Life Cycle Assessment of LEED vs. Conventionally Built Residential Units

The United States Air Force constructed 1,028 energy efficient homes at Biloxi, MS. To analyze and compare these energy efficient homes to conventionally built homes, this study employed a hybrid LCA and energy simulation. These energy efficient homes 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 compared to conventional homes. The simple payback period of the project to payback this initial 1% construction cost increase is 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 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 hold off on performing energy simulation until determining which energy efficiency measures to implement as permitted by the project timeline, cost, and other factors influencing the project.