Analyzing Building Energy Models from a Life Cycle Perspective

摘要

Life cycle assessment (LCA) is a quantitative tool used to evaluate the environmental impacts of products or processes. With respect to buildings, LCA can be used to evaluate the environmental impacts of an entire building life cycle. Currently, LCA in the building area is used in a limited capacity, and primarily for selecting building products. In order to determine the causality for the lack of whole building LCAs, focus groups with members of the architecture, engineering, construction (AEC) communities were held. This research ascertains first the current level of knowledge of LCA in the AEC community and then discusses the benefits and barriers to the practice of LCA. From the focus group results, the most important benefit to LCA was: Provides information about environmental impacts. The results did not identify a prominent barrier; however, building-related metrics were ascertained to be one of the more crucial barriers.udOne limitation of LCA is the uncertainty associated with its results, which in this research is exemplified in the correlation between LCA and building energy models. In past research, results from energy models have been utilized to calculate life cycle operating energy of buildings in order to predict environmental impacts through LCA. Due to assumptions and variations between input data, past research has indicated substantial error rates in energy model results. In order to employ a life cycle perspective, the relationship between total life cycle energy use and energy modeling results has been studied. The main question guiding this research was: what is the acceptable error rate between predicted and actual life cycle energy use? Three different energy modeling programs with varying levels of detail were utilized to generate energy data for a case study, low energy home. EnergyPlus, Energy-10, and GBS all indicated error rates of 41%, 70%, and 20% respectively regarding life cycle primary energy consumption.ud