Integrated energy and environmental life cycle assessment of office building envelopes

Building envelope, which separates the interior conditioned from exterior unconditioned environment of a building, is the key determinant of thermal and energy performance in many types of buildings. The building envelope is primarily designed to restrict the heat transfer between inside and outside in order to regulate the thermal characteristics of the interior environment and reduce the heating, cooling and electric lighting demand of buildings. The key goal of the present research is to examine the life cycle energy and environmental performance of building envelopes by conducting a comparative energy and environmental life cycle assessment (LCA) study of several envelope scenarios in which some of the major components of building envelope vary. The varying components include insulation material, window-to-wall ratio (WWR), window frame material, and double-glazing cavity gas. The generic building model used in this study was a hypothetical 2-story office building with 335 m ² (3600 ft²) of floor area. The results revealed scenarios with low to medium WWR and fiberglass window frame result in the lowest impacts. The research also shows that use phase of the life cycle is the primary contributor to most environmental impact categories for all scenarios.