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DOE Zero Energy Ready Home Efficient Hot Water Distribution I -- What's At Stake Webinar (Text Version)

Below is the text version of the webinar, Efficient Hot Water Distribution I -- What's At Stake, presented in January 2014.

Jamie Lyons:
We're running a series of four-hour training sessions all around the country and we started that about a year ago, and we're continuing that, and this is our Zero Energy Ready Home training series. These are great sessions. They go into the business case, the market messaging, and some of the technical specs for the program. But in that kind of format we don't quite have the ability to get as far as we would like to, and as far as many of our partners would like us to, to get into the details of some of these technical challenges. Things like how do we design energy- efficient, high-performance hot water distribution systems. So that brings us to this webinar series where we are going to spend 60 minutes, maybe 90 minutes for some topics getting into the technical details of how do we do some of these things to enable our partners to be successful.

So today we're happy to have you along for the ride on our very first technical training webinar of 2014, Energy Efficient Hot Water Distribution 1. The "1" means there is something following that, and that's going to be the "2." So about three weeks from now, I think exactly three weeks from now, our speaker Gary Klein, who I will introduce in a minute, is going to conduct the second of the two-part series. And as Lindsay mentioned on the question side, we will field your questions, and we will tackle most of them towards the end, but today we are going to focus mostly on clarification questions. Helping understand the spec, the terminology, the technical questions, and we are going to stockpile some of the design and discussion-based questions for the second webinar, which is taking place in three weeks. And further, you will get to see an email towards the end of the talk today, where if you come up with a question sometime between now and tomorrow at this time, you can email it in, and again we will stockpile those discussion-type questions, and tackle them in our second part of this two-part series.

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So what we see here on this slide is actually the language for the DOE Challenge Home hot water distribution spec. So these are the rules of the road and how the spec is articulated in our program requirements. And it is actually brought in right from the ENERGY STAR WaterSense program. So we have this limitation of how much stored water volume we can have, 0.5 gallons. And then we have a total amount of water we can get from the fixture before we have a 10-degree temperature rise. That is 0.6 gallons. And then we have some rules for which type of recirculation systems qualify, which don't. And the idea behind those is that we want recirculation to work in some systems, but we also need it to be energy efficient and not just run indefinitely, wasting, pumping energy and putting hot water water into the loop when we don't need it. So, this is what our specification looks like. Challenge Home also deals with water heater efficiency. That's not a topic of today's talk, but it's in our program requirements and it's also another very important part of an efficient, high- performance plumbing design in a home. So, if you roll all of these up, we have different components. We have our fixtures, we have our distribution system, whether it's a recirc, whether it's core-plumbing. Whether it's using a manifold system. And then we have the source of the hot water, which is going to be water heater of some type. So each of these is easy to look at in isolation bubble, but we really want to start understanding today is the end result, the performance. Do we get our hot water, do we get enough of it, do we get it fast enough? And the efficiency -- how much energy we are using, hopefully how little energy we are wasting. Both of those elements are really dependent upon not just part of the system, but all the different components as they work together. So to help us understand that, we need to look at them as a system, and that is what Gary Klein, our speaker for today, is going to help us understand. So before we turn it over to Gary, just a word about his background. Gary has been very closely involved in energy efficiency and renewable energy since the early '70s. One-fourth of his career was spent in the Kingdom of Lesotho, the rest in the United States. He is definately an internationally recognized speaker and educator. And over the past 15 years he has spoken regularly at conferences in the U.S. sponsored by groups such as ACEEE, ASHRAE, ACI and the American Society of Plumbing Engineers. He has also spoken internationally. Gary has actually been involved in developing the hot water distribution credits and requirements for programs like LEED, NHB, Build it Green, and the U.S. EPA WaterSense program. So with that, we will turn it over to Gary, who is with Affiliated International Management, to hear him help us understand energy-efficient hot water distribution for the DOE Challenge Home program. Gary, we're going to make you the presenter now.

Gary Klein:
Thank-you. And let's see ...

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So, I had a thought, Jamie, before we go any further, is that given that we've got three weeks to the next seminar, I think we can give people a whole week to come up with bright ideas and questions to ask. So why don't we make the COB as next Friday, not tomorrow.

Jamie Lyons:
That's fine. You can also type in your questions during the webinar, or you can email them to an address you will see at the end.

Gary Klein:
It is our intention to use the questions to help frame the discussion for the second webinar. So if you've got questions, you want to be sure you cover, please make sure you get them in. With that, let's move forward.

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So, we have some learning objectives for this session. Understand the relevant size of water heating compared to other end uses, and to our budget. Learn about the magnitude and variability of hot water use patterns. Know the meaning of the terms "time to tap," "volume until hot," and "it's all about the feel." Compare the Challenge Home criteria to these performance metrics. And then gain some insights into what it takes to increase customer satisfaction. The purpose of today's discussion is to get us ready for the second webinar, which is to put it all together into a good system design.

