV panels flows back into the grid, causing the meter to run backward and giving the owners a credit on their electric bill.”
Water from the solar tank is circulated via the water-to-air heat exchanger inline with the RecoupAerator 200DX, an energy recovery ventilation system. Only 210 cfm of air is used to heat the house. The ventilation system exchanges the stale air with clean fresh air about once every couple hours. The ventilator captures temperature and moisture from the outgoing air and transfers it to the incoming air stream, and is programmed to regulate heat exchange automatically to prevent frost buildup.
The RecoupAerator has two fans. One fan draws in fresh air while the other pushes the stale air out. The two air streams cross and pass through the patented heat exchanger that transfers both heat and moisture from one air stream to another, so the heat from the air being exhausted is transferred to the air going into the building or home. Also, when outside air enters the RecoupAerator, it is also forced through a MERV 12 filter, capturing incoming contaminants.
To seal off outside air, the motorized dampers close off the home’s ductwork to the outside when the heat recovery ventilation is not operating. To monitor occupant level in the home, CO2 sensors are utilized, which also modulate the heat recovery ventilation rate. If heating demand is greater than ventilation needs, the heat recovery ventilation speeds up to meet that demand. A digital controller manages the HVAC and solar, so occupants in the home can change set points and monitor the system via Web based controls.
For the cooling system, the Oasys, an indirect-direct evaporative cooler was installed. When the cooler meets its set point, a damper opens to the house and two windows upstairs open, so the air has an exit path. The OASys produces up to 3.5-tons of cooling while using less than 600 Watts. The cooler consists of an Indirect Cooling Module, which cools incoming fresh air without adding moisture, and a Direct Cooling Module, which cleanses the air and optimizes humidity. The water used in this process is renewed by a self-purging reservoir, so the waste water from this process can be used to water landscaping.
*PHPP*
Brach Design Architecture oversaw the Passive House Planning Package (PHPP), the main design tool used for the Breezeway House. PHPP, developed by German physicist Wolfgang Feist who built the first passive house in Germany in 1990, is used by architects and designers to evaluate design solutions immediately without the need to wait for dynamic simulations to run.
According to Brach, with a passive house, energy modeling is done at the same time as the architectural design in a fully integrated process, often being the most crucial distinction of passive design.
Brach was trained by Klingenberg in 2008 and became the first fully certified passive house consultant in the country with the completion of this project.
PHPP energy modeling is climate-specific and allows the architect to make critical decisions during schematic design, regarding the form of a house; the size, location and type of windows; and the amount of insulation to put in the floors, walls and roof. It also allowed the architect to assess different shading strategies, which resulted in the use of custom-designed wood shade devices over all the south windows and the shade structure for the outdoor dining area.
By using PHPP, all of the formal components of the house were optimized to achieve passive house levels of energy use and to heat and cool the house using primarily passive strategies.
“It [PHPP] gives the designer the ability to manage the complexity, to optimize each part of the building envelope and mechanical system to each other in regards to energy consumption and with that also in regards to the cost effectiveness of a certain measure,” said Klingenberg.
The house recently received certification from the Passive House Institute of the U.S. (PHIUS), and it is the first building in the Western U.S. to be a certified passive house and one of the first 10 nationwide.
Jun 2, 2010 1:04 PM, BY CANDACE ROULO Of CONTRACTOR’s staff
MILLCREEK TOWNSHIP, UTAH — The Breezeway House, a passive 2,800-sq.ft. home located here, near Salt Lake City, was completed last December, taking approximately eight months to build. Since energy efficiency is at the heart of passive houses, many energy-efficient technologies and systems were used, including an efficient HVAC system with an energy recovery ventilator and a photovoltaic system.
HVAC systems can be minimized in passive houses because these houses focus on conservation first, employing the strategy of minimizing losses and maximizing gains through super insulation, air tightness, high performance doors and windows, and ventilation with highly-efficient heat recovery, according Katrin Klingenberg, executive director of the Passive House Institute of the U.S.
