The Water Energy Nexus: Demonstrating Energy Savings in WaterSense-Labeled Homes

And welcome back to The Authority Podcast: Plumbing & Mechanical. I’m your host, Christoph Lohr. And it is my great pleasure today to have Jonah Schein, technical coordinator for homes and buildings with EPA WaterSense, joining me on the show. Jonah, welcome to Authority Podcast.

Jonah Schein: Thanks for having me, Christoph.

Christoph Lohr: Excellent. Well, I had the distinct pleasure of listening to Jonah’s presentations at the Emerging Water Technology Symposium here in Scottsdale, Arizona, and also the Next Generation Summit in Santa Fe, New Mexico. I didn't get to listen to it just once, I got to listen to it twice, and just  many amazing, uh, impactful moments in that.

And I thought, for our listeners, we needed to get Jonah here on the show. Jonah, your presentation title was titled, “Saving Energy and Reducing Carbon with WaterSense-Labeled Homes.” And it was a granular case study that discussed the impacts of water efficiency and how that can impact energy consumption and carbon emissions.

And you used a couple of case studies of WaterSense-labeled homes in Southern California to kind of highlight how those detailed estimates can be used to estimate energy usage in the different phases of the water supply cycle. Can you kind of frame the problem a little bit for our listeners that you discussed in that presentation?

Jonah Schein: Sure, Christoph. And I’m going to assume anyone who cares enough about water and plumbing codes and everything to be listening to this podcast, you probably know, hey, guess what? Water and energy are inextricably connected. That’s not necessarily news to us anymore. But what we’re trying to do with this study is maybe take it a step further beyond this really high-level connection and talk about what are the specific influences that using water more efficiently can have and how do we capture and quantify them. When you think about it — and I’m going to share something for anyone who's following along on video — you have to take a step back and ask yourself, well every gallon of water has a specific signature, and that variability could be a lot, and it could be easily 10x from one location to another.

So we have to sort of start with this question of, I’ve got this gallon of water. I know it took energy and carbon to get it here to where I need it — how much? And that’s really a function of a lot of different things. Starting with extraction. What do I have to do to get the water?

It doesn’t just exist right where I need it. Do we have to pull it out of a river or surface water? Do we have to drill it out of the ground? Do we have another form of capture available? That all takes energy. Where we get it from is also going to influence how far we have to move it. Once again, it doesn’t do us the favor of locating itself right where we need it most of the time; we’re going to have to move it. Water is heavy; 8.35 pounds per gallon. So we’ve got to move it to where we need to go. Every source is also going to have a different quality. That means we have to treat it, and the amount of energy we put into treating it is going to vary based on where we got it from and what the quality of that specific water is.

From there, we’ve got to get it out to our homes and our businesses and our community where we're going to use it. And how we use that water is going to influence it as well. Some of it we’ll use outside, and that’s pretty much the end of the story as far as its energy signature goes. Some of it will go down the drain and have a sort of second life of energy consumption as we handle it as wastewater, which also has an energy impact. And then some of it’s going to be heated, which adds even more of an energy burden and an embedded carbon to the water that we use. It’s a lot of information we have to take and process to really answer this question of, I have this gallon of water; I used it. What’s the impact on energy and carbon as a result?

Christoph Lohr: Excellent. We put up on the screen again for our video listeners, as Jonah mentioned, just that snippet of his presentation that showed that. Does that kind of capture all the, you mentioned the energy usage for water. And I think that was one of the most impactful things for me was how you linked the delivery of water and the usage of water, and the energy associated with that with the water consumption portion of it. And I think what was really impactful to me is you showed those two case studies and there were some really significant results from that, and we’ll put that up on the screen here as well. Can you touch on a little bit, for our listeners and viewers, some of the results that you found from that connection between the energy associated with water and water usage?

Jonah Schein: Yeah, exactly, Christoph. And that’s really what we’re trying to accomplish here. In this instance, our case study is taking place at two communities in Menifee, California, built by our longtime partner, KB Home; there will be, at completion, 219 WaterSense-labeled homes. These are homes that were built very specifically with water conservation in mind.

They’ve got WaterSense-labeled plumbing products, WaterSense-labeled products. They have design features, they have technology that was chosen specifically to use water as efficiently as possible. And what we found from these 219 homes, we expect that they’ll save about 3.4 million gallons of water a year across the two communities, which is a lot of water, but that’s also not new.

