Hummingbird House: Design for Everyone Part III
Tell us about passive-solar siting. I hear you have a different view on it than I would think. The general orientation of the Hummingbird House—the house you designed and share with your wife, Suzanne, in the Monterey area—is not what I expect. While the roof and its solar panels face south, most of the glass is on the north side of the house.
Larry Weingarten: A lot of people address solar dwellings by putting a lot of south glass up, putting a lot of mass where the sun will hit it. Okay … historically, it hasn’t worked very well. It’s very hard to carry off. I’m sure there would be a lot of people that would disagree with this. Vehemently. But I wanted something that normal people—not only a solar zealot—could live in.
So that the house doesn’t grate on people’s sensibilities?
LW: Right. You don’t want a house that looks like a solar house. But beyond that, you want something that’s comfortable. Undeniably comfortable. If you can keep the temperature swings down to a minimum in the house, you’ve gone a long way. If you store the heat remotely from the living space, and put the heat into the house as you need it, you suddenly have very even temperatures. If you can do what you can to avoid solar gain—I know that sounds like an anathema, and you should kick me—you’re not having to put up with collecting heat and trying to store it without feeling its effects until you need the heat later in the day or later in the night. I like the example of the Wright Brothers designing a plane that was inherently unstable. It required controls, but it flew. A low-mass house requires control of the Btu input, but it can deliver better temperature control.
It seems backwards to me because we have been trying so long to make people live in a solar collector, because that’s what the house becomes. So let’s collect it, store it separately—and put it into the house when it’s needed. And that way I don’t have to figure out fancy shading devices for all that glass I put up. For a long time, there have been two camps in solar thinking—active and passive. Passive aims at elegant simplicity, which I admire, but I’m finding that a little tiny bit of active performs better and is so much less trouble. This allows me to keep the house looking fairly conventional.
There was something I noticed you didn’t have to have on your house. On your west side, even. You don’t have significant eaves.
LW: The west-facing glass is not large, and it being a tall house, I’d have needed huge overhangs to have an effect. That would make for a big sail if the wind came up.
Interesting, because SIPs are relatively lightweight?
LW: I do have significant and well-supported eaves on the north side, covering a porch there.
This is fascinating to me because—especially in the natural-building world, where I spend a lot of time—we are so married to the notion of passive-solar siting. It’s so important to choose your site accordingly.
LW: And that’s fine. I have a nice, big south-facing roof. I collect it all up there. With a clerestory it gives me north light. I don’t want a lot of direct light because of fading. Because I did that in my last house. I thought, Okay, I’m going to warm this house with the sun. I added a big south-facing sliding glass door on the second story. It ate the carpet up and faded everything and overheated it. I’ve been there. I’ve tried that, and a lot of other people have, too. You see? Old books have some good stuff in them, sharing lessons learned.
Since the ’40s, people have been trying solar direct-gain things. And it’s tricky. How do we sidestep all that trouble?
For this house I tried to sidestep big troubles. There’s very little ductwork in the house because ductwork leaks. The average leakage rate of ductwork is 30%. So what’s the point of putting a super-efficient furnace on your ductwork, because you’ve just lost 30%? Bill Holloway was here. He’s a teacher for Pacific Gas and Electric Company (PG&E) for their energy training center. So I sat in on one of his classes where he was saying that’s what it really is. It may be 34%. It’s way up there. So if there’s no ductwork in the house, there is no energy loss at all through ducts. I did have to add that vent for the fridge, which bothered me, but there we are.
Attics and Crawlspaces Peripheral Storeys
And there is neither an attic nor a crawlspace. Those things cause troubles, ranging from rodent habitat and air leakage to moisture and indoor air quality problems.
And they’re there to access the mechanicals. Is that part of the reason for them?
LW: Crawlspaces are in the West because you can build on a hillside without much digging. And attics are sort of a waste of space, either indoors or out. It’s easy to install a home’s equipment without these spaces if the distribution lines are small. The actual machinery is better off in an equipment room, rather than tucked away. Attics get too hot or cold and leak indoor air back outdoors. Crawlspaces are often damp, and either one can invite critters. You know there’s all this downside to these spaces that can’t happen if the spaces aren’t there. It may simply be these spaces still exist because there’s a lot of inertia in the building industry, and we’re slow to change.
