CFL Savings Affected by Heating and Cooling Impacts

The dramatic energy savings reported for compact fluorescent lamps (CFLs) over conventional incandescents typically do not take into account the impact on space heating and cooling energy.

A study at the Canadian Centre for Housing Technology in Ottawa used two identical houses, both on fixed lighting schedules for their 31 lamps, but one outfitted with CFLs and the other with incandescents. During the heating season the CFL-equipped house showed an 8%–33% higher heating load; during the cooling season the CFL house used an average of 3.1 kWh less electricity per day for air-conditioning. The study used the HOT2000 residential energy simulation program to extend its conclusions to 33 locations in a wide range of climates.

Nowhere did increased heating costs negate the savings from CFL use. But the simulation found that in predominantly heating climates, increased need for space heating can reduce CFL savings by 40%, while in cooling climates savings can be increased by 30%.