Here is the text version of the webinar Efficient Hot Water Distribution: You Know that Hot Water Distribution is Important, presented in September 2016. Watch the presentation.

Ally Waranowski:
... the Department of Energy Zero Energy Ready Home technical training webinar on hot water distribution. This webinar will last today from 12 p.m. to 1 p.m. Eastern Standard Time. We're really excited that you can join us today for this session on efficient hot water distribution systems that meet the EPA's WaterSense and the DOE Zero Energy Ready Home requirements. Our presenter today is Jonah Schein of the EPA WaterSense program. My name is Ally Waranowski. I'm the coordination support for the program, and I'll be covering some general notes on webinar housekeeping. All attendees will be in listen-only mode throughout the webinar, however, we do invite you to ask questions if you have any that pop up. You can do so through the questions application in the GoToWebinar program. We will be monitoring these questions throughout the webinar, so if any come up, we'll definitely ping Jonah to answer some along the way. Otherwise, we'll cover some questions at the end of the webinar. This session is being recorded, so if you would like to revisit it afterward, we will be putting the webinar recording on our Zero Energy Ready Home's resource site. That way you can access it later on. Please allow some time for the recording to be transcribed and added to the DOE YouTube page. With that said, I'm going to hand it over to our technical director, Jamie Lyons, Newport Partners, who's going to talk a little bit about the Zero Energy Ready Home program and will introduce Jonah.

Jamie Lyons:
Great. Thanks, Ally, so much for the quick intro, and thanks, everybody, for joining us for part of your busy day to dig a little deeper into energy-efficient hot water distribution systems.

First slide:
Before we hand it over to Jonah, as technical director for Zero Energy Ready Home, I just wanted to give a little bit of context about where we are as we talk about efficient hot water distribution, through the lens of Zero Energy Ready Home. So the slide here is just a high-level view of the program requirements for a project to be DOE Zero Energy Ready Home labeled. There's a couple different aspects to the requirements. We have our mandatory requirements. These are kinda must-haves for a building to have the efficiency and the performance to earn that Zero Energy Ready Home label. We have the target home specs, which -- we'll leave the details of that for a different day -- but essentially they set the measuring stick for how efficient the building or the home needs to be. And then there's a size adjustment factor, which is the exact same method used by ENERGY STAR® Homes, that makes the efficiency of the home a little bit more stringent if it's larger than a benchmark home size.

Next slide:
So a real quick story of the program requirements. And today, we really want to zero in here. We have those mandatory, those must-have requirements, and then one of them is water efficiency. And just to take a quick step back on what that really means in a Zero Energy Ready Home, I think most, probably all of us, can think of a home, a building where we've lived, where we turn on the shower early in the day, to get a shower -- what do we do? All of us, we wait 30, 60, 90 seconds for hot water to arrive. And if you think about what's happening during that wait, we have lots and lots of water going down the drain that really didn't help anybody, serve any useful purpose. You add that up, it'd come out to a hundred or in some cases several thousand gallons annually. And we also, we're losing a lot of energy in that water. That water once upon a time was heated up and it stayed in that hot water piping, and then it cooled off. And again, the energy that went into that water didn't really serve a useful purpose. So that's sort of the background for why water efficiency and in particular the hot water distribution system is critical as part of a Zero Energy Ready Home.

Next slide:
Just a little bit more context. This is the home page for Zero Energy Ready Home, buildings.energy.gov/zero. And I'd just like to point, in these webinars that we do, that if you visit this site, that there's four big blue boxes there, the "Resources" box -- click on that ...

Next slide:
... it takes you to a number of resources, including over two dozen recorded trainings. And these trainings deal with sales and marketing of Zero Energy Ready Homes, and they also deal with quite a few of these deeper dives into a technical topic. We've done recent recorded webinars on high-R value building enclosures, optimized HVAC systems, indoor air quality design and technology, disaster resistance, and so on. We just want to make the group aware that all these recorded webinars, which tend to be roughly an hour, they offer a whole host of resources for our DOE Zero Energy Ready Home partners.

Next slide:
So I'll leave this slide up here for a second; it has the Zero Energy Ready Home website, as well as a contact -- an email contact if you have any questions of any type, really. So I'll leave that there for a second as I introduce our main speaker, Jonah Schein of the EPA WaterSense program. Jonah is the technical coordinator for the new homes aspect of the EPA WaterSense program, and he's also been involved in the technical development and implementation of the WaterSense new homes specs, and their certification systems since their inception. Jonah's also involved in efforts to expand the WaterSense program and its reach out into the commercial and the multifamily sectors. And just on a personal note, Jonah and I have worked together for several years, and he's very effective working with builders, their designers, their plumbing contractors, and help them understand sort of the fundamentals of good water efficiency and hot water system design. As part of his work with EPA WaterSense, Jonah is with the Earth Day Network, and similar to what he does now, he is promoting water efficiency, efficiency through green building strategies, in work that took him both to the U.S. and to the Middle East. So without further adieu ... Jonah, I'm going to change presenter and let you get rolling with your slides.

