Are Passive House Standards “Overkill”?
GBA Editor
| Posted in Energy Efficiency and Durability on
I’ve often questioned the appropriateness and necessity of the rather extreme levels of insulation and air tightness that the Passive House standards require, though they seem to be setting the new bar for “green” builder’s to aspire towards.
But do they make sense? Or are they arbitrary and excessive?
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Replies
On the Global Straw Building Network listserve, there was recently a discussion about whether a straw bale house can ever reach Passive House air tightness levels.
John Straube, whom many of you know as one of the pre-eminent building scientists and now a principle of Building Science Corporation, offered this perspective:
There is no doubt that straw bale can meet the 0.6 standard. To do so requires attention to sealing ALL the joints. Even one crack 1/8" long, hidden behind baseboards, window trim, intersection walls etc that is maybe 30 or 40 ft long, will essentially mean you meet it. However, the question should be "Why would we meet 0.6 ACH at 50"?
The metric is questionable (CFM50/SF is better although the industry is only now shifting away) and that 0.6 target is totally arbitrary. Why 0.6? Why not 0.5, 1.0 or 1.5 or 2. The PH people chose the target based on flawed logic (condensation control is apparently the reason) and in many climates it is insane to expend too much effort to get to 0.6.
In the cold climate anecdotal experience of Canada, houses over about 3 ACH50 tend to have a risk of interstitial condensation. Rates over about 5 or 6 tend to be dry. Houses under 2 ACH50 tend to perform quite well and only gross local errors cause condensation problems. When the rate falls under 1.5 we note problems with high winter RH. This is all just rough numbers but is based on a lot of houses and a lot of people in Zones 5, 6 and 7.
Depending on your energy goals and climate, you might want to get lower than 2 ACH50. BSC targets 0.1 CFM50/SF for very low energy / Net Zero houses in cold climates and hot-humid climates. But some of the production builders we work with have reduced their fleets to under 2.5 ACH50, with the occasional one at 1.2, and find no problems (except the need for mechanical ventilation and controlling high winter RH via using HRVs not ERVs). In milder Zone 3 and 4 climates of the Southeast, getting the houses under 3 ACH50 has been remarkable for improving almost all aspects of performance.
If you can get the house to 0.6 ACH50 for no cost, by all means do so (and of course, this means you can't use normal range hoods in small homes, as they will extract 200 CFM + and may cause odd problems). In my experience, airtightness costs money in terms of supervision, inspection, testing and a small amount of materials. There is a tremendous benefit to getting as tight as 3 or 4 ACH50 . And it would be worth hundreds of dollars more to cut it in half. But would it be worth it to cut it to 1/8 at the cost of thousands. I think not: better bang for buck is a small HRV, or an upgraded window.
Robert,
Is your only issue with the PH standard the perceived additional cost of construction and/or your cost benefit analysis? Or are you questioning the building science?
A related question:
Should a new construction meet an energy standard (vs. best building practices defined by assembly R-values)?
(Soapbox warning)
New residential construction is not necessary. People who choose to built new buildings should be regulated in recognition of the impacts associated with building and conditioning a structure.
Regulation requires setting limits. We can be more precise about regulating energy consumption if the limits/standards are defined in units of energy consumption. (Yes air tightness is a separate matter.)
If PH is to move beyond the realm of architecturally designed homes it will only be if the regulatory systems within our American culture find that having an energy standard defined in units of energy consumption is useful to leverage limits to national energy consumption, national carbon reductions etc.
Whether the ACH limit is .6 or 1 or 2 is a lesser matter.
High efficiency design can be rather resource intensive to construct. That applies to houses as well as hybrid cars and other technology. Using extra material (trees, foam, batteries, etc) in order to save energy becomes a tradeoff and challenges the virtues of "efficiency". Low operating cost doesn't necessarily mean low environmental impact.
Efficiency would be easy without the presumed need to suit modern lifestyle standards. Strictly speaking there is no need to make walls and roofs extra thick in order to meet PH levels of energy use--you could just be flexible about thermal comfort. Of course that variable is off the table in discussions of efficiency. Likewise for transportation--you can already get 1,500 MPG (equivalent) in a human-powered vehicle, if flexible about top speed and exposure to the elements.
It's good to bring up straw bale here, because maybe it is possible to achieve very low energy use plus thermal comfort without consuming a great deal of resources up front.
there are already a number of passivhäuser utilizing straw in various forms, such as compressed straw fiberboards and straw bales (strohballen), and rammed earth (lehmbau). georg reinberg is doing some of the more interesting work with respect to these methods.
many PH projects in EU utilize low-embodied energy materials and achieve high efficiency/low operating costs without high environmental impacts (one of many reasons the EU bau biologie groups are pro-PH: http://www.baubiologie.at/europe/austria/austria.html?id=165)
regarding airtightness, the PH 0,6ACH50 wasn't based on "flawed logic" and condensation control is not the only reason, just the main one. as i understand it, the number stems from building physics and measured results from a number of research prototypes (the kranichstein house and CEPHEUS projects) and a balance between comfort, cost and keeping performance low (the 15kWh/m2a space heating demand, specifically)
additional reasons for the airtightness:
1. avoids uncontrolled infiltration heat losses
2. avoids drafts resulting in owner discomfort
3. avoidance of exfiltration
4. necessary with the maximizing efficiency of heat recovery ventilation
5. improved sound insulation
"excessive" depends whether you believe significantly reducing the space heating demand, (source) primary energy demand, increased comfort and significantly reduced CO2 emissions/energy costs over lifetime of building is worth the slight increase in construction and materials.
Robert. I've wondered the same. I've heard of a Vermont house where the builder says the upgrade to PH Standards added $50k to the cost of the house. This same builder already has tight baseline construction (I'd guess 2 - 3 ACH50 and 40 - 60 HERS ratings). I don't think the house will ever have an fuel / electric bill payback (vs their already efficient baseline). Say nothing of the energy / environmental impact of all the polyiso foam. . . . . imagine what would happen if that same $50k was used for weatherization programs for existing, inefficient housing stock.
Thomas your comments are to the point I think.
I think there is much to learn from PH design (especially in Europe) with regards to construction technique and material specifications but in certain climatic contexts, the performance targets lead to absurd levels of material consumption.
Going into the future, I think any truly energy-efficient design outside of certain moderate climate zones will have to find some balancing point between material use, performance and occupant comfort.
I have mentioned it before, but I'll do so again:
There needs to be a commonly available tool to evaluate the relationship between (total life-cycle) energy invested in construction and anticipated operational energy savings. There is possibly an avenue to such a tool through some type of adapted EROEI calculation.
I have been trying to create such a model myself... but to be honest, I'm not sure my math skills are up to the challenge.
In any case, well-intentioned efforts that make errors in understanding this energy balance do more harm than good - despite good intentions.
In my opinion the reason this discussion often takes a turn for the contentious is that we try to talk about all forms of residential construction as one entity.
The question about whether or not Passivhaus makes sense for a single family home out in the woods of New England surrounded by plentiful low cost firewood is a very different question than whether or not it makes sense for a series of townhouses in an in-town neighborhood with access to only electricity and natural gas as fuel sources.
There are many different forms of homes out there, but we need to keep our focus on radically reducing the damage we're doing to human and planetary health.
I appreciate the Passivhaus goal of a 90% reduction in heating energy and their reluctance to allow people who live in colder environments a pass on using more energy for heating, which aligns well with the necessary reductions in global carbon dioxide production. There are other ways to reduce that carbon dioxide heating impact, however, and those who can do it in other ways should do it in the most positive way possible.
Don't forget the Sunbelt states where about 90% of new homes are being built and the primary user of energy is air conditioning. According to latest NAHB stats all of the New England states combined accounted for 3% of all houses built last year.
Exactly my point, Allen. Didn't Houston have as many housing starts as all of New England last year?
Kristen,
I'm afraid your slip is showing when you say "perceived additional cost of construction", since there is a dramatic incremental cost, as John Straube suggests, to get from very good performance to a PH level of performance.
Once we're honest about the additional expense and effort required, then we can debate the cost-benefit ratio - and I agree with John Straube that the benefit curve does not approach the cost curve.
And I agree with John Straube that both the air exchange standard and the total source energy standard are arbitrary (that's not debatable - all standards are to some degree arbitrary) and unnecessary to achieve rational conservation, comfort and durability goals.
