Below is the text version of the webinar Low Load HVAC in Zero Energy Ready Homes, presented in January 2016. Watch the presentation.

Lindsay Parker:
Hi, everyone. Welcome to the Department of Energy Zero Energy Ready Home technical training webinar series. We're very excited that you can join us today for this session on low-load HVAC for Zero Energy Ready Homes, presented by Greg Cobb, president and CEO of iEngineer, LLC. Today's session is one in a continuing series of technical training webinars to support our partners in designing and building Zero Energy Ready Homes. My name is Lindsay Parker. I'm the coordination support for the program, and I'll be covering some general notes on webinar housekeeping. All attendees will be on listen-only mode, however, we do invite you to ask questions during the webinar in the questions application on the GoToMeeting program. At the end of the webinar, we'll be covering the questions, and we'll try to cover as many of them as we can. This session will be recorded, and the recording will be placed on the resources page of the Zero Energy Ready Home website. Please allow some time for this, as it does take a couple of weeks to process. But in the meantime, I will be sending out an email to everyone who is registered with a PDF of the presentation for your reference, as well as information on upcoming webinars. Now I'm going to hand it over to Sam Rashkin, chief architect at DOE and director of Zero Energy Ready Home program, to tell you more about the program and introduce Greg.

Sam Rashkin:
Welcome, everyone, to the webinar.

First slide:
Again, the purpose of these webinars is that we're so anxious to make sure that our stakeholders understand everything that's asked of builders to do for Zero Energy Ready Home's really off-the-shelf solutions, proven innovations that really entail not taking any risk on something completely new. And these webinars give us a chance to showcase the ready-made ways to apply new technologies and best practices that help you achieve the program requirements. And today does just that. In every Zero Energy Ready Home, the heating-cooling loads are so reduced that you have to start thinking about how to make sure your system works and delivers comfort at all times. It's not the same beast as a typical, inefficient home. In fact, even if you're building a code home, these kinds of good, high-performance systems are also critically important. And so that's why we're here today. Low-load heating-cooling systems that work are critical to the Zero Energy Ready Homes. And we have a great, great expert to give you really good advice today. Greg Cobb is the president and CEO of iEngineer, LLC, based in Phoenix. iEngineer provides HVAC design services throughout the U.S. They have a focus on energy efficiency and have designed thousands of HVAC systems for ENERGY STAR®, Environments for Living, Zero Energy Ready, and other above-code programs. Greg has also helped developed intelligent fresh-air ventilation systems in the ASHRAE 62.2 that very importantly are low-cost, energy-efficient, and they shift the ventilation load to off-peak hours and manage inbound humidity, again, a critical issue in many climates. He's also president and board member of the Energy and Environmental Building Alliance and a past member of the Advanced Energy HVAC Advisory Board. OK, that's the traditional background. Just a few points before I hand off to Greg why he's such a great speaker today on the webinar. It's easy for many experts to come talk from just being someone who thinks theoretically, but Greg is out there hands-on, working with builders around the country on solutions that are actually being applied, solutions that meet very critical budget and cost objectives, and solutions that can be consistent with the capabilities of the HVAC industry today. So hearing from Greg is hearing from someone who's not just preaching what to do but is out there walking the talk and making it happen. So he's just a great resource to have. I hope you all enjoy his presentation, and I'm going to hand it off to Greg.

Greg Cobb:
Thank-you, Sam. Alright, we'll switch over the screens.

Next slide:
Well, good day, everyone. Appreciate you taking the time to go through the webinar today. And Sam, thank-you for that introduction. We'll walk through the presentation. Lindsay, when did you want to go through the poll questions?

Lindsay Parker:
Whenever you're ready.

Greg Cobb:
Why don't we start off with those? We can get a sense of who all is on the call and what issues they'd like to cover. So why don't we go through the poll questions now.

Lindsay Parker:
Sounds great. Alright, so the first poll question we're asking everyone is, who is on the poll today?

First poll slide:
So your option is either builder, energy rater, architect or engineer, manufacturer, or code official. I'll give everyone just a little bit of time to answer those, and then we'll see the results. ... Alright, thank-you so much. I'm going to go ahead and close the poll.

First poll results slide:
And so everyone can see it, seems like about 42 percent of everyone here is an architect or engineer, 19 percent are builders, 28 percent are energy raters, 6 percent are manufacturers, and 5 present are code officials. Thank-you so much for submitting your information.

Second poll slide:
The next one we have is, what regions of the country do you operate in? And with this one, you can select more than one choice, if you travel or work in different areas. Northeast, mid-Atlantic or Southeast, Midwest, Southwest, Texas, California, or the Northwest, Northern California. ... Alright, thank-you, I'm going to go ahead and close the poll.

Second poll results slide:
Seems that it's all pretty evenly split. About 42 percent are from the Midwest, 47 are from the mid-Atlantic or Southwest, 28 percent are evenly split between the Midwest and Southwest, or Texas or southern California, and 21 percent are from the Northwest.

Sam Rashkin:
So the earlier you have to wake up for this webinar, the less likely you are to attend.

Lindsay Parker:
Now we know. Alright, there's two more poll questions.

Third poll slide:
This one is, what HVAC challenges are you facing currently? You can select more than one. Could be either equipment sizing, room-to-room comfort, ventilation, humidity, or insulation or conditioning quality. ... Alright, thank-you for submitting your responses. I'm going to go ahead and close the poll.

Third poll results slide:
Seems that 58 percent are dealing with equipment-sizing issues, 48 percent are having room-to-room or comfort or airflow issues, 65, the majority are having ventilation issues, 46 percent are dealing with humidity challenges, and 42 percent are having insulation issues. So it seems like Greg has a lot to talk about.

Greg Cobb:
We're not going to be bored.

Lindsay Parker:
The last poll that we have is, what types of projects do you work on?

Fourth poll slide:
And you can also select multiple options. Single-family / entry-level, move-up, luxury homes, custom homes, and multifamily. ... Alright. Thank-you so much for submitting your responses. I'm going to close the poll and share it.

Fourth poll results slide:
It also seems pretty varied. The majority is single-family custom homes, with the runner-up being single-family / entry-level. There also seems to be several multifamily people on the call today, and 51 percent with move-up, and 38 percent of luxury. So thank-you, everyone, for participating, and that gives us a really great way to see who's on the call.