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This is what we will cover over the course of the two webinars.

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First question: How big is hot water? Well, annual energy for hot water, how much is it? There has been a great deal of debate over many, many years, and there has been some studies -- you will see some data in a little bit -- but the estimates are somewhere between 10 to 20 gallons per person per day on average. If you have teenagers, all bets are off. But you will see that there are large variations within and between households. So, under the assumptions that we are using 10 to 20 gallons per day, that is somewhere between $150 and $300 per year for water heating if you have natural gas. It's a bit more with electric resistance or propane; by the way, they tend to to be fairily similar priced in market. And then approximately $130, $150 a year for water and sewer combined. Somewhere in that ballpark. And that is based on 0.7 of a cent per gallon for water and sewer costs combined. And some of you on the phone are going to say, that's not what it costs me! It costs a lot more, it costs a lot less! I live on a well... Yep! I understand that; this is the national average for suburban areas, including, oddly enough, Los Angeles, which ought to cost more for water given where it is. But it doesn't ... So let's get some numbers here. Let's assume we are on the low end, and somewhere in the middle. We will call it $200 a year for water heating, and we will call it $100 a year for water and sewer combined. So for our discussion today, somewhere around $300 a year or so for water heating is the cost I will use. OK? Just to give us a sense for scale, that means approximately $25 a month. These numbers hold for average -- why do I say that? There are about three people in a household. So it's approximately right. If there are two people or one person, you could expect to have lower costs. If you are a family of six to seven and lots of teenagers, you could expect to have higher costs. Whatever they are, they are.

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Right now, we are somewhere in the order of $25 a month. So, it's the first or second largest residential energy use. 30% of the household's total energy pot. Well, what's No. 1? If water heating is No. 2, what's No. 1? And I would describe space conditioning. The combination of space heating and space cooling. But there are a fair number of people who are building efficient homes, and they are following the DOE Challenge Home procedures, and they are doing all sorts of stuff to do great construction on the shell and the HVAC equipment. And even in very northern climates like Vermont or Wisconsin, even parts of Alaska, water heating can be bigger than space heating and cooling. And that is a surprise to everybody. As an aside for points of reference, most of my discussion is based on single-family detached residences. For those of you that have questions specifically about multi-family, let's put those up for the discussion for next time, I will cover them. So if water heating is No. 1 and No. 2, what is No. 3? Well, if you have two refrigerators, it might be two refrigerators. And if you got your second fridge full for stored food that you either hunt, fish or otherwise store, I will give you a pass but if all you got is a couple six-packs of beer, and a few bottles of soda, I think you ought to disconnect your fridge and see if your utility will pay you to take it away. But it's probably not the fridge, and it's probably not the lights. It is probably the set top boxes that are attached to our entertainment systems. And most homes now have more than one of them. So the percentage of water heating grows as households and appliances get more efficient. How does 25 bucks a month compare to your cell phone bill? Which one's bigger? I am guessing it is the cell phone bill. How about your Internet bill? I like high-speed Internet. I know my Internet bill is higher. How about cable or satellite bill? Well, that might not be the right for this group, but I bet you know folks who have the sports package. And what about your designer coffee bill? Those of you on the East and West Coasts love their coffee a lot, and I know people who spend $25 bucks a week at their favorite coffeehouse. Even in a recession. Are you going to give up any of your cell phone, Internet, cable, or designer coffee? Nope! Why are you going to pay attention to hot water? Even though it is the first or second biggest energy use in your home.

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It's a problem of scale and relativity. And we need to keep it in context. Why do I work on hot water? One of my projects for the Energy Commission was to study the energy intensity of cold water. Looking at how many kilowatt hours are attached to the water in society. And the range in California is from 5 to 25 kilowatt hours per 1,000 gallons. But the energy intensity of hot water is roughly 50 times more energy intensive than indoor cold water. It depends on the way you heat the water, and it depends a bit on what your energy intensity of cold water is, but it's on the order of 50 times for standard average practice. You know, if you are going to work on a big problem, hot water is a big problem.

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The most valuable water to concern is hot water on the top of the tallest buildings, with the highest elevation in the area with the greatest pressure drop. If the design of energy-efficiency programs were up to me, and I wanted to work on water, I would start at the top of the tallest building in your town, and work down. Fixing hot water first, then cold water, then work your way outside. That is where you get the biggest bang for the buck.