Jonah Schein:
OK. Thanks so much, Jamie. ...

Next slide:
OK, well, again, thanks very much and thanks to everybody for being here. Just to give a quick overview of what I want to cover today. I want to give a little bit of background on why is hot water such a big deal? Something that we talk about I think to an increasing extent within the building industry, and I really think it's important that we have some context to understand why something that is receiving and really warrants the amount of attention that it's gotten in recent years. I also want to give a little bit of historic background on how it got to be a problem in the homes that we build these days. And of course, I'm going to talk about some strategies for addressing efficient hot water distribution. Then finally, I'm going to talk a little bit about pipe insulation. I'm going to look a little bit ahead to some of the developments that we're starting to see in various areas, both base and reach codes that will be coming most likely to jurisdictions near you in the near future. I am going to save some time for questions at the end, but I really do encourage people to, if you have questions as I'm going along, go ahead and type them in. Jamie's going to be kind enough to monitor the question box, and he can jump in with any particular questions that people have. I know this is an area where typical practices vary greatly based on the individual builders you're working with, the different trades, the regions, everything that influences this type of construction that happens in the building industry. And to make it as useful as possible to you as I can, I really do want those questions. I'd like nothing more than to not be able to get through all of my slides because people are asking too many questions that relate directly to the projects that they're working on. So by all means, there will be time for questions at the end, but please, don't wait. Feel free to ask away whenever you see fit.

Next slide:
To give myself a little bit of background, though, and so that I really understand where the audience is coming from, I did want to start out with just a few basic questions.

Poll question 1 screen:
So my first poll is, what is your standard hot water distribution system? And certainly this could apply if you're a builder or a rater or an architect, but really, if you have any role where you're engaged in projects, just let me know what type of systems do you typically see. ... I'm going to give this a few more seconds. It looks like people are still responding. OK. I'm going to go ahead and close this one out because I do have a couple more questions for you. That's very helpful to know -- looks like most of the people in the audience today typically do trunk and branch.

Poll question 2 screen:
Alright, for the next question, for those of you that answered that you typically do recirculation, which is close to a quarter of the audience, I'd like to ask, well, what type of recirculation? Is it continuous operation, demand controlled, is it controlled by some sort of timer or temperature sensor, or any of you using some of the newer-generation smart or adaptive scheduling technology that's out there? And again, I'm going to give this just a few more seconds to give everyone a chance to respond. ... OK, great. Thanks again, everybody. Looks like we have a good mix of different technologies used in play here.

Poll question 3 screen:
And then finally, I'd like to ask the last poll question, but I'd like to ask, what is your top challenge to using efficient hot water distribution? Is it that you don't feel you have the technology or the system choices, that you don't have the education or the knowledge on what those possible strategies are, do you experience resistance from your plumbing contractor or your trade partners, or is it really an issue of incremental cost, it's just too expensive to do properly? ... OK. I'm going to go ahead and close this one out, but thank-you again, everyone. It looks like once again, we have a mix of challenges. And I'd say, this is pretty representative of the industry. As I said, hot water distribution hasn't traditionally gotten a lot of focus, and so it is an area where we need a lot of education. We're just starting to develop the tools and technologies that we really need to be effective at it. And because it is new and it does involve a building trade, it can be a little pricey to implement, especially if it's a new concept.

Next slide:
OK. So as I said, I really did want to start with some background on why is water a big deal when it comes to energy. And truth is that water uses a lot of energy. We can start at the really big scale, the really big picture item that every drop of water -- every gallon of water we use has a footprint. Water weighs a lot. It weighs more than eight pounds per gallon. So when you consider the fact that we consume trillions of gallons as a country, that's a lot of weight that we have to move around, so we use energy to move water. We take energy to treat water and distribute it to our homes so that it's clean and healthy and safe to consume. And then on the other end, we use energy to treat that water. So combined, our water and wastewater industries consume about 70 billion kilowatt hours a year. A pretty significant chunk of energy. Still only a few percent, when we look at our entire energy consumption as a nation, but remember, that does not take into account end use. So that's not taking into account the energy that we put into water once it enters our home because we're going to heat it up with our water heaters. Energy and water is a little bit better documented in California than it is elsewhere in the country. Where in California we estimate that it's using about 19 percent of electricity and 30 percent of nonpower-generation natural gas. So of all the energy consumption in our larger states, in the state of California we're using almost 20 percent -- almost a fifth of that energy, of that electricity -- just for water in some form, be it moving it, treating it, treating wastewater, or heating it up in our homes. It's a really significant amount of energy.

