Conservation versus energy supply: An economic and environmental comparison of alternatives for space conditioning of new residences

This work compares energy-supply and energy-conservation alternatives for a single end-use of energy: heating and cooling of new houses. It uses computer simulations to determine the energy-saving value of individual construction changes for a single-family house in seven U.S. climates. It then determines the construction costs of the changes, and the resulting costs of saved energy. These costs, and a variety of environmental effects, are compared with the costs and effects of supplying energy with coal, oil, and natural gas.; Wall and ceiling insulation and multiple-pane glass save heating and cooling energy in all climates; "passive solar" designs generally do not. Non-south-facing windows are big energy losers, while south-facing windows of double-pane glass approximately break even in most climates. Only with nighttime insulation can south-facing windows save much energy. Thermal mass saves very little energy.; Assuming that the real price of energy will rise at the discount rate and that the economic lifetime of conservation measures is 30 years, the cost of saving energy is less than the cost of buying energy in virtually all continental U.S. climates for insulation of walls to R19 and ceilings to R30. Double-pane glass is economical in all climates. In cold climates, triple-pane glass and R38 ceiling insulation is economical. In severe climates many of the conservation measures save so much energy that they pay for themselves on a cash-flow basis.; Conservation measures are even better environmentally than economically. Conservation measures not only produce less air pollution during materials manufacture, they also avoid entirely energy-supply systems' much larger emissions from operation. Supplying energy also produces water pollutants, solid wastes, toxins, land-use problems, environmental conflicts, and increased dependence on energy imports. Saving energy entails none of these. Instead, it brings such ancillary benefits as increased comfort, better soundproofing, and resilience during extreme weather and power failures. Further, these benefits, together with any liabilities conservation measures possess, accrue to the occupants and workers employed in their construction, while supplying energy imposes its burdens on non-beneficiaries. All these considerations support policies that encourage conservation measures, even beyond the economic margin.