Greg Cobb:
Great; thanks, Lindsay. Alright. Everyone see this screen now?

Next slide:
OK. So going through the overview and objectives for today, we're going to start off with describing what has changed, that's driven the need for more attention than in the past for really understanding how HVAC systems are designed and commissioned. Next we're going to go to looking at HVAC design execution -- what are the steps that you should follow to get good results? We'll go over some pitfalls to avoid. There's plenty of those out there. Some challenges in doing this right, in getting not just good results but happy homeowners, as well. Then looking to the future -- what other changes are coming? So that's the overview of where we're headed.

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Starting off with what has changed. If you look at the graph on the right, the key thing that you can see is over time, the load in homes has been going down, because the construction quality has been going up. The biggest driver of that has been windows, insulation and really ensuring that we have much less envelope leakage than in the past, paying attention to duct gain and leakage. So all of that has been driving the load down. The opposite effect is looking at ventilation load; that's something that's been relatively new in the production home arena of trying to increase ventilation. And so that's increasing load, while the others are going down. And so what the net result is, we have a much larger amount of conditioned square feet that's covered by a single system than we have in the past. Also, homeowners are using their homes a little differently. The number of appliances, the lifestyle, the density that we're living in is changing, as well. However, homeowner expectations have not changed. So even though we are now not able to manage the envelope with a much-smaller system, homeowners may still treat their equipment as if it was an old, leaky house with an oversized system, so they will allow the temperature to drift up 10 degrees and move their thermostat and say I want it to cool down 15 degrees in half an hour, and the systems aren't sized to do that, of course. So even though the envelope has changed, and the equipment has changed, the homeowner expectations have not. So we need to work on that to make sure we get a good result. On the chart you may see that there's ventilation load in the 2009 code-built home, but not in the ENERGY STAR version 3 home on the far right. The ventilation load is there but it's using a time-shift technique to remove that load from the peak load that you size your equipment on. We'll touch base on that when we get to the ventilation section.

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So here are the key steps to ensuring that HVAC systems can be designed and executed well. Five steps. And these are things that are -- some of it is the basics, but we'll drill into some of the details of when you're doing a Zero Energy Ready Home, which has an even more pronounced effect than what we displayed on the ENERGY STAR Version 3 home previously. What are some of the key things you need to pay attention to when you're building homes to that standard? So the five key steps are: Making sure you have an accurate load, size your equipment properly, have a well-designed and balanced duct system, the proper controls in place, and then of course, integrating ventilation into that overall system. So starting with the load. We would recommend that you have a room-level, configuration-specific Manual J calculation. So what does that mean? So running a Manual J on a individual plan, if that plan is going to be built in multiple configurations. So maybe in a community of multiple lots with different solar orientations, it can have different options included, adding square footage, adding glazing space. So really making sure that your Manual J calculation is room-level, so it's not just a block load, and is also specific to the configuration that you're going to build the home. So there's different ways to do that. So you have to really pay attention to those options -- floor plan and glazing. Also, your orientation -- solar orientation -- if you can build your home in a near configuration, garage right or garage left. So here are some best practices in doing that.

There's a group design approach, which is, you do a set of heat loads, using the most common configurations of the home. And if the configurations are very close, then you group those other configurations into those sets of loads, instead of running a specific load for each lot. Next, if you're doing an actual -- most common if you're doing entry-level homes, just to keep things simple and low-cost. Next, if you're in a move-up category, we'll show on the next slide a layer-cake design approach where you calculate the load impact of each of the different options as the different configurations, and you're able to stitch those together when a specific lot comes up. That way you can have a customized load and target air flows for each lot. Then, of course, if you're in the luxury arena or you're building custom homes where it's hard to predict the different options where a plan can be built, or it may be built only one time, then of course, you determine that design specific for that lot.

Next slide:
So if you're looking at a layer-cake method of design, what does that mean? So what it means is if you take a base house, which is shown in this bar graph along the bottom, that's the base load of the standard house. And looking at that at eight different orientations to the sun. Then if you see the different options that can be added to that home, those options will have a different load, as well, based upon the different orientations available. So you can see the total load will differ based upon which options are selected and which orientation that home is at. On the far right you can see here is what the equipment capacity will provide. So for a house that has a south orientation and is only the base design, well, a two-and-a-half-ton unit would be able to cover that house's total load. Whereas if you are at a southeast orientation and you have all options, the house is fully loaded up, well, it's going to need to go all the way to a three-and-a-half-ton unit, to satisfy the needs of that house. This allows you to dial in very rapidly to what size of equipment should I use based upon the options that were selected and which orientation the home is at. You don't have to calculate every possible configuration up-front, which could go into the thousands of potential combinations; using this layer-cake approach you can rapidly determine what size of equipment do you need for your specific lot.

Next slide:
So getting to equipment size, you now have your layer-cake approach, where you've calculated your exact load for that load. Now we need a configuration-specific Manual S. So you have your load; now you want to calculate what equipment should I use. And so it's not just using the HRI capacities, which is at a single design condition, you want to use the manufacturer's extended ratings published data for the exact conditions for where that home that will live. So if you are in the Northeast, it will be very different that if you're in the desert Southwest, as far as the capacity that the equipment can provide. So making sure your designer uses that approach. What type of equipment should you use? So if you are doing entry-level homes, usually budget determines that you're going to have to use traditional, single-capacity equipment. If you are building move-up homes, then of course, exploring a move to dual-capacity equipment is a very high recommendation, particularly if you're in humid climates. Those shoulder seasons where you don't have a lot of cooling load but you do have high levels of humidity, being able to operate the HVAC equipment at a lower level of capacity to get longer run times, to help remove some of that indoor moisture is key. So that will be a good investment to improve the overall comfort of the home, as well as its durability, ensuring that you maintain good indoor humidity levels. Then if you're going to a luxury level or custom homes, you may want to consider using variable- capacity equipment. Inverter-driven technology now allows equipment to step up or down in one percent increments, allowing you to have very precise control of temperature, which at the same time helps in managing humidity because you get much longer run times at much lower electricity consumption levels. So while that equipment is expensive, it provides great results for homeowners in managing both humidity and temperature. If you're doing something at a more extreme level -- say you're building to Passive House standards -- then you may be looking at multizone mini-splits. If you're trying to eliminate ductwork to try and have an even tighter system and fewer penetrations into the envelope, then consider using mini-splits, because that's another great technology that's available in sizing that equipment to that specific load, which would be a very low-load home indeed.