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Looking a little bit more specifically at how we use energy inside of our homes, well, we look at the sort of energy use pie, we see a lot of things that we expect, right? Space heating is a really big chunk. This is above 7,000 heating degree days, so it's a cold climate; we don't use much on AC. But we've got this big, significant chunk of the pie here that's water heating. One of the things I hear people say a lot of the time is that really varies based on climate. And it's absolutely true that it does. But you'll see as this pie shifts and I'm moving from a cooler climate to a warmer climate here, well, things move around. I use less and less for space heating and more and more for cooling. But hot water is basically always the No. 2 or 3. And that's pretty consistent to what we see in energy end use studies. In most homes nowadays, hot water is usually the second most consumptive end use that we have for energy in our homes. There's a lot of energy to be saved here. Another interesting thing that's happened over time is that when we look at energy-efficient homes, that slice that goes to water heating actually tends to get a little bit bigger. And what that tells us is that we're simply not making the kind of gains as an industry in water heating efficiency holistically -- I'm not talking just water heaters; I'm talking about the entirety of the process. We're not making the same gains in water use heating, in water use efficiency, that we've seen elsewhere in the industry in terms of building envelopes, efficient HVAC equipment, and what-not. So we really have a lot of work to do here. But there's also a lot of opportunity.

Next slide:
So let's break it down. I just mentioned, I just made a point of saying that when I talk about hot water, I'm not just talking about the water heater. I'm talking about the entirety of the system. And let's look at the entire system. And look at some of the ways that we can save energy when we look at hot water use from a systems approach. So what are we going to do with water once it enters our home? The first thing we're going to do is, we have to make it hot, right? And we have tools that we can use to make that more efficient. We can use better water heaters, higher recovery efficiencies, lower standby losses. I can even use technology like drain water heat recovery, which effectively lowers the amount I have to heat the water because it's essentially preheating that water. What am I going to do after I heat it? I'm going to distribute it, right? I'm going to take it from the water heater and I'm going to move it through the home to the point of use, to the bathroom, to the kitchen, to the clothes washer, to the point where I need to use it. And again, we have a variety of techniques that we can use to improve distribution efficiency. And we'll talk more about some of these. But we can use demand-based recirculation, structured design, pipe insulation -- are all tools that are going to help us get water from the heater to the point of use more efficiently and ultimately save both water and energy. And then finally, what are we going to do after we get the water to the fixture and to the point of use? We're actually going to use it. And once again, of course we have a variety of technologies we can use to improve efficiency there. One of the best and easiest is you can look for WaterSense-labeled products, which is the certification, product certification program that my program WaterSense runs. They're widely available. They're available at all price points, every style. No one should have any problem finding them. They're third-party certified for both efficiency and performance, so they're a very easy way to, again, increase both the water and energy efficiency within a home.

Next slide:
On this slide I also want to talk about some important changes that have been done to HERS. For those of you that are in the industry and use HERS ratings, up until very, very recently the only way that a HERS score adjusted for hot water efficiency was at the water heater. So if you put in a more efficient water heater, we knew that you were going to use less energy in the generation phase, and we could represent that in a HERS score. As of homes permitted I believe after just last month, there's a new methodology in play for calculating the modified end use load for hot -- for water heating in a home. And now HERS accounts at least in some way for every phase of the process. And so, I know it's on the first slide -- there's still quite a few people in the audience who are still using uncontrolled recirculation. The bad news I have for you is that you're going to get dinged for that now in HERS. And truth is, it's more accurate. It's really not a very energy-consumptive practice. The good news for both you and everybody else is that if you're using recirculation with say a demand control, and if you're further reducing the demand through efficient use with WaterSense-labeled products or some other technologies, you're actually going to receive a couple of HERS points. So it's a really important shift that's been made within the HERS rating system. And if you haven't encountered this yet -- as I said, it's really just homes based on permitting dates, so many of you are probably either seeing this within the last week or two for the first time, or will be seeing it for the coming month.

Next slide:
So, let's talk historically about how hot water got to be a problem. The truth is, our hot water systems don't work like they used to because we don't build homes like we used to. We don't build homes like we used to, and we don't have plumbing products like we used to have. So both the physical layout of our systems and the usage patterns we subject them to have changed. Again, going back to the polls, I noticed that most people are still using trunk and branch systems. And once again, I think that's pretty representative of the industry. We've been using trunk and branch systems for years. So essentially, we're using the same design strategies, even though the demands of the system and the layouts of the -- and the size of the homes that we have to consider, have changed quite a bit. So this really becomes an issue if you think about what homes used to look like. My grandfather was a plumber, and his market was I'd say 1,200-square-foot, one-bathroom bungalows in western Pennsylvania. Well, when I had a 1,200-square-foot bungalow, and a lot of people have probably been in these homes, seen these homes, or even live in these homes. But you have a water heater in the basement, the kitchen's right above the water heater, and the bathroom's right above the kitchen. That's it, right? It's essentially a wet wall before we called them wet walls. So when I had that type of system, trunk and branch really worked well, because everything was real close together. So if this is my trunk and branch distribution system, and everything's stacked right on top of each other. Remember, this was designed 50, 60, 70 years ago, which means I had a five-gallon per-minute showerhead on the other end. Well, might have a 10-foot, three-quarter-inch branch, or a one-inch branch, and then I might have a trunk, rather. I might have a five-foot, three-quarter-inch branch, and then I have a couple feet of a twig. All said, I'm only storing about 75 ounces of water in there. Because I'm only storing 75 ounces of water, and I have a really high flow rate at the point of use, I can get hot water really quickly. I'm going to pull all of that cold water out. I'm going to bring the hot water quickly to the fixture. And I'm going to get hot water really fast. This is a really inefficient system. Don't make any mistakes about it. But it works. And to be honest, there's a lot of things we did in the '20s and '30s and '40s and '50s and much, much later, that we don't do anymore because we know they're not sound building practices, and we know that they're inefficient. So we have this history of really relatively inefficient plumbing systems, but at least when we were building 1,200-square-foot bungalows it worked.

