LIFE CYCLE ENERGY AND GREENHOUSE EMISSIONS OF BUILDING CONSTRUCTION ASSEMBLIES: DEVELOPING A DECISION-SUPPORT TOOL FOR BUILDING DESIGNERS Robert H. Crawford Faculty of Architecture, Building and Planning, The University of Melbourne, Parkville, Victoria 3010, Australia Email: rhcr@unimelb.edu.au ABSTRACT Architects and building designers are faced with complex design decisions on a day-to-day basis as to the optimal construction assemblies for use in particular design projects. These decisions are often made on an aesthetic and financial basis. Little consideration is given to the environmental consequences of these decisions. When addressed, the environmental performance of these construction assemblies is often assessed based on their thermal performance alone. Occasionally, the impacts associated with the manufacture of individual materials or components are also considered. Rarely are both issues addressed simultaneously, due primarily to the complex nature of the issues involved. For architects and building designers to make informed design decisions on the optimum solutions from a holistic life cycle environmental perspective, detailed knowledge is needed to enable comparisons to be made between alternative building construction assemblies. This paper presents the findings of an initial pilot study used to develop and demonstrate a model for assessing the life cycle energy requirements and emissions of building assemblies, integrating best-practice embodied energy assessment techniques with building thermal performance simulation modelling. A comprehensive database of the life cycle energy requirements and emissions of a range of standard construction assemblies for use in specific construction elements will be developed to facilitate the building design decision-making process. This will enable building designers to select individual or combinations of construction assemblies for the various building construction elements in order to create buildings that are optimised across the building life cycle. Keywords: Built environment, energy, greenhouse gas emissions, life cycle assessment, building assemblies 1. INTRODUCTION An enormous range of construction assemblies for building wall, floor and roof construction elements currently exists. Architects and building designers require detailed environmental performance data in their efforts towards reducing the environmental impacts associated with the buildings that they are designing. As buildings are responsible for approximately 40% of all global energy consumption and related greenhouse emissions [1], a focus on their life cycle energy or emissions is generally considered to cover the most significant environmental impacts associated with them. Whilst a traditional life cycle assessment will cover a much broader range of