A house without a furnace?!

January 9, 2015 7:49 AM

Help me understand the heating and cooling system of this house we just toured.

Mr. WanKenobi and I are house hunting in upstate New York. Almost every house we've seen listed has oil or propane heat.

Yesterday, we looked at a really interesting house built in the 1970s whose listing boasted "greenhouse to provide solar heat for house." There were also electric baseboard heaters in each room (not running) and a fairly new woodstove in the den in the basement (also not running). It was one of the coldest days of the year so far, and the house was nicely warm. The selling agent provided copies of the last two year's electric bills--very low compared to oil heating costs in the area--and described the heating system as follows: "The solar exchange on the side of the home heats up in the winter and brings hot air into the south side of the house thru four openings. That, along with the wood stove helps with keeping costs down."

There was also no central air, but a whole house fan. Google tells me this is also quite cost-effective and efficient.

I've never heard of heating a house this way. My husband is very frugal and excited by the idea. Are there any drawbacks to this kind of system? What should we consider in weighing the pros and cons of a house heated and cooled this way versus more conventional oil, propane, or gas heating?

posted by PhoBWanKenobi to Home & Garden (25 answers total)

This is called passive solar.

We looked into stuff like this when we started the design process for our house. We have too many trees though, so any sort of solar system wasn't gonna work.

The downside is if you have a bunch of cloudy days in a row you won't get as much solar heating. That's when the electric baseboard heaters kick in. You saw some low electric bills, but at what temperature did the previous owners keep the house? Were they ok with 55 degrees all the time or did they manage to keep the temp at a nice 70 degrees while still keeping the electric bill low?

Efficient woodstoves or fireplaces can be awesome, but if they burn logs you have to be around to feed them every hour or so.

Houses like this are kind of rare, but they're out there. If done right they can work. If not done right, well...

You might want to do some research into who designed it, who built it, and who the original owners were. How long did they live there? Why did they move? Did the person who designed and/or build it build others like it? Did they know what they were doing?

We asked all the builders and architects we interviewed if they were familiar with green building technology. They all sort of shrugged and said "sure." The truth is, this is a science and you want to make sure the person who built it did it right.

Personally I'd be all over something like this. Worst case you freeze one winter, or use a lot of electricity, and look into upgrading.
posted by bondcliff at 8:05 AM on January 9, 2015

The house design seems akin to a passive house. There are lots of resources and homeowners sharing their experiences online.
posted by JackBurden at 8:06 AM on January 9, 2015

My uncle's (late 70s/early 80s) house in Maine works similarly. I don't think he has the greenhouse style solar exchanger, but he uses a combination of woodstove and passive solar, with electric baseboards he doesn't use (I think they were required for code reasons). It is generally uncomfortably warm for me in the winter. I'm not sure how much maintenance the system requires.

The low electric bill is nice to see but it's of limited use, IMO, since you don't know how much the previous owners were using the woodstove (maybe you love using a woodstove, but wood isn't free, and a woodstove obviously requires a lot more active work than other kinds of heating). Also, is this a full-time home or a vacation home (i.e. would it be for you and was it for the current/previous owners)? That also is going to have a big impact on fuel costs - if you can leave the thermostat at 50 on a well-insulated home (in general this type of house is also super-insulated, although you should probably check on that), you're going to save a lot.

Drawbacks - if you're using the woodstove as a major source of heat, it's more work than setting a thermostat on a gas furnace.
posted by mskyle at 8:07 AM on January 9, 2015

I bet you can find some good books at the library to give you an overview of how this works. For a broad look at passive strategies check out Sun, Wind & Light. You might also contact your local energy consultant to give it a look-over. Researching the original owners/builders is a good idea, too. I'd be very interested in a house that works this way! Whether it's a system that takes you in to the future or whether you add additional passive strategies or supplemental systems are the things to consider.
posted by amanda at 8:10 AM on January 9, 2015

I should add, while a woodstove or fireplace is very nice to have, as a heating source it requires a bit of work. Every year we get a cord of wood delivered and dumped in our driveway. We spend at least a weekend hauling it, stacking it, and splitting a good chunk of it. This is hard, but satisfying work. Ask me how satisfying it will be when I'm in my 60s.

Every couple of weeks we move a lot of wood from the main stack to our porch. Every night we clean the fireplace glass (only takes a minute) and bring in the night's wood into the living room. While we're doing stuff in the living room we're watching the fireplace and feeding it every now and then.

