Interview — Living in a Passive Solar Home

In the early 1980’s, my parents built a passive solar home on the East Coast of the United States designed by Adirondack Alternative Energy. The main principle of the house is thermal mass – where most homes have a basement, there is six feet (about 2 meters) of sand to soak up heat. There is a small chamber sunk into the sand and fitted with a fan which helps to circulate this heat through the house – and in a nutshell that is how the house ‘works.’ In summer, cool air blows through the house, and in winter, the sand is allowed to warm during the day and then radiate that warmth at night.

I recently asked them about their experiences living in such a home.  

Dax: What are the main features of the house?
: When you say main features, do you mean the main components…
Dax: Of the passive solar part.
Dad: Active solar has working parts, this is passive which means – this is more of a geo-solar home because of the way we have the sand in the basement. The sand heats up, we have windows, but we don’t have a ton of windows, our main windows are on the south and west side. The other thing is, at the time, the insulation – this is an R37 and back then that was a lot, a real lot. Most of the houses back then were like R9s, R11s.
Dax: What did you do to get that high of an R value?
Dad: Well look at our windows: they framed everything out with 2x8s and 2x12s instead of 2x4s, so the insulation was like 6 inches thick instead of 2 inches thick.
Dax: Did you use special insulation or just more of the regular stuff?
Dad: It was not the fiberglass, it’s the foam sheeting.
Dax: And do you have to replace that at some point?
Dad: Well, if we have little bastards chewing on it, i guess we will. (there is some mouse or squirrel in the wall right now that they’ve been trying to trap)

circulation chamber
Circulation chamber, partially sunk into the thermal mass and adjacent to the woodstove.

Getting Started

They were the first home in their area to be built to these specifications, and remain one of a handful even now, 30 years later. How they came to build their home was always something of a mystery to me, as they don’t fit any of the stereotypes that come to mind when I imagine the early adopters of renewable energy.

Dax: You wanted to [build a passive solar home], but how did you find out about it?
Dad: I was just always interested in passive and – well, I didn’t even know the difference between passive or active solar. I always just used to look at, like, Popular Mechanics magazines and things like that.
Dax: But how did you hear about it originally?
Dad: Well between school and Popular Mechanics, yeah.
Dax: How hard was it to go from this idea to actually building it?
Dad: It was hard because the only [contractors] who would even listen to us back then, 30 years ago, was [a local contractor]. None of the other contractors around here would even entertain the idea.
Dax: What was it that they had against it? Or they just never thought about it before…
Dax: People had thought about it, but everybody said it would never work – right over here , [another local contractor], you know, Chuck and Dave.
Mom: Standard contractors
Dad: Yeah, they said it’ll never work around here, but chuck has solar stuff now and they’re talking about it. The attitudes have changed a lot in 30 years.
Dax: And what was the motivation to do this?
Dad: Well, motivation was a lot of things, number one it was going to cost more initially, you know, it was going to cost more initially but hopefully it would save us a lot in the long run. Plus, the thing was, I would have rather had a system like that wasn’t burning coal and all that kind of shit.
Dax: So was it for energy savings or what was the main thing you wanted to try to get?
Mom: Energy savings.
Dax: Efficiency, or…?
Dad: I didn’t want a heating bill, I liked the technology, but energy savings was big, too.
Mom: And it was the last year of the tax credit that we took advantage of.
Dad: If the system worked – and, i think this system has worked for us…
Dax: Wait, but so you also got a tax credit?
Dad: Right
Dax: But it was based on…
Dad: But it was only based on 40% of the first 10,000.
Dax: So that’s $4000
Dad: Right, we got $4000 back.
Dax: But what was that tax credit specifically for?  Just green something in general?
Mom: It was under Reagan, and then they took it away, that was the last year…so we took advantage of it then.  We only had the foundation up but because the foundation was up, we were able to get the tax credit.  We didn’t have the house fully built, but because the foundation was in, we could get the credit.

I recently read a series of posts1 from John Michael Greer’s The Archdruid Report that puts this all in a more comprehensible context. ‘Appropriate Technology’ – essentially ways to put sustainable principles into practice – was very much part of the cultural consciousness after the energy crisis of the 1970’s, and it was one of the narratives people at that time used to envision the future.  This helps to explain how my parents knew about this (from “school and Popular Mechanics” – that is, it was simply in the air), but their own responses mirror Greer’s posts. Sustainable practices were popular but not mainstream, and the removal of government grants and other funding when Reagan was elected made sustainability less appealing for the masses.