The PH 0.6 ACH50 standard was primarily a durability standard, to prevent moisture problems, and I agree with John Straube that a properly designed and detailed cold climate house with 2-3 ACH50 will not suffer moisture problems.
As for total source energy consumption during operation, this has to be balanced against total embodied energy, embodied global warming, and the entire ecological footprint of both the building materials and the building process.
Hmmm....
Time for Texas to secede - or else let's give it back to Mexico.
Jesse
Yes, Houston had more starts last year than 47 of the 50 states, I think we built 27,000 new homes, down from a high of 46,000 in the peak years. Of course there are 19,000 builders here :)
The Passive House standard is beautiful in its simplicity. I agree with Jesse that the standard should not be reduced in cold climates.
Simply stating the logic was not flawed without demonstrating the validity of the logic is mere dogmatism, and the PH movement has taken on cult-like qualities with its true believers defending it against all challenges (often with purely dogmatic defenses).
And Wolfgang Feist has stated on this website that the ACH standard was for condensation control.
I don't believe this is the PH position, but let's take them one by one.
1. It would require 0 ACH50 to avoid uncontrolled infiltration heat losses. The question is what level of uncontrolled infiltration is acceptable.
2. Any house tighter than about 3 ACH50 (and otherwise well designed and built) will not have a comfort problem from drafts.
3. The simplest method to minimize exfiltration (it can't be avoided), and consequent moisture problems, is with an exhaust-only ventilation system that can provide more negative pressure than the stack effect of the structure. And, as John Straube has effectively argued, it requires only tightening to 2-3 ACH50 to virtually eliminate moisture problems.
4. The efficiency of an HRV is a function of the design of the unit. And because a balanced ventilation system does not change the natural stack effect air exchange of a structure, it necessitates a much higher level of air tightness than an exhaust-only system to have it become cost-effective.
5. The amount of air leakage in a moderately tight house will have no impact on sound attenuation. That's a function of mass and windows.
Again, operating energy is only one part of the overall ecological footprint of a house, so it's meaningless to discuss it without a broader context. This is not a matter of "belief" (that's for dogmatists and cultists), but about mathematical life-cycle analysis and ecological footprint evaluation. And, once again, "slight increase in construction and materials" is such an understatement that it smacks of either dogmatism or propaganda.
A truly simple building standard is not merely one that has an abstract mathematical elegance, but one that is simple and cost-effective to implement.
If the PH standard was really that simple and beautiful, then every builder would be using it.
Robert, it's very possible to build a Passivhaus in your climate for a "slight increase in construction and materials". Friends of ours did just that, they built one with an R-40 / R-80 envelope, FPS, triple glazed windows, good passive solar, etc for $160/SF. It's very similar in many respects to the houses you have designed and the methods you advocate for: https://www.greenbuildingadvisor.com/blogs/dept/green-building-news/cohousing-community-readies-construction
deleted double posting
Jesse,
To make a statement about a cost increment, there must be a baseline. So what is the additional cost of that house compared to an IRC code house, or compared to an Energy Star 5+ house?
The last R-45/R67 2 ACH50 house I built in VT cost $105/SF. So the PH you describe cost 52% more than my superinsulated house. I would call that a huge increase.
Not to mention that, as with so many PH projects, it's ugly.
Response to Lucas post #8
Jesse Thompson shared this information in the 'thermal bridge' thread
If you're interested in calculating and modeling total impacts of new construction I would suggest looking to Europe to see how far this field has been developed instead of starting from scratch.
I've heard as a rough rule of thumb that operating energy for homes accounts for 80% of its impact while the embodied energy of materials accounts for 20%. I don't know the legitimacy of this and I agree this should be looked into further. However I think generally in green building circles the belief is operation energy is so much more significant that prioritizing it makes sense.
(The 20%/80% split could be about commercial structures, unfortunately I've lost the source.)
J,
That embodied/operating energy ratio is typical of residential structures over an assumed 100 year lifespan. If a perhaps more realistic 50 year lifespan is considered, the ratio drops to about 1/2.
The more efficient we make the operation of our homes, the larger relative impact the materials have on the earth, and the longer the payback period (second graph).
But there is a truly simple way to reduce both operating and embodied energy, as well as ecological footprint, and that's to live in shelters that are no bigger than what essential human needs require - perhaps 150 SF per person (which is luxurious by global standards), and to build them out of local, natural materials.
In Texas and other hot climates, there's an even stronger argument to question standards of thermal comfort. The PH concept hinges on Superinsulation, which isn't nearly as useful in hot climates, simply because incidental heat sources (people, lighting, appliances, sunshine) work against thermal comfort rather than helping. Regardless, energy demand can be minimal if people live the way everyone did a century ago, before air-conditioning.
Excessive energy use results from insisting that every day should be cool and comfortable--indoors. People are saying, I require hundreds of dollars a month in electric power, because my thermostat is set to 68°F. And likewise, I require hundreds of gallons of gasoline, because I don't go anywhere without my 5,000 lb vehicle.
But, Thomas, if people lived without AC they would sweat a lot more.
That means they would have to drink more and we are already having fresh water shortages.
And with global warming, we already have far too much airborne humidity causing more powerful storms. If we add our sweat to the atmospheric burden, there's no telling what might happen.
robert,
simply stating that 0,6ACH50 is "flawed logic" without demonstrating the validity of the flaws is also "mere dogmatism" - it works both ways. but you also claim that the 0,6ACH50 is 'totally arbitrary' which isn't, but i'm not eloquent or loquacious enough to describe why.
there are three conditions for soundproofing construction
-heavy mass for low frequency transmission
-insulation to reduce high frequency transmission
-airtight construction to prevent transmission through air
saying that it's a slight increase is far from an understatement. many of the costs of the first PH projects in the U.S. are significantly higher for several reasons - including applying the standard to projects already designed, high efficiency products not available in the states and contractor uncertainty. as familiarity and industry acceptance increases, those costs will come down considerably. but a couple have budgets closer to the house you built in VT. katrin klingenberg's smith house in urbana was completed for about $110/sf. several in the states have been done for around or under $150/sf. several thousand in europe have been done for less than $150/sf.
a passivhaus is no more, or no less, ugly than most superinsulated houses. and as the 'designer' of several aesthetically confused and ugly houses, you really shouldn't be criticizing the design of others.
instead of screaming dogmatic, unwavering belief that the passivhaus is not affordable, i have a challenge for you. email me the material quantities, costs and plans/sections/elevations for the vermont house, and we can do a legitimate analysis on how much more it would take to achieve passivhaus with that project. with 12" thick dense pack walls, i'm thinking the only increase will be triple pane windows and HRV. with the right triple pane glazing, i'm also willing to bet the amount of insulation can be significantly reduced. a majority of folks in the PH community are already interested in or building lower embodied energy projects, and view PH (or living building challenge) as an approach to significantly reduce operational footprint as well.
thomas,
in hotter climates, super insulation levels aren't as high, in achieving PH proper shading becomes more important. and with a PH, the energy modeling is only certified at 68 degrees. if comfortable with 64-66 degrees, it is possible to have little or no space heating needed.
J, thanks for the information.
I have dabbled at creating a "total impact" model without much success so far. A big obstacle has been finding a sufficient quantity of high-quality data to feed into such a model - so perhaps, as you suggest, there is yet more to borrow from the European PH folks.
I wonder (if true) if that rule of thumb is based on the European way of doing things... From what I can tell European PH construction details rely far more extensively on materials with potentially much lower embodied energies... Wood fibre and cellulose as opposed to CC foam or XPS...
Also, Robert makes a good point about building life-expectancy as well.
Anyway, if such a modelling tool were available, we'd at least be able to quantify some answers.
It was John Straube (perhaps the most respected building scientist in North America) who stated that the 0.6 ACH50 standard was both arbitrary and based on flawed logic. And he explained why this was true. Both my experience and my building science agree with Straube, and I explained why.
If you are unable to justify your assertion, then you're asking us to take it on faith - in other words, to accept it as dogma.
Soundproofing does not require 0.6 ACH50 construction, or even anything close. It requires eliminating the gross acoustical bypasses such as cracks under doors or back-to-back electrical outlets.
Again, quoting project square foot costs is meaningless without an equivalent and local baseline to compare each one to. The first superinsulated passive solar house I designed cost less than $30/SF to build. So what? What was pertinent is that it cost only 5% more than the identical house built to code minimum standards and yet required about 1/5 of the operating energy.
Thomas,
Congratulations on hitting the nail on the head.
We humans are the elephant in the room.