We expect WaterSense-labeled homes to save a lot of water. But when we go in and we drill down to, because of the mix of sources that we’re using to supply this community, and in part because they’re WaterSense-labeled, we have a really good lens into the granular details of how these homes are going to use water.

Well, in total they’re going to save almost 640,000 kilowatt hours per year and almost 358,000 pounds of carbon each year just by using water just related to their energy and carbon impact associated with water use. So it’s really a pretty significant impact that we’re able to have, and we can pinpoint exactly where that impact is happening and what the design and technology choices that resulted in those savings are.

Christoph Lohr: And that's really helpful, Jonah. And that part to me, those total numbers for those two communities was, Was oh so impactful for me. I remembered hearing from other folks at different conferences, especially like here in Arizona, the amount of energy that goes into getting that water to places like where I live in Phoenix, Arizona, and just the methodology you had there in terms of the problem and that solution.

The results, that was, again, it just really stuck with me. For our listeners’ sake, can you help them connect the problem that you described at the beginning and then the results you received just, and again, we can share a screen here again from your presentation for our listeners’ benefit, excuse me, our video users’ benefit, and maybe you can describe it for folks kind of how that all kind of fits together.

Jonah Schein: Yeah, absolutely. I say first off there’s three sort of big data pieces we need to model this all together. Lots of little pieces as well. And anyone who’s ever done any type of energy modeling or large-scale water use modeling can certainly relate to that.

But first and foremost, we need to know what are the sources of water that we’re going to use to supply, in this case the Eastern Municipal Water District, the utility that’s serving these communities, what are they going to use to supply these homes? In the case of California, we can always get that information.

Eastern Municipal would have given it to us; they participated in the study. They’re a great partner of ours and are very enthusiastic about the prospect of using water efficiently, saving water and the resulting energy impact as well. But we can always get it from the water management plan for any utility in California.

We also, we need to know what the source energy intensity on a source-by-source basis are for this specific location. The state water carrier, for example, the State Water Project, isn’t going to have the same signature for conveyance in Southern California as it would in the Central Valley.

We have to take it a lot further to get it all the way to Menifee, and that means that its signature is going to be a lot larger because of the additional mileage it has to go.

Christoph Lohr: For our listeners’ sake, Jonah, can you kind of describe some of the numbers, maybe just kind of give them a range of the energy intensity from the source?

What, what were some of the ranges that you found as part of this case study?

Jonah Schein: Yeah. Once again, you know, for anyone who’s following along  on the video, I’m going to put these numbers up here. But for anyone who’s listening along, you can either go to the video later, or you can find this in the report that’s available on our website as well.

But Christoph, the ranges are huge, depending where the water comes from. It’s more than when you add everything up, from start to beginning, going back to my original point, from extraction all the way through the end of the story, so to speak, so potentially all the way through wastewater treatment.

That’s a variance of more than 20X, depending on where the water comes from and how it’s going to be used in the home. Again, you really do need to understand all of those factors. Where’s the water going to come from? What is the proportional mix? How are we going to use it in the individual home or how are we likely to use it in these homes, again, because of the technology and the design choices that we’ve put in place. Otherwise you might be 1/20^th, estimating 1/20th the actual impact.

Christoph Lohr: This slide, I’m so glad you put this one up. For audio viewers, this was probably one of my favorite slides. The one that really impacted me. I had heard about Arizona, especially the Phoenix water was very energy intensive, but just for our audio-only listeners, local imported water extraction conveyance was 33 kilowatt hours per acre-foot, and the Colorado River was like 2000-plus kilowatt hours per acre-foot; State Water Project was over 3,000 kilowatt hours per acre-foot.

Jonah, this slide here was so impactful for me, and it reminded me of this conversation, or this post I put out on LinkedIn, maybe a year or two ago, where a lot of people are saying, ‘Oh, desalination is the solution.’ And to me, at that point I was starting to make that connection between energy and water.

And it’s like, keep in mind, if you put that desalination plan up there, there’s some pretty, I mean, you show too that there’s energy requirements to push it through the RO membranes, to get the salt out of it.

Jonah Schein: That's exactly right.

Christoph Lohr: Yeah. When I did the calcs, Jonah, at a home-by-home basis, it was like, without any new energy sources, the equivalent of getting your water from desalination was similar in the range of your refrigerator running.