Next slide:
So assuming you're not using mini-splits, the third step is if using conventional equipment, you need to design your duct system. And this is one of the most critical components of design of HVAC systems. If you size your equipment correctly based upon the lot-specific load, then getting the right amount of air flow to each room is critical. That is the part that allows you to size equipment properly, and still maintain comfort. This is usually the Achilles heel. If you hear people talk about, oh, you can't use Manual J; it doesn't work, we have hot rooms and cold rooms. Manual J has nothing to do with hot rooms and cold rooms. It has to do with what's the total load and what -- Manual S is how you size your equipment. Manual D determines how do you get the right amount of air to each room. So with a room-level configuration- specific Manual J, you can then do that. You should know, here's my target air flow in every room for this specific house. So if you have a lot of glass in a particular room, and that room happens to be facing west in one configuration and north in another, the equipment size may be the same, but the air flow to that room can be dramatically different. And that air that when that room is facing north, it may need much less air flow, and that air is going to be needed in another room. So having a lot-specific Manual D is very important. Of course, the manufacturers publish data not just for how the equipment's capacity performs but also their blowers. So how much air flow will a particular blower provide, at a defined level of static pressure? And then they publish coil data, which shows, here's how much static pressure this coil will have, whether it's either dry or wet depending upon the season. That is the information you can use as a designer to calculate, here's the total air flow I can get out of this system, tie it in with your capacity that you're expected from your Manual S. So again, your designer should be doing all of that math in the background to make sure that the right amount of air flow is being used to get the capacity you need, and that capacity is being delivered to each room.

So how do they do that? We highly recommend a compact duct design, particularly if you are in a slab-on-grade area where your ductwork is in the attic, trying to keep those duct systems as short of runs as possible to minimize heat gains, in a vented attic. If you are doing cathedralized insulation, that's much preferred. Still prefer to have a compact duct system, because the shorter runs allow for less static pressure and less consumption of electricity by the blower. If you are in an area where it's basements or crawl spaces where the air flow is coming up from underneath the floor, less ability to have a compact duct design; still may need to put it out toward the extremities of the house, but where possible, if it's wall registers or otherwise, using that compact design to throw the air across the room. So there you have to pay closer attention to the registers. What is the size of your register, what's the design of it, so you get the right amount of air flow within a room and throughout the room to ensure proper comfort. Building entry-level homes, you want a fairly simple duct design that you're able to use in that more budget house and multiple configurations. You're probably going to be a little more budget- conscious on your contractor you're selecting, so the ability to be custom on a per-lot basis may be restricted. In those scenarios, we recommend what we call a loose duct design. So the ducts are sized so that they will be able to handle the amount of air necessary in the peak condition if that room were at its worst case configuration. That way you will not have high static pressure if that room is -- you're trying to put the proper amount of air into that room. Then what you would use is balancing dampers. And those dampers are placed throughout the duct system to route air throughout the system. And those are adjusted at the time of startup by the startup technician. So you're not able to design in a balanced system; you design in a more standard, loose system that can be adjusted at startup. However, if you're building move-up homes or if you're going into the luxury / custom arena, we absolutely recommend that you do a lot-specific balanced duct design. The duct system will often outlive multiple iterations of equipment. So if you have equipment that lasts 10, 12, 15 years, then that equipment can go through two or three replacement cycles before the duct system is ever touched. So you really should put the time and energy into building that duct system right out of the gate. So designing a balanced duct system is the key to ensuring that the right amount of air flow is reaching each room.

Next slide:
Fourth step is controls. It's key to pay attention to where you locate your controls, not just what type you have. Whether it's your thermostat or it's remote temperature sensors, you do not want to place those controls where they will be in the airstream of the supply duct. Now if it's blowing hot or cold air across the T-stat, of course, it will not sense the proper temperature within the room. Also, you want to avoid locations where direct sunlight or other things can cause the thermostat to sense something other than what's the true temperature of the space that it's conditioning. Here's another thing that many people really don't think about, of how their T-stat should be used. We recommend a set-it-and-forget-it approach. If you're building a Zero Energy Ready Home, you're going to have a very low-load home. If your equipment is sized correctly, you don't have immense amounts of excess capacity to catch up with if the house does get into an uncomfortable condition. So homeowners that treat a low-load home the same as they did their old leaky house with an oversized HVAC system do not get the best results. So we recommend to people that they do not program their thermostats. If they do, it would only be no more than 2 or 3 degrees from what they would consider a comfortable temperature. If someone sets their thermostat to go 10 degrees from their comfort point during the daytime, and when they get home in the afternoon in the summer and expect it to cool down quickly, or vice-versa, with the heat up in the wintertime, they're going to struggle. Because that HVAC system doesn't have that excess amount of capacity now to catch up quickly. So it can create comfort calls. So again, we found that particularly in areas that have a time of use metering, that it's much better to have a set-it-and- forget-it approach instead of the extremes, because right at the time when the utility costs are at their worst, that's when your HVAC system will be struggling to catch up, and it will be running nonstop, in its least-efficient mode. So we recommend a set-it-and-forget-it approach. Also on controls, today mobile connectivity is often expected. Some sort of remote access through a smart phone app is very common. Every time a homeowner walks in a Home Depot or a Best Buy, they see these wi-fi enabled thermostats, so when they buy a new home, they're often going to expect that, as well. One comment is that you stay away from highly intelligent thermostats that are designed for older leaky homes. And NEST is a good example. Great product, very smart on helping homeowners manage the costs, if they have an older, inefficient house with an oversized HVAC system, because it learns how you live and it will turn your system on and off and allow temperatures to drift, and it will manage that process for you in the background. It is not designed for a low-load home with a right-sized HVAC system. So we have actually had challenges of homeowners that are fighting the NEST logic, because it's trying to anticipate how their house should perform, and it has created more challenges than it has been worth. So actually we would recommend if you're building high-efficiency homes, to not go that direction.