I love referencing this case study.
From the conclusion:
Lucas,
Many have attempted to quantify life-cycle impacts, but I think the most comprehensive and salient metric is Ecological Footprint : the amount of earth's land and water base required to supply all resources and absorb all wastes from a certain lifestyle.
It's easier to calculate the Footprint of a nation, but it's possible to approximate that of a person, and there are websites and books to help quantify each individual impact.
This is a far more comprehensive measure than simple shelter impact, since just as our choice of lifestyle determines our choice of shelter, where and how we choose to shelter ourselves determines our lifestyle.
Lucas,
For a short while at an architecture firm I sought data from manufacturers via an Environmental Impact Questionnaire. Its interesting that interior designers have leverage to get some of this type of information because they (especially at the commercial scale) make decisions that can move a lot of product. They can imply 'get me the info or I won't consider your product'.
When it comes to building components (the structure, the envelope etc.) there is little reason for manufacturers to bother going out of their way for an interested architect at least - unless there is a marketing angle through some larger organization like the USGBC for instance.
I guess you need to be in a socialist society to get meaningful data ; )
Some sort of payback calculation should be devised as per Lucas Durand
Upfront construction costs vs. btus saved or kwhs saved per ACH based on the efficiency of the appliances.
If the house actually generates electricity, than obviously the payback will be much shorter. You can't sell BTUs back to the power company and in some states you can't even sell KWHs back. (unfortunately)
I'm not sure if a hard number exists for the amount of BTUs used per ACH based on an 87% efficiency boiler heater.
The same can be applied to AC and kwhs.
So for example: 10,000 dollars more in construction costs will gain you one ACH. One ACH saves you X amount of BTUs per year with an 87% AFUE Boiler. The payback is 126 years, (just kidding)
This doesn't account for the energy expended in producing the materials and getting them on-site.
People pay extra for conservation. Its diverting money away from power consumption and into the equity of the house. Not everyone drives Priuss' , some drive Cadillacs.
Robert said: "Jesse,
To make a statement about a cost increment, there must be a baseline. So what is the additional cost of that house compared to an IRC code house, or compared to an Energy Star 5+ house?
The last R-45/R67 2 ACH50 house I built in VT cost $105/SF. So the PH you describe cost 52% more than my superinsulated house. I would call that a huge increase.
Not to mention that, as with so many PH projects, it's ugly."
As soon as I wrote that post I had that sinking feeling of what the comeback would be. I naively thought that the example I posted might represent a positive example of a house that compares extremely favorably to any custom home designed and built recently in our region, even leaving out their energy goals (most houses built with that level of construction quality easily end up in the $175 - $200 / SF around here, perhaps we just pay skilled carpenters too much money, $20/hr, horrors!...).
But no, any house more expensive than a Riversong house is an excessive house, any house that doesn't look like a Riversong house is an ugly house, and on and on. It's such a toxic conversational tactic, I always hope the conversation won't end in that place, but it always seems to.
I don't know if I've ever read an internet poster (and I've been reading forums in one form or another since 1994 on usenet) who provides such a complicated combination of brilliant analysis backed with a constant stream of subtle digs, a never ending series of delicate pokes between the ribs designed to provoke less patient people (like me) to fly off the handle and overreact, at which point you can retreat behind a facade of "pure logic" and claim that "the other guy started it".
Oh well, perhaps I'm just too weak to handle the "truth-telling" I know you think you provide, but your mean side is the major reason I don't post here very much any more. Let the Riversong show continue...
Robert,
"I'm afraid your slip is showing when you say "perceived additional cost of construction", since there is a dramatic incremental cost, as John Straube suggests, to get from very good performance to a PH level of performance."
Robert,
I don't find a suggestion to be a compelling argument, with due respect to John. I'd rather see built projects and real numbers (cost, modeled, and actual performance data).
I am familiar with Habitat for Humanity's work in Washington DC, They just completed a development of about 50 duplexes, which all met the Earth Craft Platinum and Energy Star Plus standard, which is their baseline standard. Kent Adcock, the president of Habitat here, did the math and found that the add per unit to get the Passive House standard is about 15k per unit. They had several PH units in design last fall; construction may have already started. This (the 15k) wouldn't account for additional labor costs, as all their labor is donated, but it's an interesting number. I don't have sf data, but these are 2-3 bedroom units.
Part of Adcock's calculations are in the long term cost of home ownership for the clients he serves, and energy is the dominant cost after a mortgage. For him the numbers worked.
,
[Paragraph deleted by GBA editorial team.]
All puns about hands and slips showing aside, I like Robert's question because it gets to the heart of where theory meets reality. I live in Houston. I don't have gobs of cash sitting around. With a wife and three kids and running a small business, the appeal of 'going green' has to involve some practicality. This site has already been a huge benefit. There was a post about open top plates with a photograph that might as well have been in my own attic. Sure enough, next to a fur down for master bath canned lighting was just such an opening down the wall also shared with the master bedroom. I plugged that with insulation and spray foam yesterday. I have done much to improve the building envelope and insulation over the years, and plan to do more still...economically. I have no idea what resulting ACH50 reading I will attain in any future blower door test. But I do know that making staged, economical improvements with wisdom imparted by websites like these will be more honoring to this environment than abandoning this 30 year old home in favor of building something that consumes far more resources (embodied) than I consume in my current habitat, not that I could afford $110 or $150/sf construction costs in the first place. What people need to understand is that not every reader of This Old House magazine can afford to have their dream historic property trucked to another plat like the magazine assumes when writing articles seemingly targeted to the uberwealthy. Solutions need to be relevant to the vast majority of the middle class, and therefore need to be cost conscious and resource consumption conscious.
As we've (hopefully) all learned by now, home equity is as much mythological as stock value - and it can vanish in a moment.
But, if people have to pay extra for conservation, then it becomes merely another perk of the wealthy - a way for them to assuage their guilt for having more than they need.
True conservation involves living smaller and simpler, and is much less expensive than living high on the hog.
Jesse,
You're exactly correct that the problem is that "less patient people (like me)... fly off the handle and overreact".
I offered my house as another meaningless comparison - another "so what".
But I presented the completely objective issue that any comparative data needs a baseline for comparison. And I suggested a couple of objective baselines: an IRC code minimum house or the best of the Energy Star homes. Take your pick or use another meaningful baseline so that the cost data you offer becomes useful.
And stop this adolescent blaming of me for your impatience, over-reaction or inability to present data in a meaningful way.
We agree on this, but neither did you present any concrete data to support your statement.
And $15,000 to go from Energy Star 5+ to PH, without factoring in additional labor costs, is an enormous increment, particularly since Habitat starts from a pretty low baseline cost.
That one piece of data, alone, supports my (and Straube's) contention that the incremental cost would be very difficult to justify, since an additional $30,000 (typically materials and labor are proportionate) makes most homes unaffordable.
Mark,
I can't really offend anyone. I don't have that kind of power over anyone else. If people choose to take offense, that's their problem and a reflection of their immaturity.
"If you're not offending those who ought to be offended, then you're doing something wrong."
- Noam Chomsky, American linguist, philosopher,cognitive scientist, and political activist
"He who dares not offend cannot be honest."
- Thomas Paine, author of Common Sense, instigator of the American Revolution
"Freedom is the right to tell people what they do not want to hear."
- George Orwell : English novelist, essayist, and critic, 1903-1950
"Every man who says frankly and fully what he thinks is so far doing a public service. We should be grateful to him for attacking most unsparingly our most cherished opinions."
- Sir Leslie Stephen (1832-1904), literary essayist, author,The Suppression of Poisonous Opinions, 1883
That's cool. I look forward to some choice 'n' bombs from you based on your dead people quotes.
Another point about being green without the need to go PH related to a project of mine three years ago. I wanted a media room. The purely PH standard might have said I should add that media room with R-two billion insulation and an air tightness that could suffocate a church mouse. OR I could make one of my rooms do double duty. And so my 'hideaway home theater' was born: a projector boxed into the ceiling with upholstering, a retractable electric screen behind a decorative beam, and some in wall speakers combined with homemade subwoofer under the lamp table. My theater room is more PH without even being PH.
Robert,
You've got me. I don't have all the data to give to you. Those houses are most certainly not built yet, so no one has complete costs or modeled v actual performance data. My only claim is that one developer, who has built a very large number of homes to be sold to to people with a low income (less than 60% area median income as defined by HUD), thinks that Passive House makes sense for both first costs and the long term cost of home ownership.
