ARTICLE: Right-sizing Water Distribution Pipes and Water Heating Systems

This article summarizes a CARD project to study water supply pipe and end use sizing to investigate opportunities to reduce energy use and construction costs in new residential buildings. The project team evaluated the peak water demand calculator (WDC) from the 2024 Uniform Plumbing Code (UPC) Appendix M to compare its performance against the traditional water supply pipe-sizing method in four Minnesota multifamily buildings.

Results from the study showed that the WDC method designed for water demand flow rates much closer to actual usage than the traditional method, which overestimated flow rates by up to 25 times. Based on their findings, the team made several recommendations to ensure the successful implementation of the UPC Appendix M, including launching education and outreach for plumbing and building industry professionals, considering incentive programs to bundle WDC demand sizing measure with heat pump water heater installations, and more.

This project is led by 2050 Partners and supported by a grant from the Minnesota Department of Commerce, Division of Energy Resources, through the Conservation Applied Research and Development (CARD) program.