So what are some best practices here? Remote temperature sensors are a great way to allow a broader space to be kept comfortable, because now that you have a much more square footage that's covered by an HVAC system than in the past; thermostats can be a long distance away from where the sources of heat or cooling are needed. So with remote temperature sensors, your T-stat can sense what's going on in those other rooms and cycle when necessary to maintain comfort without adding the extra complexity of zone systems or multiple units. If you're going to a move-up home, then zoning is a way, if you're -- particularly in larger homes, certainly on multilevel homes -- that you would use zoning to route air from one area of the house to the other. So even if you have one system, zoning allows you to direct that air to specific regions of the house that need the cooling as the sun goes across the sky during the day, or at night if you have different areas that need more heating than others. If you're moving to a luxury or custom homes, often you're using the higher-end equipment. If you're using the variable-capacity equipment, there you need to use the manufacturer- specific thermostats, because they're a communicating system. It's communicating with the outdoor units and the indoor units, so they are ramping up and down in small increments all the time. So combining that with the zoning allows you to have very precise control of the temperature and humidity in each area of the home.

Next slide:
Step 5, ventilation. So here we recommend smart ventilation to meet the ASHRAE 62.2 level of ventilation that's the international standard. So how do you provide smart ventilation? We all know that if you're building a tight envelope and you are ensuring that you are controlling the air flows across the air barriers and thermal barriers, then when do you bring that ventilation in, is critical to ensuring comfort and ensuring you have a good energy efficiency. So a time shift in your load with smart controls that are sensing what is going on with the outdoor conditions, or what is going on with utility rates, allows you to time when you provide ASHRAE 62.2, so that you can avoid peak periods. You still want to ensure that you are providing the proper amount of air flow and consistently enough throughout the day, so that you maintain the level of contaminants at a low enough threshold. But time shifting allows you to do so with a little more intelligence for energy efficiency. You want to have a climate-specific strategy on how you bring that air in. It is going to vary based upon, if you are in a cold climate, you're in a warm-humid climate, or warm-dry climate, or otherwise, or mixed, whether you're doing a supply approach, an exhaust approach, or balanced. So again, you just have to pay close attention to what's happening. You do not want to draw -- you do not want to push warm, relatively moist air through your building envelope in a cold climate that could create condensation or even frost within your building structure. So you would not want to do a supply-based approach in a cold climate that could cause that. Likewise, you would not be concerned at all if you're in a warm-dry climate of pushing cooler, drier air through your building envelope. So a supply approach in a warm climate is just fine. A dehumidifying ventilator is something that we highly recommend if you're in a humid climate. Gulf Coast states, areas that have high periods of humidity, not just in the summertime. Summertime usually if you have the properly sized equipment, you get plenty of moisture removal from the HVAC equipment itself. It's really the shoulder seasons. It's the spring and fall where you have those days that are in the 60s or 70s with 80-percent-plus relative humidity outdoors. Don't have a significant amount of sensible loads, your HVAC system is not running, or maybe even in heating mode because overnight you need just a little bit of heat. So if you're bringing in that type of air, and you're not managing that moisture, you can easily get indoor RH levels well above 60 percent, to the point where you're outside the comfort zone and into the range where it can be harmful to not just the occupants, but also to the structure, potentially growing mold or other things. So there are now products available that provide ASHRAE 62.2 levels of ventilation. They're smart about when to bring it in, and they also have the ability to strip out moisture before it comes in. That way you have -- you maintain your indoor environment. With your HVAC system controlling your temperature, and then via dehumidifying ventilator ensuring that you're not repeating moisture levels. If you're ventilating in cold climates, then you may want to consider adding a humidifier, of course, with the same objective: Let's maintain a healthy, comfortable level of indoor humidity, bring in the right amount of air to ensure that we don't have high levels of contaminants.

Best practices on ventilation is, for entry-level homes, single fan. Just basically sized properly to provide the right amount of air, and being intelligent about in what climate zone you're in, whether it's supply-based or exhaust-based. And if you're in cold climates and even in entry-level, we'd recommend doing a balanced approach in those areas. Going to move-up homes, that's where it usually is worthwhile to integrate smart controls in your ventilation system. If your designer is using that information, they can determine that I will never ventilate during my peak load conditions; I can then either reduce or eliminate my ventilation load from my HVAC sizing calculations. And in extreme climates where there is a high level of ventilation load, relative to the overall structure, that allows you to perhaps reduce the equipment sizing by a half a ton or so depending upon the size of your home. That reduction in equipment can often pay for the smarter controls of the ventilation system. So it's a neutral cost approach and provided a higher level of energy efficiency. And it's a good selling feature, because homeowners can realize that I would not open my window to get fresh air on really hot or really cold days if my ventilation system is smart enough to do the same at times when I should bring ventilation in during the day, then they're more apt to actually use the system. Then if you're in cold climates or if you're building luxury or custom homes, highly recommend most of the time an ERV. Occasionally an HRV is a better solution. But a balanced approach that, with an ERV, allowing you to maintain your proper indoor moisture levels in addition to using the conditioned air inside to precondition the new air coming in. That's the best practice for homes that can afford those solutions.

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Pitfalls to avoid. So worst-case loads is not the right way to go when you're building homes in multiple configurations. If you do a single load and say, I'm going to build them all the same, your equipment often will be the wrong size, and certainly your duct system will not be balanced based upon how that house is built to different configurations. So if you have a designer that says, I built them this way for years, this is the way to do it, particularly in production homes, they really should think twice about that. And if you're building to ENERGY STAR standards, that is not allowed anymore. So you really should not just have one single worst-case design. Spend a little bit of extra time and energy. It's not that much more expensive to have a plan that has different load configurations, different loads for the different configurations it can be built in. That way you get a good result no matter how that house is built. Next one to avoid is rule-of-thumb equipment sizing. If someone is not using the extended ratings tables of the manufacturing package for the specific match-ups that they're going to be installing, then they're really shooting in the dark of how to size their equipment. Manufacturers publish the data; it's not difficult to obtain. It's not that taxing to calculate it, so there really is no excuse to not use the data that's available, instead of just rule-of- thumb. I'm sure we all have stories of our HVAC contractors that have said that, look, I've been doing it this way for 30 years, and it's never been wrong for me, or, that's the way I do it in this region. And if they're a contractor that does retrofits and remodels of older homes, that rule of thumb may have some basis in fact. But if you're building a Zero Energy Ready Home, it's going to perform so differently than the older housing stock that they're used to working with that it's just -- they will often be way off the mark from where they normally would. In hot-dry regions, we often hear 400 square feet per ton is the standard. And our designs often in those same areas are 850 to 900 square feet per ton, so they would have twice the tonnage that they should on many designs, if they use their rule of thumb in their local area.

