Environmental and economic life cycle assessment of PEX and copper plumbing systems: A case study

Cross-linked polyethylene (PEX) pipe has become viable alternative to traditional copper pipe to be used as residential water plumbing systems. PEX pipe is relatively cheaper and more versatile compared to a copper pipe. This study employs Life Cycle Assessment (LCA) to compare the economic and environmental performances of PEX and copper pipes over the life cycle of a student housing project in Lancaster, Pennsylvania. To achieve this objective, the costs in different life stages were extracted from three different sources in the market (RS Means book and two material suppliers; “Residential Copper Plumbing Products Limited Warranty” and “Uponor PEX”) and a Life Cycle Inventory (LCI) was used to quantify the energy and emissions of the two plumbing 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 piping system through all life cycle stages. BEES model adopts Tool for Reduction and Assessment of Chemical and other environmental Impacts (TRACI) life cycle impact assessment methods developed by the U.S. EPA Office of Research and Development. The LCA framework used in this study was based on a life cycle methodology that follows the International Organization for Standardization (ISO) 14,040 standard for LCA. The results of the analysis indicate that use of PEX piping instead of the traditional copper piping systems in residential buildings, would considerably reduce the total cost of the building up to 63% over its life cycle. Moreover, it can significantly reduce the carbon dioxide (CO₂) emissions (approximately 42%) and lessen the negative effect of environmental impacts to land, water and air.