“The remaining peak loads are around 1-1.5 Watts/sq.ft.,” explained Klingenberg. (1W equals 3.412 Btuh). “A very tiny HVAC system can take care of that. Most of the year the building is fine ‘passively,’ not needing any conditioning.
“Ideally, all space conditioning would be transported through a ventilation system that is needed for indoor air quality anyway,” added Klingenberg. “Passive home balanced ventilation systems provide usually continuous air supply at very low-flow rates, between 50-80 cfm. That requirement limits the heating and cooling that can be transported through the system significantly. The envelope has to be designed to reduce the losses to a point that the peak heating load is very small and doesn't exceed 1 Watt per square foot. For cooling that number is even smaller, around about 0.8 Watt/sq.ft.”
According to Mark Fisher of Fisher Custom Building, based in Salt Lake City, the project’s general contractor, the Breezeway House’s mechanical system was the biggest challenge.
“Our heating load was only 12,000 Btuh, less than a tenth of a code built house,” said Fisher. “A passive house is very specific on the amount of energy the house uses per square meter. You can meet these criteria by adjusting the amount of insulation type, of glass type and of the heating system.”
“Air-tight construction is a crucial component of a passive house system,” said Dave Brach, owner of Brach Design Architecture, based in Salt Lake City, the project’s architecture firm. “The standard is less than 0.6 air changes per hour at 50 pascals of pressure. This is very difficult to achieve, but Fisher Custom Building was instrumental in their dedication to realizing this goal and was able to ultimately get the house down to 0.46 air changes per hour.”
*HVAC, solar system*
**
Heliocentric, an energy and environmental engineering firm based in Salt Lake City, was a key member of the project team during the construction documents phase. The firm designed and installed the HVAC system. Installing the system took approximately three months.
“They [Heliocentric] were the only mechanical contractor in the whole state of Utah that was able to cost effectively design and install the integrated HVAC and renewable energy system — a system that utilizes the mechanical ventilation system to efficiently deliver the small amount of space heat required by a passive house,” said Brach.
When designing the HVAC system, a thorough energy analysis was done by running a 3-D model of the house in a simulated climate for the Salt Lake City area. Heliocentric used EnergyPlus to look at all of the dynamic aspects of the building, including mountain shading, seasonal tree shading, mass thermal storage, natural ventilation and detailed thermal loss analysis, according to Troy Harvey, principal engineer, Heliocentric.
The HVAC system consists of a 2 kW photovoltaic system; solar thermal panels and a 120-gal. solar tank; a water-to-air heat exchanger; an energy recovery ventilation system; radiant floor tubing in the basement and entry of the home to provide a heat boost in these areas if required; motorized dampers; a CO2 sensor and a digital controller, and an indirect-direct evaporative cooler. The solar system should provide approximately 75% of the house’s energy needs per year.
“The solar thermal panels provide heat for domestic hot water and for space heat by heating the liquid in the storage tank,” explained Brach. “The remaining space heat demand is provided by an electric resistance element in the storage tank (and only indirectly by the PV panels). The excess energy created by the PV panels flows back into the grid, causing the meter to run backward and giving the owners a credit on their electric bill.”
Water from the solar tank is circulated via the water-to-air heat exchanger inline with the RecoupAerator 200DX, an energy recovery ventilation system. Only 210 cfm of air is used to heat the house. The ventilation system exchanges the stale air with clean fresh air about once every couple hours. The ventilator captures temperature and moisture from the outgoing air and transfers it to the incoming air stream, and is programmed to regulate heat exchange automatically to prevent frost buildup.
The RecoupAerator has two fans. One fan draws in fresh air while the other pushes the stale air out. The two air streams cross and pass through the patented heat exchanger that transfers both heat and moisture from one air stream to another, so the heat from the air being exhausted is transferred to the air going into the building or home. Also, when outside air enters the RecoupAerator, it is also forced through a MERV 12 filter, capturing incoming contaminants.