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So some issues. Over my working lifetime, flow rates have been reduced. They were reduced either by law or by voluntary purposes for lots of things, but in the 1990s we had a federal act that went into place, one of the Energy Policy Acts, that says fix your flow rates for showers and sinks in particular we care about for this meeting, will reduce to showers 2.5 at 80 psi, and sinks 2.2-2.5 at 60 psi. So this is just -- the fixtures have increased. In general, houses have gotten bigger over the last 40 years, going from 1,600 to a little over 2,400 square foot is the U.S. median home right now. The potential for simultaneous flow is generally overestimated. It turns out that the mathematics that underlie the plumbing code, which is the next point, have not been revised since before flow rates were reduced. Hunters curves and the underlying mathematics that have been embodied in our plumbing codes were written down in the late '40s, and no one has gone back to revise the math based on current flow rates. As far as efficiency and green programs generally focus on the component, not the hot water as a system. As Jamie pointed out in the introduction, we really need to pay attention to system performance, otherwise we can do things that appear to be efficient but drive consumers nuts.

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And therefore drive us nuts because they're going to complain. So some topics. We're going to talk about flow rates and fill volumes. We'll talk about pipe insulation. We're going to talk about the volume from the source of hot water to the uses. Methods of controlling circ loops and heat traits, drain water heat recovery, water heater energy and water heater efficiency, and will vary requirements, you have to think about how that varies, other things. Oh, we need an energy rating that actually takes into account reduced hot water use. We don't currently have that.

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What are we aiming for? People want the service of hot water as efficiently as possible. It does not make sense to discuss efficiency until the desired service has been provided. Anybody remember when we introduced low-flush toilets back in the mid-'90s? First time, second time, third time's a charm? How about low-flow showerheads that felt like a mist, not like a shower? And what about those early compact fluorescent light bulbs that you had to buy harp extenders for? What's a harp and why do I need to extend it? And by the way, the light that came out of them made us all look like the wrong side of a morgue. None of those products should be considered efficient because they didn't do their job well. In my opinion, we must first do the job well, and then do it efficiently.

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So I've been interviewing people in meetings around the country and around the world for the last 15 to 20 years and I've been trying to figure out what people want in the way of services. And the services that they want for hot water are hot water now, and never run out in my shower. And there's lots of things people expect. They expect it to be safe. They expect it to be reliable. You know, they expect that stuff isn't going to hurt them and it's going to be easy to fix and it's not going to cost a whole lot. Great expectations, by the way. But what they want is hot water now and never run out in my shower. So we need to define how you get instantaneousness. And we need to define what we mean by continuousness. And ultimately, what we've learned from asking, I don't know, over 30,000 people now, people want hot water to show up pretty darn quick. And the question that we have to answer is, how quick is pretty darn quick? Is it a minute? Is it two minutes? That's going the wrong way. Is it 30 seconds, 15 seconds?Five seconds. You've got to pick some number in terms of time or volume and then work backward to design the plumbing system to provide that performance. So in relationship to the Challenge Home, then choosing the WaterSense spec, it says it's acceptable to meet the spec, if hot water shows up in 0.6 gallons, which is a little over a half a gallon, and it doesn't say anything about time. Oh, by the way, it's not actually hot water; it's a rise of 10 degrees above ambient, so you know that hot water's coming behind it. So it's actually likely that the hot water will show up in about a gallon's worth. And if you have a gallon of water coming out of the pipe, before hot water arrives, and you're moving water at a gallon a minute, which is a reasonable assumption, that means it's going to be about a minute before the hot water gets there. Is that acceptable? That's the question we have to ask and answer. What's your behavior going to be like if you have a minute of wait? If you go two gallons a minute, which is the other extreme, that might be as little as 30 seconds. But it's somewhere in the 30 second to one minute range and my question for us, and we're going to discuss it in some length, and particularly in the second meeting, is that what you want to sell your customer? Is that acceptable to you? So, it's an important question. And then continuousness has to do with having a big enough burner or a big enough tank to keep up with your shower. By the way, people tell me they don't want to run out in their shower but they want their teenagers to run out in theirs. And I think if somebody came up with an interesting parental control switch for showers, they could sell it for a lot of money. But personally, I think you ought to have a better conversation with your kids. It's not that much money to run these showers, at least I don't see it as being a huge amount. Not compared to the other things I care about in my budget. Anyway, we have to think about both of these things. And by the way, people mean they don't want to run out in their business shower. They don't really talk a whole lot about those special events on a Saturday evening with candles and special foods. What they're really interested in is their basic running-out during the work-a-day week, when they have schedules and they have to be on time.

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So what are the key components of the hot water system? There's water heaters, there's pipes there's fixtures, fittings, appliances. There's behaviors and water running down the drain. So of these five components, which is the biggest variable in determining water and energy use? Well, I'm going to vote for behavior. Was your hot water use pattern today exactly the same as it was yesterday? About the same as it will be tomorrow? Oh, I bet it's close, but it's rarely identical. You'll see that in a little bit. And then the other question is, how do the interactions among the components affect system performance? Anybody know somebody who's installed water efficient fixtures and then they bought the tankless water heater and they're in their shower, and the water goes cold. And they do that a couple mornings, and they get upset. They call the people who sold them the water heater, and the folks go back and check, and the manufacturer says oh, turn on another tap while you're taking your shower. That wasn't what people thought they were buying. They thought they were buying something that worked together. That's just another point that it's a system problem.

