September 28, 2010
Passivhaus High Home Efficiency Shows Up In America
A Prius is so 5 years ago as a way to signal your dedication to energy efficiency or the environment. The German Passivhaus extremely high efficiency home design standard represents a far bigger dedication to energy efficiency. It is so cool (er, warm) that I'm tempted to move somewhere cold to justify building one. The 106F temperature in my town on Monday makes that an even more appealing idea.
A so-called passive home like the one the Landaus are now building is so purposefully designed and built from its orientation toward the sun and superthick insulation to its algorithmic design and virtually unbroken air envelope that it requires minimal heating, even in chilly New England.
Why mess around with wimpy Energy Star and LEED design goals when you can step up to some serious techno-geek levels of efficiency?
Energy Star and LEED aim for efficiency improvements of at least 15 percent over conventional construction and both programs can earn a variety of tax credits and other incentives. The passive-home standard, perhaps because its unfamiliar to many officials who create efficiency stimulus programs, is eligible for few direct government subsidies, despite the fact that homes using it can be up to 80 percent more energy-efficient, over all, than standard new houses and consume just 10 percent of the heating and cooling energy.
Want to have serious bragging rights? Build to the Passivhaus standard. Also, while the German Passivhaus institute has an American affiliate that uses English style spelling you can emphasize the sheer engineering geekiness of what you are doing by using the more chic German spelling.
But seriously, I am impressed that such a large improvement in home efficiency is possible at an affordable increment in cost (maybe 10% or 15% according to the article). Given where I expect oil and eventually natural gas prices to go the only other long term feasible option for heating in really cold areas is ground sink heat pumps. Electric power costs won't rise as much as first oil and later natural gas. So heat pump heating costs will stay low compared to oil and natural gas. But since the migration away from heating oil in the US is over two thirds complete I do not expect the coming rise in oil prices to provide a major impetus for PassivHaus.
The article neglected to mention one advantage of PassivHaus design: in the face of the spread of the Asian stink bug the extreme sealing characteristic of PassivHaus will keep out the bug invasion.
Mr. Jacobs, the urban entomologist, said the response to stink bugs so far is not an overreaction. Im standing here in my living room watching some of them crawl up my walls, he said. The best thing to do is make your house as tight as possible. Use masking tape to seal around sliding glass doors, air-conditioners.
PassivHaus will protect you from foreign insects from other continents.
Those efficient German and Scandinavian houses are sealed tight.
Considering the thousands of chemical off-gassing from things in one's house, a little draft might be the difference between health and illness.
But they've got air exchange systems with heat exchangers. How well does that work? These houses could be measured for VOCs and probably some have been already. I'm curious to know the results.
Also, regards out-gassing: Do not use carpet or other materials that out-gas. I'm also thinking that the clothes washing room ought to have its own separate air supply from the rest of the house.
Interesting post. Two concerns come to mind.
1. As to the water-to-air heat pumps, what is the story regarding durability (do they last) and long term total cost to operate & maintain in cold-climate areas? In the US Southeast, you hear anecdotal horror stories/concerns regarding calcification buildup in the pipes, etc., ruining the system in just a few years. Admittedly, this may be an old issue now somehow overcome.
2. Is it cost-competitive? From an American comfort-loving perspective, are there any significant livability "gotchas" to the Passivhaus standard?
It seems to me that it's all a question of economics. Either you pay XX now or pay XX later. You certainly can spend WAY too much for such extreme insulation schemes to get a payback within a reasonable time. It remains to be seen if such extreme insulation schemes are cost effective - so far it appears NOT [just as home solar electric schemes are limited by real world costs]. Given the recently exploited and proven new nat gas shale reserves, the entire premise of increasing heating costs has been thrown into disarray.
You can adjust the amount of air exchange to suit your needs/concerns about 'normal' indoor 'pollution' with these kinds of systems; it really is not a major concern provided you have designed the capacities properly, adjust behavior, and are willing to pay the energy costs such air exchange costs. The article discusses using alternative clothes drying tech. Cooking is a major concern that is generally not adequately addressed in these systems since it generates quite variable amounts of 'contaminants'. I would imagine one bout of winter fish fry would be the last rofl. These types of systems cost a lot more than money - I would not enjoy being a slave to such green constraints. In most of the USA, cheap renewable wood heat and a reasonable investment in insulation is a far more economical green rural alternative.
I built a home like this in 1979. Passive solar, massive heat sink (concrete floor covered with slate), movable insulation to cover the 30 foot tall glass south wall, wood heat for backup and electric heat for backup backup. Super insulation and airtight vapor barrier. The air exchanger had to be custom built then. It worked wonderfully.
1800 sq ft. 40,000 $CDN.
Don't know what it would cost now (and the 34 acres cost $12,000) to build, but I'm guessing less per sq. ft. adjusted for inflation. This is an idea which should attract an X-prize.
My wife and I built a 6500 sq ft house in 2005. The vast majority of thermal leakage/energy loss is through holes, cracks and seams of the exterior envelope of a house that - in aggregate - are about the size of a continuously open window. To prevent this during framing, I ensured w/my own eyes that there were the absolute minimum of construction perforations (hammers gone wild) and plugged the few that happened with expanding styrofoam. Over this we laid interlocking foam sheets in order to cover all wood/studs. It's not well known, but appx 25% of any exterior wall is equal to the R value of wood studs - R1 per inch (ie pathetic). So, we covered the exterior of all studs with foam sheets to prevent the thermal short circuit through the wood. Over that sheathing we then double wrapped the entire house (yes, twice) with highest quality vapor and wind barrier (it still breathes but you NEVER feel anything during even 60 plus MPH high winds in winter).