What happens when we take this same design and we apply it to a 2,300-square-foot home? That might have two and a half or three and a half bathrooms, which, by today's standards is not even really that large of a home. Well now, my 10-foot trunk becomes a 30-foot trunk. So I've got 30 feet of one-inch copper L piping stretching across the home in all sorts of weird designs, because we have design elements that pull these bathrooms into different corners of the house. Off that 30-foot, one-inch trunk, I might have a 10-foot branch that's made up of three-quarter-inch copper piping. And then, I'll still have only a few feet of a twig. But all said and done, I might have 200 or 300 ounces stored in this system. The other thing that's changed is I'm not using five-gallon per-minute at my showerhead anymore. Now, say I've got a nice efficient WaterSense-labeled showerhead that's using two gallons per minute. Let's make no mistake about it -- that's a good thing. That product that's using two gallons versus five minutes is saving money, saving water, saving energy, and performing well. But I'm not going to be able to bleed all of that water out of the system as quickly as I would have.

Next slide:
More importantly, to really change in the dynamics of how water is pushed through my system. So it turns out that as water moves through, the rate that it's flowing at has a really big impact on how that water mixes within the pipe. So you can see up here where I have really high flow rate, I have what we call the plug flow. You can see there's not a whole lot of mixing that's happening. And because I'm moving the water through very quickly I'm not going to lose a whole lot of water to the pipe. Essentially we have to heat up the pipe before we can get hot water at the point of use. When I start to slow down a little bit, that plug starts to dry out and we get what we call the long bullet. As you can see, I'm likely to have a little bit more mixing. And because I'm moving the water more slowly, I'm going to lose heat to the system a little bit more quickly than I might have otherwise. And then finally, when I start to get to really low flows you can see the hot water sort of starts to creep up along the top of the pipe and I'm going to start to get a lot of mixing. Once again, since I'm moving very slowly, I'm going to lose a lot of heat to that pipe. I start to let it radiate that heat out. So, as I said, we've really fundamentally changed the nature of the system here. And if we're still just putting in trunk and branch systems and not accounting for the volume of water that we're storing, we're really not doing a very good job. We're not acknowledging that fact in making the changes that we have to do to keep our systems high-performing and high-efficiency in terms of both water and energy consumption.

Next slide:
So what's the end result? The end result in best case scenario when I'm storing more than 200 ounces of water in the system, well, rather than waiting 20 seconds and wasting a half-gallon or three-quarters of a gallon, now I'm going to wait a minute and a half. And I'm going to waste three gallons. And again, this is a best case scenario. If someone's gone outside the building envelope, add time to it. If they've gone under the slab, add time, add water. If they've taken a circuitous route, again, it's just going to add time, it's going to add to the wasted water and add to the wasted energy. So now we've got a system that doesn't perform well, wastes a lot of energy, wastes a lot of water. Again, from a performance perspective, homeowners aren't happy with this. People aren't going to stand there for a minute and 30 seconds waiting for hot water. They're going to start to develop other routines. They turn on the shower and they go make coffee. They turn on the shower and they pick out their clothes for the day. They turn on the shower and they brush their teeth. They develop coping mechanisms for these things, because they're simply not going to wait for a poor-performing system to get hot water to it.

Next slide:
So let's look at what some of the different implications of this might be in the field. So I didn't do a poll for this, but I do want to ask you a question: What do we typically ask plumbers to do when we bring them into a house? Do we ask them to plumb an efficient system that will perform well over the life of the home? Or do we ask them to plumb the house as quickly and inexpensively as possible in the time we've allotted them? I would say, typically, we ask them to do the latter. I don't think anyone would disagree that we should be asking them to do the first. You should be asking them to design smart and efficient systems that will perform well over the life of the home. But that's simply not the case most of the time. So let's look at some housing layouts. In this case, I've got my three-bedroom, two-and-a-half-bath home, and we'll try to apply my trunk and branch system. So as you can see in this case, I've got my water heater in the corner of the home, which is a fairly common place for it to be located. I have two bathrooms right on top of it, a half-bath right next to it, a washer and dryer adjacent, and then the kitchen right down the line. So ... So if I look at these showers up here, how quickly can I get hot water to them?