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This is a typical simple hot water system. You have fuel coming in to the water heater. Water comes into the water heater. Usually, hot water leaves it. They go to hot water outlets, meaning plumbing appliances and plumbing fixtures. And then energy is needed by some of them like dishwashers and washing machines, and mixed-temperature water runs down the drain. I understand why we run water down drains to go to the sewer. I got that point. But I want to know why we let it leave the building with heat still in it. We pay to heat it; why aren't we reusing -- recapturing some of that heat, and we will discuss that again next week. I mean, the next session.

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This is a typical central boiler system. We see these generally in bigger buildings. So a boiler is just a way of heating the water. The storage tank is to store it. So you've got a capacity. And then because it's a bigger building we put in a recirc loop. Not the only way to do that, but that's pretty typical. And why do we put the loop in? We wanted to bring the source of hot water closer to the fixtures. Well, one of the questions that we need to ask is, what does (inaudible) tell us about the volumes from the source to the use? Currently the 2012 International Plumbing Code says no more than 50 feet from the source to the use, and the source is either a water heater or boiler system, either one. A recirc loop or a heat traced trunk line. All of those are legitimate sources of hot water, and the code says 50 feet. The Uniform Plumbing Code, which is the other big national code, is silent on this question. You can have any number of feet. Notice that neither code says what the volume is. And it's volume times flow rate that determines time. Right? Those are relationships, and people care about the time to tap, not so much the amount of water. Well, the amount of water has to do with how much energy ultimately gets lost. All of these things have to be worked together as a system. OK? Now, the WaterSense spec that we use in Challenge Home says you can't have more than 0.5 gallons as the run-out. Well, that's interesting. Because for the 2015 International Energy Code commercial -- not residential, unfortunately -- it says no more than 0.5 gallons from the source of hot water to the angle stop or valve at the use. Which is essentially what the WaterSense spec says. And we've got the WaterSense spec coming up in 2015 for commercial building. For everything except public lavatory faucet, and public lavatory faucets are a special case. You need to be much closer to the volume of use is so much smaller and so is the flow rate.

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I have a couple of definitions. The newest one is what we call a twig, and twig serves one outlet or appliance. The diameter of the twig should be related, determined by the flow rate of the appliance that it serves. But code has minimum diameters, and they never call it a twig. Some call it a fixture branch, some call it, I don't know, another branch. When they start calling it the same thing, I'll call it what they call it. Right now, I want to call it twig. A branch serves more than one twig. A trunk serves branches and twigs, just like a tree. A main serves the building. And hot water locations usually have some cold and hot water outlets both.

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So what are residential hot water patterns? You know anybody who waits a long time to get hot water somewhere in their house? Think about yourselves, what it is. Do you wait -- anybody wait a minute or more to get hot water? Two minutes or more? Alright? Is that what you want? You know someone who's ever run out of hot water? It's called teenagers. For me, it was Thursday morning. On Thursday mornings, our school district told our kids to come to school an hour later. I've got smart kids; they got up an hour later. That put them in my shower window. And it's the middle of winter, and I'm running out of hot water just after I get finished getting all soaped up for the shower. And I'm late, and I'm paying the bills. Has anyone ever had a useless conversation with a teenager? Me, too. I decided not to have that conversation. On Thursday mornings, I got up first, took my shower before my wife, who took it second. My son took his shower third, and he never once complained about running out of hot water. He came home from college last year, and I asked him, how did he know it was time to get out of the shower when he lived at home. And without missing a beat, he says, I ran out of hot water. You give him an endless shower, he might still be in eighth grade. Pay attention to that problem. Any communities have a you-can't-build-unless-you-guarantee-a-long-term-supply-of- water ordinance? Tucson, Arizona. Legally you're not allowed to build unless you can guarantee 100-year supply of water. They're in a desert. How do you do that? Does anyone have a routine that they do while waiting for hot water to arrive at their shower or their sink, or for the dishwasher? Dishwashers need hot water. Oh, you have to be able to talk about that routine in public. Anyone want instantaneous hot water? You need to define instantaneous. And we will discuss that at some length a little later, but roughly five seconds is the maximum people seem to want to wait. I've asked 30,000 of them. And the answer comes back two to four seconds and if people got hot water within two to four seconds, they'd be thrilled every time their hot water showed up. But I think it's just as important that it be consistent as well as short. Right now, the arrival of hot water is a random event. Sometimes it's a minute. Sometimes it's five seconds. Both at the same fixture. As you move around your house, depending on the distance from the water heater, it changes throughout the day and throughout -- and depending on where you are. So, and whether you're the first or second user at that point, for the last hour or so. All of that changes the delivery time. I want to make it consistent and short and I think that's a critical thing that can be accomplished in Challenge Home. Anyone who thinks a tankless water heater's instantaneous? They're not. In fact, there are no instantaneous water heaters in the tankless category yet. Maybe one. Maybe one. Anyone think the whole house manifold plumbing system is going to save water? I haven't seen it yet. If anyone's confused about how to implement these credits well, you should be. Every one of these organizations came to me and asked for my help, and all of them have it written down slightly differently, apparently because it changes based on the name of your program. Would anyone like to learn how to get hot water to every fixture wasting no more than one cup waiting for the hot water to arrive? We will cover that, in particular in the next session. And if anyone would like to know the answer, me, too, and it's not 42.

