228 comments on US Housing and the Passive Home Standard
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228 comments on US Housing and the Passive Home Standard
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Great article. Just to clarify a couple points, if you will. When you say 120 kwh per m2 per year for the overall consumption of primary energy can you confirm for me what is meant by primary energy? If, for example, my home is supplied with fossil-fired electricity and the utility's average heat rate is 10,000 BTUs/kWh, does that mean the allowance at the meter is 30 kWh/m2? Alternatively, if it's 120 kWh/m2 at the mast, then I suspect a good number of fairly conventional homes would have little difficulty meeting this target. I live in a cold climate (colder than Buffalo, NY) and my home's total energy use falls well below this upper threshold and although extensively upgraded in terms of its thermal efficiency, I can't imagine it would be anywhere near Passive House standards (very little passive solar gain, an un-insulated concrete slab floor and significantly higher air leakage).
Secondly, with regards to air tightness, I take it the 0.6 ACH standard is measured at 50 Pascal?
Cheers,
Paul
Paul,
Perhaps this may help answer your question;
Thanks, Will. I had suspected this was the case, but it could be easily interpreted to mean something quite different.
Obviously, the relative size of the home, local climate and the number and age of its occupants would skew the results rather dramatically (I shudder to think of the effect of four shower-loving, laundry-generating teenagers) but, last year, our two person household used a combined total of 72 kWh/m2 and, this year, with the addition of the second heat pump, that number should fall closer to 60 kWh/m2. It wouldn't be too difficult to improve on this. For about $2,000.00 CDN, I could replace my older unit with a model that is 1.5 times more energy efficient and conceivably get that number down to perhaps 50 or 55 kWh/m2; likewise, a solar DHW pre-heater or heat pump water heater and a drainwater heat-recovery system might further reduce that to 40 or 45 kWh/m2 (doing laundry with cold water would help too). Unless there's something I've missed, 120 kWh/m2/yr seems downright generous.
Cheers,
Paul
How does this post, which leads off with a picture of a house that over 90% of the population of the planet could not afford, and in fact if you include the current economic crisis it might be more like 99% of the population can't afford, benefit any one?
It's like calling everyone together on the titanic into the Grand Ballroom and discussing ship building . Jesus H. Krisip!
I've got an idea for a subject of discussion for TOD;
What if we could BUILD a just and equatible world to live in? WWWWoOooooooooooo!
Sorry, I guess I am just being stupid. AAAAAAAAhhhhh, Build better Mc Mansions, yeah, that’s what I meant to say.
I am sorry but I truely don't get it. Please explain to me how this relates to the current problems facing mankind in any sort of relivant way. Other than someone planning on building their dream house.
Well said. I am currently going through the growing pains of trying to live in a house that is supposed to be a passive solar with an in floor radiant heating system as a back up, and a wood stove to back that up. I did the design and take all the credit for the success or failure of what I am building. I have been using a lot of salvaged materials. We are by the way the only species on the planet that has someone else build our homes for us. Well it is a very steep learning curve and I am very glad that I have enough friends that have come to the rescue! wood I spent the day today cutting wood we have had 4 weeks of -20 to -40 degrees celcius and the home is not yet finished but it has been trying. The thrying includes a frozen septic tank. What an amazing learning curve this has been, I'm sure that I will be better prepared next winter than this, and likely better the one following.
cheers mike
Hang in there Mike is gets better. I built mine 30 years ago and I'm still fine tuning. Quite a few mistakes, nothing that hurt the structural integrity. There is no feeling to compare with sitting warm and toasty while it howls outside, knowing you built it. Putting you hand on the brick chimney you built and feeling the stored BTUs. I'm at about 7 degrees, and it's close to 75 inside. Snow again later tonite.
The wood thing does cease being work and becomes more like meditation. I actually prefer to split when it's very cold, when the wood is frozen it just explodes apart. Chop wood, carry water.
Don in Maine
I've been hand-splitting some ~30" dia. cottonwood logs (cut just a month or two ago) lately. The maul bounces off them until they finally crack. The same wood unfrozen will require the maul to be wrenched free fairly often.
A frozen SEPTIC TANK? My mind, having spent all it's life, except for vacations, in the southern US, boggles.
Hi souperman2,
I'm not sure I can properly answer your question, but I fully appreciate your point. It's an impressive looking home and without knowing the price tag, I can honestly say well beyond my price range.
FWIW, I prefer simple, cost-effective solutions and would much rather we repair and rehabilitate our existing housing stock than simply tear it down and build anew. I happen to live in a city where a good number of buildings are over two hundred years old (nothing out of the ordinary with respect to Europe and other parts of the world, but a bit of a rarity on this side of the pond) and they very much define the character and spirit of our community (e.g., see: http://en.wikipedia.org/wiki/Halifax_Town_Clock and http://www.pbase.com/halifaxphoto/downtown_halifax&page=1).
