Austin architect Peter Pfeiffer tours Green Builder Media's VISION House Austin, explaining how climate-responsive passive design, shading, daylighting, a ventilated radiant-barrier roof and short duct runs combine to make an affordable zero energy home that also ages in place well.
00:00:02:21 - 00:00:30:22
Peter Pfeiffer: We're here at Green Builder Media's Vision House Austin. This is a wonderful project to demonstrate realistic, practical sustainability. As matter of fact, it's a zero energy home. It truly operates off the grid, but for a very reasonable price. Let me have you come on and set and let's look at the home.
00:00:30:25 - 00:00:56:02
Peter Pfeiffer: We've been doing zero energy homes for almost 40 years now, and have gotten it down to a bit of a science. It starts with a good, sensible project programing and then a good design that's oriented well for its site. Now what I mean about project programing is we talk to the client and find out not only what they want, but why do they want that and what are the consequences?
00:00:56:02 - 00:01:17:20
Peter Pfeiffer: What are the ramifications of what they're asking for? Because that's the part of a project where you, as an architect or a builder, can inform your client about what they're asking for so they can make more informed decisions. Of course, when you're designing a custom home for a particular client, you need to understand who they are and what's important to them.
00:01:17:23 - 00:01:55:19
Peter Pfeiffer: The judges in this case are both in their mid 80s. This is their final home. We had to make sure it was a home that could age in place well for them, but also not be too much for them to maintain. We kept it at about 1800 square feet, plenty big enough for two people, and still put up their kids when they come to visit, but not the 3000 4000, 5000 square foot homes that, in our experience, we found that most older couples don't want to maintain and end up selling within 5 to 10 years of building them because they just built too much of a home to take care of.
00:01:55:22 - 00:02:16:08
Peter Pfeiffer: So it's about 1800 square feet, and that's an important aging in place strategy. Of course, we've got the properly placed grab bars in the shower and around the tub and even around the toilets. But another aspect of this design is that everything is on one level, and there are no step ups or step downs. It's a minimal step out to the deck.
00:02:16:08 - 00:02:44:16
Peter Pfeiffer: It's a minimal step out to the screened in porch. It's a minimal step in from the front door. We don't want tripping hazards. We also use light colors throughout the house. Light colored cabinets, light colored walls just to make it easier for them to see. Tripping hazards are a key factor in most older folks having injuries. So the light colors and the fact there are no steps was key to making this house good for aging in place.
00:02:44:18 - 00:03:07:10
Peter Pfeiffer: But so was, of course, the light colored countertops, because the kitchen is where you use the most amount of lighting and energy in a home, and it's where you use the most amount of energy from your body. If you're cooking, you're doing a lot of things that's requiring a lot of use of your eyes. So a lighter countertop and lighter colors make it easier for you to see and less eyestrain.
00:03:07:12 - 00:03:28:18
Peter Pfeiffer: So who would think that things like the color choices of the countertop, or even the placement of light fixtures to be closer to the task would have that much to do with even aging in place, but it does. From a design perspective, it. In looking at this home, we have an open floor plan the kitchen, the dining and the living area all feed off of each other.
00:03:28:18 - 00:03:56:17
Peter Pfeiffer: So because we don't have walls separating them, we could get the feel and the look of a much larger house and fewer square feet. We also did things like lowering the ceilings where we are coming into the bedroom areas or the private zones of the house. We don't need exceedingly high ceilings in bedrooms because remember, the more ceiling height you have, the more cubic feet of air you have to air conditioned and dehumidifiers.
00:03:56:20 - 00:04:16:11
Peter Pfeiffer: So we do want to give you some dynamism with some good ceiling heights, but not excessive. I think we raise up to 14ft from about 11ft in this house, and then all of the bedrooms are at nine feet. Plenty enough to give you that comfort and looks without having too much air to dehumidifier, to filter and to cool.
00:04:16:13 - 00:04:37:00
Peter Pfeiffer: So we try to help our clients avoid what's trendy or the current fad, and do what's going to make for a very comfortable, energy efficient and long lasting home. So the same things that make the house comfortable and energy efficient are the same things that will make it more durable. And that is really what sustainability should be about.
00:04:37:03 - 00:05:00:01
Peter Pfeiffer: So let's go further and talk about what we did outside the home before we come on inside. You'll notice here that we've got generally a lighter colored exterior, which makes it so the house doesn't absorb as much heat. If there is masonry, it's a light colored, in this case locally harvested or locally quarried masonry that will keep its cool.
00:05:00:03 - 00:05:22:08
Peter Pfeiffer: We've also got broad overhangs on the house to protect the windows and the doors. The less of an overhang you have on a home to protect the windows, doors and siding, the more problems you can have over time. So if you're looking for sustainability in the idea of not having to replace things or have a lot of maintenance, one of the most important things you can do is design the home to protect itself from the elements.
00:05:22:08 - 00:05:44:21
Peter Pfeiffer: And we do that here. We also oriented the house so that there is a screened in porch at the one end off the kitchen, facing in such a way that it receives the prevailing breezes, yet protects itself from the cold winter winds. The placement of the porch is such that the house itself acts as a buffer between it and the colder winter winds.