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Alright. Here's a typical hot water event. There's a delivery phase, there's a use phase, and there's a cool-down phase. The delivery, we'd like it to be short. Right now, it's random, sometimes very long, sometimes very short, but we'd like it to be consistently short. Use is use, and I am not going to spend much time at all talking about changing people's use. We're going to give them fixtures and appliances that work well at most flow rates. If they don't work well, they'll be unhappy. And then when you turn off the tap, the temperature of the water cools down. Right? And the question is, how long does it take to cool down to an un-useful hot water temperature. And for purposes of our discussion, we've been using 105 as a useful hot water temperature. And the reason we picked 105 is that seems to be about the temperature people are willing to get in their shower. Even though the shower is not the most -- the next most likely event in a day in my use of a home, it's not hot enough for the shower, you have to run water down the drain while you wait.

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It's hot enough for washing your hands, you'll use whatever comes out. If you'd like it warmer than normal, than it will be warmer than normal. So I want to show you the results of some field studies of hot water use. You can see that they are all over the United States. They're not in every climate zone. They're not in every state. There's a few up in Canada. Which you can sort of see up here, in the upper right, the Toronto area. But lots of data.

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More than we've ever had. And the summary is this. There's 12 studies, 159 houses, 250 configurations of water heaters and end uses. This, a lot of the studies were like, we'll trade out a water heater for you know, we'll pick a storage water heater, put in a tankless, and see what we get. See what changes. That's why there's different numbers and dates. Almost 23,000 days of monitoring. 1.6 million hot water draws, and when you do the math, it works out to be 73 draws of hot water per day. And the source of this information is from Jim Lutz and Moya Melody from LBL and this is from November of 2012. So, for those of us who are data junkies, this is very exciting to have all of these studies in one spot so we can compare them. And you'll get to see the numbers in just a minute. 73 draws a day is an enormously high number. And it's hard to figure out how we get that many, but think about single lever faucets, and think about really tiny rinsing that goes on. Where you might be mixing things that come out of the water heater. You've got a single lever faucet, and if you've ever lifted it straight up, taking whatever temperature comes out, and put it back down again, and you did that for a few seconds, you just created an event at the water heater, because the valve is mixing both hot and cold in the middle position. You could be all the way to the right to get cold water only coming out of a typical mixing, single lever mixing valve. The other case is that I'm a righty, and when I want to rinse my toothbrush, the left-hand faucet is closer to my knee than the right-hand faucet is, and oh, by the way, someone's designed my bathroom such that I can't put my hand through the raised spout, so I would normally go to just the left-hand faucet, which is the hot. And I'm just going to rinse whatever comes out. I don't really care. I'm not looking for the temperature; I just need water. And you have to consciously think about making changes in your patterns to get the numbers down.

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Real hot water draws a day, for things that you really want -- people really want hot water, are significantly less than 73. So a lot of the data that we're going to look at in a minute, Jim's primary work over the last 15, 20 years, has been to support the Department of Energy in developing standards for water heating. And so one of the things he's paid attention to is the DOE test pattern, which says 64 gallons -- 64.3 gallons per day -- divided into 6 equal draws of 10.72 gallons per draw, you run the water at 3 gallons a minute, which means you get 3.6 minutes per draw. You do that once each hour for the first six hours, and then you wait 18 hours, and you repeat the test. And the question that's been in our minds for many years is, well, what relationship does that have to anything that's hot water use? Well, it turns out, not much, but it provides some useful background for us to look at the data.

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So here's the daily hot water use. And you'll notice that there's a cross-over here on the left. And that crosses at 6 draws per day and 64.3 gallons. And you'll notice that that cross doesn't seem to have a whole lot to do with any of the numbers, the little circles in this chart. And there's 22,000 days plotted here. I look at some of the outliers. Look over here at this house. There's 450 or so draws a day, representing about 40 gallons. I have no idea what they were doing. I don't get it. How about this one here, 275 gallons and 275 draws. Again, huge thing. And a whole bunch. Most of the data set is down here in the small end of the segment.