Next slide:
And I do want to point out that you'll notice when we talk about hot water distribution, hot water efficiency in homes, we talk a lot about showers. And there's a reason for that. The reason is that we know that hot water that comes out -- excuse me, water that comes out of the shower when we're calling for hot water that isn't hot, is going to tend to get wasted. We know that because you're not going to get into a shower until it's that temperature. The range of temperature that human beings are comfortable in is really pretty narrow. If you like really hot water, if you tell me you like a really hot shower, that might mean you like 105 degrees. If you tell me you like a cooler shower, that might mean you like 102 degrees. We're not dealing with a huge range of comfort in this instance. So what we see when we look at shower draw patterns is something like this. We turn the water -- the user will turn the hot water on, it will stay cold, stay cold, it will come up to temperature, it will get hot. This is 110 degrees, which is too hot for most people to shower in. And then we see this throttling effect. And that's when someone's actually getting in the shower, because they're taking that water that's come up to temperature and they're adjusting it to get it to that 103, 104, 105 degrees, that they're actually comfortable in getting in.

Next slide:
So why do we talk about showers a lot when we talk about hot water? Well, we talk about them because they're a large user of water and energy in a home. But also because we know that almost 25 percent of a typical shower is wasted. It's that warm-up period or that throttling period where the person hasn't gotten in the shower yet and they're just running that hot or once-hot water down the drain, wasting water and wasting energy. That's really a different story than faucets. The data tells us faucets are routinely used for draws that can't possibly deliver hot water. There's no physical way that hot water could be emitted from that faucet, given the design of the home and the amount of time that it lasted for. But it happens. OK? Someone turned the faucet on, they turned the faucet off, they washed their hands, they rinsed something off. They did whatever they had to do and they went about their day. So in that sense, we've created a waste, right? Because we've heated water and we haven't actually resulted in any effectively used hot water. We can't save anything there, though, right? Because if we do fix it so hot water does actually come out of the tap, we've created a better-performing system, we fixed the waste, right? We're now getting functional hot water out of the sink where we didn't get it before, but we're not using any less water. We're not using any less energy because we're not reducing the load of that. So showers is really where we can save a lot of water through an efficient hot water distribution.

Next slide:
And again, I'll remind people that WaterSense-labeled products are really among the easiest and cheapest energy upgrades that you can make to a home. As well as ENERGY STAR-certified products that often include water factors or embedded energy savings. So for things like dishwashers and clothes washers, turns out that manufacturers looking to meet the ENERGY STAR certification figured out long ago that the most effective way to reduce the energy factors to reach that certification level was to reduce the amount of hot water they used. So that's very much the strategy that they use to get that certification. You do get benefits of both the emitted water savings in addition to the energy savings in that factor, in that efficiency.

Next slide:
So Jamie mentioned this briefly at the beginning, but having acknowledged this problem -- getting a little bit of background on why it became an issue, how do we turn that into a specification? Or to design requirements? And what we've used in WaterSense and has been adopted further by Zero Energy Ready Homes, is we have people design for maximum of a half-gallon of water between the source of hot water and the furthest fixture. Typically the source is the hot water heater. It could also be a demand control recirculation loop. So by ensuring that there's no more than a half-gallon of water between those two points, we can ensure that we're not going to have to bleed out that much water in order to get that much sort of tepid or cooled-off water, in order to get hot water at the point of use. We also know that because we can't store that large of a volume, the water's not going to -- the pipe's not going to take too circuitous of a route. We're not going to lose a lot of heat at right angles that we don't necessarily need, and we're going to be able to save a lot more of the heat energy than we would have otherwise. So that's how we get to the 0.5 gallon requirement, which is very doable in many situations but also quite a bit better than the standard practice. To be honest, the standard practice is that we just don't pay attention to that volume.

Next slide:
How do we calculate that? We do have a very sort of quick and easy Excel calculator available on our website. It's just a matter of adding up the volume stored of all the individual components, and the calculator does a really nice easy job of helping you do that.

Next slide:
So getting back to my layouts here. This is my typical three-bedroom, two-and-a-half-bath, call it 2,300-, 2,500-square-foot home. Like we talked about before, everything's kind of clustered together here. So I can do a pretty effective job at getting hot water even up to those second-story bathrooms pretty quickly.

Next slide:
Even in the absolute sort of worst case in this instance, which is the upper-level bathroom sinks, where I have low-flow, because I have to go up a level, have higher volumes stored, I'm still able to get in just under the half-gallon requirement, and I'm going to have wait times that are what I would say acceptable. If I look at the showers, I'm still under 30 seconds, which I would venture to say is quite a bit better than the industry standard these days.

Next slide:
But what happens, and you know, I'm sure a lot of people have experienced this in the field. I see it all the time in my work. The designer comes in and -- or whoever -- for whatever reason, they decide, um, you know, the kitchen really needs to be on the right-hand side of this home, we need the utility closet over there on the left.