Field-designed duct systems, that's pretty obvious. If you are not doing the math in designing a balanced duct system, asking the guy in the field to just wing it, even if he's pretty experienced, you will not get the results and the consistency that you'll desire. So having someone actually design a properly balanced duct system for that lot is going to be the key to getting consistent good results. If you're building multistory homes, do not have a single system with a single thermostat. I can't stress that strongly enough. The stack effect is going to inevitably create comfort issues, and even if you leave the blower on, where it's on all the time, just to circulate the air, you're still going to have several degrees temperature difference between floors. So adding a zone system in with a thermostat for each region allows you to maintain the same temperature consistently throughout the house. That's a much better way to go. It's a little bit more money, but to ensure that you're providing comfort in a low-load home, that's important.

Don't ignore humidity. A lot of people pay just attention to sensible load and they're not paying attention to humidity. These homes have such dramatically lower sensible loads than in the past, and if your HVAC system isn't really paying attention to the latent load of just the moisture that's generated from people living in the home, taking showers and cooking, then you can often get into bad results. Make sure your designer is considering the latent load and they're managing it properly, particularly if they're in a humid climate. Some level of dehumidification during the shoulder seasons is included. Do not have someone just light your HVAC system at startup and move on. They really need to commission it. Are they using the proper blower setting? Is the static pressure within the desired range? Is the air flow correct? Is the charge correct? Doing all those things will ensure that the system works well and provides comfort in a very energy-efficient manner, right out of the gate. If it's not, then the amount of buffer from oversized equipment that allowed people to poorly commission units and get away with it -- that's really gone. If you design your systems well, it must be commissioned to get good results.

Also, if you want to achieve good results, the list of three components there -- you need two of those three to be strong. You need a good HVAC designer, contractor, and energy rater / inspector. We often hear that contractors in a certain region are not familiar with the new construction standards and they struggle a bit to get comfortable to build homes in a more modern fashion. So by having a strong designer, and a good local rater / inspector, providing the guidance on the front end of here's the design, and we're going to inspect to ensure that that design is actually commissioned and delivered correctly, you can still have an average contractor and get good results. But any combination of those -- if you have more than two of those that are weak, you can often have a bad result. So you want to have all three strong, is best, but you can get away with two of the three.

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So what are some challenges of building low-load homes with properly sized and designed HVAC systems? To start off with, homeowner expectations have not changed. It has been drilled into the head of homeowners for so many years that they should set the thermostat back during the day, allow the temperature to drift up, and then have it come back down at night. So they will treat their houses the same way, even though they're not inherent to perform that way. So over-communicating with the homeowners during the sales and construction process, at closing and during the orientation, and then if there's any service and warranty calls -- that's going to be the key to convincing homeowners that they need to change their behavior to get the results they're seeking. Properly designed systems will maintain proper comfort, and it will do so very energy efficiently. They just can't treat it as they have in the past. So just again, go back to set-it-and-forget-it. If they are concerned about that, tell them, look, if you wish to go from using your approach of allowing the temperature to drift up and then requiring it to catch up, watch your utility bills for a month, and then go for a month of set-it-and-forget-it, I think they'll be surprised. The set-it-and-forget-it approach will provide just as good if not better utility costs and significantly better comfort. As was mentioned before, if you're having challenge with HVAC contractors, book-end them with good designers and good inspectors and raters. That's a key way to get good results if your local contractors just don't believe in the more-modern methods. Another tricky part is your bidding and pricing complexity are going to increase a bit with this. It's no longer this plan has this HVAC design and I know what my costs are, and I'm going to build them all the same. There is going to be some variation. The cost variation usually isn't dramatic, but getting good execution in the field, making sure those cost variances are taken care of, and really tying the pricing to equipment tonnage changes and option material changes, is where we found having the best luck. So that way contractors don't feel like they're getting shortchanged, and builders are capturing some of the value of the savings from right-sized equipment.

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That's where we are today. What's around the corner? Well, one item that people have been familiar with for a while is focusing on makeup air for high-flow kitchen exhaust hoods. So if you're building a more luxury- style home that has a commercial-style kitchen with a 800 up to I think 1,200 CFM exhaust hoods, that is extracting an immense amount of conditioned air from the home. So having your makeup air really be more of a commercial style where it is very close to that hood, so the makeup air is grabbing the contaminants from the cooking process, and that makeup air is re-exiting the house -- you're not pulling all the conditioned air out -- is key. Otherwise, you really have to pay attention to supplemental capacity, if you have someone that is a high user of their high-end kitchen and hood. Otherwise if they're are drawing that much conditioned air out of the home, there will be times when they will not be able to maintain comfort. So that's something you have to pay close attention to if you're building those style of kitchens. ENERGY STAR Revision 8, we touched base on that a little bit earlier. That is a change to where it's still very similar, of the Version 3 Rev. 7 -- that's what we've been operating under for almost two years now. Revision 8 is tightening down a little bit the HVAC design requirements. So the ability to use a worst-case design has not been allowed for, for some time. But this is a really narrowing-in of the amount of variance that's allowed to have a group design approach. So, how much square footage of floor space difference, how much square footage of window area, and looking at your orientations. Those items are now specified more tightly in Revision 8. So that will mean your designers have to take that into account when they're designing systems. And that becomes effective July 1 of 2016. So any homes, any communities that are being planned to come out this year, really should have your designer paying attention to the Rev. 8 requirements, so that way if you're an ENERGY STAR builder, you can have that built into your process.

