SOLAR WATER HEATING RESEARCH

Solar thermal systems - providing heat for domestic hot water and sometimes space heating - are a key element in homes nearing zero energy. CARB has monitored the performance of two solar thermal systems in cold climates for more than a year.

While both systems performed well (providing 60-65% of water heating energy), we found that without careful design, circulators can consume substantial amounts of electricity. In one system, electricity needed for pumps negated 25% of the natural gas cost savings. The study also found that commissioning of the systems is key, especially when using a tankless water heater for auxiliary heat.

Currently, we are evaluating the performance of a new roof-integrated solar thermal system. Developed by Dawn Solar, Inc., this system consists of plastic piping run beneath metal roofs. When the sun is shining, antifreeze circulates through these pipes and transfers heat to storage tanks in the basement. This system reduces fossil fuel use without any visual affect on the home.

For more info, view: Cost, Design and Performance of Solar Hot Water in Cold-Climate

making strides towards affordable, sustainable, "zero-energy" housing. Computer modeling of their latest home, currently under construction, shows 80% less source energy consumed when compared to the Building America "benchmark". This project exemplifies the collaborative support from suppliers, utilities, and the building science community that CARB and the Building America program can bring to a project. Through a partnership with Lawrence Berkeley National Laboratory (LBNL), heat mirror windows will be installed throughout the home. The solar thermal system, provided by American Solar Works, with support from Western Massachusetts Electric Company (WMECO), consists of three evacuated tube collectors and a 115-gallon storage tank. Auxiliary heat will be provided by a sealed-combustion, propane-fired, tankless water heater.