Comparative sustainability evaluation of two engineered wood-based construction materials: Life cycle analysis of CLT versus GLT

The environmental emissions and energy from construction activity and building materials contributes significantly to a building's sustainability. Previous research dealing with wood or engineering wood's energy requirements compared to reinforced concrete and steel structures has shown that embodied energy and embodied carbon is significantly lower in wood-based construction. This study has assessed the environmental impact and costs of glued laminated timber (GLT) or cross-laminated timber (CLT). Hardwood and softwood variants of both GLT and CLT were considered. We compared the life cycle costs (LCC) of these alternatives to discover the lowest cost. The comparative results indicated that GLT has higher emissions in Global warming potential (GWP), Terrestrial Ecotoxicity (TE), Land Use (LUP), and Ozone layer depletion (OLD), while CLT has higher impact in Human-Toxicity Potential (HTP), Fossil Depletion Potential (FDP). The results indicated that using CLT significantly reduces embodied energy by 40%. However, a comparison of costs showed that CLT is 7% more expensive than GLT. Establishing which material performs best based on environmental and economic criteria thus required further analysis. Thus, the multi-criteria decision making (MCDM) method was applied. This showed that CLT manufactured with softwood is the most sustainable choice among the alternatives considered. This study's findings are important for aggregate level decision making of different wood materials for residential buildings.