Next slide:
That's a fine thing to decide, but the gap that I always impress upon people is we can't assume that the hot water system is going to work the same way if I have fundamentally changed it by relocating the water heater. So by switching sides of the house, now what do I have to do? Now I've got to go, in addition to going up a level, I have to go all the way across the home. So having spread the system out in this way, I'm no longer going to be able to meet the requirements.

Next slide:
And it does turn out that when I add everything up, not only do I have more than the half-gallon of water that we've allotted for all of these upstairs bathrooms, but now I'm up over a minute of wait time. And I think now we're in the range where we can safely say, this system does not work. This is not acceptable to homeowners. And I think, you know, it's more, we're probably in that danger zone where, because people aren't going to stand there for a minute as their water heats up, they're going to start to develop coping mechanisms for that.

Next slide:
So what are some of the options we can use? Well, I could switch this to a manifold system. Manifold systems, which are typically PEX piping, run individual lines that are much more narrow diameter. Because they're more narrow diameter, they store a lot less water.

Next slide:
And so, if I look back to my sort of more efficient design, you can see that for each of the individual fixtures, I've reduced the volume stored and the wait time quite a bit.

Next slide:
Now, there are some down sides to manifold systems. For one, I always impress upon people, they're really hard to retrofit. And they're hard to retrofit because all of those individual lines are completely independent. And so if there's a single trunk or just one or two trunks, we have some options where we can turn that into a recirculation system. I can't do that with a parallel pipe system. You do have to make sure you get it right the first time. Another thing that we lose out on in this instance is that hot water use in homes is extremely clustered and has really short duration, in average. So it's turning a faucet on for five seconds at a time but doing it 10 times over a short period. Or it's using the shower and then using the sink that's right next to it in close proximity to each other. So when we do that in a trunk and branch system or another design, we get some benefits of consecutive use, because the first use effectively primes the use for your next one. In a parallel pipe system, we only get that if you're using the same exact fixture. So you would get some benefits to consecutive use if you're, say, washing dishes and turning the tap on and off. You won't get it if Mom or Dad wakes up first and goes to take their shower and 10 minutes later one of the kids wakes up and goes to take their shower in the second bathroom. They're different lines, so you don't see those types of benefits. So there are some down sides to that system.

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Just to give an idea -- of course, the Cadillac, so to speak, the most efficient way from a water energy perspective, is the on-demand recirculation system, where we actually bring the water up very close to the point of use, either by push-button or by motion sensor or by something that indicates there's going to be a demand for hot water at that point of use, so it's right there. But both structured design, structured design with parallel pipe, on-demand recirculation, all legitimate tools to meet the requirements of this home. The one that doesn't meet the requirements is the one where we just didn't really pay any attention to it. Again, the point I really try to make is just hot water is too resource-intensive of a system to not pay attention to. You can't just move around components and not account for them and think that they're going to influence the performance of the system.

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So I did want to take a few minutes to talk about pipe insulation, not only because it's a good practice, but also because this is one of those things that we're seeing increasingly more and more in code. As I said, pipe insulation is a really good practice. It improves efficiency in two ways. Number one is that it minimizes the heat loss that occurs while the water is sitting in the pipes. We just talked a little bit about those consecutive-use benefits. It essentially elongates the window that we have to realize those consecutive-use benefits, because it keeps the water in those pipes hotter longer. The other is that it maximizes heat potential of the system. So as that water, as we talked about at the beginning of this presentation, as that water moves through the system from the water heater to the point of use, adding insulation on it keeps the pipe from radiating out heat. If you've ever used it or you've even just been to building shows and you've seen the vendors, has anyone ever noticed how similar radiant floor heating looks in terms of materials to, say, PEX plumbing piping? It basically looks like the same thing, and the truth is, it is the same thing. So we're essentially using something that's specifically designed to radiate heat outward in an instance where we very much want to keep heat contained. And so pipe insulation really does help with that. Now, let's be clear, though: It's a good practice, but it's not a panacea. It's not a cure-all. Insulating a bad systems pipe is a band-aid. It will make it better but not good. And so you can't just put insulation on a hot water distribution system and expect it to perform well. It still needs to be designed properly. There are some instances where I think we should really need to be on the lookout for, and those of you who work with builders or build homes or work in the field should know these. The one I see more than anything is when hot water pipes go under the slab. What's under the slab of a home? In a best case scenario, cool, wet dirt, which is essentially a heat sink. I'm running pipe that as we said radiates heat through a moisture-heavy, cool environment, I'm going to lose a lot of heat in that process. You see this a lot either because the general practice of the plumbing industry in the area is to go under the slab, or in kitchen island sinks, is another really common instance where the plumbing will go under the slab and then come up. So anytime it goes under the slab, anytime it has to go outside the envelope, which it shouldn't do, anyhow -- but for whatever reason does have to go outside the envelope of the home, then you should definitely be on the lookout for pipe insulation in those instances.

