Integrated LCA-LEED sustainability assessment model for structure and envelope systems of school buildings

In Canada and USA, nearly 80 million students and teachers spend at least eight hours daily in schools that could be unhealthy and restrict their ability to learn. Despite this fact there is lack of adopting sustainability principles in school buildings. Even though life cycle assessment (LCA) and LEED^® could serve as sustainability measurement tools, studies show that the integration of sustainability principles to LCA has not become standard practice yet. This paper presents an integrated LCA-LEED model that incorporates LCA into LEED and assigns corresponding LEED scores to achieve a high level of sustainability assessment, for the structure and envelope systems of Canadian school buildings. In this model, the selection of the most sustainable structure and envelope type for school buildings is done through the evaluation of three categories of the LEED rating system: energy and atmosphere, materials and resources, and LCA (incorporated under the innovation and design process category of LEED). Various options are tested by considering structures such as concrete, steel, masonry and wood, and envelope types such as precast panels, steel stud, wood stud and cavity wall. Energy simulation is performed by eQUEST^® (version 3.64) program and LCA is performed by ATHENA^® impact estimator. The results show that concrete and masonry buildings have high energy consumption and global warming potential during certain life cycle stages such as manufacturing, construction and demolition. However they have lower annual energy consumption and environmental impact during the operating stage, as well as for the overall life span. Concrete building with minimum insulation has obtained the highest total LEED score (19) followed by masonry (17), while steel and steel-masonry buildings have the least score (14).