So it was kind of like, would you rather have — without any new energy sources — would you rather have that water coming out of your tap or having your refrigerator run? Pick one. And it’s one of those that we have to think about that nexus. And that’s where I, again, this slide here was one of my favorites in your presentation.

It was so impactful to me because it really kind of showed that range.

Jonah Schein: Yeah. There is some desalinated water used here, but it’s brackish groundwater. Which means it’s not quite as salty as sort of like seawater desalination. Eastern Municipal doesn’t have access to, it’s not part of the sort of water portfolio.

In this case, if it were, I think in Southern California, I believe the number just for treatment, so just, again, for anyone who’s listening along, we have to break it down to basically four columns here, four categories here: extraction and conveyance, treatment, distribution, and potentially wastewater. Just treatment for desalinated seawater is about 8,000 kilowatt hours per acre-foot. Right now the largest, again, as Christoph was mentioning, these values range. They might be as low as, again, just for treatment, 205 kilowatt hours per acre-foot, all the way up to 1,400 kilowatt hours per acre-foot.

We’re seeing all of these tremendous energy and carbon savings, but that’s without desalinated seawater. If we start adding a bunch of desalinated seawater to the portfolio, that’s going to skyrocket. And that’s one of the reasons, that’s one of the things that makes it just so expensive.

Christoph Lohr: Yeah. I was going to say, I don’t know if you want to go back to the other slide, the Venn diagram you had, if there’s anything else you want to wrap up there, but again, that slide with the numbers, that one as an engineer, for me, I just, I was blown away. And that really solidified that main point that I’ve been thinking about for a while, which is that energy and water are so linked and the amount of water we use, there’s such an energy component behind it.

Whatever it does to get out of the tap, there’s energy behind that and we can’t forget that. Is there anything else you wanted to chat about with our listeners?

Jonah Schein: Yeah the one other thing I think that’s really resonated with people is, well, when you think about it at this community, and we didn’t get into details on this but in addition to being a very water-efficient community, it's an extremely energy-efficient community. It’s got a microgrid to help reduce its carbon. It’s got solar power. It’s got the absolute top of the line in terms of heat pump water heaters. And so it’s great when you think about it, because we’ve got these three different strategies to help reduce the energy and carbon impact of water in this case. We’ve got the the microgrid, we’ve got the heat pump water heater, so more of a conventional energy efficiency strategy, and we have water efficiency, and one of the questions the first time I started sharing this work with anyone, it’s a very natural question as well what gets attributed to each strategy. And in practice, it’s sort of an impossible question to answer because everything’s happening simultaneously. Did you reduce the water use first or did you reduce the energy you needed to heat the water first? It’s sort of a philosophical question, but what we can do is we can isolate each of these and compare it to sort of a reference.

If we were to only do one of these strategies, and again, for anyone who’s following along, we can look at that and we can model it. In the case if we just did the microgrid but we didn't do anything else. We’re not doing anything to save energy. We’re not doing anything to save water, but we are making sure that that energy that we’re using is carbon free. Well, don’t save any energy that way, but we do save a lot of carbon, about 289,000 pounds of CO₂ per year. If we were to just do the heat pump water heaters, not do anything else.

So we’re not doing anything. We’re pulling off this quote ‘dirty grid.’ We’re not doing anything to make the homes more water efficient, but we are being efficient with how we keep the water. That’s about 221,000 pounds of carbon reductions per year. And if we were to just do water efficiency, so nothing with the efficient water heaters, nothing with just pulling our energy off the ‘dirty grid’ but just using water more efficiently, we’d save 119,000 pounds of carbon per year. So we’re going from 289,000 pounds with the microgrid scenario, 221,000 pounds with the heat pump water heater scenario, and 119,000 pounds per year with the water efficiency scenario. Maybe that's sort of, one, two, three, maybe that’s the order you might've guessed in, but what if we start putting dollar figures associated with this?

Christoph Lohr: (Chuckles) Yeah.

Jonah Schein: And we look at it from the point of view of dollars per pounds of carbon that we avoid? All of a sudden water efficiency shoots off the scale here. There’s so much low-hanging fruit when it comes to using water more efficiently in our homes, in our communities that it’s really a tremendous opportunity to save energy and save carbon while also saving water.