The wood burning stove in my parents’ house. Built on a layer of bricks for safety reasons as well as to hold heat, the circulation chamber is directly behind the brick wall, helping to heat the whole house with minimal heat loss even on the coldest days.

Total Energy Use

Dax: How much wood do you actually burn in a year?
Dad: 3 cord2 max?
Dax: That’s on a cold year, so normally you’re burning what, 2 cord?
Dad: 2 cord, yeah, if that.
Dax: And what’s the average temperature in the winter?
Mom: About 64 [~18C] in the morning and then when the sun comes in and heats up it goes up to 75 [~24C].
Dad: If you’d look at what the average temperature would be, it’s about 68 to 70, without the woodstove.
Dax: But it sounds like it works without the woodstove, you said it’s relatively comfortable without burning any wood?
Dad: Well…
Mom: For the first ten years we didn’t have any baseboard heater or auxiliary heat, only the solar system and the woodstove and it was a little bit cool in the bedrooms.
Dad: In a normal winter, though…well the last two winters have been exceptional.  but on a winter like this [a warm winter], you see it we don’t have the stove going, we have some of that little heat going on up here, but really that’s hardly anything.
Dax: Now that you have auxiliary heat, what are your heating costs?
Dad: This is first year we’ve had electric heating, but our electric bills average…last month it was $126.
Dax: That’s with everything?
Dad: That’s with everything.
Mom: That’s with our electric hot water heater, our freezers, everything.

According to the U.S. Energy Information Administration, the average monthly electric bill (as of 2014) for someone living in Pennsylvania (where my parents live) was $113.723. So in fact, after installing some auxiliary electric heating, they pay just above the average during winter. However, they have no other utility bills, which is not the case for many Americans. I tried to find comparable information regarding heating costs per family, but since this is often tied up with electricity, it’s difficult to do so. I would suspect, though, that they are in a much better situation than many, as even on occasions when they lose power for several days, they’re never without heat or the ability to cook meals via their woodstove.

The top of the circulation chamber, this is where air flows to the rest of the home and it’s fitted with an air filter to reduce dust, mold and other impurities.

Passive Solar Today

Dax: Do you think it makes more or less sense to build this house today?
Dad: More.
Dax: Why’s that?
Dad: A lot of the glasses are much improved…
Dax: Windows, you mean?
Dad: Yeah, windows. More efficient. I’m sure they would have more efficient ductwork, stoves, everything you can put in is just a little bit better. I think you could build this same house today and i think it would be much more efficient because the technology they have in other areas of the building industry.
Dax: You said that you’re still heating your hot water heater by electric, but that as well could be solar.
Dad: That could be solar, when we built the house they had mentioned that they could run piping down through the sand in the basement that could heat the water – we didn’t do it, but all that is now is radiant heat. That’s what I’m saying, had that technology been more developed, we could have run radiant heat through the floor and we would not have even needed this stove.
Dax: Would you still have gotten the stove?
Dad: I probably would have still got it, but if i built this house today, with all the other things available now, you could heat your water, have radiant heat, and be able to heat your whole house with just the passive solar, and it would be much more gentle than burning the stove.
Dax: What about the summertime?
Dad: You need air conditioning. But don’t forget, we don’t have shade trees. This works best with shade trees which we didn’t want to get because of the well…the ideal would be to have deciduous trees that lose their leaves on the south and pine trees on the north side. Our neighbor has some pine trees [on the east side] and that does us a favor because it breaks the wind.

Passive solar, especially when the basis of a whole home system, is amazingly sustainable because it requires so little to work in the first place. There’s no maintenance, because there is nothing to maintain, no noise, no fumes, no chemicals and no dependency on supply lines or externally generated power. When paired with a wood-burning stove – or even better, a Rocket stove – many energy needs become immediately irrelevant.

The downside is that many passive solar systems need to be built-in – which is to say they cannot easily be added to existing homes or apartments, and are therefore not prevalent in cities, where they could effect great change. This is something we’d like to explore in future posts, but if you know of any examples of passive solar systems or components in an urban setting and/or added to pre-existing buildings, please mail me: dax at

You can read more about thermal mass at the following site:


  2. A cord is a strange but very common way to measure an amount of firewood.  See the Wikipedia entry for more details.

Cover photo from

7 years ago

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