The real problem, in my opinion, is not whether the voluntary PH standard is "overkill", but (1) that the US has building codes that are lacking in rigor in regards to energy efficiency and which need to be strengthened quickly, and (2) we need more information about existing buildings, which is where the real energy efficiency battle. Consumers get more energy data when they purchase a refrigerator than when they purchase or lease a home, office, etc. The International Energy Agency, of which the US is a member, recommends required, not voluntary, energy performance certification for buildings as a policy tool that can reduce over all energy use. Their full report is here: http://www.iea.org/papers/pathways/buildings_certification.pdf.
An additional issue, as I see it, is incomplete building science data and the lack of funding for building science research in the US, especially given that buildings account for over 40% of the energy used in this country. The challenge we face is reducing energy use and GOG is not with new construction, which we could control better with policy, but in reducing the energy demand of the existing building stock. A related issue of course is the lack of building materials research and development, and the policies to support this.
toxic... well put, jesse. well put.
robert,
is that a no on the challenge then?
[Paragraph deleted by GBA editorial team]
Kristin,
How long have you been involved with building? In my 30 years, I've seen the building codes go from no requirements for energy efficiency, air tightness and indoor air quality to nation-wide energy codes which stipulate all three to a standard which, while not ideal, is light years beyond what they were just one generation ago.
And I've seen interest in efficient building grow from a tiny number of us early pioneers into the mainstream, with first state and then federal efficiency programs and the NAHB jumping on the "green" bandwagon, and the USGBC and LEEDS and so much more.
Mike Eliason, co-founder of Brute Force Collaborative.
Seems an appropriate name.
Robert,
The question isn't "Why do people have to pay extra for conservation". Your question was "does the extra cost of building to PH standards pay for itself in energy savings."
In other words; is it worth all of the extra labor and materials upfront to bring a structure to PH levels. my answer to you is, I don't know. :)
Wow I'm really surprised to see this discussions going on. All I'll add is that I live in Texas, and am building the first Passive house here in Austin. You can actually find an article on this site about it. Just keep in mind that extra insulation can help you in a hot climate when you have the right technology and the right internal heat gains, which ARE considered in the Passive House software. Ar a certain point your insulation begins to hurt you but you have to find the sweet spot. As an example I have a hybrid heat pump water heater in my home that actually removes heat from the home while providing hot water, so its actually more like an air conditioner than a water heater, but the point is that if you have your home balanced correctly, you can benefit from both the heat gains and the cooling you put in your home. Also here in Austin .6 ACH is the local code for new buildings, and its really just been a few small changes for builders that yield huge results for home owners. Tape here, tuck this under, common sense stuff. I also know that Passive house is the most proven system in the world for design performance meeting actual performance. We are light years ahead of where we were but we're still light years behind the rest of the world, because until recently (with the exception of a few energy scares) we haven't had to be efficient. Energy was cheap and it all comes down to dollars. Which brings me to another point that I am building my 1700 sq ft Passive House retrofit for $60K. And if you look at the pictures you'll see it more like a new construction project. Here's the link
https://www.greenbuildingadvisor.com/blogs/dept/green-building-news/aiming-passive-house-texas#comment-23885
I agree that "going green" needs to be cost comparative to standard building practices. Also I believe that Passive House is the only way for "going green" to be cost competitive with standard building practices. That was the goal I set out to prove with my house and so far i've been right. Eliminating a massive furnace, boiler or AC system removes $15-30K from your construction costs (depending on the house), you take that and spend that on good windows and extra insulation, which gives you a house for the same cost that uses almost no energy. So you have all of your "green" energy saving stuff for the same price. So whether you have appreciation, annuitized blah blah doesnt matter. you have the same priced home with minimal energy bills. The reason people think efficiency costs more money is #1 because until recently mainly the affluent have been interested in efficiency, and green builders could charge anything they wanted and there was almost no bar to gauge against. #2 no one knew any better. Doing incremental things are almost never going to pay for themselves. But not many contractors will tell you that. Most PV systems will NOT pay for themselves (without everyone's taxes subsidizing them), most windows won't. Replacing your furnace probably won't, it might but probably not. Unless you're starting from scratch or doing a serious remodel you will probably be losing money on mos tof the efficiency "upgrades " you decide on. But its in no ones interest to tell clients this. I do, maybe that's why I'm building my own house now instead of remodeling someone else's, haha!
Nicholas,
Are you sure Austin's building code requires .6 ACH 50?
He didn't say 0.6 ACH50. He said 0.6 ACH. Big difference.
There's no building codes in the US that require PH standards for either insulation, air tightness or energy consumption.
No, that is not my question. Though it's a legitimate question, and the one everyone asks: what's the payback.
To look at merely construction cost vs operating energy savings is a pretty narrow perspective. Even on the simple financial level, if the upfront costs make a house unaffordable to own, then it matters not at all how long the payback period is.
But we must also consider the additional costs to the earth of the extra materials (which in the US market are largely petrochemical). And, more importantly, what other options are there that cost less, have a smaller ecological footprint, and create more responsible shelter.
We Americans believe that a "basic" house has to have luxuries that few kings of old could dream of, and we believe we need 1000 SF per person. We do not. We need shelter from the storm, a place to sleep and a place to prepare and eat meals.
A small hand-hewn log cabin with no insulation is more green and responsible than any Passive House any where in the world.
The only question worth asking is "Why do we think we need anything more?"
PH is relatively new, particularly to the US. So it's hardly had a chance to prove itself on any level. All the homes I've designed and built had actual performance almost identical to design performance, and that was without anything more fancy for energy modeling than my own spreadsheet.
I don't know where you've been, but I (and other pioneers) have been building super-insulated homes for 30 years.
None of my clients have been even close to affluent. In fact, most of them participated in the construction process to keep the costs down. The affluent are now interested in "green" because it's chic, but traditionally they were the least interested since they could afford to be wasteful.
But I though that accepting Jesus as your personal savior was the only path to heaven. "Only Way" people are true believers, and - as I've noted a number of times - the PH movement has taken on the qualities of a cult. That makes it dangerous, and most certainly not the path to salvation.
Robert,
So then the question should be asked. 'Can a house be built to passive house standards using only natural building materials?'
Natural building, using materials provided to us by the Earth, is in line with the truest sense of the term 'Green'.
If a house is laden with engineered materials that used huge power-sucking machines to fabricate and transport, it definitely is not as 'green' anymore.
Anything made of metal, i.e. standing seam, joist hangars, screws, already has a ton of energy input in the material before you even touch it.
Shane,
Good luck building a house without any nails or screws! It's possible, of course, especially if you build a masonry dome, or a timber-frame building with pegged joints (and clapboards installed with small wooden pegs) -- but it's tough.
Does your strict "all natural" rule allow the use of windows?
Shane, of course you are right that building with natural materials is the "green"est way to build - and European PH builders seem to do a lot more of this already.
I don't agree, however, that there is anything wrong with Robert's original question. I think one thing that is being over-looked is that strict adherance to PH performance standards in some climates (very cold for example) could almost certainly lead to absurd quantities of material use.
I think the point has already been made by several people that at some point energy performance needs to be balanced against material use and most importantly expectations for occupant comfort.
In other words, if you must live in an extreme climate turn down the thermostat, get used to wearing a sweater indoors and ditch the high expectations for thermal comfort.
It's much more "green" to wear slippers than put 16" of foam under your slab.
And for the non-believers, it only took 6 months of battling over thermostat settings before my wife got used to the sweater and slipper approach ;-)
I'm still trying to figure out how on this God given green&blue earth, any responsibile human being could begin to claim that the use of TOXIC PETRO CHEMICAL building materials in homes is green.
There is absoulutely nothing green about using known dangerous, un-proven foam to create a healthy home. FOAM AIN'T GREEN PEOPLE....
The PassiveHouse standards are overkillers.
Robert, I agree that the "Ecological Footprint" model is a valuable metric but I aslo think that sometimes such metrics are too abstract to be useful in making smaller decisions.
I still think there would be value in a model like the one I described in that quantifing the relationship between life-cycle energy costs and operational energy savings might make more clear the advantages of reduced consumption.
In other words, I think it would help people who want to do the "green" thing make better decisions in terms of balancing energy performance, material consumption and occupant comfort.
My gut tells me that if we accurately plumbed the depths of life-cycle energy costs we'd probably learn quite a bit about how much energy use we externalize.
