Life-cycle assessment of LEED vs. conventionally constructed residential units

Abstract

The United States Air Force constructed 1,028 LEED for Homes Silver and/or ENERGY STAR certified energy efficient homes in Biloxi, Mississippi. To analyze and compare these energy efficient homes to conventionally constructed homes, this study employed a hybrid LCA and energy simulation. Compared to conventional homes, the energy efficient homes were found to have a 16% less environmental impact, consume 15% less energy, and save 2% in total life cycle cost while incurring a 1% cost increase in project construction. The simple payback period for the 1% construction cost increase was 10 years. The most effective energy efficient measure implemented was increasing the air conditioning seasonal energy efficiency rating (SEER) while the least effective measure was increasing the roof insulation R-value. Lastly, energy simulation results from the schematic design phase were statistically different compared to energy simulation results from the detailed design phase. By comparing the results of energy simulations from both design phases, simulation results from the detailed design phase were more accurate. The recommendation for a design team is to delay performing energy simulation until determining which energy efficiency measures to implement as permitted by the project timeline, cost, and other factors influencing the project.