High Performing Buildings - Spring 2009 - (Page 62) Lessons Learned and future work • The air leakage goal set at the project out• Better windows would be another place set was met, and the heating performance to look for improvement. Triple-glazed winvery closely followed the predicted perfordows would have a significant impact. The mance. However, it is clear that with more double patio glass doors used at the back attention to detail, a more airtight enclosure were particularly poor performers, both in could be achieved. Testing showed that the terms of air leakage and thermal qualities. major air leakage areas were around the And the thermal scan showed that keeping range hood fan exhaust and at original extethe existing wood front door was probably rior wall electrical outlets that could not be not a good decision. sealed at the baseboards. Other major air • A heat recovery ventilator (HRV) installed leakage occurred where interior plaster and inline with the return of the second floor baseboard were removed but not replaced, air handler would likely have a significant specifically behind the new kitchen cabieffect on the heating savings as well, so nets. One of the replacement windows was plans for the fan cycling will be coupled particularly leaky, and plans have been with an HRV installation. made to replace it. • The installation of photovoltaic units could offset the electrical loads, and based on actual electrical use, it is clear that a 3.5 kWp system would reduce the electric load to next to nothing. By late April, a 4.9 kWp system will be installed on a south-facing boat shed in the backyard in anticipation of the plug-in cars of the future. • Work that involves new construction technologies cannot be done without the help of experienced and patient contractors. • Finally, this project was informed by the work being done under contract with the Department of Energy’s Building America Program, which aims to lead the country to zero-energy homes by the year 2020. In April 2009, 28 photovoltaic panels with micro-inverters will be installed on the shed. They will further offset the house’s total source energy use to approximately 40 million Btu. 62 HigH Performing Buildings spring 2009
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