More to the point, when you renovate a home, you can start small and take things one step at a time, doing only as much as you can comfortably afford. For example, I upgraded my loft insulation from R6 to R60 in one afternoon -- no special tools or skills required and I re-cooped my initial investment in a few short months. Those 3M window kits, foam gaskets and all that caulking and weather stripping? Ditto - ditto. Two key points to keep in mind: One, if you continue to reinvest those savings in additional upgrades, these enhancements become largely self-financing. Two, you don't need to spend a lot of money to achieve large savings -- your first $100.00 will always save you more than the last $100.00.
BTW, thanks for keeping the conversation grounded -- we need to keep things real.
Cheers,
Paul
Often, the most cost effective energy improvements are replacing old HVAC systems with modern high efficiency units.
I am all for easy upgrades like Energy Star replacement windows, extra insulation in attics and even foam insulation in uninsulated exterior walls. However, if a home is old enough to not have insulation, in most cases it is more economical to build a new house. Fixing an old house is like restoring an old car. You will spend a lot of money and not make it new.
Most of my career was spent designing large manufacturing facilities. At various times we would have modernization programs and install new equipment in old facilities, thinking we were saving money by taking advantage of existing boilers, rail facilities, electrical substations, boilers, steam turbines, etc. So we might spend $300 million on an old plant instead of building a new plant for $750 million. What typically happened was that we found out that our cost estimates overlooked or underestimated something or and this resulted in a major cost overrun.
Invariably, the new facilities proved more profitable because everything was state of the art and had lower operating costs. Typically the old, rebuilt facilities ran another decade or so and were shut down. The new plants stayed competitive and will last many more decades.
Housing shares a lot of similarities.
Hi Paul,
In the commercial and industrial sectors where facilities are more finely tailored to the specific needs of each business, and where the choice of alternative sites is more limited and relocation to a new facility is considerably more complicated and costly, I see your point, but I'm not so sure the same can be said of our homes. The residential real estate market is much larger and more fluid, and there's a far greater range of product to chose from; consequently, if your needs or personal circumstances change (e.g., a divorce/separation, birth of a new child, kids move out, etc.) it can be easily exchanged for another. In any event, tearing down an existing structure and rebuilding from scratch involves a large commitment of capital, all of which must be secured upfront, whereas improving the thermal efficiency of a home can be accomplished over an extended period of time, as and when funds permit -- for a good and growing number of us, there's really no other option. In addition, some of us simply prefer older homes to new construction, for a variety of reasons, not withstanding their various deficiencies.
Secondly, although upgraded homes may never achieve the same level of technical performance, as you start to narrow the gap, it becomes pretty much a moot issue. I use this same argument when comparing air and ground source heat pumps -- it doesn't really matter if a ground source heat pump is twice as efficient as its air source counterpart if the home heating costs of one is $50.00/year and the other is $100.00. At some point, good does become good-enough. Along the same lines, if I can't afford to replace my old, leaky windows with new, high performance, low-e/argon units, a couple of inexpensive 3M window kits might very well do the trick -- my heating costs may be a little higher, but it's affordable and it could free up funds that could be better spent on other efficiency improvements that will generate a much higher return at the margin.
Cheers,
Paul
"FWIW, I prefer simple, cost-effective solutions and would much rather we repair and rehabilitate our existing housing stock than simply tear it down and build anew."
Hear, hear!
That is the post in this series I am waiting for. I hope I'm not disappointed.
lilith
yes that was my reaction to the photo in the article as well,(out of my price range), though I did like the "non-lawn" in the picture.
you might find some of the houses being built to the Passive House standard by e-co lab less like Mc Mansions
http://www.e-colab.org/ecolab/Projects.html
I understand they are working with a modular home manufacture to develop a more affordable package.
I think somewhere around 30% of our energy use is for homes, this obviously won't solve all the worlds problems, but I would argue that when we build new houses they should meet (or be much closer to ) the passive house standard, since the premium isn't that high, pay back would rather quick.
while my preferences lean toward organic agriculture in our current system natural gas is also used to make nitrogen fertilizer then on to food,feed, and even E-85 fuel. So their prices are dependent on each other.
a)The author did not provide a photo with his/her article, so I lifted the image off of the internets. You are likely right re affordability.
b)regarding 'benefitting anyone', please feel free to submit your own ideas on what/when/where/how we should proceed going forward - this series will only be as good as reader submissions/content.
Nate,
How about once in a while TOD just posts a TOPIC for discussion on Campfire, and let every one post on what they are doing about that topic.
Like say...preserving meat, or curing meat or butchering it.
The general topic would be about how to handle meat when the grocery store on longer works.
Chickens might be another good topic.
Hand tools another.
The list can grow but if its just refined to a particuliar subject then much good information can be exchanged by those who have ideas and plans that actually work ,in the dirt, so to speak.
