Hey, what if you could have a house that’s much friendlier to the environment and costs about a tenth as much to heat? Passive houses are here:
Even on the coldest nights in central Germany, Mr. Kaufmann’s new “passive house” and others of this design get all the heat and hot water they need from the amount of energy that would be needed to run a hair dryer. […]
Using ultrathick insulation and complex doors and windows, the architect engineers a home encased in an airtight shell, so that barely any heat escapes and barely any cold seeps in. That means a passive house can be warmed not only by the sun, but also by the heat from appliances and even from occupants’ bodies.
The concept has been tried before, but failed because of problems with mold and stale air. A new air circulating system, in which cold air gong in is heated by the warm air going out, has solved this problem.
But the sophisticated windows and heat-exchange ventilation systems needed to make passive houses work properly are not readily available in the United States. So the construction of passive houses in the United States, at least initially, is likely to entail a higher price differential.
Moreover, the kinds of home construction popular in the United States are more difficult to adapt to the standard: residential buildings tend not to have built-in ventilation systems of any kind, and sliding windows are hard to seal.
Sounds like the sort of thing that some sort of big green infrastructure investment stimulus package might want to invest in.
I grew up visiting a lot of solar architecture-my dad designed them for decades-and I am still heavily involved in LEEDS developments now. Just a nomenclature issue FYI: you are describing a particular type of superinsulated extremely airtight home. Passive doesn’t mean “airtight” though that is an important aspect of it as convection leads to quick heat loss. A passive system can be as simple as a correctly placed slab under south facing skylights, which absorbs heat by day and releases it (passively, of course) in the evening. So my mom’s house (which is far from superinsulated) nonetheless requires very little supplementary heat to stay warm, courtesy of good design.
Heh. i’m sorry to say that we’re a long way from good design; in many areas it’s hard enough to get local builders to point the houses south! Superinsulated supertight homes are extremely energy efficient of course, but as with all things there are diminishing returns as you approach the best levels. And many of the things you can mainly do to reduce heating costs are things which many US home builders (and buyers) do not want to do: reduce floor size, reduce windows, etc.
How much more energy does a house like this cost to produce (both to produce the materials and to actually build it)?
Not to argue against the concept, but what are the actual costs to put it into practice?
Re: costs, the article says,
A bigger problem for Americans probably will be the size constraints — it’s difficult to build passive houses that are McMansions.
Airtight, good idea. Not only will some Americans probably suffacate themselves like the poor fools who listened to Cheney’s duct-tape-your-house-to-survive-anthrax idea, but the place will start smelling like nothing but shed human skin and other bodily affluence within days.
Passivhaus is a European standard. Although the proper translation is “passive house”, it is not the same as what we think of as passive homes. It does include an air sealing standar, nor more than one air change every 1.5 hours. This has been around a while. Amory Lovins wrote about it in the 90s. And properly done, there has never been a problem with mold or air quality. If you look at my online book (available for free download on the website linked to my name) you will see it includes a very brief discussion of this. – published in 2004. Though I can’t claim any great prescience for discussing then, since (as I noted) Amory Lovins discussed it fairly extensively back in the 90s.
Yep, lots of McMansions built in my neighborhood. 3000 or 5000 sq. ft. on small lots, tall ceilings, lots of glass. My wife and I kept asking, “Who’s buying these? Where are they getting the money? Why? Who wants to clean all that? Is someone going to buy them down the line when they want to move out?” Turns out the answer to that last one is “Nobody”. Turns out the answer to “Where are they getting the money” is “From you and me, bailing out their ARMs and sub-prime mortgages.”
PG, energy efficiency on a house level (measured on a per-square-foot basis, for example) can be accomplished in large structures as well as small. In fact, I know plenty of people who are designing and building large LEED certified homes. It’s just that large structures are inherently wasteful, because the per-person energy use is so high.
Also, any tight house can have as much ventilation as you want, given the requirement to add fans. it’s just an issue of heat exchange capacity. Even a tight house will leak a bit, and in theory the exchanger will compensate for everything else (though you do need to be OK with the fan noise.)