To seal off outside air, the motorized dampers close off the home’s ductwork to the outside when the heat recovery ventilation is not operating. To monitor occupant level in the home, CO2 sensors are utilized, which also modulate the heat recovery ventilation rate. If heating demand is greater than ventilation needs, the heat recovery ventilation speeds up to meet that demand. A digital controller manages the HVAC and solar, so occupants in the home can change set points and monitor the system via Web based controls.
For the cooling system, the Oasys, an indirect-direct evaporative cooler was installed. When the cooler meets its set point, a damper opens to the house and two windows upstairs open, so the air has an exit path. The OASys produces up to 3.5-tons of cooling while using less than 600 Watts. The cooler consists of an Indirect Cooling Module, which cools incoming fresh air without adding moisture, and a Direct Cooling Module, which cleanses the air and optimizes humidity. The water used in this process is renewed by a self-purging reservoir, so the waste water from this process can be used to water landscaping.
*PHPP*
Brach Design Architecture oversaw the Passive House Planning Package (PHPP), the main design tool used for the Breezeway House. PHPP, developed by German physicist Wolfgang Feist who built the first passive house in Germany in 1990, is used by architects and designers to evaluate design solutions immediately without the need to wait for dynamic simulations to run.
According to Brach, with a passive house, energy modeling is done at the same time as the architectural design in a fully integrated process, often being the most crucial distinction of passive design.
Brach was trained by Klingenberg in 2008 and became the first fully certified passive house consultant in the country with the completion of this project.
PHPP energy modeling is climate-specific and allows the architect to make critical decisions during schematic design, regarding the form of a house; the size, location and type of windows; and the amount of insulation to put in the floors, walls and roof. It also allowed the architect to assess different shading strategies, which resulted in the use of custom-designed wood shade devices over all the south windows and the shade structure for the outdoor dining area.
By using PHPP, all of the formal components of the house were optimized to achieve passive house levels of energy use and to heat and cool the house using primarily passive strategies.
“It [PHPP] gives the designer the ability to manage the complexity, to optimize each part of the building envelope and mechanical system to each other in regards to energy consumption and with that also in regards to the cost effectiveness of a certain measure,” said Klingenberg.
The house recently received certification from the Passive House Institute of the U.S. (PHIUS), and it is the first building in the Western U.S. to be a certified passive house and one of the first 10 nationwide.
Found a good link to a recently completed net zero house in Kamloops, Bc, built and designed by students and faculty at the local School of environmental science, what blew me away was how complicated and no doubt expensive the roof was, with all those brackets for supporting the PV panels, and the openings for wiring, hot water pipes, you name it, and how many potential places for leaks does that create?
This really brings to mind my longstanding idea to do solar renos on bungelows by replacing the existing roof with a transparent polycarbonate roof, just like a sundeck or sunroom, but out of the way with better solar access.
Now inside that upper sunroom one can start seedlings, and behind the racks you can put up PV panels that double as solar thermal collectors, in fact you can start putting up simple hollow metal boxes painted black behind the seedlings, the heat can be extracted with a car radiator and sent to a watertank below the plant bench for cold nights, and when it getss too hot inside, open up the ceiling vents, and as the heat exits by natural convection, that heat can be scavenged too by radiators in that airflow!
This vent stays open all summer to extract heat from under the roof, i am working on a cupola with built in heat scavenger, that can use your existing roof as a solar collector, and the heat gets extracted and piped to a tank in the basement upstream of the existing waterheater.
http://www.greendreamhome.ca/thehome.htm
http://www.greendreamhome.ca/thehome.htm
food production industrial versus organic, urban, small scale and integrated, the way we practise by building a healthy soil and a diverse biological population
Approaches to producing food must be measured partly by their impact on the natural ("life support") systems that we depend on. The currently dominant system of industrial agriculture – which voters and taxpayers have unknowingly promoted and subsidized through ill-considered government food and farm policy choices – impacts the environment in many ways. It uses huge amounts of water, energy, and chemicals, often with little regard to long-term adverse effects. But the environmental costs of agriculture are mounting. Irrigation systems are pumping water from reservoirs faster than they are being recharged. Toxic herbicides and insecticides are accumulating in ground and surface waters. Chemical fertilizers are running off the fields into water systems where they generate damaging blooms of oxygen-depleting microorganisms that disrupt ecosystems and kill fish. Unmanageable and polluting mountains of waste and noxious odor are the hallmarks of industrial-style CAFOs (confined animal feeding operations) for poultry and livestock.