As the areas move to using the 2013 version of ASHRAE 62.2, and if you're building a much tighter and more energy-efficient home, which you would be if you're a Zero Energy Ready builder, then if the ASHRAE 62.2 2013 version, there's no longer a set formula based upon square footage and occupants. It is now taking into account how tight is your house. So it's going to require a higher level of air flow than in the past, and then you get an infiltration credit. So if you're building a tighter house, it's a way of determining that you're providing the right total amount of air flow into the home. So what that's going to mean is, if you're building a very low-load home, your ventilation load as a percentage of your total load is going up. So paying even closer attention to ventilation than in the past is going to be key, especially in extreme environments. If you're in a very cold climate or in a climate that you're managing humidity, you have to really pay attention to ventilation now. It's not just something that, you put a duct to the return and you don't worry about it. It's going to require more attention to detail. And that language is tied into the ICC 2015. So that's where you're going to start seeing that becoming covered in certain regions. And as that gets implemented, paying attention to ventilation becomes even more critical.

High-velocity duct systems are a good technique, particularly if you are building with tight spaces or you have other humidity management or other issues you're trying to address. So you may start seeing more of that as a way of building tight envelopes with HVAC systems that perform well. Load time-shifting, we talked about that in ventilation. This is a key issue in markets where the utilities are having a higher and higher level of solar supply that's being put onto the grid. Utilities are trying to do what they can to push more and more of their load off of their peak, which is shifting to the 5 to 9 p.m. period instead of the 1 to 7 p.m. period, which we're most familiar with. You may have heard of the duct curve. I won't go into the details here, but you will probably start seeing more products and more attention to detail to move load off of the peak, and HVAC being the biggest driver of that. You'll start seeing products in that area to help shift that load. So for the builder, keep that in the back of your mind. You may start seeing utility rebates tied to load-shifting techniques.

And last is, you may start seeing heat-pump ventilators. As I mentioned, as ventilation becomes an even higher level of load in the home, this would be a step beyond an HRV or ERV. It's actually using a heat pump to draw air in and exhaust air at a balanced approach. I think we're probably not too far away from seeing those. There are a few of those products on the market. I think over time they'll become more popular.

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So to wrap up: We've touched base on what's changed, and how homes are performing differently. We've walked through the HVAC design and execution methods, looking at the five techniques to ensure that you have a good overall system. Walked through some pitfalls and challenges. And then we've looked into our crystal ball to see what's coming.

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So at this point I'd be happy to take any questions participants have, and address any you do.

Jamie Lyons:
We'll try to highlight here and queue them up for you, Greg. Let's see. This is sort of a comment question you might want to respond to. Many affordable housing and production home projects are currently using HRVs. Why recommend them only for luxury homes?

Greg Cobb:
If you're able to build that into your budget, I absolutely recommend an ERV or HRV for affordable housing or entry-level homes. So in many parts of the country, to get proper ventilation and to manage it well, that's almost a necessity. In many parts of the country, though, the budget just isn't there for it. So just working with a number of builders in different areas, recognizing that the key is to get good ventilation. And if there's a way to do that without the cost of an ERV, then great. But if it's in your budget, more power to you.

Jamie Lyons:
Here's another one on the topic of balanced systems. Do you need another dehumidifier besides an ERV in seasons when cooling isn't needed?

Greg Cobb:
An ERV is not a dehumidifier. It will help to keep the indoor conditions that you have somewhat consistent. So it will allow not just heat transfer but some moisture transfer as the outdoor air is brought in and the indoor air is pushed out. So if you have a condition where you're in the shoulder season and you have a high level of humidity inside the home, you're north of 60 percent RH, and the air that you're bringing in also has the high levels of humidity, then the ERV really will do nothing about it. Because it's not designed to remove moisture. It's designed to balance the moisture between what's inside and what's outside. So if you get high on both sides, you're going to have high moisture inside your home. So yes, I would recommend that you have a supplemental dehumidifier. And that's why we look at just doing whole house dehumidification. Usually you take a pretty good electricity cost hit for doing that. So that is one method. By integrating it into your ventilation system -- so then you have a single component that you're using as your ventilator that has a fan built in and a dehumidifier built in. If it has the logic that links in with your system, it will only dehumidify when your HVAC system is not operating in cooling mode, which is providing enough dehumidification alone. So that allows you to minimize the cost of not having two components; you just have one of the install. It minimizes the utility cost by running the dehumidifier only when necessary. And you're doing that on the inbound air where the moisture is the highest concentration. So you're removing the moisture before it ever gets into the home.

Jamie Lyons:
Good. Here's another one regarding cooling. The question is asking, what's the role of SHR -- sensible heat ratio -- what's the role of that when selecting HVAC equipment in a low-load home?

Greg Cobb:
It becomes even more critical, because the sensible heat ratio, you're looking at essentially what's the difference between your sensible capacity and your latent capacity. Most of the time, that is driven by how rapidly are you pushing the air across the cooling coil. So if you are in a dry climate, you want to have a very high SHR, because that allows you to move air very rapidly across your coils. You get the maximum sensible cooling capacity through that approach. And it minimizes your latent. The flip side is, if you're building a very low- load home and you're in a humid climate, you're going to want to slow that air down. And by slowing it down, it has the ability -- the coil can get colder. You get a greater level of moisture removal. You lose a little bit of sensible capacity. But it shifts over into latent capacity, and again, if you're focusing in on moisture removal, that is often something you want to do. If you have high indoor moisture levels or are in a humid climate zone, you'll want to slow the air down and get a higher -- greater temperature split across your coil.

Jamie Lyons:
OK, good. Plenty to pick from here, and I guess, just from the perspective of DOE and the Zero Energy Ready Home program, I think one of the things that we really like to highlight to our builders and their teams as we do trainings and work with them, is that for all the specs in the Zero Ready program you have a sort of a toolkit of solutions. It's definitely not a one-size-fits-all proposition, in terms of which technologies and which building methods are used. We sort of like to remind our audience that specific recommendations are very good regarding using a certain control or not. But from working with our builders, we see sort of a wide range of creative use of different technologies, different designs, that really work for them, whether it's the HVAC and indoor air quality or whether it's the building envelope or controls or other parts of a high-performance home. So just a little bit on that perspective. Let's shift to exhaust fans and radon here, Greg. If I'm in a high radon risk area, and I'm using a single exhaust fan for ventilation, is this creating negative pressure, because the envelope will be too tight? And then will that negative pressure in turn induce radon into the building assemblies?

