Household heating and cooling energy use in the northeast USA: comparing the effects of climate change with those of purposive behaviors

For most residents in northern temperate zones, the most direct economic impact of global climate change is likely to be changes in home heating and cooling (HC) expenses, estimates of which should be of widespread interest. These residents are increasingly likely to make HC deci- sions (e.g. switches to electric heat, thermostat settings, conservation investments and behavioral change) in a wider context. The question turns from 'will projected climate change reduce my HC bills?' to 'how will projected climate change, with and without these various actions, affect my HC bills, my total energy use and my greenhouse gas emissions?' We modeled these 3 variables (HC expense, energy use and GHG emissions) on average households in 13 states in the northeastern United States under projected climate change alone, and under projected climate change with 3 modeled choices: increasing use of air-conditioners (AC); switching from petroleum-derived fuels to electric heating; and investing in insulation and efficiency upgrades. High climate change was pro- jected to reduce annual HC expenses for average households in each state, the effect increasing through the century. These savings varied with ratios of heating degree-day to cooling degree-day changes, and with ratios of petroleum-derivative heating to electric heating households; both ratios varied along a north-south gradient in this region. Increasing AC use increased total energy use and CO2 emissions more than it did expenses. Fuel-switching increased the first 2 more than it reduced the third. Upgrades provided the greatest savings in all 3 variables under low and high climate change. Effective energy policies and effective communication with energy users both require require explicit investigation of HC intensities at the household level, and modeling of conservation behaviors as well as purchased upgrades.