So it's a bit of work, but it's worth it for the nice toasty fireplace feeling. YMMV.
posted by bondcliff at 8:14 AM on January 9, 2015

The seller is an old man who was the original/sole owner of the home who is moving because his wife passed away. Home seemed like a very lived-in, well-maintained family home, though it needs cosmetic updates (there is a LOT of wood paneling and some really ugly carpet). It would be a full-time family home for us to raise Baby WanKenobi. My husband and I both work from home, so feeding a wood stove would be doable, though, of course, the need for heating and electric go up when you're working from home, too. The attic looked well-insulated and the windows were new and seemed well-sealed.

Will ask for more info on the designer of the solar system (solar system?!). There is another, very similar-looking house on the same street, built at the same time, with oil heat so I'm pretty curious how this happened!
posted by PhoBWanKenobi at 8:15 AM on January 9, 2015

I know we're not here to vote, but I totally vote to for you to buy that house. Support solar! Support unconventional and innovative ways to build houses!

Plus, the fact that the same person has lived there for 40 years is a good sign. Nobody is going to stay in a house that isn't comfortable.
posted by bondcliff at 8:20 AM on January 9, 2015

My parents built their home as passive solar in the late 1990's. On sunny days, even when it dips significantly below zero, the house is nice and toasty. In the summer, well designed cross-ventilation keeps things nice and breezy. They use a woodstove for snowy/gray days and they also have oil heat for backup, but that only kicks in if the internal house temparature drops below 45 degrees. I think they refilled the 500gallon tank 2x since building the house.

It's a pretty awesome system, and it's pretty cheap- I think they pay about $350 a year to have a cord of wood dropped off and stacked in the woodshed (or less if we're around and will do the stacking), and that usually takes us through a winter in the catskills.


Also, these houses are fairly common in the Catskills for houses built in the 70s-90s, so people are very familiar with dealing with them.

If I could swing a passive solar house in NYC (perhaps a tiny house on top of an apartment building?), I would be all over that shiz.
posted by larthegreat at 8:21 AM on January 9, 2015

The baseboard heaters may be required for code, I don't know, but I do know they are required to make the house insurable. Insurance companies want thermostat-controlled electric, oil, or gas heat to ensure that even if you're gone on a three-week ski vacation in January, the house still stays at a temperature which prevents freezing pipes, mold, etc. I don't think passive solar counts, and the woodstove certainly doesn't. So those have to stay.
posted by rabbitrabbit at 8:39 AM on January 9, 2015

When we were looking for houses out here in environmentalist-mecca-land, we ran across a few houses that had similar sorts of systems (passive solar, and at least one house with passive water heating which was cool). One thing that was very apparent was that these sorts of houses tended to be better-built and better-maintained than similar-vintage houses, at least in our area. Generally, the type of person who was motivated to design and build a house like this had done it thoughtfully and wasn't cheaping out on the materials for the "bones" of the house, even if the cosmetic stuff was pretty dated. These houses also tended to have very little deferred maintenance compared with other houses of similar age on the market. In contrast, when we looked at older houses that had been renovated to have newer kitchens and bathrooms, it was about 50/50 whether it was done well, or whether someone had cut corners because they were ultimately most concerned with how it looked and not how well it functioned.**

We weren't able to make the money work for one of the passive solar houses we looked at and loved, but we'd consider it a huge plus when looking at future houses, not only for the break on heating bills but more generally for what it says about how the house was built and cared for.


**Example: re-doing the bathroom in slate tile, but using the cheap-o slate from Home Depot and failing to keep up with sealing the stone every year, so that the many of the tiles are actually flaking off the walls and ending up on the shower floor from the constant exposure to water. Some days I really curse you, cheap previous owner who did a nice-looking but shoddy reno.
posted by iminurmefi at 8:57 AM on January 9, 2015

Everyone has hit on most of the important points. One final thing I would check into is how "tight" the house is. A very energy efficient house like this can be quite tight to outside air. This is a great thing energy-wise, but can have indoor air quality implications. Since there are wood burning appliances there must be provision for relief air. Find out what it is. Some buildings from this era have moisture issues because as they were made tight (or tighter over time) the controlled movement of air wasn't addressed. Your young family will likely be adding a lot more moisture to the space than I suspect this old couple did.