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I mentioned code a couple of times. And part of the reason I do want to mention it is these things are coming. Why do codes tend to gravitate toward insulation? Well, from a code official's perspective, insulation's a lot easier to verify than an efficient distribution design. That's tricky. Especially when they come into the home and drywall's off and the system's behind walls -- there's some things they can do to check to make sure you've put insulation on the pipes, but it's a little trickier for me to check and ensure that you've actually designed it efficiently. So a lot of you are going to see this in coming years as jurisdictions adopt the more-recent codes. You see it in the 2015 UPC -- Universal Plumbing Code -- as well as the 2015 IEEC -- it's referenced in the international plumbing code -- which are the two major base codes. Like I said, those base codes. Those are minimum requirements that tend to get adopted widely throughout jurisdictions. We certainly see it in the regional codes, and of course the green building programs also acknowledge and give points for hot water pipe insulation. Good practice. Like I said, hopefully you can recognize the places where it absolutely needs to be done, but for many of you, it's going to be a mandate to the near future if it isn't already.

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So again, just a couple other thoughts on codes and standards. We know, we have really good data that our plumbing systems are way oversized. To some extent, our codes are requiring that. So there's a really dramatic need of updates. I don't know of any example in the built environment where it works well to dramatically oversize a system. You might want to oversize an air conditioner a little bit. You might want to oversize a hot water heater a little bit. There are instances where it helps to have a little bit of breathing room. But certainly that's not what we're dealing with. The place where that becomes an issue is that -- we talked about pipe size. Most of our plumbing codes we're allowed for adjustments down to three-inch piping. That's really difficult to implement in the field. And so as it is right now, because of the steps you have to go through in order to use it, in the codes. So I emphasize this because a lot of people are involved in codes at the local level and the national level, and I really think it's important that we have an awareness that codes do have a role to play here, and that there are updates we can make that would make it easier for those of us that are in the building industry to design high-performing systems.

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And I've tried to save, as promised, some time at the end for questions. I'm happy to take any of those.

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I did just want to put some additional resources up, and this will be available to people after the webinar. But these are all resources that are available on our website. And of course, you can feel free to contact WaterSense with any questions that you have.

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Jamie, any questions come through yet?

Jamie Lyons:
Yea, Jonah. We have several. Thank-you for taking us through that talk. Want to click back one slide quickly -- one of the questions actually pertains to some of the resources. There's a question as to the best place to find the hot water volume calculator.

Jonah Schein:
That's on our website. This should -- you can see the exact URL -- but we'll double-check to make sure it's clickable when this goes on the resources page at Zero Energy Ready Home. And if not, we'll make some edits to at least make the URL visible.

Jamie Lyons:
Great; thank-you. I imagine it's able to be located right off the main WaterSense site, as well, right?

Jonah Schein:
Ah, yea, if you go to WaterSense -- New Homes and to Building, is where you can locate it.

Jamie Lyons:
OK. Had a few questions pertaining to demand recirc systems, asking about some of the design tips on those, and I guess a good high-level question to start in with, Jonah, would be: How does a demand-based recirc system actually save energy? Don't we have the same amount of water sitting in that pipe after a hot water event, with all the same embedded energy that then cools off? Looking at your slide there, -- maybe we could go back to that first design example? Slide 18, 19, somewhere around there? And maybe speak to what if that house had an on-demand recirc? How would that look, and how would it be different from the trunk and branch?

Jonah Schein:
Let's be clear: On-demand recirculation is the only way where you have a chance to save energy with recirculation. You can still design it poorly and not realize that benefit. There's a handful of benefits. If we were to, say, redesign a recirculation system for this home, again, it's not terribly spread out, so we would of course come out from the water heater. We would probably come straight up to service the two bathrooms above, and then we would run that line out, back down and out, to the kitchen. The reason we would do that is that we probably want to prioritize the master bathroom above everything else in terms of distribution efficiency. So in that instance, our -- can you guys see my cursor?

Jamie Lyons:
Yea, we can see the cursor.

