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I’m a small building energy modeler, and the tools of my trade are airtightness, insulation, window placement, and heat-recovery ventilation. These are also the tools of the international Passive House standard (known in Europe as the Passivhaus standard). And yet, almost every week, some veteran home builder patiently schools me as to why these building performance strategies — or Passive House requirements — are a waste of time or money.
I have compiled the most frequently cited arguments I hear; let’s call them “Ten reasons not to build a Passive House.”
Myth #1: Too expensive
I hear this almost every time I hand out my business card. It doesn’t seem to matter whether I’m listening to the builder of a $4 million luxury home or a $400,000 townhouse; nearly everyone assumes a Passive House costs more.
The truth is counterintuitive: If you include operating costs in the equation, Passive House emerges as the most affordable way to construct any building.
Here’s the math: Passive House walls and windows cost more than code construction, while Passive House heating systems cost less. On balance, Passive House construction costs up to 10% more than code. (Costs for land, carrying and marketing remain unchanged.) Upon completion, Passive House buildings require an average of 90% less heating energy than code buildings.
Amortize the one-time construction premium over the life of a mortgage, subtract the annual savings on utility bills, and most Passive House owners save money every single year.
This inherent affordability is no accident. The Passive House standard evolved from research experiments in which European scientists sought to calculate a balance point below which the installation of more insulation provided a measurable return on investment, and above which more insulation returned no economic benefit. This economic “sweet spot” is what defines the Passive House standard, as well was what distinguishes Passive House from most green building standards.
Myth #2: Too stuffy
Passive House buildings are ten times more airtight than typical new buildings. But this does not mean they feel “stuffy.” A Passive House window opens like any other. And because the Passive House is better insulated, its residents may choose to leave windows open more days per year than the resident of a code-minimum home.
It’s when the windows are closed that the Passive House excels, however. Stale indoor air is continuously exchanged for fresh outdoor air through a high-efficiency heat recovery ventilator. The New York Times recently described the resulting air quality of a Passive House this way: “The air inside the house feels so fresh, you can almost taste its sweetness.”
Myth #3: The walls are too thick
The outer walls of a Passive House are usually more than a foot thick. Wall thickness varies by climate: thicker in Iqaliut, thinner in Vancouver.
In a conventional home, residents pull away from bay windows and sliding glass doors during the winter. In a Passive House, however, every square inch provides the same exceptional thermal comfort all year long. This unique sit-by-the-window-in-winter comfort adds more square feet of usable space than the loss of 6 inches along the perimeter due to thicker walls.
Myth #4: Too many exotic materials
The Passive House standard requires no specific products. However, it is easier to design a Passive House using assemblies that have been modeled and windows that have been certified to meet Passive House guidelines.
These products are now readily available in the U.S. and Canada. (Dozens will be on display at the upcoming Passive House North 2013 conference in Vancouver on September 27 and 28.)
Myth #5: Too complicated
Here’s the Passive House standard in a sentence: Heating load ≤ 10 W/m2, annual heating demand ≤ 15 kWh/m2, annual primary energy demand ≤ 120 kWh/m2, thermal bridging Psi ≤ 0.0, airtightness ≤ 0.60 ACH@50Pa. That’s it.
Passive House is like hockey: It’s a simple game with a steep learning curve. It’s an experience that is easier (and more fun) with an experienced team. Architect and Passive House consultant Bronwyn Barry has noted that “Passive House is a team sport.”
Myth #6: Too rigid
There’s more than one way to build a Passive House.
Creative approaches are encouraged, and learned lessons are openly shared on a unique site called Passipedia. Likewise, there’s more than one way to certify a Passive House: via the original Passive House Institute (PHI) in Germany, the Canadian Passive House Institute (CanPHI), or a growing number of certification authorities in the U.S., U.K., or Ireland.
Myth #7: Too ugly
Consider the diversity of designs evident in the Passive Houses featured on the GBA site, or in the buildings (of all types) that have won PHI’s annual Passive House Award. If you want, Google the offices, apartment blocks, and high-rise Passive House buildings erected in Europe during the past few years.
Passive House is a performance standard; beauty is in the eye of the deed holder.
Myth #8: Too soon
The ideas at the heart of Passive House date back to the 1970s. (For example, see the Sasketchewan Conservation House.)