With no attic, a roof can overheat and curl shingles, but a cool roof solves that problem. I don’t think you got a chance to crawl up on my roof.
I peered over the top on the south side from the ladder.
LW: If you did, you would have seen a silver roof coating on the roofing itself. So there’s a rubber roof—Bituthene, it’s called. Self-adhesive stuff. Then I put roll roofing on top of that, and then I painted the roll roofing with this silver coating stuff so that it won’t wear out in just a few years and it’ll stay cool.
Sounds like what my travel trailer had.
LW: Exactly the same stuff. And it’s on the solar roof, so I wanted to be able to maintain all that. Walk on it. I didn’t want it to be a tile roof, but it’s still a relatively flame-resistant roof. Burning embers could land on that without a lot of trouble. Fire’s a real big concern where I am. You know, a lot of California burned recently, so I wanted to design something that would do well. So a lot gets taken into account here.
So keep the roof surfaces cool. Doesn’t damage the roofing. I don’t really need an attic. An attic is just a place to run pipes if you have to, but if you’re smart about all that, you don’t need it. We’ve gotten rid of ductwork. What else do you run up in attics?
We raise rats in our attic.
LW: In cages or are they free?
They’re free. Free-range rats.
LW: I know about them.
Where did you live before you built this house?
LW: Del Rey Oaks is a small town between Seaside and Monterey. Next to the airport. It was a mid-’40s- built house. Copper pipe under the slab in direct contact with the ground, so the kitchen faucet, which was a door away from the water heater in the garage, still took 45 seconds to get hot.
I learned something recently about faucets, which is that those single ones that feed both hot and cold through the same fixture tend to be—because of aesthetics—left right in the center; and people come along to use them and they lift them straight up, drawing both hot and cold, and wasting the hot.
LW: You’ve listened to Gary Klein.
Yes, at the conference on hot water put on by the American Council for an Energy Efficient Economy, right here in Monterey, and he has written about water use for Home Energy.
LW: And he’s shown me the draw patterns, and you look at any house and there’s a whole slew of little tiny draws for the hot, which are nothing but waste, because the hot water never made it to the tap. But in the design of the faucet, it promotes this waste. In my place, I stepped back to using two-handle faucets, except in the showers.
Your water is preheated by the solar panels. Are you using another water heater for backup?
LW: Yes, it’s a tank-type direct-vent heater, plumbed in series with the solar.
Unfortunately, I‘ve got a sort of litany of complaints about the long-term viability of tankless. So I put a tank in. They’re simple. You know how to maintain them. If you don’t have a large load in the first place, it’s just not a big deal.
So if I’m doing 80% of my heating with solar feeding into it, it’s not firing much. Yes, there’s standby loss, but it’s in the equipment room with the big, warm solar tank, so the standby loss is lower than if it lived in a cooler place.
Also, my manifold for plumbing is sitting on top of it, so it’s full of hot water all of the time. It’s insulated. When I turn on a tap, I’m running out only what’s in the 3/8-inch tube. The manifold starts hot, so I get much quicker hot water than from a standard manifold. And quicker than what a tankless heater can do, because a tankless has to heat up from scratch. That’s adding—depending on who you talk to—7 to 15 seconds before you get hot water. That’s a water waste.
Gary Klein says that water is 30% of California’s energy use. If you look at how we spend energy on all the different phases—pumping, treating, heating, disposing of, moving it from Northern California to Southern, taking it over the single highest lift in the world. All that neat stuff uses energy.
So being water efficient is being energy efficient. Again, what are the effects? How does everything in the house affect other things? Looking at all that, I recognize that tank-type heaters are not the most efficient. It’s still for me the best thing, because of the amount—we use roughly, and I’m having to guess—about 25 gallons per person per day total water use. So how much of that’s hot water? Probably something better than half. But does it make sense to get Navien High Tech, or some other high-tech water heater? Not for me.