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Median daily hot water use, another look at the same basic data. Again, the DOE test pattern is out in the field and not related to anybody. And let's look at one of the big 500-day circles. There's 500 days of data where it's about 50 draws little over 50 draws, little under 50 gallons a day.

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Same data set, the bulk of the configurations are using less than 44 gallons per day, and if you take the DOE test procedure here, almost two-thirds of all households in the sample are using less than 64 gallons a day. So there's debate as to why we have those numbers.

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So let's look at this one. How big are the draws? The reason we're going through this stuff -- I'm going to take an aside -- is that if we don't understand what the patterns are, it's really hard to design hot water systems that will meet those patterns, given that we really don't know what the next user's going to do. I've had some people talk to me about, in ways it sounds like they're planning to design plumbing systems, and water heating systems, such that when the occupant leaves, they'll take it out and bring a new one in for the next occupant. I just don't think that's very realistic. I think we are going to build them and they're going to be with the house for 50 to 100 years. We better start paying attention to the way the patterns work and do some predictive thinking about how those might change over the next 50 to 100 years, so that we can future-proof our buildings and still be high-performance. So the DOE test procedure says 10 to 11 gallons per draw. And if you take the red line and cross the green line, which is the average of the sample, you will find that at 10 gallons per draw is the 97th percentile, so 97 percent of the time, hot water use is less than 10 gallons per event. What events are bigger than 10 gallons? Let's see, showers might be. Filling bathtubs. And old washing machines that had a big bucket and pretty much one size fits all with the water volume. That's about it. By the way, for showers, it includes the waste while you wait for the hot water to get there. OK? So all of that is there. Let's go down to the other end. Half of all draws are less than a pint. One of those water bottles we all carry around. So a large number of very small draws. A very small number of very large draws.

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How long is each draw? Well, the DOE test was done in about three and a half minutes, and it works out where the red line crosses the green line looks to me to be about 88th percentile, so 88 percent of the time the draws are less than three minutes long. Well, what draws are longer than three, four minutes long? Taking showers, filling bathtubs, and filling old washing machines. And there might be some case that you could make for filling new washing machines and filling new dishwashers, because the flow rates are so much lower than they used to be. And all of these are possible in the sample. Half of all draws are less than one minute long.

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There's not a lot of big, long draws. How much time between draws? The DOE test is an hour apart. So, and then you wait 18 hours and repeat the test. And so, taking the hour-apart category and running the red line over to the green line and projecting down, it looks like the 92 percentile, and so we're in here, at the 92nd percentile. 92 percent of all events are less than an hour apart. What events are more than an hour apart? Well, I bet some of you went to bed last night and got up more than an hour later and used hot water at both ends. That qualifies. And if you're off to work today and you left home, and you're not going to be near the house, you're not going to use hot water at home during the day and you come back eight hours later, well, there you go; that's another one. And then on weekends, you get up in the morning, you leave, you go out and you know, out and about, you come back for lunch, you go out and about in the afternoon, come back again. Those events are more than an hour apart. And I work from home. If I take a break more than an hour apart, such as on this webinar, and I use hot water before and after, that would be more than an hour apart, too. But they only represent 7 or 8 percent of all events. Half of all events are less than three minutes apart. And what that tells me is draws are highly clustered. The second thing it tells me is that pipe insulation will help us improve performance of hot water systems for all draws up to an hour apart.

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I'll cover that in more detail later. What are the flow rates? The DOE test was done at three gallons per minute. Now, the three-gallon-per-minute line crosses at the 97th percentile. This blue line is for showers at two and a half gallons per minute. That's for sinks at 2.2, and they cross at 94 to 96 percent, and half of all events are less than a gallon a minute. So what events are bigger than three gallons a minute? Filling -- separate, stand-alone bathtubs, filling old washing machines, and two or more things, maybe three operating simultaneously. But 95 percent of the time you can predict that only one legal device is likely to be operating at a time in a home. So what do we need, one and a quarter inch supply lines on the piping? One-inch supply lines on the piping for hot water? There's a lot of debate going on in the industry about what the means and how to fix it. It's not yet ready for primetime.

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Inlet water temperatures. The test sample is from all over North America, the U.S. and Canada, at least parts of it, and the inlet temperature for our test was 57.5. Sorry, 57.6. And the DOE inlet temperature is 57.5. I just say we got lucky. But look at all these temperatures. When the inlet temperature is coming in at 75, 80, 100 degrees -- how is it possible that a day's worth of data in the hot water use is coming in at over 100 degrees Fahreinheit? To our knowledge, none of the houses have solar thermal. This is all other cases. Anyway, think about that.

