Life cycle assessment of exterior window shadings in residential buildings in different climate zones

Abstract

Use of exterior shading systems is important to increase energy savings in residential sector, mainly in warmer climates exposed to direct sunlight. These types of shades can keep inside temperatures cooler and consequently reduce cooling loads and costs. This study employs Life Cycle Assessment (LCA) to compare the effects of three different shading materials on building energy consumption and their impacts to the environment within five major climate zones defined by American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE). To achieve this objective, A Life Cycle Inventory (LCI) is used to quantify the energy and emissions of the exterior shading systems during the manufacturing process, in-service and end of life. The Building for Environmental and Economic Sustainability (BEES) model and SimaPro 8.0 software (Ecoinvent 3.0 database) were employed to develop the life cycle inventory of the shadings through all life cycle stages. The LCA framework used in this study was based on a life cycle methodology that follows the International Organization for Standardization (ISO) 14040 standard for Life Cycle Assessment and the ASTM standard for Multi-Attribute Decision Analysis. Based on the analysis conducted for wood, aluminum, and polyvinyl chloride (PVC) shadings, it may be concluded that the use of external shadings on residential window panes, in most cases, carries a positive effect on fossil fuel depletion impact, while it increases environmental loads in other environmental impact categories. Among the three aforementioned materials, wood and PVC shadings are the most and the least environmentally-friendly materials, respectively.