Also, no electricity use is one of my goals where possible. So my water heater uses no electricity, and all of the other fancy ones have electronics, so there’s a problem for me.
Refrigerators and Heaters
Any big lessons learned or interesting major hurdles or mistakes or surprises with building the way you did?
LW: One surprise—just what comes to mind first—is the fridge. It’s a gas-powered fridge. I didn’t vent it when I put it in—I gave it combustion air and combustion exhaust, but I didn’t vent the coil in the back of it, and that heated the house up to 90°F, and that was a surprise. [We laugh.] I did not expect that.
Hummingbird House: Design for Everyone,” HE Jan/Feb ’10, p. 24.)That’s when you installed the overhead vent. (See “
LW: Yeah. The walls weren’t closed up yet, so I could run a chase up and out the roof.
Hummingbird Operation Manual
Say somebody comes to house-sit for you. You and your wife take a vacation to Hawai’i. How big is the instruction manual to the house?
LW: Well, there isn’t one written. I guess there could be…
But is it a sheet of paper or is—do they really need to understand a bit more in order to run your house?
LW: I don’t have the water totally automatic. So I check a pressure gauge. When the pressure gets down, I turn the well on. If they visit at any other time than winter, there’s a meter that tells me the state of charge of batteries. If the batteries get low, I would tell them to turn the backup generator on, which requires a few steps to learn. It’s not really that complex. If they show up over that three-quarters of the year and the weather’s okay, they would need to look at water use. Look at a gauge and flip a switch if pressure’s low.
I’m trying to think if there’s anything else. Not really much. Things to bear in mind, you don’t want to waste. I’ve turned into one of those weird guys that turn the lights off. Just like we complained about our parents, “He follows me around turning the lights off!” My father’s bills were probably $10 a month. So I’ve turned into one of those, because living off-grid you just are more aware of energy. It’s not a bad thing.
You’re interacting with it.
LW: Yeah. It’s instant feedback. If you use too much, “Oh! My batteries are discharged!” Or they’re discharged more than I want them to be. The system with 630 watts of PV, and lots of batteries, is tolerant. I try to never let the batteries discharge more than 10%. Because that way they’ll last a really long time. And I know that’s pretty strict.
You’ve made a good argument for what they’re calling oversizing, which in your case may be not oversizing but just good planning.
LW: Right. Again, keep the loads down and everything else falls into line. It’s easier on equipment. The house took long enough to build that my first set of batteries, four L-16s 350-amp-hour batteries, each lasted seven years, so when I replaced that, I doubled it. And so I have eight of them now. It allows me to more deeply discharge them without any trouble. I still don’t like to let that happen. But if someone came to house-sit and they discharged them a little more, fine.
You can afford that.
LW: So it’s pretty resistant to damage. If house sitters turned everything on and left, that would be harder, but one can abuse things. But if they’re paying any attention at all, it’s not difficult to manage so there wouldn’t be much they’d have to think about. Suppose I’d better write that sheet of instructions anyway.
Design for Comfort
One very remarkable thing, entering your house, is that it’s comfortable and it feels like it maintains a temperature range between just a couple of degrees, 68°F or 70°F.
LW: Anywhere in the house is generally within two degrees of anywhere else. Most of the time within one.
I’m very sound sensitive and live in the city. Your house is quiet.
LW: That was designed. That was on purpose.
That’s a big part of comfort for you.
LW: I think everyone needs to take the idea of comfort and see how it applies to themselves. And not listen to somebody else’s rules. I don’t mean to diss LEED and any of the other dozens of rules out there. The one that sort of got me going is that there’s a peak energy rule. A peak energy house. You design your house so that you reduce peak energy use for the power company. Their problem, and you have to build your house—
For their comfort!
LW: Wonderful! Okay! We’re off-grid. Done with it!
That pretty much makes up your mind.
LW: That told me that we’re being silly. That it’s time to do things differently.
Leslie Jackson is the associate editor of Home Energy.
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