Greg Cobb:
Yes, you would want to have a radon control built into your system. So having the methods of having a pipe underneath the slab or underneath the basement where you're able to draw the radon out and exhaust that out of the house to the roof before it ever enters the home. But you would not want, if you're in a high radon area, to have an exhaust only approach, which would, of course, as the questioner suggested, that would help to encourage radon to be drawn into the envelope. Even though it would be exhausted back out, the level of contaminant -- you can better manage that level by having a supply or balanced system with the proper radon control underneath the slab.

Jamie Lyons:
OK. Thank-you, Greg. Here's a question regarding sort of finding the right team members. You had mentioned the three different roles, which are critical for success. Here, the question is if there's a good resource to find local contractors and sellers that are better qualified to do these types of high-performance, Zero Energy Ready Home projects. And before I hand that over, from the DOE perspective, one resource, and it's sort of built-in as a requirement, is to use an HVAC contractor that is quality assurance certified under the EPA ENERGY STAR for Homes program. Because ENERGY STAR Homes is a prerequisite for DOE Zero Energy Ready Home, and that's part of the ENERGY STAR Homes requirement, to have the QA-certified contractor for the HVAC install. And there's a listing of those contractors available on the ENERGY STAR website. You can simply do an online search for ENERGY STAR QA-certified HVAC contractor, and find those resources. Any additional thoughts on finding qualified contractors, Greg?

Greg Cobb:
Jamie, you stole my answer. No, that's the approach I was going to take. Beyond that, it's really networking with other builders of highly energy-efficient homes in your area. And just trading stories on who they've worked with and had good results with. But no -- the best resource online would be starting with the ENERGY STAR listing of QA- qualified contractors.

Sam Rashkin:
The only thing I'll add to that answer is that there are many locations around the country where you can't find a quality assured contractor. Then you just have to be your own best advocate and ask the right questions of the contractor to see if they follow the best practices that Greg shared with you today.

Greg Cobb:
Yea, I think I'd agree with that, Sam. If you have someone that's telling you they're using a rule-of-thumb approach for equipment sizing, and they design their ducts in the field, and they don't believe that Manual J stuff, you probably should head a different direction.

Jamie Lyons:
OK. Heat-pump ventilators. You mentioned that toward the end of the talk. The question is asking about the challenges of installing them, and who is making them today. And again, I'll just remind the group with the caveat that DOE doesn't want to go and endorse particular products, but Greg has mentioned the groups that are providing products in the marketplace. You can certainly share that. Heat-pump ventilators, Greg.

Greg Cobb:
There is one process that combined heating and cooling system that also has the ability to preheating and precooled air coming into the home. And its name slips my mind right now. But I've only seen one manufacturer that has a product that actually does this. There's been a few others that are close. And I've been twisting the arms of a number of manufacturers, explaining to them why ventilation load is increasing, why it's becoming a more critical issue. And to be honest, there are not good cost-effective solutions in the marketplace. The ones I've seen are in the $30,000-plus for a combined HVAC system and ventilation system. So it's a very select system, but it's not cost-effective yet. So stay tuned. That's something that I continue to voice my opinion that there's a great opportunity for that because of builders that are on this call. It would be a very useful tool to a builder to be able to precondition that air, both moisture and temperature, before it ever enters the house. They can even size your HVAC. That method would really open the door to using mini-splits to provide the heating and cooling in the different spaces. And then you have a heat-pump ventilator to control the conditions of the air coming in. Unfortunately, I don't have a good answer on where to find them and how to install. They just don't exist very well yet.

Sam Rashkin:
Do you have any sense, Greg, of the cost premium that should be expected once these heat-pump ventilators become more mainstream?

Greg Cobb:
They will be probably in the cost range of a quality ERV. The total materials involved would be at a similar level. So the equipment on its own probably being in the neighborhood of, you know, in the $1,000, $1,200 range. Because they can be pretty compact and but still being in that range, plus installation. And over time, they'll be able to drive those prices down sub-$1,000. But I think you would expect to be in that range of a quality ERV.

Jamie Lyons:
Within the DOE Zero Ready community, we've seen these areas where there's a growing need for an innovation, whether it be in ventilation, efficient hot water distribution, the building envelope. And really within the period of half a year, a year, in each of those areas, more and more innovations come in the marketplace at lower prices. Opportunities like this webinar and our conference presentations are good chances to check in to see what's new in making Zero Ready homes more achievable within the marketplace. I saw a multifamily question here we'd like to get to. We're seeing more and more multifamily projects come into Zero Energy Ready. The question is, how would you suggest ventilating a multifamily home in a humid climate?

Greg Cobb:
That is a tricky one, because most multifamily, the ventilation is exhaust-only. And so, that's really, in trying to manage that in a humid climate, the debate upon the size of the structure -- I believe the dehumidifying ventilators are a good option. If there's sufficient space to have those installed. Otherwise, you run into the same issues you do in single-family of providing the proper amount of ventilation and just not being able to control the indoor humidity levels. So I would probably go with the dehumidifying ventilator as a good option to do that. And if you're building smaller units, having one dehumidifying ventilator providing air into multiple units could be an option, if you're following proper provisions with local code.

Sam Rashkin:
Greg, I'll also mention, there's one true wall ventilator system that's imported from Germany that's an ERV or multifamily that's a pretty interesting option but costly. But it looks like on spec it might be an interesting choice for that situation. I don't know if you're familiar with that or have any experience. You know which one I'm referring to?

Greg Cobb:
Yea, I am. And those, particularly in mixed climates, I think that would be a very good option, where you have humidity for a bit of the year, and then you get into cold periods, as well. So I think that's a very good solution for that. If you're in extreme humid climates -- your Gulf Coast, south Florida -- then the ERV just -- if you have high humidity indoors and out, it's not going to help much. So that's where you need some sort of supplemental dehumidification to control the indoor environment.

Jamie Lyons:
We'll tackle a few more of these. I think this is scheduled for a 1:15 Eastern wrap-up, so we have a little bit more than five minutes left. Not enough time to tackle a few more questions. And again, thanks to the group; these are really good questions and speaks to Greg's knowledge here. Here's one about using an ECM blower motor in constant circulation mode. If we're doing that, do we then eliminate the need for additional ventilation control in a home?

