Comparing the Impact of Energy Model Results on Life Cycle Energy: Focus on High Performance Residential Building

Studies have shown that design-phase energy models, such as those used in Leadership in Energy and Environmental Design (LEED) calculations, have significant error rates, sometimes as much as 50%. These same energy model results are also being utilized in the field of life cycle assessment (LCA), where energy model results are being input for electricity and energy inventory calculations for the entire life cycle of the building. Error rates in energy modeling results have been well documented; however, research is lacking on the effect of this uncertainty within LCA, specifically life cycle energy. This research analyzes energy modeling results in terms of building life cycle energy use and metered energy data with a case study of a Solar Decathlon House. The life cycle assessment results indicated that the impact of energy model results is dependent on the impact category. Life cycle energy, however, appeared to be dependent on the electricity, resulting in an average error rate of about 44%. The sensitivity study analyzed these discrepancies and produced results that reduced the life cycle energy error rate to 26%.