The vast majority of current and future homeowners will never, in their lifetime analyse building science the way that this site does. I don't think they really care about nat's wiskers in shelter the way that some here do. Homes that can be built or made safe and healthy first, and then affordable and efficient should bear the Green Label. Kiss
Robert,
Your posts come across as very condescending. Are you aware of this?
To answer your question, I have twelve years of professional practice under my belt, and my experience includes a broad range of building and construction types. Several of the projects I have worked on have received awards for design excellence, sustainability, and/or historic preservation. All had unique challenges requiring project-specific (and frequently innovative) solutions. I am very proud of the work that I have done. I am grateful to have worked with outstanding teams, including consultants who specialized in energy efficiency, building envelopes, life cycle cost analysis, mechanical engineering, etc.
As for your comments about codes, I would suggest that it is not a question of how much things have improved, but whether or not the current codes are where they need to be regarding energy efficiency. To which I respond that they are not. I am familiar with the model codes that you allude to. But model codes are worthless if they are not adopted. As of 2007, there were 10 states which had not adopted both a commercial and residential energy code, although some of these have local codes in some municipalities. Of the remaining states, it would be interesting to see which versions of the model codes are currently in force.
For those who are interested in LCA and seeking a useful calculator and/or data, you might want to look at the Athena Institute’s work. http://www.athenasmi.org
I’ll step away from the thread now.
Robert,
I agree. Whatever you want to name it, using energy modeling software to leverage passive solar gains to radically reduce heating loads in cold climates with the tri-tandem of well insulated envelope, good SHGC windows and attention to air tightness is just being implemented in many areas. Yes, we've had pioneering efforts in the States but like it or not PH is currently the most effective vehicle to spread this creed, among the architectural community at least.
As much as I appreciate your continued challenges of a 'taken for granted paradigm of modern thought' the idea that simple reversion to pre-industrial ways of living does not serve as a model for mass change (and you often hold PH to this criteria).
Per my Thich Nhat Hanh quote in another thread, the movements I most support are grassroots efforts to live genuine and simple lifestyles. However if everybody in my area at once reverted to log cabin living, aside from all the infrastructure disparities, we would soon find that the concentrated population along with our non-mobile homesteads would quickly deplete our local resources.
That's why in this day and age, unless we can move populations, it is our responsibility as designers and builders to dramatically minimize the fuel necessary to heat our structures in cold climates (the heat fuel Las Vegas' of the North). In this regard your approach, the PH approach and the BSC approach have a common enemy and thru continued 'dialog' will each fine tune each other's method as we scrutinize the weak points.
Be careful, Lucas. Don't forget what this suggestion did to Jimmy Carter.
From PBS:
Beginning by rejecting a limo and walking down Pennsylvania Avenue on his cold Inauguration Day in January 1977, Carter waged a symbolic war to bring his own simple, austere style to Washington. Wearing a cardigan sweater, he asked Americans to turn their thermostats down; he turned the lights off around Washington's monuments; he sold the presidential yacht; and he bombarded Congress with legislation while trying to cut the pork barrel projects it loved. His actions quickly ended the honeymoon period Carter enjoyed with his fellow Democrats who controlled Congress, and his initial popularity with the public began to decline as his programs became mired on Capitol Hill.
Carter's Brave Vision on Energy
by David Morris
Published on Monday, October 10, 2005 by the Minneapolis Star Tribune
George W. Bush asking Americans to save oil by driving less reminds me of Jimmy Carter wearing a cardigan sweater and asking Americans to save oil by turning down our thermostats and, yes, by driving less.
But former President Carter was asking for individual sacrifice as a small part of an aggressive, national campaign. President Bush is asking for individual sacrifice instead of a national initiative.
Carter gave his first energy speech in February 1977. In July 1979, four months before Americans were taken hostage in Iran, he delivered his fifth energy address. To this day, that speech and its aftermath illuminate the profound differences between the way Democrats and Republicans address the oil crisis.
"Ten days ago I had planned to speak to you again about a very important subject -- energy," Carter began. "But as I was preparing to speak, I began to ask myself the same question that I now know has been troubling many of you. Why have we not been able to get together as a nation to resolve our serious energy problem?"
He told us he had set his speech aside and talked to hundreds of individuals. His conclusion? Americans had lost confidence in our capacity to act decisively and collectively to address and solve our problems. Republicans quickly dubbed the address the "malaise speech."
But to Carter the energy crisis offered an opportunity to regain our sense of hopefulness and national self-confidence. "Energy will be the immediate test of our ability to unite this nation, and it can also be the standard around which we rally," he observed. "On the battlefield of energy we can win for our nation a new confidence, and we can seize control again of our common destiny ... . It can rekindle our sense of unity, our confidence in the future, and give our nation and all of us individually a new sense of purpose."
Carter established a clear goal. "Beginning this moment, this nation will never use more foreign oil than we did in 1977 -- never. From now on, every new addition to our demand for energy will be met from our own production and our own conservation." By the end of the 1980s, the nation would reduce "our dependence on foreign oil by one-half."
To achieve these goals Carter requested of Congress "the most massive peacetime commitment of funds and resources in our nation's history to develop America's own alternative sources of fuel -- from coal, from oil shale, from plant products for gasohol, from unconventional gas, from the sun."
For Carter, fairness was to be an important criterion in shaping energy policy. Since the poor suffer most from rising energy prices, "Our nation must be fair to the poorest among us, so we will increase aid to needy Americans to cope with rising energy prices ... ."
Carter also applied the principle to the other end of the wealth spectrum: the oil companies reaping enormous profits because of OPEC-inspired price hikes.
"Congress must enact the windfall profits tax without delay," Carter insisted. "It will be money well spent. Unlike the billions of dollars that we ship to foreign countries to pay for foreign oil, these funds will be paid by Americans to Americans."
Congress enacted much of what Jimmy Carter proposed. Coupled with the energy-efficiency standards for cars enacted by an earlier Democratic Congress, and the passage in 1978 of five energy bills directed at spurring energy efficiency and renewable energy, the Energy Security Act of 1980 created a comprehensive and coherent energy policy directed toward eliminating our dependence on imported oil.
Why don't we remember this? In part, because Ronald Reagan entered office only a year after Carter's speech and immediately set about dismantling or dramatically cutting back most of the programs enacted in the 1970s. The energy crisis subsided. A severe worldwide economic downturn in 1981 and 1982 cut the price of crude oil by 75 percent. Depending on imported oil didn't seem so important. The nation dropped back into lethargy.
Fast-forward to 2005. The price of oil again doubles. The Republican-controlled Congress passes an omnibus energy bill. But unlike the energy legislation of the late 1970s, this one does not target imported oil. Indeed, it contains virtually nothing that would reduce our reliance on oil.
Bush tells us to drive less, but unlike Carter, he refuses to demand that our cars become more efficient. Indeed, when California recently enacted legislation requiring new cars to reduce greenhouse gas emissions, the Bush administration joined the car companies in arguing that to achieve greenhouse gas reductions, car companies will have to raise fuel efficiency, and only the federal government has authority over vehicle efficiency. Even when the federal government refuses to do anything, Republicans argue, states cannot step in.
Give me Jimmy Carter in a cardigan sweater any day.
- David Morris is vice president of the Institute for Local Self-Reliance, based in Minneapolis and Washington, D.C.
Lucas,
My wife and I wear sweaters and hats in our home during the winter. An electric blanket preheats the bed for a short while before we go to sleep. Despite this if my home were built to Passivhaus standards we would only be using 6% of the heating energy we use despite our attempts at frugality. Mine is an older home but is representative of a good portion of housing stock in Minnesota. I have done some improvements to the home since I made this calculation but not enough time has elapsed to make a new comparison.
I am not convinced that throwing a sweater on in existing code compliant housing stock represents significant energy savings. And if you are building new you'd still want to make the house as efficient as possible anyway.
The point of this discussion is that MAXIMUM is not always (or often) OPTIMUM.
Robert,
Point taken. Unfortunately I don't have the experience or information at this point to contribute to that issue further.
I think Straube sums up the optimum level of energy efficiency in the article BSI-025: The Passive House (Passivhaus) Standard—A comparison to other cold climate low-energy houses
Numerous BSC-designed Building America prototype homes have been built in cold climates (Zone 5 and higher) that compare well to the Passivhaus standard in terms of their primary/source energy consumption. That is, they consume perhaps 40 to 60% more than a Passiv Haus, but are more cost-effective. Typically, these houses use a minimum of R-5 (U=0.2) windows (triple-glazed, low-e coated, warm edge spacers), R-10 sub-slab insulation and R-20 wall insulation in a conditioned basement, R-40 above-grade walls and R-60 ceilings (the "5/10/20/40/60" approach). All thermal bridges in these BSC houses are controlled by using insulation on the exterior of the framing. These R-values are comparable, if on the low-end, of the range that PH use.
