The effect of building retrofit measures on CO₂ emission reduction – A case study with U.S. medium office buildings

Building retrofits have great potential to reduce CO₂ emissions since buildings are responsible for 36% of emissions in the United States. Several existing studies have examined the effect of building retrofit measures on CO₂ emission reduction. However, these studies oversimplified emission factors of electricity by adopting constant annual emission factors. This study uses hourly emission factors of electricity to analyze the effect of building retrofit measures on emission reduction using U.S. medium office buildings as an example. We analyzed the CO₂ emission reduction effects of eight building retrofit measures that related to envelope and mechanical systems in five locations: Tampa, San Diego, Denver, Great Falls, and International Falls. The main findings are: (1) estimating CO₂ emission reduction with constant emission factors overestimates the emission reduction for most measures in San Diego, while it underestimates the emission reduction for most measures in Denver and International Falls; (2) The same retrofit measure may have different effects on CO₂ emission reduction depending on the climate. For instance, improving lighting efficiency and improving equipment efficiency have less impact in emission reduction in cold climates than hot climates; and (3) The most energy efficient measure may not be the most efficient emission measure. For example, in Great Falls, the most energy efficient measure is improving equipment efficiency, but the most efficient emission measure is improving heating efficiency.