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So in California we did a three-year program recently. Gas Technology Institute did the work. It was funded by the California Energy Commission. We've done some field studies, some lab studies, and I want to show you the hot water use patterns in 18 homes.

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Here's the daily hot water use. L.A. means Los Angeles area. San Diego and then PG means (inaudible) territory mostly between San Francisco and Sacramento is the area that the houses came from. Notice that -- the key. Greater than 100 gallons a day, less than 10 gallons per day, everything else in the middle, and let's look at the average. So the average house used about 56 gallons per day and had almost four occupants in it. So, and you'll see that each in the average, there are 100-gallon-per-day days and less- than-10-gallon per-day days. How do you get a less-than-10- gallon-per-day day? Has anybody ever taken a short vacation? Left nobody at home? Well, if you leave no one at home, you ought not to use any hot water and you would show less than 10 gallons. And then you come back from that field trip, with all the family and the camping gear, and you've got to wash it all and that gets you your 100-gallon-per-day day. I have no idea what's going on in PG2. I think there might be a lot of people in that particular case. But I want to take your attention over here to LA6, and you can see in LA6 that even though they only use on average 25 gallons per day, there's 100-gallon-per-day day in their data. At least one of them in their average. Huh. So even if you're a relatively small user, you could have big days. And even if you're a relatively big user, you could have small days. We need to design for that. And you'll notice here the standard deviations are very large.

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It's easier to see on the next graph. When the standard deviation of something is sort of equal to the mean, you know it's not a controlled situation. And here is a case where hot water use varies both within and among households in very, very large amounts. OK? And we have to learn to design for it.

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So to summarize this stuff. How do we use hot water? Frequent, short, low flow rate draws. Occasional long draws at low flow rates. High flow rate and high volume draws are rare. As are simultaneous draws, and draws are highly clustered.

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These are the simple, basic principles by which we need to understand how to design hot water systems for occupants.

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I'm going to go quickly through some things with fixtures and flow rates. Kitchen, you can see that the peak flow rate for the kitchen is around 1.4 gallons per minute. OK? And yet the legal fixture was 2.2. We rarely use sinks at full flow.

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Lavatory faucets is at 1.2 instead of 2.2, or 1.4 it's a little bit less. Has to do with what we do in the bathroom as opposed to the kitchen.

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Showers, the average volume of the showers in this study was almost -- was almost 14 gallons per shower with a standard deviation of 9. Lots of variability.

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Time and temperature at master bath sink. Look at all these events when the hot water never arrives. Started out at around 70, ended up around 70, as much as 30 seconds or so into the event. It was still -- they were done, and it still hadn't reached the fixture. Here's a case where you can see the hot water events got there -- hot water got there. They waited long enough for it to arrive and then they used it past the arrival time. And here's a bunch of events where the hot water was there immediately. Remember I said it was sort of a random event? This is a case where coming in second wins. Because if someone else has used a fixture before you have, and they got hot water to it, like here, then if you're the next user, you get the benefit of having hot water there. By the way, this fixture in the master bedroom is approximately 50 feet of three-quarter-inch pipe and another 5 feet of half-inch pipe away from the water heater.

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So another question for us to consider: How long should we wait? What's an acceptable wait time? So, the Challenge Home spec says you can't have more than 64 ounces in the pipe and you can't wait more than 0.6 gallons, which is a bit more -- 72 ounces or something like that, for the water to actually rise 10 degrees. OK? I would say that's not actually hot, so we'll use the 64- ounce number just to work with. Well, if you've got 64 ounces in the pipe, and it's a gallon a minute, and you clear it out it's going to take 30 seconds. It it'stwo gallons a minute it will take 15 seconds. Not bad. But what's happening with the flow rates of the fixtures we're putting in the Challenge Home? They're going down. Right? I think we should be designing things based on the one-gallon-per-minute number, because that's a typical use at sinks. And we're headed that way for showers. We're not going to get down to a gallon in the near future, but we might in time -- kind of the plumbing in the home. But where do these green and yellow and red things come from? They come from a conversion that I did from an ASPE document -- American Society of Plumbing Engineers, which has a design manual that their engineers are supposed to use for designing buildings that they've designed. And they decided that acceptable performance is up to 10 seconds, marginal is up to 30, and unacceptable is greater than 31. And I would say that we ought not to design buildings that have unacceptable performance. We do. How many feet of pipe does it take to get out here where you've got more than a gallon of water in the plumbing? You need to know your pipe sizes. It turns out that water waste is really a function of flow rates.

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Water waste is a function of flow rate -- it's really the velocity, what I mean to say. And what we've found is that as your flow rate goes down for a given size pipe, the amount of waste of water before the hot water gets there goes up. And the velocity is going down. And so the slower you move the water in the pipe, the more heat it gives up, and if you move it slow enough and long enough in a bad enough environment, it'll never get there.

