Can Right-Sizing Lead to Energy and Water Savings? Science Says "Yes"

Eyeroll Moment: Yes, You Can Get Water (and Energy Savings) from Right Sizing with the Water Demand Calculator?

Sometimes I get asked if the IAPMO Water Demand Calculator and right-sizing of water systems can save water and energy.?? I've even seen one disingenuous article try to dispel the notion that the right sizing by the Water Demand Calculator could lead to water savings (there is always that one person in class…).? I'll save you all some time and say there is a mountain of evidence that continues to grow supporting the idea that right sizing leads to energy and water savings.? In fact, when I recently presented to the Los Angeles Department of Water and Power (LADWP) La Kretz Innovation Center for the American Society of Plumbing Engineers (ASPE) LA Chapter on California’s adoption of the Water Demand Calculator, I got to engage the insightful Jim Kemper, of Los Angeles Department of Water and Power, who clued me in on a new Title 24 report that quantified energy and water savings by California adopting the Water Demand Calculator - Report 255321-4: 2025?CASE Report Multifamily Domestic Hot Water.? In this report some of the highlights on energy and water savings by adopting the Water Demand Calculator were found to be:

• The report looked at four different multi-family prototype buildings and estimated water savings between 257 gallons to 320 gallons per unit per year by right sizing the hot water system via Appendix M.? This is similar to the values identified in the Arup Sustainability Report.?? [GU1]?
• Electrical Savings were estimated between 55 to 137 kWh per unit per year.
• The state of California was estimated to save more than 9 million gallons of water in the first year in new construction and additions in multi-family construction.

So, if someone tells you that right-sizing doesn't lead to water and energy savings, tell them think again!

Highlight of the Month: La Kretz

On May 8, I had the distinct privilege of presenting at the Los Angeles Department of Water and Power (LADW) La Kretz Innovation Center for the American Society of Plumbing Engineers (ASPE) LA Chapter. I spoke on California’s adoption of the Water Demand Calculator (Uniform Plumbing Code Appendix M).? Reading my first sentence a second time and thinking about my experience, a distinct theme emerges instantly: the meeting of water and energy.? Plumbing design professionals often joke with our peers in electrical design about how we "don’t want to mix water and electricity.”? But this jest recently has been one that I am reconsidering — these two items are linked.? Water and electricity — otherwise known as energy — are not only linked, but they are the foundation of our modern civilization.? And the LADWP La Kretz Innovation Center is one of the best embodiments of the water energy nexus.? Stay tuned for my full column on this subject in an upcoming PM Engineer Magazine.

Mind Blown Moment: Water Efficiency leads to Energy Savings

While attending the 2024 Emerging Water Technologies Symposium in Scottsdale, Arizona I spent two days learning from a gaggle of industry experts.? One of the most impactful sessions for me was by Jonah Schein with US Environmental Protection Agency (EPA) titled “Saving Energy and Reducing Carbon with WaterSense Labeled Homes”.?

When talking about the water energy nexus and the goal to reduce energy consumption, I was pleasantly surprised to learn about the EPA study on water efficiency playing a critical role in energy reduction.? In fact, in Jonah's excellent presentation, he shared the results of a February 2024 report .? Some of the most impactful items from the report and his presentation were:

• Each water source requires a different amount of energy to extract, convey, treat, and distribute the water. Data from the California Public Utilities Commission (PUC) Water Energy Calculator details this information for each source of water and each geographic region of the state…

• 219 homes within the Oak Shade and Durango communities in southern California provide significant water and energy savings from water efficient provisions only.? These communities will reduce water-related energy consumption by approximately 530,000 kWh per year, equivalent to the average electricity consumption of 49 homes.
• In Jonah's presentation he also reminded audience members of a UC Davis Analysis of California EO B-29-15, which showed that when comparing energy conservation measures to water conservation measures in terms of kWh per dollar spent, the clear winner is water conservation not only in total energy reduction, but also in terms of economics: ?There was only 2.7 kWh saved per dollar spent on energy savings while there was an incredible 10.3 kWh saved per dollar spent on water savings!? See charts below from Jonah's presentation that summarize the findings at UC Davis (used with permission):

#LohrThoughts: Right-Sizing Paradigm Shift

I had a great conversation with my friend and business colleague Gary Klein at the Uniform Plumbing Code Technical Committee meetings in San Diego.? We were talking about the aforementioned CASE Report and how the same approach was taken as in the EPA report to try and evaluate energy savings from right-sizing via Appendix M.? The problem?? The numbers kept coming back with an "error" because the cost savings were negative because the Water Demand Calculator was LESS expensive than the base values.? Most energy conservation measures cost MORE, and so the normal calculations wouldn't work.? Talk about changing paradigms!?

If you are interested in learning more about pipe right-sizing via the Water Demand Calculator, and the energy and water savings potential, make sure to check out IAPMO’s Authority Podcast: Plumbing and Mechanical episodes on the subject:

·???????? Check out our episode with Seattle King County discussing their proposed mandate of the Water Demand Calculator to save energy and water.

·???????? Learn more on this episode with PGE and 2050 Partners on why California plans to adopt the Water Demand Calculator on July 1st of this year for water and energy conservation purposes.

Shout Out

?I just learned that the Water Demand Calculator was used on one of the City of Phoenix ’s most prominent projects. The East Tower is 33 stories of Retail, Office and Multi-family with amenities. The West Tower is 22 stories of student housing and the Metro Center offices. Kudos to Michael Rogers, CPD and the Henderson Engineers team for their forward thinking in promoting water and energy savings in Phoenix.

https://www.dhirubhai.net/posts/christoph-lohr-pe_hendersonknowsdesign-phxskyline-hendersonengineers-ugcPost-7199813975738388480-mOeb?utm_source=share&utm_medium=member_desktop