Airtightness levels of 3 ACH@50 Pa can regularly be achieved by production builders if airtightness details are tested, and some training and airtightness testing is undertaken. In our experience, and that of others, airtightness levels of 1.5 ACH@50 Pa can be reliably achieved if significant effort is taken in designing details for airtightness, and on-going training, testing, and inspection is employed. In the experience of the Building America and the Canadian R2000 program, such airtightness levels are achievable, but with some effort. The biggest obstacle to achieving lower air leakage may be complexity in building shape. Given the state of practice of air barriers and trade skills, the 0.6 ACH@50 level demanded by PH is too difficult to achieve for production homes (although achievable in custom homes), and hard to justify in any case given the small incremental benefit to energy, air quality or durability.
The BA program expends a significant amount of effort to ensure that a BA house is more durable and healthier than equivalent housing. There is essentially no discussion of durability and little on IAQ in the PH standard: the effect on the durability of exterior building materials when the insulation levels rise to the levels used is not discussed, nor is the need for heightened rain control requirements, although damaging air leakage condensation is likely controlled by the very low acceptable air leakage.
I find it funny that people are personally attacking each other for their opinions. But for the record, I was wrong. Austin's updated building code in 2006 calls for .5 ACH:
402.4.4 Testing of the Building Thermal Envelope for Infiltration. Leakage of the
building thermal envelope shall not exceed .50 Air Changes per Hour (ACH) as measured
by the blower door test. The testing procedure shall be based on ASTM E779 (Standard
Test Method for Determining Air Leakage Rate by Fan Pressurization) or
ANSI/ASHRAE 136 (A Method of Determining Air Change Rates in Detached
Dwellings).
The ASTM standard actually calls for 75Pa and I'm not sure 100% sure about the Ashrae but obviously 50pa is the most common. I've put in a call to my HVAC guys to confirm it but I'm 99% sure its 50 pa.
I'm not trying to insult any of the pioneers of superinsulated houses here in the US because certainly lots of people were building houses efficiently before. But you can't it hasn't been until the last few years that as a society America has started to think about the importance of conservation in the main stream.
Anyways, it sounds like mulitple questions are going around. One is "why don't we all live in 150sq ft houses that meet our basic shelter needs", and another is "is passive house excessive". And when you compare anything to a 150 sq ft house, anything is excessive.
It's not at all funny. It's terribly sad and a measure of the emotional immaturity of so many modern "civilized" people.
This should be a forum for discussing substantive issues, not the "style" of posts or how people imagine it makes them feel.
We should be encouraging critical responses which push people beyond their comfort zones and beyond the limits of their belief systems. The one thing that's certain is that we are not going to achieve sustainability without breaking out of the current dysfunctional paradigm. A breakout requires a breakdown of old beliefs and self-imposed limits.
"0.5 ACH" by itself is a meaningless metric. It has to be at a particular pressure differential or under average "normal" conditions.
I will state again: There is no building code in the US which mandates Passive House levels of air tightness.
Almost certainly, what you are referring to is 0.5 ACHnat, which can be determined by dividing tested ACH50 by an adjustment factor (LBNL) based on climate zone, building height, site shielding, and relative tightness.
Current air tightness standards are these:
IRC requires ≤ 7 ACH50
Energy Star (old version) required ≤ 5 ACH50
Energy Star V 3.0 (2011)
Infiltration rates shall be less than or equal to the following values:
6 ACH50 in CZs 1,2
5 ACH50 in CZs 3,4
4 ACH50 in CZs 5,6,7
3 ACH50 in CZ 8
Envelope leakage shall be determined by a Rater using a RESNET-approved testing protocol.
Energy Efficient Building Association criteria is less than 0.25 cfm of leakage per square foot of building surface area (including floor) @ 50 Pa
In the same BSC "insights" article that Brett cited, John Straube concludes:
From a point of view of the wise use of capital, the Passivhaus approach in cold-climate zones of North America can lead to more expensive, less architecturally flexible, and even potentially more energy intensive houses than a more flexible approach that focuses only on the least cost, most durable means of achieving a primary energy use per area target value. Perhaps the most important contribution made by the PH standard to low-energy North American housing is that one cannot simply buy $200,000 worth of PV panels to meet the target, as too many net zero homes have done.
Homes in cold climates (DOE Zones 5-7) that employ:
- minimum R-5:10:20:40:60 enclosure,
- 1.5 ACH@50 airtightness or better,
- condensing (>95%) gas furnaces with ECM fan motors,
- right-sized (ASHRAE 62.2) efficient (> 65%, >0.6 W/cfm) HRV’s
- condensing (>92%) hotwater natural gas water heaters
- appliances in the top 10% of Energy Star combined with CFL lighting
deliver total energy and environmental performance that approaches the Passivhaus standard in cold climates. Such houses depart in relatively minor ways from standard North American construction, accommodate a broader range of architectural styles, can be modified easily for different climate zones, and can even be built by production builders.
Achieving the specific Passivhaus target of 15 kWh/m2/yr for heating on site energy use, results in investment of materials and money that often will exceed other less costly and environmentally impactive solutions. Achieving the equally arbitrary 120 kWh/m2/yr has more direct environmental benefits than the heating target, but may best (i.e., with least cost and environmental damage) be achieved using some on-site or renewable off-site power generation.
As new clean, local, and renewable energy sources come on line over the next 25 years and become more affordable than current PV prices, it is unlikely that the extreme conservation measures taken by Passiv Haus to meet the specific requirements will be considered an optimal deployment of resources for cold climate housing.
Robert,
Just a reminder to you and other GBA readers: the John Straube article you are posting (in chunks) in this thread was published in its entirety as a GBA blog on October 14, 2009. Here's the link: Comparing Passivhaus Standard Homes to Other Low-Energy Homes.
J, I quite agree with you.
My argument isn't that we ignore energy-efficient building, but rather as Robert suggests avoid rediculous extremes - and I think PH can lead to rediculous extremes in extreme environments.
The house I will be building in the spring (for my 10K HDD climate) has been designed more along the lines of the 5/10/20/40/60 approach that Brett points to in #63. Beyond R values, effort was made in the design to eliminate most thermal bridging and provide a simple and well defined air barrier.
With a house that's "good enough" (still light-years ahead of code-compliant stock around here) combined with the "sweater and slipper approach" my requirement for heating energy should be something I can live with... literaly, since I'll be cutting and splitting my own firewood to heat the place ;-)
Yes Robert,
The bullet points in the conclusion of Straube's article is a good summation of how builders should build in cold climates.
John Straube is a pretty smart dude. When he speaks/writes I pay attention.
Mike,
R-29 slab insulation is 3 x's the insulation of the BSC approach, R-22 is double. I would not consider this as "significantly less rigid insulation/GWP."
What John Straube is asserting is that it's primarily the air tightness standards of the PH approach which are arbitrary, unnecessary and costly. And he makes a very compelling argument.
brett,
when you take into account the overall insulation of the BSC approach (wall/slab/roof) my PH project would utilize considerably less rigid insulation (364 ft3 for PH) as opposed to the BSC approach (597 ft3).
but you are right, on a part by part basis, the PH slab has more insulation.
Mike,
Again, trying to find a balance between energy savings, materials and resources, and comfort is the issue at hand.
R-29 slab insulation requires a lot of materials for very minimal energy savings and added comfort compared to R-10 under the slab.
And, according to Straube's compelling data, going from 1.5 ACH50 to 0.6 ACH50 requires considerable incremental cost and effort that can be better spent elsewhere.
So the conclusion still stands: In cold climate America, PH standards are arbitrary, excessive, unnecessary and unreasonably costly. In other words, they represent an inappropriate or non-optimized cost/benefit balance.
I was re-reading an interesting thread from a while back ("Alternative (Non-Foam) Outsulation Strategy Using Rockwool") and came across the following exchange that seems relvant to this discussion:
How about going back to four in a bed, or letting the pigs into the house to add body heat?
Or building above the horse barn to take advantage of their heat output?