When an ag agent comes to a meeting and espouses a new idea many will ask him "Yeah but how does it work in the dirt?" meaning lab research is fine but does it really work?
For instance two years ago an ag prof told me and another few that the ideas being put forth about so much nitrogen and chemicals was way overrated. He said we are using way way too many chemical/nutrient inputs.
Airdale
souperman2,
This article kinda fits with Will's solar passive articles and "builds our foundation of knowledge".
I have already started planning big time on doing what I can with my existing urban mini-house based upon Will's first article. This article adds a bit of detail to my thinking.
Our family will make significant reductions in energy use and consequent reduction of carbon footprint from practical application of the information in these articles. My garden won't die from heat exhaustion next summer either.
Majorian, thank you for your addition to my knowledge base.
Primary energy is fossil fuel or nuclear energy, not electricity which is figured from the grid. It's 120 kwh/m2 of space within the envelope per year for all heating, cooling domestic water and appliances. So for a American size 2000 square foot home-185 sq. meters-you are talking about in rough numbers
22.3 Mwh per year (the equivalent of about 14 boe/yr). The average US household uses 11 Mwh per of electricity
which is ~33 Mwh of primary energy plus another 11 Mwh of natural gas or +44 Mwh per year: 44000 kwh/185=237 kwh/m2 per year(graph shows 270 kwh/m2/yr).
It is actually more difficult to meet the Passive House standard for primary energy than for space heating,cooling(15 kwh/m2/yr). In a Passive House, domestic hot water is the greatest user of energy.
It's also interesting that the standard does not favor electrical use over fossil fuels because it honestly looks at reducing primary energy.
Your climate in Buffalo is considered very challenging compared to Germany. The solar passive features work only if you have a south facing exposure so things are even worse. If you look at a situation having your south winds blocked
in January by your neighbors you may find that your walls will 'grow' from 16" thick to 24" thick. In other words passive solar space heating helps a great deal but is not absolutely necessary to meet the standard.
Without analysing your house, I'd say that it probably can't be retrofit as a passivehouse short of a complete rebuild.
In Europe basements are unheated and outside the building enverlope. Heat loss thru the ground is critical.
An air tightness of .6 airchanges per hour is actually quite difficult to honestly achieve. You need to careful maintain the continuous air barrier around the interior. Verification is by a blowerdoor test with thermographic camera. 50 Pascals = 0.2 inches of water column or 1 PSF. A 20 mph wind produces 1 PSF at ground level. Of course for a Passive House, a mechanical ventilator provides code required fresh air of 0.35 air changes per hour, not infiltration.
Thanks for clarifying this, majorian; your explanation is more inline with my understanding of the meaning of this term, however, it does raise an interesting point. If my home were located in Manitoba, British Columbia, Québec or Newfoundland and Labrador, where electricity is predominately hydro-electric, I would be in far more enviable position than if I resided in, say, Alberta or Nova Scotia, which are heavily dependent upon thermal generation. That seems a little unfair.
With respect to air tightness, I had an energy audit performed on my home a few years ago as my renovations were underway, and the blower door test indicated that my air leakage at that time was 4.8 ACH @ 50 Pascals. I was disappointed with the results and I've since tightened things up further, but I won't really know how much things have improved until I'm re-tested.
For those who have a better technical appreciation of this than I, the results were presented to me as follows:
Cheers,
Paul
This is in UK - windy, often wet, temperate, cool temperature winter and summer, with brief occasional serious cold (very rarely colder than -10degC or '18 below' F).
I intend to replace part of a building with a 'superinsulated' box, designed also to achieve some modest spring / fall solar capture to help heat the adjoining structure. (The latter has a high heat-mass. The new building will also help gain control of air-ventilation of the old stone building.)
I intend a load-bearing woodframe 'box, with walls cast round the frame, using a 'hemp-lime' mix that will provide a warm-wall envelope with good air-tightnes round all windows etc, in addition to a very long-life wood preserving environment. A fairly light-weight mix of the fiber and the binding lime can be hand cast in sections that rapidly set into a self supporting wall. The wood plywood board that 'shutters' the cast, is removed within the hour and used for the next section. On an industrial scale, the wet mix can alternatively be blown on to a backing material. The whole must be protected from serious water penetration, but the hygroscopic properties of the surfaces has advantages of both 'feel' and dealing with occasional higher air-moisture levels inside the structure. Inner and outer surfaces are finished in suitable 'lime' render.
I understand the hemp/lime technology is adapted in modern form from traditional techniques from France.
Quibble - Serious cold, to those of us who have experienced it, would indeed be in the neighborhood of 18 below F, as you say. However, that equates to -28 C, as zero F is already itself -18 C. The -10 C temps you occasionally have to deal with is 14 F above, cold, but not seriously so by North American standards.