This wall system is very effective for keeping heat/cold in, for keeping bugs out (we've had NONE so far other than when the door opens and moths get in) and for making the house supernaturally quiet. We used to have a townhouse of 1800 sq ft occupied by 3 people. Now our house (8 people) is almost 4 times that size, and everyone works in the house (telework full time) but the energy bill is exactly the same as the 1800 sq ft house was.
The system we devised is simple, very inexpensive, and uses no special materials. The extra sheathing and house wrap paid for itself within 6 months - not including not needing exterminators for stink bugs :-)
A problem with too much insulation is it plays hob with acoustics. Of course if you grew up in a library...
The article gives away the falsehood of the 15% at the very end. Mr. Landau says his total cost will be about $550,000. You can build a 2000 sq. ft. home in the Boston area for about $250,000 to $300,000, including all the site work, but not including the cost of the land. I know, I am in the process of building a 3500 sq. ft. house near Boston - total cost, not including the land, but including all site work, appliances, heating, cooling, well, etc. will be about $500,000.
So, the premium for the Landau's house is about 100%!
You can buy a lot of heating and cooling using electricity, gas or oil for $250,000 - in fact perpetually - if you invest that $250,000 in a nice interest bearing account. Invested in a 2% interest bearing CD will give you $5000 per year.
For my current 3000 sq. ft. house I pay $300 per month for gas and electricity. I am expecting that my new larger house will be about the same because it will have better insulation and more efficient heating and cooling systems as well as more efficient appliances.
So, if I invest my savings from not building a PassivHaus, I will earn an extra $1400 per year on my investment after paying for utilities.
I suspect a ground sink heat pump makes more economic sense than the most extreme form of PassivHaus. But we do not know what Mr. Landau is doing to boost costs. Sounds like he's opting for some cost increasers to make it exactly what he wants.
I would be curious to know about building costs for other PassivHaus projects in the US. I'd also like to know the details on what boosts cost. Sounds like the wood isn't making the walls 3 times thicker. Its the insulation. So how much of PassivHaus cost is insulation? I'd like to see a detailed materials cost break down for a PassivHaus. Also, does labor cost scale up more or less than materials cost?
We need more details.
As always with these type of articles - yes, we need more details. I find that this is typical for 99% of the "lets go green" articles. They give you little or no details on the economics.
In fact, I find very few people do the economics when they select a "green" alternative. OK for them, if they feel better after spending their money. I always do the economics. I have not found a "renewable" energy source yet that will actually pay for itself on a personal residence (house) - I keep watching the prices and my new house will have a nice big south-facing roof ready for solar. As I posted above, I always compare the expenditure to what I could earn on the money in a conservative investment and use the investment to pay for the equivalent energy from a local utility. The above example was very simplistic - my real models include inflation and not just using the interest from the investment, but allow a draw down on the principal over time if required.
You mentioned the one economical best selection for heating and cooling that I have found for my area (Boston) - that is the ground loop (sink) heat pump - I'll be installing one of those. Carrier makes some sophisticated units for residential/small industrial buildings - they call them Geothermal Heat Pumps, which I find to be a misnomer - I think a Ground Loop Heat Pump is the proper terminology.
Regards the ground loop (or ground sink or geothermal) heat pumps and calcification: One can do open loop or closed loop. If one is in an area where calcification is a potential problem then closed loop would avoid the problem. Use software water in the closed loop. Closed loop can cost more to install though.
I'd like to see a cost curve for building heating efficiency. A derivative of that curve (with some additional math to account for the cost of money) would show the marginal cost per amount of heat saved. The cost curve will vary by location of course. Choose a point on that curve that comes up to the cost of a ground loop heat pump.
Don't forget risk abatement when calculating benefits. A large savings account can be wiped out by bank failure or taxes and energy costs can spike, but good insulation is there for the life of the building.
Some of the high-efficiency construction methods (e.g. SIP) allegedly save lots of labor at the building site. If we hadn't had such a huge influx of illegal-alien construction workers, everything would probably have switched over to SIPs already due to lower cost and buildings would be heading toward Passivhaus specs anyway. We wouldn't be having this discussion, as it would be "just the way it's done".
Have you seen any other examples of labor productivity improvement that compete with cheap labor? IOW, things that might be used if cheap labor went away?
I'm curious how crops would be picked, and dishes washed, if cheap illegal labor went away?
I've done ParaPundit posts on illegal aliens and automation. Society would actually become more convenient if low price illegal aliens were taken away.
Cherries used to be picked by hand. Now they're dislodged by shakers, and collected onto stretched fabric webs like trampolines.
Australia's wine grapes are largely picked by machine today.
There have been immense advances in machine vision and machine manipulators since the Bergland policy was articulated in 1979. Jobs like meat processing could be done by robots using X-ray imaging to see bones in ways that even the most expert human can't. Machines don't take breaks, don't bring diseases from home or from failing to wash properly in the toilet, and can be disinfected using chemicals no human could tolerate. They can operate in conditions too hot or too cold for people to keep meat fresh and avoid the spread of pathogens.
We need an anti-Bergland policy, starting about 10 years ago.
Has anyone seen a good discussion of why Mexico lags so far behind the US in education and prosperity?
I wonder whether the pressure valve of Mexican emigration has supported a bad situation there.
You're not the first to wonder that.