How about restoring our physical vitality and health by learning to live in a variable indoor environment? I'm always amazed by people who wear light clothing all winter because they have to go outside only a few steps at a time between an overheated house and a pre-heated car and an overheated store or office. And then they get in a car wreck and their primary complaint is hypothermia.
I just rescued a couple of New Jersey folks who flew off the road in their SUV at "only 55-60 mph" in a 50 mph zone around a curve with snow on the road, and landed on their side. They were shivering (as were the two drunks we pulled up an embankment last weekend).
Come late November, I put on my long johns and take them off in the spring.
brett,
PHPP calcs:
PH: R-29 slab, space heating demand is 4.41kBTU/ft2a
BSC: R-10 slab, space heating demand is 6.79kBTU/ft2a
how is the PH approach - which uses 61% less rigid insulation in sum (walls/roof/slab) while achieving 53% better space heating performance compared to the BSC approach - 'unbalanced'?
robert,
i recall the 100k house guys mentioned the approach to hit 0,6ACH50 didn't require "considerable incremental cost "
and we can add the internal heat gain of horses - PHPP has a tab for that.
In #76 Lucas is referencing a comment I made.
Please note a more recent comment I made as a response to Martin's NetZeroEnergy vs. Passivhaus blog-
It is more difficult to meet the heating standards the less square footage you have. Germany doesn't have a McMansion culture so the concern for building a bigger house to meet the standard may not be a concern, but it is something to watch out for here.
As RRiversong said, PH hasn't been around long enough in the states to prove itself. We PH designers in NorthAmerica have not optimized the approach for cost, we haven't faced that pressure yet. To make a determination against PH on a cost basis is premature. PH projects are primarily in the architecture custom home market. If you are arguing on a cost-effectiveness basis you should not include this sector of building. What production builders are using PH? I do recall a partial prefab outfit out east being mentioned on this website working on a home designed to meet PH criteria.
On the other hand I think the PH community should be open to the scrutiny and in the end we can all design and build more reasonable buildings.
I've spent considerable time correcting the misinformation on the 100k house web site.
I'm not interested in guesses, assertions, allegations, or promises.
Show me the numbers. Anyone advocating the PH approach as a cost-effective strategy has an obligation to show carefully documented cost comparisons between a baseline IRC or ES house and an otherwise identical PH.
I didn't use the excuse that homes had to cost more during the learning stage - every house I've designed and built has been less expensive than an equivalent code-minimum house or no more than 5%-6% additional to achieve tight super-insulated levels.
J,
My concern with PH has always been that it requires an excessive amount of material to meet the PH performance requirements in extreme climates - and that there should be balance between energy performance, material use and occupant comfort.
An R70 envelope requires an excess of material in my opinion - not to mention dificult to engineer.
An ~R45 envelope seems much more sensible in that there are a number of good off-the-shelf envelope designs that can achieve this - without an excess of material use.
If the requirement for R70 can be reduced to ~R45 by reducing the size of the house, then that is exactly the type of balance or compromise I am arguing for.
With respect to air-tightness, I believe in "the tighter the better", however I also agree with Robert that it is wasteful in many ways to try and force "tightness" on a design that is at odds with this goal.
Personally, I would be exstatic if my own up-coming project achieved <0.6ACH50, but it would have to be the natural result of good over-all design. I will not try to force it to happen.
I have always read that perhaps the biggest obstacle to air-tightness with an otherwise good envelope design is the complexity of architecture.
This is possibly a second means of balance or compromise - that a Passivhaus should be as close to a simple cube as possible. This seems consistent with many European PH designs.
I was just today reading an article titled "Real green living" which takes a walk-through of a town in Germany called Vauban. The article features a substantial (but somewhat general) look at Pasivhaus in that community. Here is an intersteing tibit:
This quote brings to mind this video John Brooks dug up a while ago:
http://www.youtube.com/watch?v=wBQHBr7zn0M&feature=related
Maybe the best means of constructing a passivhaus is with pre-fab components - another compromise?
I suppose what I am driving at is that there isn't anything wrong with PH per se... but in certain climates, the blind pursuit of performance goals without willingness to make significant compromises will almost certainly lead to rediculous extremes.
Anyway J, don't let anyone tell you that you aren't a reasonable person ;-)
I'm an advocate of elegant simplicity of design, but there's no reason that energy efficiency or "greenness" has come at the expense of aesthetics. Too many PHs, including in the US, are not just "simple cubes" but ugly cubist structures with no deference to the timeless qualities of shape, mass and proportion.
I don't think this is even true. While manufactured housing has come a long way toward tighter, more efficient assembly, they still don't come close to a well-crafted hand-made house. And when the parts are factory-assembled, they don't require "skilled, vigilant craftspeople" to piece them together on site - they require merely another set of "assemblers" to complete the construction.
Energy efficiency does not have to sacrifice aesthetics, or quality, or craft, or affordability, or indoor health or ecological responsibility.
I agree. Which is one reason why I, personally, would never build a passivhaus. But if you can stomach the looks of a modern cubist house then your reward could be higher levels of air-tightness.
I'm not so sure. It seems to be happening more and more and it makes sense that consistently tight tolerances could be achieved in a factory setting... though I too would hesitate to use the description of "skilled, vigilant craftspeople" when refering to this type of construction.
lucas,
vauban is actually a neighborhood of freiburg. i spent a significant number of pleasant evenings in vauban when i worked in freiburg (a lot of study abroad students @univ. freiburg live there). rolf disch and michael gies have built some decent ultra-low energy projects in a very interesting and vibrant neighborhood.
robert,
once again, your limited knowledge of passivhaus is incorrect. the overwhelming majority of passivhaeuser in the EU are not stunningly simple and beautiful 'cubist boxes', but are actually closer in form and massing to your warren,VT house - albeit with better performance, significantly better proportioned windows and significantly fewer clunky details.
Lucas I find that you are very reasonable as well.
And while I rarely find Robert Riversong "reasonable" I see him like an urban chicken whom everyone complains is violently tearing up the lawn and acrimoniously sh**ting everywhere, when in fact he is leaving nutrients and aerating the surface building better soils ; )
Peace
Off topic but I think another interesting aspect to PH being imported to the states are the cultural differences between the US and Germany. The unknown consequences of implementing the PH standard in different climes notwithstanding I think a resistance towards meeting a defined set of performance criteria through energy modeling is a characteristic American mindset.
I remember hearing a fascinating radio documentary about when some American car manufacturers acknowledged the Japanese were producing superior cars. One American plant that faced closure brought its workforce to Japan and learned the Japanese 'teamwork' approach to fabrication at the manufacturing plant. This workforce showed a change in mentality and returned to the states and lead a quite successful car plant for some time (wish I could remember the name of the car plant).
However any subsequent efforts to copy the Japanese model in the US failed. According to the documentary this was due to two factors - 1 significant cultural differences in the workers mindsets, and - 2 different economic infrastructures.
Is the lesson here we shouldn't have tried to learn from the Japanese or that we should have considered more seriously changing the American mindset towards making cars?
J Chesnut,
I find it interesting that the design & methods of modern Japanese Auto Manufacturing were strarted by an American......... W. Edwards Deming
http://en.wikipedia.org/wiki/W._Edwards_Deming
And the roots of Passivhaus are in America.
Great article , Thanks John
I don't dispute this. The problem comes from the fact that these modular boxes or panels have to be assembled (typically by factory-trained assemblers, not carpenters) out in the weather, on an out-of-square foundation, with heavy cranes that aren't precision machines, with provisions for cabling that make tight fit difficult, and with the use of thick gaskets to take up the slack.
Even with precautions such as glued and screwed drywall with spray foam flash at all framing, the modules arrive after their road trip with cracked walls and out-of-plumb doorways. A big part of the "finisher's" job is to repair or hide all the flaws. I was one of those finishers on Vermont's first large modular development at Mt. Snow in the 80's, but I saw the same problems evident in a recent erection of a "high-end" modular custom home last year.
Now, let's not get too nationalistic or chauvinistic here.
Deming might have introduced some statistical tools to encourage and improve quality control, but what created the post-war Economic Miracle in Japan and the stunning success of its automotive industry had far more to do with the ancient Japanese culture of respect, loyalty and cooperation - the group mind instead of American individualism and competition.
The Japanese car companies brought these practices to their US plants and the American automotive industry soon copied some of their more collectivist approaches, though not without filtering them through our own cultural biases. Ironically, it was Toyota's adoption of the American drive toward dominance of the market that drove it to begin cutting corners on quality and putting too much emphasis on appearance, power and luxury that led to the recent spate of recalls and out-of-court settlements for tragic deaths.