00:05:44:23 - 00:06:13:06
Peter Pfeiffer: So this house or this porch can be used almost all year round here in our climate in Central Texas. People talk about energy efficiency, and one of the first things that comes to their mind is insulation levels, but something that will help you decide what makes sense to do in your setting is to imagine yourself in what would make you comfortable in that particular setting, and then that's how you would build your home.
00:06:13:09 - 00:06:33:15
Peter Pfeiffer: So in our climate here in Central Texas, we have very mild winters putting a lot of insulation around us in the form of a heavy overcoat is maybe going to benefit us 10 to 20 days a year. That's it. Now, on the other hand, if you could get out of the sun and stand in the shade, that will benefit your comfort probably 300 days a year.
00:06:33:22 - 00:07:02:17
Peter Pfeiffer: So what will make you comfortable in this climate is not so much the amount of insulation levels, but by shading the windows and the doors and doing the right type of roof that reflects heat or reduces the heat that will come down into the home. And it's also going to be very tight because we don't want that humidity coming in from the outside, which is why we are not necessarily fans of automatically going to excessively ventilating a home with an energy recovery ventilation system.
00:07:02:20 - 00:07:31:02
Peter Pfeiffer: We would instead like to make the house very healthy by eliminating the sources of pollution as much as possible. From a design perspective, let's look at some of the things we've done to make it this zero energy home. Firstly, we did careful daylight harvesting, which means it's all reflected light coming into the home. So even though we've got broad overhangs on this house, it's still very light and airy on the inside.
00:07:31:09 - 00:07:55:17
Peter Pfeiffer: And the reason why that's important is not only makes you feel better, but it makes it so that we can use less electric lighting to make the house comfortable, and for it to enable you to see what you're doing. So what are the strategies we did there to enhance the daylighting or the lighting in the house? Well, first and foremost, light colored horizontal reflecting services like your countertops and your floors.
00:07:55:19 - 00:08:20:21
Peter Pfeiffer: The lighter they are, the more light reflects up to your eyeballs. The less light you need to see that tomato that you're dicing. The second thing we did was we put the light fixtures close to the task. The closer the light fixture is to the task, the less output is needed to show you what you're doing. So we're not trying to light this countertop here with recessed lights 12ft up in the air.
00:08:20:23 - 00:08:46:07
Peter Pfeiffer: We brought the light fixtures right down to a reasonable height within the task. So that's those are two examples of how by design, we're reducing the amount of lighting we need in this house provided by artificial means. And the advantage of that in this particular climate is the less lighting you have on. The less heat is generated in the home, the less heat this generated means less air conditioning needed.
00:08:46:10 - 00:09:09:20
Peter Pfeiffer: So we're saving energy with the air conditioning. We're saving run time and wear and tear in the air conditioning because we made informed interior design decisions regarding horizontal reflecting surfaces and the placement of the light fixtures. But let's step back for a little bit and talk about what are these passive strategies that we're employing to make this home first and foremost.
00:09:09:25 - 00:09:30:17
Peter Pfeiffer: So energy efficient and sustainable. It really comes down to for first you want to make the house so that it keeps itself comfortably cool in the summer. That's why we have the lighter colored exterior and the light colored stone. And my gosh, we have a light colored roof. We don't have a dark painted roof. As a matter of fact, we don't have a painted roof.
00:09:30:19 - 00:09:59:11
Peter Pfeiffer: The second thing we have is the windows and overhangs are designed so they still do let sunlight in in the winter time to give you passive heat. So it's passive cooling and passive heating as a function of the window placement and the awnings and roof overhang designs. The third element is natural ventilation strategies. These are operable windows in the living room, dining room, kitchen, in the bedrooms, and strategically placed so that you can ventilate the house effectively.
00:09:59:13 - 00:10:23:12
Peter Pfeiffer: We've got windows that are very easy to open up on the prevailing breeze side of the house, and other windows on the leeward side of the house help draw the air through the house. So it's not just random placement of the doors and windows is strategic placement to enhance the natural ventilation in the house. The fourth element, of course, is something we've talked a bit about, which is daylighting by design.
00:10:23:14 - 00:10:49:04
Peter Pfeiffer: The more you can harvest nature's natural light, the less you will have to use electric lighting inside your house. So it's passive cooling, passive heating, natural ventilation strategies, and daylighting. By design. So we talked a little bit about the passive cooling strategies. And I talked about the roof needing to be a special roof to deal with this hot searing summer sun that we have here.
00:10:49:07 - 00:11:09:23
Peter Pfeiffer: The roof is a volume roof. It's installed in such a way to act as a shading brella. It's actually installed above the roof underlayment so that we can induce ventilation between the two. It's a roof system that we developed at our office at Bali five for architecture about 24 years ago. We've tested it. We know it works wonderfully.
00:11:09:25 - 00:11:37:09
Peter Pfeiffer: We like using volume as a roofing material because the whole roof is coated with molten aluminum and zinc, so it acts as a great radiant barrier. The underside has got the radiant barrier coating such that it only lets about 20% of the heat penetrate through the roof to the airspace below, and then that airspace below is ventilated. So we have a ventilated shading umbrella roof, yet a sealed attic below.
