'via Blog this'
The Peveril Solar House is solar heated all year round - using summer time storage of electricity in the grid and thermal energy underground in boreholes - making it better than carbon zero.
There is a 4 kW photovoltaic (PV) array on the east roof, producing a consistent average of 3,330 kWh per annum. During the first two years, the ground source heat pump consumed an estimated 4,800-5,200 kWh/annum. The owner has added 4 sqm of solar thermal panels on the south wall. These deliver approx 3,000 kWh/ annum directly into the deep boreholes, raising the efficiency of the ground source heat pump. The GSHP has its own meter, and is currently operating in a range of 2,750 to 3,250 kWh for all space heating, hot water and pump circulating requirements. On regulated inputs and outputs measured annually, this makes the building better than carbon zero.
The house started as a modern British developer house, so it has no specific passive features other than good insulation. The heating is provided by liquid circulating underfloor heating on both ground and first floor. Heat is delivered by a ground source heat pump working to twin 48m deep boreholes next to the house. Reliable heating and good insulation gives a consistent temperature range of 19º-21ºC internally, whatever the external conditions.
The house is a compact saltbox shape, good for heat loss. But the orientation is unhelpful, with the ridge running North-South and the roof pitches 40º. The primary windows face East-West. The South gable wall has enough space to fit solar thermal panels. Due south of the house is a large hill which reduces thermal and PV gain during three months of the winter solstice. Summer months are good.
The diagram with the Sin wave illustrates the effect of a GSHP on the temperatures in the deep ground. With solar charging, the ground remains a consistent temperature range. Without this, it gets progressively chilled.
The solar thermal installation took 8 months to think out and build, because it was a project that required considerable invention - a choice of panel, a location, the plumbing, the electrical controls, and the anxiety of whether it would work at all. There is no precedent for a solar thermal charging system on a single house. The system uses 4 square meters of swimming pool panels, enclosed in a polycarbonate solarium of 3 cubic metres. The polycarbonate is triple skin insulated. The solariums take advantage of direct sunshine or of the greenhouse effect on cloudy bright days, thus warming the fluid circulating into the ground loop.
The whole project is described in a website/blog called http://chargingtheearth.blogspot.com/
Visitors are welcome, but should make a prior request by email.