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This chart is to look at the gallons wasted as a function of time and fixture flow rate. Again, it's a way to convert flow rate and time and gallons all into things that are measurable and comparable. Everything in green is less than two cups. Everything in red is more than a half a gallon. And I suggest to you we should always be designing for aiming for less than two cups waiting for the hot water to arrive and settle for something in the middle. I don't think we should be designing for half-gallon waits and waste. I think we have to do better than the minimum allowed in the Challenge Home. That's Gary speaking personally here.

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This is looking at the gallons wasted again, and we can do an example. If you are at a fixture and you measure 15 seconds and a half a gallon comes out, then you know that the flow rate was two gallons a minute. Fair enough. But there's less water in the pipe than a half a gallon, because you have to clear out the whole pipe plus a bit, and so, if imagine you go to a one gallon per minute flow rate, it's actually going to take more time and waste more water than you would have at two gallons per minute. And my belief and my understanding is that fixture flow rates are going down, not up. Over the life of the plumbing in new homes it's going to be going down, not up, and we ought to future-proof the building.

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I'm going to skip these, just a moment, and skip here.

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It's all about the feel, not the flow rate. Here's an example of three different aerated streams. Each of you has a preference. I have mine. I personally like the one in the middle, the laminer stream. I want to feel the water on my hands. And within reason, you can get both of these at any flow rate about one gallon per minute and above. This was typically only made for flow rates less than a gallon a minute, and it's used in public lavatory faucets. I've had some aerated streams that felt so dry I couldn't tell I was getting water. You want to have it feel right.

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And then the second point is that, have any of you ever been in a situation where you're taking a shower and it sort of felt really wimpy? And then later, you know, you took a shower at a different time of day in the same place and it felt just fine. Well, it turns out that fixed orifice aerators, which are most common, follow this pressure flow curve. At 60 psi you're allowed 2.2 gallons per minute. By law, it can't be more than that. But if the pressure is at 80 psi, you can have 2.5 gallons a minute, and if it's 30 psi, you're going to get 1.25 gallons a minute. Follow this curve. There's a device called a pressure compensating aerator, which gives you rated performance at any pressure above 25 psi. And the reason this is important is that you don't know at any given time at any given hour of day what is going on in pressure in your home or your building. The city supplies pressure or your pressure pump supplies pressure. But depending on what's going on around you over which you might have no control, your local pressure can vary rather enormously. And what you want is to have the rated performance happen under most conditions. Pressure compensating aerators are a way to improve systems with essentially zero marginal cost. Most of the U.S. manufacturers of showers, for example, I've been checking recently, are selling all of their products with WaterSense specification in their showerheads.

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Which means that they're going to have pressure compensating aerators in them. OK. So I'm ready for questions.

Jamie Lyons:
OK, Gary. Thank-you for walking us through sort of the basics, the metrics, and the design parameters that determine performance and efficiency. And I'm happy to say I think you did such a good job, we have no questions at this point. Believe it or not. I have a feeling we'll want to stockpile some more, so let me point out a couple resources for the group before we wrap up here in a couple minutes.

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It's going to be two websites. Here we go. The first is buildings.energy.gov/challenge. And that's the DOE Challenge Home main website. There's a lot of good information there. A couple key points to show is the events tab, which is over on the left. So that's -- that will take you to those in-person training seminars that I mentioned at the outset here. And it will also relate what the upcoming schedule for technical training webinars. As I said earlier, we'll be going though a whole series of those in 2014 covering topics like this, HVAC, ductwork, and so on. And just as a reminder, part 2 of today's training will take place three weeks from today. Also on the Challenge Home website, there's a partner locator to locate our builder partners and rater partners. The program specifications are located there, as well. And then also, recordings of webinars just like this one will be posted probably by the end of this month, middle of February at the latest. So our intent with all these -- all these webinars is to invite partners like yourself to join us but if you can't be here live, this content will be made available in a recording format on our website. And the second website to note there is the Building America Solution Center. That is a resource which DOE launched in 2013 which does a really fantastic job of organizing an immense amount of research findings and recommendations for the building industry and putting them into a format that's far more navigable and searchable and easy for industry stakeholders to make sense of. So you can navigate it through different tools, find information, technical guidance, specs, right vs. wrong photos, and many other layers of information on building systems. So I wanted to point that out, as well. And that's at basc.pnnl.gov.

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So with that, on behalf of DOE and Gary Klein and our staff here, thank-you for joining us today. You can see the invitation there and the little -- on the right side, which notes the time and date for the follow-on webinar as part of this series. And again, if you have questions which pop up, which you'd like to have looked at in that second webinar we're having, you can email them to doechallengehome@ newportpartnersllc.com. Thanks for joining us very much. Bye-bye.