Jonah Schein:
So in this instance, my pump would probably be somewhere around here. Now, it would do a couple things for me. In addition to getting hot water more quickly to where we needed it to be, I would lose a lot less energy in the process of moving the hot water to the point of use than I would otherwise. The reason being that demand pumps function at a much higher flow rate. And so I don't radiate out as much heat as I would otherwise. Secondly, the water that I'm putting back into the water heater at that point, and most demand pumps these days do have thermistors in them, so they will shut off when they actually see hot water. But hot water is 105, 95 degrees. The water that I'm putting back into the water heater is still significantly warmer than it was when it entered the home through the water main. And so now I've reduced the Delta T for any water that I've bled out, whereas before, I was dumping that lukewarm water down the drain. So I give a little bit of that energy back. And of course, there's also the embedded element, right? So that water that I was running down the drain that I'm now recirculating back into the system, that has energy in it even before it entered my home, where I heated it, where I heated it up. So there's -- like I said, there's a handful of places where we have the opportunity to save energy by using on-demand recirculation. We still have to be careful. We still have to design the system intelligently and effectively, otherwise we're not going to get to that point. But the data does show that if you do all those things right, you can come out on top, even though you're using some energy to run that pump. Now where we certainly will not save any energy -- in fact, we'll lose a lot of it -- is if that pump is always running. So if that pump is always running, it's going to, A) take a lot of energy to run the pump, because the pump will always be on, and B) it's going to keep my water heater firing all the time. The instance where I always want people, and I can't count the number of instances that I've seen this in the field, and unfortunately a lot of times, they come from places where homes had a sort of deep energy retrofit, and the homeowners complain that after all of that really aggressive energy efficiency measures to implement, their energy bill goes up. And what's happening is they've got an on-demand water heater but an always-on recirculation pump. That's just an enormous energy sink, because you're always firing that on-demand water heater in that instance. So it's a tricky technology, because as I said, if we do recirculation right and we have good demand controls on it and insulate the main recirculation loop, and we've done it in an efficient layout, then we can actually save energy. But if we do recirculation not well, then we could actually use a tremendous amount of energy.

Jamie Lyons:
Couple additional thoughts, Jonah. Maybe you can comment regarding the design of demand-based recirculation. One of the things that we often point out to partners that are looking at this design option is, when we're talking about that amount of stored volume between the water heater and the furthest fixture, that essentially changes, right, when we have a demand recirc loop? Now our "source" of the hot water is no longer the water heater; it's the loop. So when we're trying to evaluate our stored volume between the source and the end-use fixture, it's really that branch off the loop for the showerhead. We're looking to achieve that 0.5 gallon limit along that pipeline. Is that correct? And can you add to that?

Jonah Schein:
That's exactly it, Jamie. Effectively what we've done, because we're controlling the operation of the recirculation loop with demand controls. We know there's a need for hot water. We know that that loop is hot, right? I walked into the room and set off a motion trigger, or I pushed a button and called for hot water. So, as you said, the source is no longer the water heater. The source is the recirc loop. And because I've taken that source of hot water and I've distributed it throughout the home in a strategic way, not all the time, but specifically when I need it, where I need it, it's going to be a lot more flexible, in terms of designing the branches off of that main recirc line, so that I'm under the half-gallon recirculation -- the half-gallon storage limit. And more importantly, the residents are going to get hot water quickly and easily without having to wait for it and without wasting water and energy in the process.

Jamie Lyons:
And great. One more last point -- we have a couple minutes here left. Still on the demand recirculation design topic. There's a fair amount of discussion in the industry about the loop design. A dedicated return line or a cold water return line. Are there any tips, any guidance on sizing that loop to promote more mixing to mitigate cold-water sandwich effects, that kind of thing?

Jonah Schein:
Good question. As you alluded to, Jamie, there's two ways to do recirculation. One is to have a dedicated return line. The other is that you essentially use the cold water line as the return. There's an energy benefit to having a dedicated return line, because I'm going to get -- as we talked about before, I can return that lukewarm water back to the water heater in a more efficient way than if I have to plumb it through the cold water system. Both of those solutions will help mitigate the hot water sandwich. The hot water sandwich is a nod to our manufacturers. It's not as large of a problem as it used to be, because the manufacturers are making better on-demand water heaters. But in the early generations, and what we see to a lesser extent in newer generations, is if there's hot water sitting in the plumbing system, when you turn on a faucet or showerhead or fixture, you get the hot water that's already in the system. Meanwhile, at the water heater, it's taking a second to heat up. Right? An on-demand water heater, when you think about it, -- again, hats off to the technology -- it really does a pretty amazing job, when you think of everything it has to do. It has to detect a flow, it has to purge its chamber, it has to bring its heating element up to temperature, and before it actually starts producing hot water. So for several seconds, cold water will actually flow out of that water heater. What that means to the user is you turn on a fixture, first you get the hot water that was in the pipes, then you get the cold water that passed through the water heater before it really turned on, and then you get hot water again. So it's a sandwich with hot water, cold water, then hot water again. Recirc, in either case, whether or not it's a dedicated return or you're using the cold water as a return line, recirculation will help with that. In terms of sizing, it's really just an issue of -- I hesitate to give general guidance on sizing, because I think the largest influence of that is actually the pump. And I would encourage people to go with manufacturer recommendations on that.

Jamie Lyons:
Very good. Thanks, everybody, again, for joining us and dedicating part of your day to this training session on efficient hot water distribution systems. Jonah, you want to fast-forward to your contact slide, and we'll sign off with that? Just a few reminders to everybody. I reminded the group earlier of the resources available at the DOE Zero Energy Ready Home website at www.buildings.energy.gov /zero. And on this slide you can see the EPA WaterSense program website, along with contact info for today's speaker, Jonah Schein. We'll be posting this recorded webinar on the Zero Energy Ready Home website within a couple weeks, so we invite you and your colleagues to ...

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