Using marginal emission factors to improve estimates of emission benefits from appliance efficiency upgrades

Abstract

This work uses marginal emission factors to analyze avoided emissions from household energy efficiency improvements in air conditioning and lighting. This approach considers CO 2 , SO 2 , and NO x emissions avoided from the marginal power plant that would have been dispatched to meet demand, and compares the results to the more commonly used average emission factor approach as well as time-averaged marginal emission factors. Results from the lighting analysis indicate that, depending on location, a household can save $50–$430/year on electricity bills and avoid between 600 and 1300 kg of CO 2 /year by switching from a mix of compact fluorescent and incandescent to LED bulbs. For air conditioning, efficiency upgrades save between zero and $600/year in electricity cost and avoid zero to 300 kg of CO 2 /year. When comparing the marginal approach to the traditional average emission method, the average approach can underestimate CO 2 , SO 2 , and NO x emissions by 50% or overestimate by 100%, illustrating the relevance of the marginal emission approach to the study of efficiency-induced emission reductions.