PH may have been inspired by some of the early American super-insulation pioneers, but it represents a uniquely German approach to engineering and numerical precision which is not directly translatable - and hence not necessarily appropriate - to the American culture.
Thanks to everyone for generating a very interesting thread! A couple of thoughts come to mind. In Europe the PH standard is well excepted and going strong and here PH, as well as more energy efficient housing, struggles, why? It would be easy to say that Europe's much higher energy prices tilt the balance more in the favor of contructing energy efficienct houses, but perhaps other reasons may come into play as well. IN europe old houses are measured in centuries, where here in the west it is measured in decades, perhaps that mindset makes it easier to invest more in energy efficencies that take longer to recoup.
For my first and probably only attempt at building a house to PH standards, the only extra work required, beyond good design and craftmanship was a were 4 days of "family time" caulking and foaming, which I believe to be a worthwhile investment. wouldn't be nice if you could present a graph to the clients you were going to build for, showing what the different blower door results would due to your utility bills versus extra contruction costs, and let them decide what works best for them.
Much the same could be done with insulation values of walls, ceilings, subslab comapring cost and utilities. Same for windows values. Make it easy for the consumer to take home and play with the results, letting them change some of the assumptions and see how it effects results....like how fast energy prices might inflate overtime, expanding your timeline and watching the results. I have used the PHPP software, and I consider myself reasonable intelligent and certainly passionate, but easy to use it is not.
I, like others in this forum find it hard to believe that houses are not required to be energy rated like our appliances are, gving the home buyer a chance to know upfront what their expences are going to be, and creating some incentive for housing industry as whole to become more efficient. When you sign up for you home mortgage they are required to tell you how much the loan will cost you by them time you have finally payed it off, which can be rather staggering when you get a 30 year loan. What if we were required to do a "Truth in Housing" paper telling people how much they were likely going to spend on their utilities over the coarse of 30 years before procedding with construction, might help drive the market towards more responsible construction. Kevin O'Meara
Americans live for the moment with little thought about the future. If they worried about the total cost of a mortgage, nobody would buy a house on credit. They want to know only what's it going to cost each month.
And there is widespread resistance to any kind of government mandate. Look at the revolt happening now over required health insurance. But voluntary programs, like Energy Star with their HERS ratings, are an attempt to demonstrate the annual energy costs of a house.
Vermont requires that every new house be certified to meet it's energy code, and has one of the best energy conservation utilities in the nation which gives free advice and energy auditing as well as financial incentives to build to higher (Energy Star) standards.
Until all new housing is made in a factory, it would be pretty difficult to assign accurate operating energy costs, but we're making progress in that direction.
Europe has long been ahead of the US in conservation (they use about half the energy per capita of Americans), but much of the pioneering work in efficient homes happened on this side of the pond.
If we profligate 'Mericans could just reduce the size of our homes, we could dramatically reduce energy consumption while reducing construction costs. But everything here has to be "super-sized". We just don't have an intuitive appreciation of limits.
This IS a great thread!!! I appreciate everyone's input, and am so glad that people have finally gotten down to a profession discussion and away from personally attacking each other (for the most part). I am wondering why people look at all these different building programs as being in competition with each other when they mostly fit together and can enrich one another. They're all tools for different things and give us all, as builders, architects, homeowners multiple angles at which to attack a problem. PH for example makes no attempt to conserve water, use native plants, or really do anything other than save fossil fuels. But the modeling software is so dang precise (I mean calculating the cooling effect of water from flushing your toilets?) that its a vaiuable too in and of itself even if you have no desire to actually build a PH. But drawing from all of these programs and being creative about where to draw from gives a huge advantage as to how to meet clients needs and hopefully inject a little bit of sustainability in there too. Because as Robert has observed, here in Merica, until China takes over or we're bombed off the planet, everyone still wants the super sized version of everything.
And I haven't forgotten about Austin's air tightness code. By Monday night i'll have a definitive answer that the code calls for .5ACH50.
Champagne only comes from Champagne...
But sometimes, there's a fly in the ointment.
The one good attribute, however, of American individualism is that we have many pioneers and exemplars in superinsulated passive solar design and construction and don't need a single Führer.
On the note of Japanese auto production. These companies have adopted the lean manufacturing approach. Its based on a book called "lean manufacturing" written by a Japanese gentleman whose name escapes me.
reply to Nicholas Blaise Koch
The Austin code does not require 0.5 ACH50. Although the code language is poorly written and ambiguous, the fact that it references ASHRAE 136 indicates that they are referring to an estimate of ACH natural (since that's what ASHRAE 136 is all about). The approximate ACH50 requirement would then be somewhere around 10 ACH50. IMO, a code requirement of 0.5 ACH50 would be ridiculous anywhere but clean rooms.
I wrote my PassivHaus comment on another thread just before this one got started:
https://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/passivhaus-homes-are-extremely-tight-and-energy-efficient
But here's a couple points worth mentioning:
1. PassivHaus certification has not been proven to add to your resale value, so use the tool, but don't sweat certification.
2. A consumer-friendly rating system (NOT another standard or a code) is what this industry really needs.
Neither the govt. nor the association of automobile manufacturers give prescriptive methods to car manufacturers on how to reduce emissions or improve MPG.
Yall are right, Austin's Code requires that you do a blower door test at 50 pa. They take that number and plug it into an equation to make sure that your ACH natural is below .5. But after talking to my inspectors, blower door company, and HVAC company, even that is somewhat dependent on the house you're building or remodeling. Inspectors cut you more slack apparently if you have an older house, so the "Standard" is seems to be enforced about as ambiguously as it's written into their code.
As I noted, the 0.5 standard had to be the Normalized Leakage rate (according to the LBNL formula), which approximates natural leakage. That's a pretty weak standard.
IRC requires ≤ 7 ACH50
The Old Energy Star required ≤ 5 ACH50
Energy Star V 3.0 (2011)
Infiltration rates shall be less than or equal to the following values:
6 ACH50 in CZs 1,2
5 ACH50 in CZs 3,4
4 ACH50 in CZs 5,6,7
3 ACH50 in CZ 8
Envelope leakage shall be determined by a Rater using a RESNET-approved testing protocol.
The Canadian R-2000 program has an airtightness standard of 1.5 ACH50.
A 2002 LBNL study of 8300 new homes in the US built from 1993-2000 found a mean Normalized Leakage of 0.3, which is the equivalent of about 5 AHC50.
Comparing people who advocate for the Passive House standard to people who followed Hitler is the last straw, Robert. That is insulting to the memory of the millions of people who were murdered by the Nazis. I will not reply to any more of your posts.
Greg,
I'm glad you're not going to respond any more, since you both misunderstand and over-reacted.
"Führer" simply means leader (in the German culture from which PH sprung), though it's more often used to refer to a tyrannical leader. I think a movement that follows the dictates of a single charismatic founder can properly be considered a cult. And the responses of some PH aficionados to any challenge to the efficacy or appropriateness of the PH approach is indicative of cult-like true believers.
Your over-the-top reaction attests to this.
Greg, GBA is taking back ownership of this site. Stay actively here and we all may learn to be politely able to discuss all things green.
Passive house is far superior to buildings that surround us all by the millions. This winter in my area is the winter of icicles showing all the fossil fuel going to waste.
[Comment deleted by GBA editorial team.]
Just a reminder to our readers: please refrain from posting comments that denigrate other GBA readers or point out perceived character flaws in other posters.
It's fine to discuss green construction, construction techniques, and building science topics, of course. But we're not here to analyze the personalities of other participants.
Robert Riversong has been banned from GBA..
Great Job~ what a shame
Robert,
PassiveHaus Isn't "based on the dictates of a single leader" as you would have it. Its just a building system that the Germans have tweaked to maximize energy efficiency. Your original question of "is it applicable in Northern North America" has apparently exhausted itself and now the comments have disintegrated into cheap pot-shots based on moral beliefs. There is a place for moral discussion, and a place for scientific discussion.
IMO the blog format should allow both as long as they are not off topic, or offensive. Its good to have open discussion on subjects however, opinions are not always taken well.
"opinions are like 'bleep' , everyone has one but nobody wants to hear it."
Robert can't hear your opinion.... he has been banned from this site because he says whats on his mind to people like you... too bad~ bleep
What happened to the double standard post from last evening?