Posted on February 24, 2009 by Martin Holladay, GBA Advisor
Designers of high-performance homes know that there is always more than one way to reduce energy use. It can be daunting to optimize investments in energy-saving measures: even with the help of computer modeling software, designers need to exercise judgment.
Designers face such questions as: Does it make more sense to upgrade the attic insulation from R-40 to R-60, or to upgrade the water heater to a more efficient unit? Does it make more sense to upgrade from double-glazed to triple-glazed windows or to upgrade from a gas furnace to a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures.?