When we talk about sustainability in housing, energy efficiency usually steals the spotlight. But as Christoph Lohr, Vice President of Technical Services and Research at IAPMO, reminded me in a recent conversation, the sleeping giant in the decarbonization story is water.
“Plumbing tends to be a bit overlooked,” Christoph explains. “We only think about it when something breaks—but that invisibility has a cost.”
That “cost,” as he pointed out, comes in the form of outdated water system designs still using methodologies from the 1940s, with oversized pipes, wasted energy, and unnecessary expenses baked into the way homes are built. It’s a silent inefficiency that affects everything from affordability to resilience.
Fortunately, the solution is clear. IAPMO’s Water Demand Calculator—now included in the Uniform Plumbing Code and WE•Stand—allows for right-sized plumbing systems that reduce materials, labor, and connection fees, all while improving water quality and hot water delivery times. “It’s not a small shift,” Christoph emphasizes. “In one multifamily project, right-sizing saved nearly $400,000, and that’s before factoring in the ongoing energy and water savings.”
Beyond cost, the benefits ripple outward. Right-sized systems mean faster hot water, less structural water waste, and reduced carbon emissions tied to water heating. As Christoph puts it, “Right-sizing is a no-brainer. You lower capital expenditures, operating costs, and risk, all while building homes that perform better and last longer.”
We also explored how builders can adopt smarter design principles, from specifying WaterSense fixtures to centralizing wet walls and incorporating leak detection and monitoring technologies. For remodelers, he offered practical advice on how to integrate efficiency without breaking budgets—proof that innovation doesn’t have to be expensive, just intentional.
Click here to watch the full interview and hear more from Christoph about the role of plumbing design in housing affordability, decarbonization, and the future of water efficiency.