In existing homes, we are likely to have to get most of our carbon reductions by decarbonizing heating systems as opposed to improving building envelopes.

Non-envelope improvements — electrification, burner efficiency, behavior changes — account for the majority of the observed decline in residential fossil energy use intensity before 2009.

An approximately 8 degree reduction in thermostat settings since the 1970s saves approximately 26% off our home space heating consumption.

Fossil appliance efficiency improvements were an important contributor to the 58% drop in residential fossil energy use intensity in Massachusetts from 1972 through 2009.

The modest shift to electric heating and other appliances from 1972 to 2009 accounted for only approximately 1 kbtu/sqft/year reduction in fossil EUI in 2009 — a relatively small contribution to the overall drop in fossil EUI of 78 kbtu/sqft/year from 1972 to 2009.