Many of the negative effects of industrial agriculture extend far from fields and farms. Nitrogen compounds from Midwestern farms, for example, travel down the Mississippi to degrade coastal fisheries and create a large "dead zone" in the Gulf of Mexico where aquatic life cannot survive. But other adverse effects are showing up within agricultural production systems themselves -- for example, overuse of herbicides and insecticides has led to rapidly developing resistance among pests that is rendering these chemicals increasingly ineffective.
Economic Costs
Estimating the economic costs of industrial agriculture is an immense and difficult task. A full accounting would weigh the benefits of the somewhat lower prices consumers pay for food and the profits of agri-business giants, including fertilizer and pesticide manufacturers, against the health and societal costs of environmental pollution and degradation, for instance.
Such costs are difficult to assess for a number of reasons. One difficulty is our partial understanding of potential harms. A good example is the potential for endocrine disruption that many pesticides appear to have. Endocrine disrupters are molecules that appear able to mimic the actions of human and animal hormones and disturb important hormone-dependent activities like reproduction. More research is needed to determine the extent of the health and environmental damage done by such compounds and the relative contribution of agriculture and other sectors and activities. And in some instances, such as water pollution and global warming, agriculture is only one of several important contributors.
Among the many environmental costs that need to be considered in a full cost accounting of industrial agriculture are
- the damage to fisheries from oxygen-depleting microorganisms fed by fertilizer runoff
- the cleanup of surface and groundwater polluted with CAFO waste
- the increased health risks borne by agricultural workers, farmers, and rural communities exposed to pesticides and antibiotic resistant bacteria
In addition, there are enormous indirect costs implicit in the high energy requirements of industrial agriculture. This form of agriculture uses fossil fuels at many points: to run huge combines and harvesters, to produce and transport pesticides and fertilizers, and to refrigerate and transport perishable produce cross country and around the world. The use of fossil fuels contributes to ozone pollution and global warming, which could exact a high price on agriculture and the rest of society through increased violent weather events, droughts and floods, and rising oceans.
The full costs of industrial agriculture—including the hidden costs of CAFOs revealed by UCS in the recent report CAFOs Uncovered—call into question the efficiency of this approach to food production.
Agriculture at a Crossroads
It is time to transform agriculture into a sustainable enterprise, one based on systems that can be employed for centuries -- not decades -- without undermining the resources on which agricultural productivity depends. The question is how to do it. The choices are to stick with the current system and adjust around the edges or to fundamentally rethink it. UCS is aiming for the transformation of U.S. agriculture to a system that is both productive and practical over the long-term. Apparent advantages of the current, industrial approach – from high yields per acre, to chemical industry profits, to profitable CAFOs (confined animal feeding operations), to foreign sales by corporate giants like Sara Lee, ConAgra, and Cargill – look very different when considered in the light of the health and other problems the approach creates, as well as the many ways in which consumers actually subsidize the destructive system with their tax dollars.
Sources
R. Drury and L. Tweeten, Trends in Farm Structure into the 21st Century, American Farm Bureau Federation, citing USDA data, 1997. Environmental Protection Agency, Pesticides Industry Sales and Usage: 1992 and 1993 Market Estimates, 8-9, 1994.
A.V. Krebs, The Corporate Reapers, Appendix C, "The Nation's 100 Largest Farms," Essential Books, 1992.
P. Raeburn, The Last Harvest, Simon and Schuster, 37, 1995.
S. Smith, "Farming -- It's Declining in the US," Choices, 8-11, (1992).
A.V. Krebs, The Corporate Reapers, Appendix C, "The Nation's 100 Largest Farms," Essential Books, 1992.
P. Raeburn, The Last Harvest, Simon and Schuster, 37, 1995.
S. Smith, "Farming -- It's Declining in the US," Choices, 8-11, (1992).
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