Christoph Lohr: And I think the slide after this one, you showed one of those studies, too, that showed when you put the dollar figures, this one was the other impactful one. This was my second-favorite slide.

Jonah Schein: Yeah. And again, Christoph, I started putting this in because, and this is for anyone listening, looking around, this is actually looking, nothing to do with my study.

This is an analysis done by folks at UC Davis of the 2015 water use reductions that were ordered in California. And basically what they found was that the water efficiency measures that were ordered in response to the, to the mid-2010s drought in California saved about as much energy as all of the state’s energy efficiency programs. And yet it costs like one-fourth the amount of money. So I put this in to show, once again, this is not new. I’m not the only one to find these results, and hopefully that lends some, not just Jonah going on about things as like the one … other people have found the same thing.

For some reason we have a tendency to forget about it, but I think it’s really something we need to hang on to and internalize.

Christoph Lohr: I would agree, Jonah. And actually it reminds me that we have the Water Demand Calculator Summit coming up on November 12th of this year, of 2024, and you’re working on a presentation.

You’re actually one of our presenters at the summit this year, and you’re going to touch a little bit more on this, more of a general topic of water efficiency. At IAPMO, we’re seeing the same thing as you, Jonah, which is that water efficiency in terms of right-sizing does have an impact on water and energy usage, and there’s reduction opportunities there. For your presentation though, you’re looking at the calculations and you’re looking at right-sizing from a length perspective.

Can you give our listeners maybe just a little sneak peek on that topic of what you’re looking at, maybe some of your initial calculations as you’re preparing for that presentation?

Jonah Schein: Yeah, absolutely. And to be fair, the modeling that we’re using at this stage is sort of just the tip of the iceberg when it comes to what truly right-sizing a plumbing system can do.

We’re not capturing diameter size of piping, because there’s, I think if you think this through, you can probably see how there’d be some challenges consistently collecting that information in the field. But we do capture run length data and what we found is that the 219 homes that we’re looking at in in Oakshed and Durango and these communities in Menifee, they’ve reduced the total run length of piping by about half.

And so on a sort of average reference home, we would expect on average these homes to have about 100 feet of total piping in them, and the homes that we’re certifying, they’re closer to around 45 to 50. Again, just the absolute tip of the iceberg when it comes to comes to right-sizing.

Anecdotally, I’d say, where does that come from? It probably comes from two things: one, eliminating the absolute worst design features. So like the kitchen sink that’s completely shoved all the way as far as can possibly be from the water heater and has a line running in a conduit under the slab or something.

It’s very difficult to convince builders to actually change the layout of homes, but there’s some things which are truly sort of egregious from a design and performance perspective that we can help them eliminate. The other is honestly probably just drilling into the builders and in turn their site foremen and superintendents who in turn turn around to the trades and say, ‘Hey, don’t let me catch you running this thing in a circuitous route, which if you’ve ever walked a new home construction site is all too common of a sight, right?

We’re just going to take direct lines. We’re going to eliminate those those unnecessary routings and things that just tend to add a lot of run length, and just doing that reduces the run length by about half.

Christoph Lohr: Wow. Wow. I’m really excited for your presentation at the summit this year.

For our listeners that want to learn more, that’s a great chance to kind of look at the next sort of phase of all this research here. As we wrap up here, if you were going to summarize your talk here today with us on the podcast in one word, what would that one word be?

Jonah Schein: I think the word has to be opportunity.

It's just, again, there’s so much cost-effective, low-hanging fruit when it comes to using water more efficiently, and we know that that has an impact on saving energy and saving carbon. It feels like we’re bending over backwards trying to reduce carbon right now, and this is probably a technique we could use a lot more.

Christoph Lohr: Excellent. If our listeners want to learn more about the report or get in touch with you, what’s the best way for them to do so?

Jonah Schein: The report’s available on our website; hopefully we’ll drop a link in the description. And always feel free to connect with me on social media or via the WaterSense website.

Christoph Lohr: Excellent. Excellent. Well, on behalf of The Authority Podcast: Plumbing & Mechanical and IAPMO, Jonah, I just want to say thanks again for your time today. It was a real pleasure having you on, and I’m looking forward to seeing you again at the Water Demand Calculator Summit.

Jonah Schein: Sounds good. Looking forward to it, Christoph.