This could be a terrific find, but these sorts of houses are "hands on". I regard that as a good thing because it keeps you engaged to your investment. But, if at all possible could you meet with the current owner to ask some of these technical questions to help you decide? I'll be there are a lot of insights on keeping that place in top shape that the owner would be delighted to share with you, and give you a sense of what to expect, even enthusiasm for the place.
posted by meinvt at 9:16 AM on January 9, 2015

I'm with bondcliff. Lady, I might have to move there if you don't!
posted by jillithd at 9:24 AM on January 9, 2015

I spent twenty years in upstate New York heating with wood. A good stove will hold a fire for several hours, even overnight, once you know how to use it properly. I wouldn't hesitate at all to buy a house like this.

In one of the houses I lived in we had access to a natural gas line so we also got a gas stove similar to this one and it worked beautifully, especially if we needed to be away and didn't want huge electric bills.
posted by mareli at 9:32 AM on January 9, 2015

I don't know a lot about these houses in general, but a friend of mine has a passive-solar-heated house, and the room that receives the passive solar heat (her living room, in her case) has a dark red hard floor (concrete? I think?) and she cannot change the color or put down any rugs ... it has to be dark to soak up a lot of heat, and it has to be whatever hard flooring thing it is for the thermal mass or whatever.

Which is totally fine with her, but if you wanted a carpeted living room, or can't stand the color of the floors .... make sure you know how the system works!

(Also while that floor is admittedly toasty warm on a sunny winter day, it gets FUCKING FREEZING when the sun goes down and my knees would rebel if I lived there.)
posted by Eyebrows McGee at 9:46 AM on January 9, 2015

You should ask how much wood he used last year as well.
posted by mr vino at 9:51 AM on January 9, 2015

The only thing I'm familiar with in this scenario is baseboard heaters. Just remember that anywhere there is a baseboard heater, you can't really put furniture on that side of the room. Also they get hot to the touch which may be a problem with the baby.
posted by radioamy at 11:07 AM on January 9, 2015

Just remember that anywhere there is a baseboard heater, you can't really put furniture on that side of the room.

Why is this? I grew up with baseboard heat, and we didn't do this. Most rooms had heaters on two walls, that would make it hard to fit any furniture in.
posted by cabingirl at 11:31 AM on January 9, 2015

I would suggest getting someone from a company like Building Science to come look at it as part of your inspection. They will be able to evaluate it and explain in detail how to make it work best for you. Good luck, it sounds like a very cool house!

Oh the greenhouse thing is probably a trombe wall.
posted by sepviva at 12:25 PM on January 9, 2015

My understanding is that passive solar design tends to be more comfortable and more consistent. In other words, a lot of modern American homes have paper thin walls and rely heavily on piping in cold air in summer and hot air in winter, which doesn't actually do a great job of keeping humans very comfortable. Passive solar design aims to keep the structure itself neither too hot nor too cold, and most people find that is actually a whole lot more comfortable than what you get with slapping together a building cheaply and then trying to manipulate air temperature.

The solar exchange on the side of the home heats up in the winter and brings hot air into the south side of the house thru four openings.

Often, what is done is that you have some part of the house that is a large structure with substantial mass that serves as a heat sink. You paint it black or whatever and it has to be angled to maximize soaking up the sun in winter. If it is really well designed, there will be some built-in means to have it not doing the same thing in summer. So, for example, there may be deciduous trees that shade that side of the building in summer, then drop their leaves come fall and expose it to full sun light. Or another option is that the roof is angled such that summer sun is blocked out but winter sun is let in, for cases where there are windows and where, for example, the interior flooring is being used as a heat sink.

If the house was designed without air conditioning, but looks a bit like a Victorian house, with the turret-like stairwells, that may be a thing similar to what they do in parts of, say, Iran and even Mexico where there is an architectural feature that helps funnel hot air up and out in summer, keeping things bearable. I can't recall the name of this at the moment (and really should be, oh, working, so I am not going to try to google it up).

In the Deep South, historical vernacular architecture includes deep porches on up to three sides of the house so the sun cannot get to the interior of the house and the windows can be left open for a cross breeze, even during rainy weather. The deep porches both shade the walls and windows and keep most rain from coming in through open windows (unless the storm is just crazy bad).

Prior to the invention of the air conditioner, historical residential architecture was typically far more well designed in terms of fitting the house to the site in question and working with the local weather and what not to achieve comfortable indoor temperatures. This became a bit of a lost art once we figure we could just flip a switch, turn on a doodad and, voila!, cool thing off like magic. So it does not surprise me that someone upthread indicated that passive solar houses they were familiar with were better designed and better maintained than average: The whole idea behind passive solar is that the physical structure itself is what mediates the temperature, not some technological wizardry added on after the fact to compensate for poor design.