00:11:37:09 - 00:11:58:17
Peter Pfeiffer: So we've got the best of both worlds. It makes the roofing material last longer too, because of any moisture it gets underneath it. It can drain out or dry out, and it makes it much more comfortable because it's literally like standing underneath a shade tree in the summertime. And then I also mentioned about, well, what's very important is indoor air quality and health.
00:11:58:19 - 00:12:31:02
Peter Pfeiffer: And how did we deal with those issues from a design and passive point of view? Well, the first one was, of course separate the polluting sources from the living spaces. We separate the garage from the house. Most people store things in your garage that you don't want to have the fumes from inside your house, but the other reason is, in our climate and in a lot of climates, the garage has got warmer and more humid air than the home, and the laws of nature kick in the garage.
00:12:31:02 - 00:12:54:13
Peter Pfeiffer: Air wants to infiltrate into the house because it's warmer out there and things go from warm to cool, and it's more humid out there. Things go from wet to dry. So it's very important to consider separating the garage from the house so we don't get that infiltration of the garage or into the house. But then by design, there's something else that plays into this indoor air quality strategizing.
00:12:54:16 - 00:13:23:03
Peter Pfeiffer: We place the air handler in the air conditioning system, more or less in the center of the zone that it's serving. We can therefore use shorter duct runs and more balanced duct runs to minimize the amount of loss we'll have through the ducks. The less the ducts leak, the less the house goes into a vacuum. The less the house goes into a vacuum, the less it's trying to pull in air from the garage or from the outside.
00:13:23:05 - 00:13:48:06
Peter Pfeiffer: So leaky ducts indeed do cause a house to suck. Because if you just have 10 or 15% duct leakage, you're not only losing 10 or 15% of the air that you just spent money processing, but because it's not going back into the house. The house is trying to make up for that loss of air by sucking more air in from around the doors and windows, and maybe in from the garage or down from the fireplace chimney.
00:13:48:08 - 00:14:12:01
Peter Pfeiffer: So air tight duct system. That's shorter makes for a healthier home. Now, I also said that's shorter. So one of the other strategies we did here is not only is there a centrally placed air handler, but there is one duct run going down the center of the house makes it very easy to move the air through it. That reduces the power the air handler needs to deliver air.
00:14:12:04 - 00:14:33:08
Peter Pfeiffer: And here's another fact. We blow the air towards the exterior instead of ducting it towards the exterior. We don't have to run a duct all the way over to a window, and then blow the air down across the face of the window anymore. Not if we're building houses tightly with a high grade spray polyurethane foam and using very good windows.
00:14:33:10 - 00:14:52:11
Peter Pfeiffer: No need to waste the money, nor the energy ducting air all the way to the perimeter. In this particular house, I mentioned earlier that the air handler is located close to the center of the house to minimize duct runs and minimize the amount of energy required by the air handler to deliver that air. But there are a few other things here.
00:14:52:13 - 00:15:18:21
Peter Pfeiffer: It's very accessible and easy for the homeowner to maintain and I think of that as an aging in place strategy. You don't have to try crawling up into an attic to flush your water heater, or change your air conditioning filter. It's all right here in the hallway in the center of the house. And because we have a soft start air handler, you barely hear it when it comes on, and we've got a baffle built into the return air chase to be a sound deadening device.
00:15:18:21 - 00:15:40:29
Peter Pfeiffer: So it's a very quiet system, but very accessible and very easy to deal with. The filter system is right here at the base of the unit, where you can just easily access it. You can flush the coil from any mold and mildew that might build up, because we have a the, a valve at the base that allows you to pour bleach water in there to backwash the evaporator pan.
00:15:41:01 - 00:16:02:28
Peter Pfeiffer: We can drain the water heater very easily, turn on and off the water, the supply, the drain it, and it runs right to the outside. So it's easy to maintain and it's not overly expensive. This is just the very efficient heat pump water heater. But you know, you don't even need to use a heat pump water heater. You could use just a super insulated electric water heater and get marvelous results.
00:16:02:29 - 00:16:26:11
Peter Pfeiffer: We found. So it's a good and simple to maintain mechanical and water heating system in this home. We've talked about the passive design strategies and programing strategies that make this house so successful. But let's not forget that the house is all electric for a reason. There is 12kW of renewable energy being generated on the roof of this house.
00:16:26:13 - 00:16:56:01
Peter Pfeiffer: The roof was designed at the right angle and facing the right direction to maximize the output of a photovoltaic system. And there's battery storage. So the homeowner last month got an energy bill that was actually a $73 credit to be applied to future energy bills. But first and foremost, the home was designed to use less energy in the first place by managing the radiation that would affect the cooling costs and the lighting and other attributes that we've talked about.
00:16:56:04 - 00:17:20:06
Peter Pfeiffer: So perhaps to wrap up, what we're demonstrating here is a home that is not overly complicated. It'll be easy to maintain. We don't want to add more equipment than necessary. That will save money in construction costs. Make the climate responsive house affordable to most people, and make it much more easy to own.