Anyway, Amp: We’re not investing in it because we’re so very far away from it. t
Take something simple, like insulation. used to be that standard was 4″ studs w/ fiberglass and no sealing. Then we evolved to stuff openings with fiberglass. then, to some degree, 6″ studs. Now even the least competent folks will (or should) build with 6″ studs and 6″ of glass, and will foam the gaps (though they do a bad job.)
but of course that is not even close to a good insulative envelope. In my area, the current gold standard that takes cost into account is a 1/2″ – 1″ spray of foam (e.g. Icynene) which completely seals and also insulates, followed by 6″ of fiberglass, on a 6″ stud. more expensive jobs use icynene for the whole thing. Some wrap the entire outside with another 1-2″ of rigid foamboard. Some build with SIPs. But in the end you still have a HUGE number of people who are building to minimal code requirements.
The small lots probably are OK for passive houses, but the article said there shouldn’t be more than 500 sq ft for each person, and I’m sure tall ceilings are right out. Then again, within my family the square footages are appropriate to our climates: my spouse and I share a 600 sq. ft. apartment in NY, where the main concern is staying warm Oct – May; my parents share a house with ten times that square footage in Texas, where the main concern is staying cool April-Oct.
i grew up in Scandinavia, and can attest that building standards in at least that part of Europe differ considerably from what i’m seeing now in the northern midwest.
windows i remember from my youth were never sliding ones; they opened by pivoting on an axis, usually a horizontal one. they weren’t meant to open for ventilation — 1960’s and 70’s era construction (which was the sort of buildings i grew up in) usually had separate ventilation hatches in case you wanted fresh air, mounted by the side of the windows. (those swung open on a set of vertical hinges.)
forced-air heating was unheard of, houses were heated with hot-water radiators and oil furnaces. these days i understand electric heat pumps are getting popular either instead of, or as cost-saving supplements to, the oil burners, and the heating water pipes are getting installed directly in the floors now. the wikipedia page on passive houses mentions heat pumps using the ground for a heat sink; the same principle can be used with the outside air, too.
these houses weren’t exactly airtight, far from it, but they were sealed up enough that most of them had separate ventilation systems to keep the air fresh. these were similar to U.S. style forced-air ducts, but not used for heating, so the registers were usually ceiling-mounted.
my parents built their home in 1979, and it got a heat-exchange ventilation system. it’s hardly high tech, a bit of sheet metal separating the incoming fresh air from the outgoing stale air as they travel in opposite directions, the latter heating up the former. i’m sure technology must’ve improved since then, though. there was a flap valve you could flip to bypass the heat exchanger in summertime, so you wouldn’t overheat the house; in the USA, you’d probably switch between heat exchanger and air conditioner.
basically, a “passive house” is pretty much the same sort of house the Scandinavians were building back thirty-plus years ago, except with vastly improved insulation all around and a fancier, higher-tech heat exchanger on the ventilation system. oh, and it seems you can make do with less of a heating furnace, too, once you have those features. the main backdraw i remember was that the air got awfully dry in winter — which i suppose might have had something to do with the many months of sub-freezing weather…
What happens in these houses during the summer? It seems like the energy you save in the winter might be lost in the summer when the heat trapping becomes a negative and people start to want A/C.
Dianne, you can design around that. Shades work wonders. ;) So do deciduous trees, which are conveniently bare when you need lots of sun, and green when summer is hot. Also, the sun angles are different in winter/summer, so you can design fixed barriers which will let in more sun selectively in a single season.
You can also use a large thermal mass. It takes the ground a long time to heat up and cool down, so it lags behind the air temperature. As a result the ground conveniently is warmer than the air when it is winter outside, and the ground is cooler than the air when it is summer. You can run pipes through the ground and pick up free thermal energy almost just for the cost of the pump.
You can achieve surprisingly similar results just with a concrete slab in your home.
And so on.
PG, if your parents are using air conditioning, and not just relying on good design to stay cool, a smaller space is always going to be more efficient. It takes more energy to cool a larger space, just like it takes more to heat a larger space.
Summer in Germany doesn’t require the same intervention that summer in Texas does. You just open the windows and use blinds intelligently.
To me, the real problem here isn’t the concept, it’s that without a plan for retrofitting existing housing stock, it won’t make much of a global difference. The article talked about the importance of siting — read that to mean that the technology is not very effective unless the house is built on vacant land. In some cases, that might mean new construction over torn down dilapidated housing stock, but in most cases, that just means swallowing up vacant land.
Ron F — yes, who wants to clean all that? My sister’s stepson bought a minimansion “because he could” and was shellshocked at the increase in his HVAC bills — he had lived in a townhome, and having a lot of houses strung together definitely reduces heating needs. So they run around cold half the time in the winter, and hot half the time in the summer. So silly.