Greg Cobb:
That's an option. And in some areas, that's a viable option. The challenge we usually run into there is, if you're using an ECM motor on your HVAC equipment, if you have a well-designed duct system that is a low static pressure, you can inch your fresh air duct up to that system. You have to run your blower at your same level that you do when you're heating and cooling to be able to draw in enough fresh air, unless you have some sort of damper system to damper down the indoor air to force enough static pressure so you can draw sufficient air from the outside. So if you're going to try to operate your blower motor with an ECM motor at a low level, so that way it can be more energy-efficient, you will need some sort of damper system to ensure that that blower is drawing in sufficient outdoor air to operate. And then have that damper system open up. When it's not in just constant "on" mode for ventilation, it opens up so that when it has a heating or cooling call, it has the ability to draw sufficient air and not have high static pressure. Usually that's not the most energy-efficient way of providing ventilation. Usually a low-wattage fan to bring that air in, and then when needed, operate the HVAC blower for distribution, is a more energy-efficient way to accomplish the same.

Jamie Lyons:
OK, thank-you. Good design insights there. We'll take one or two more. You had mentioned set-it-and-forget-it for thermostat settings. How would that kind of an approach affect load-shifting techniques, if you're trying to implement those, as well?

Greg Cobb:
It really has no impact. We are sizing equipment with a -- well, I guess there's two issues. One issue is, if you're simply shifting the ventilation load, it doesn't have an impact. If you're looking at trying to design something -- and we're working on a pilot project right now with a utility where we're going to be doing some pilot homes using essentially the thermal capacity of the house, thermal storage of the house, to do a precool and drift approach to test how can we get the ability to avoid peak load conditions as much as possible. So when you enter that scenario, we've done some energy modeling, determined that you start to blow your standard calculations. So if you have a well-designed, well-sized system, you don't have the makeup ability to do much precool and drift. So we may find ourselves going in a direction where we need to size our equipment if we're going to precool and drift, a little larger to do that. I'm personally not a big fan of forcing homeowners to be uncomfortable and expecting that to be used on a regular basis. We've been looking at other thermal storage techniques to get thermal math that doesn't require the homeowners to suffer comfort issues. So anyway, that's kind of a long-winded answer, but the bottom line is, it's correct. If you have a properly sized system, your ability to do a precool and drift strategy for load shifting is going to be limited.

Jamie Lyons:
Great answer. And let's wrap up with this one before we do closing comments here. If we have a DOE Zero Energy Ready Home and a Passive House project, how would you compare the relative loads of the two houses? I guess I'll weigh in then hand it off. A Zero Energy Ready Home is visionary, it's built to upcoming energy codes. So the minimum bar is set at a 2012 IECC or a 2015 IECC, which essentially is the exact same spec. From there, that's the minimum our builders will -- they can stop there, or they will go much further with more robust envelope designs. Putting them into that low-load category where I think all of Greg's guidance applies. Greg, you want to carry that forward and talk a little bit more about Passive Home, or your other perspectives?

Greg Cobb:
Sure. Because that's correct. It really just takes things to the next level of extreme, of the level of insulation, the level of air-sealing, for Passive House. You just ratchet it up another notch. And as you build to those more extreme standards, the rule of thumbs get even more thrown out the window, as far as the equipment sizing and how big of an impact ventilation has on the indoor environment. Because the indoor environment is so highly controlled with Passive House, even above Zero Energy Ready. So yea, it requires a very close attention to detail of each component, because you don't have the normal elements of air flowing through and drying out structures and drying out the indoor environment and other things. Yea, it requires an even greater level of attention to detail to the basic building science principles if you're doing Passive House.

Sam Rashkin:
OK, thanks so much, Greg. I'm going to hand it off to Lindsay to wrap up, but I just wanted to just make sure everyone understands one point. These webinars are the opinions and knowledge of experts brought in to share their understanding of best practices with our stakeholders. In some cases there will be some points made that are not DOE opinions that are put out to the public. One example might be the point about a specific thermostat -- the NEST thermostat. We do recognize that there are some very significant capabilities for bringing in a brain, if you will, to the house that can speak to thousands of other products in the marketplace and we work together for an optimum solution. And we do believe that some of these products will keep getting more advanced in terms of how to manage not just inefficient homes but very high-performance homes. So we want to make sure that you understand that DOE wouldn't want to say not to use a specific product like the NEST thermostat. We do see many possibilities and many directions it may go in the future. And so that's just one expert perspective. Do you want to say anything before I pass on, Greg, to that point?

Greg Cobb:
No, I agree. I think they are going after an initial target market, but they are very smart people with a lot of resources behind them, and continually getting smarter. So we expect that will be a very useful tool in the future. Just wanted to caution folks that as it exists today, just realize that it does have some challenges of whether it will help homeowners meet their comfort expectations. But don't disagree with what your comment was.

Sam Rashkin:
OK, thanks so much. Lindsay?

Lindsay Parker:
Alright, thank-you, everyone. Greg, thank-you for the fantastic presentation and for answering all of the audience's really great questions. And thank-you, everyone who joined us today. We appreciate you joining in on the polls and being very engaged.

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And on our last slide, we would like to draw your attention to our resources page, where we will be posting the recording of this webinar after a couple of weeks. It does take some time for processing. But on our resources page you can find our events, including the upcoming webinars that we have. We have one coming up in February. As well as our partner locator, where you can find builders and other partners that we have around the country, and program specs, in case you'd like to learn more.

Sam Rashkin:
I do want to highlight the upcoming webinar that's next. It's Dr. Joe Lstiburek. You won't want to miss that. Dr. Lstiburek's going to really dive deep into the best practices for how you do the most efficient, high-R assemblies in Zero Energy Ready Homes. It's really, really important to understand all the options and your best choices, and no one better than Joe Lstiburek to really address that. So do stay tuned for that webinar.

Lindsay Parker:
And I will be sending out an email after the webinar with the PDF of the presentation as well as information on how you can register for that upcoming webinar. For more information, see the Solution Center; the website is listed.

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And thank-you very much for joining today. We look forward to seeing you again for our next webinar.