Assessing regional differences in lighting heat replacement effects in residential buildings across the United States

• Replacing inefficient lamps affects heating and cooling demands of a building.
• We assess regional differences of this effect at 105 cities in the U.S.
• The effect size depends on regional factors such as climate and fuel mix.
• The effect can undermine up to 40% of originally intended primary energy savings.
• The overall effect is at most 1% of total energy consumption by a house.

Lighting accounts for 19% of total U.S. electricity consumption and 6% of carbon dioxide equivalent (CO2e) emissions. Existing technologies, such as compact fluorescent lamps and light emitting diodes, can substitute low-efficiency technologies such as incandescent lamps, while saving energy and reducing energy bills to consumers. For that reason, lighting efficiency goals have been emphasized in U.S. energy efficiency policies. However, incandescent bulbs release up to 95% of input energy as heat, impacting the overall building energy consumption: replacing them increases demands for heating service that needs to be provided by the heating systems and decreases demands for cooling service that needs to be provided by the cooling systems. This work investigates the net energy consumption, CO2e emissions, and savings in energy bills for single-family detached houses across the U.S. as one adopts more efficient lighting systems. In some regions, these heating and cooling effects from more efficient lighting can undermine up to 40% of originally intended primary energy savings, erode anticipated carbon savings completely, or lead to 30% less household monetary savings than intended. The size of the effect depends on regional factors such as climate, technologies used for heating and cooling, electricity fuel mix, emissions factors, and electricity prices. However, we also find that for moderate lighting efficiency interventions, the overall effect is small in magnitude, corresponding at most to 1% of either total emissions or of energy consumption by a house.