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Solar Hot Water System drastically reduces use of Natural Gas

October 22nd, 2008

While building a new home in northern Italy, a young family did not think twice about using energy efficient features to reduce their dependence on the expensive energy sources.

First of all, the house has a well insulated building envelope, where external walls (45cm thick) and the roof have multiple layers of insulation (placed on the cold/outer side of the wall). The windows also are multipane with energy emmisivity characteristics to reduce energy loss trough the glass and frames.

The most interesting feature of their energy efficient home is the Solar Hot Water system. It consists of two small collector panels, (total area of 2.8 m2, or ~9 ft2), set of connecting pipes, hot water tank (300 lit, ~80 gal) along with solar pumping station and expansion tanks. The system is filled with a refrigerant (antifreeze, antiboil) that exchanges the energy with the water in the tank through a built in coil heat-exchanger.
Solar panels are built in to the roof structure, set flush with the tiles providing minimal interference with any other structure on the roof while receiving good accessibility for service. The SHW system is manufactured by Sonnenkraft, a company from neighboring Austria. Total installed cost in 2005 was €5000 (about $6000 at 2005 exchange rate). The system supplies ample hot water for ALL hot water needs during months of May to October when the family switches off their gas burner completely.

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Entry Filed under: Energy Efficient Heating & Cooling