If you are interested in the subject, you might try googling info on, for example, historical city design in the deserts of the middle east. They generally were placed on a flat plateau that was a bit elevated and the streets were oriented to take advantage of the usual wind direction so that temperatures on the street were tolerable within the city and not something likely to make you pass out from heat prostration. It's an interesting subject in its own right and the potential to also lower your heating and cooling bill on top of living in a way that tends to be qualitatively superior the typical American home with paper-thin walls and modern HVAC is just icing on the cake, in my book.

I would totally buy that house.

best of luck.
posted by Michele in California at 2:41 PM on January 9, 2015

I can only address the woodstove aspect of this. Heating with wood is as much lifestyle as it is an energy source. Depending on the size and type of woodstove you might find yourself reloading it 2-4x per day in cold weather, and shoveling out the ashes every week or so. Every time you load it you have to stay in the room for a little while and make some control adjustments after the burn really gets going. If it's a newer stove then it will use less wood and emit less pollution than older ones, but it will be intolerant of the damp wood you'd typically get if you have it delivered. This means you'll need outdoor storage space to store the wood for at least a year, and preferably longer, to allow the wood to dry, which means you need enough storage space for at least 2 years' wood -- the wood you're burning this year, and the wood you'll burn next year. Firewood is heavy, and you'll be carrying it around a fair bit.

The house you're looking at sounds pretty good to me, too.
posted by jon1270 at 2:49 PM on January 9, 2015

I would not raise a child in a home with a wood stove because of health reasons. Sure, lots of people were raised in homes with wood stoves, but lots of people were also raised in homes with smokers. I wouldn't recommend it.

Your home will have a high amount of extremely fine smoke particles, the worst kind that penetrate deeply into the smallest passages of the lungs. It is even worst for young children because they spend all day in the home.

Here is what the EPA says about the health risks of wood stoves in the home. Children in homes with wood stoves have reduced lung function.

Not only that, you are polluting not just yourself but your neighbors as well. I'm sure someone will tell you that there are new "clean" wood stoves. But it isn't true any more than there is "clean" coal.
posted by JackFlash at 6:00 PM on January 9, 2015

Based on this description, "The solar exchange on the side of the home heats up in the winter and brings hot air into the south side of the house thru four openings," the house apparently has a trombé wall.

I designed and lived in a passive solar house that had no central heat. This was in the Midwest. It didn't have a trombé wall; instead the sun came directly into the living quarters and warmed the dark-colored concrete floor. I had one propane wall furnace downstairs and a woodstove, with no heat upstairs.

During the bitter cold or long stretches of cloudy days, I let the propane heater come on or used the (EPA certified) woodstove, which used outside air for combustion. If I was lazy, the propane heater was enough for the whole house, which was super insulated.

It sounds like since you have baseboard heat as a backup, you might not even use the woodstove if you don't want to.

I'd go back to that house in a heartbeat if I wanted to live in the midwest again. It was by far the most comfortable place I've lived in, with a steady temperature thanks to the thermal mass of the floor and the lack of a blowing furnace. I can't think of any drawbacks. There was even a property tax advantage -- the assessor said my house didn't have central heat, which reduced its tax.
posted by ceiba at 3:15 AM on January 10, 2015

I think JackFlash is overgeneralizing about the dangers of wood heat; modern stoves, operated properly with dry fuel, can burn very cleanly with low particulate emissions. Sadly, many wood stove owners operate them incorrectly and burn wet wood out of ignorance or poor planning, so unhealthy amounts of smoke are a common, serious problem in areas where wood heating is popular. I'd have no problem bringing kids to live in my wood-heated house because I keep a close eye on how everything is working, but if I wouldn't be eager to move into a neighborhood where woodburning was common.
posted by jon1270 at 3:30 AM on January 10, 2015

We currently live in a house w/ a wood stove and passive solar. It's incredibly cheap to heat, which is awesome. We don't have the fancy kind of passive solar you describe, but either way, it's important to find out whether the electric baseboard heaters will keep the house warm enough for you to travel in the winter.
posted by nosila at 11:17 AM on January 10, 2015

Offer in. Keep crossables crossed for us, please!
posted by PhoBWanKenobi at 7:57 AM on January 20, 2015