The first true Passive House was built in Germany in 1991. More than 40,000 buildings have been constructed in the ensuing 22 years, as Passive House has become the most tested and most rigorously verified building standard.
Myth #9: The payback period is too long
See Myth #1: A 10% construction price premium works out to a few hundred dollars per year over the life of a mortgage. A 90% reduction in heating energy totals close to a thousand dollars per year.
The savings begin in Year One, and grow as energy prices rise. That’s why organizations such as Habitat for Humanity are following the Passive House standard.
Myth #10: Net zero is better
Absolutely: Net-zero energy is better than 90% less heating energy. And net positive buildings, such as those built to the Living Building standard, are better still. But because generating energy on-site demands additional systems, the price of clawing back that last 10% can double the cost of construction.
The energy savings provided by Passive House is sufficient to meet or exceed even the most stringent greenhouse gas reduction targets. That’s why European cities such as Brussels will require all new buildings to meet Passive House-like requirements beginning in January 2015.
Bonus gripe: What’s with the name?
Beats me. The Germans call it Passivhaus; so do Brits and purists in North America. The PHI prefers Passive House in English, and most North American organizations follow suit.
Perhaps the linguistic chaos is a byproduct of an open-source standard. Regardless of what one calls it, the Passive House standard remains among the most affordable ways to build anything.
Monte Paulsen is principal of Red Door Energy Advisors, a building energy modeling and performance consultancy in Vancouver, B.C., Canada. He will present “A Loose History of Air Tightness” at the upcoming Passive House North 2013 conference. A similar version of this essay appeared in Canada EcoHome magazine.
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53 Comments
passivehaus cost
I still believe getting a home Passivehaus certified is more costly than this article claims. Especially for smaller homes. For example, lets say I build an $120,000 1000sqft home in Wisconsin. According to this I would have to spend at most $12,000 (10%) more to get the certification. Also, I don't buy the idea that I'm going to save a bunch on a heating system in my Passivehaus. Right now I can buy a high efficiency condensing gas furnace for <$800. If anything, it is going to be more expensive to find a special heating system that is going to be sized right for this Passivhaus.
Is that math really accurate?
Does the math above account for the fact that the up front costs are often financed and the utilities bills are paid in post-tax dollars? How does Passivhaus compare to the Pretty Good House concept discussed on GBA, which might not carry the 10% premium but still result in significant energy savings? How dependent are the cost numbers on square footage and climate? Is that 10% figure basically the cost of the Passivhaus consultant on the project?
As long as we are talking about misconceptions...
Monte,
Thanks for your blog. I agree with most of your points; however, you make three statements that aren't supported by the evidence.
1. You wrote, "Passive House walls and windows cost more than code construction, while Passive House heating systems cost less." It's hard to generalize on this issue, since it's (arguably) possible to install a $500 wood stove in a Passivhaus and call it done. Neverthess, most Passivhaus builders in North America aren't able to install a fully vented HRV and a heating system for less money than a conventional forced-air furnace and a split-system air conditioner. Let me quote Allen Gilliland on this issue. (Gilland is the founder of One Sky Homes, a design/build firm in San Jose, California; his company specializes in Passivhaus construction). Gilland said, “A lot of projects don’t have a budget that can afford a Zehnder HRV, which costs $7,000 or $8,000 by the time it is installed. One of our biggest challenges concerns the famous dip in the Passivhaus cost curve. In some ways, the cost curve for Passivhaus projects is going the other way. It is a hump instead of a dip.” (For more of Gilland's thoughts on HVAC systems for Passivhaus buildings, see Passivhaus Buildings Don’t Heat Themselves.)
2. You wrote, "The Passive House standard evolved from research experiments in which European scientists sought to calculate a balance point below which the installation of more insulation provided a measurable return on investment, and above which more insulation returned no economic benefit."
You are correct that this is one explanation that Dr. Feist has given. But Dr. Feist is a physicist, not a builder; construction estimates are notoriously difficult to prepare, as any builder will tell you, and it's hard to develop a spreadsheet that accurately portrays the construction costs of a variety of wall and roof assemblies, especially over wide geographical areas that include (in Europe) many countries and many climates. Suffice it to say that it's fairly easy to prove that many North American Passivhaus buildings include features which aren't cost-effective. Of all the different specifications one might cite, the easiest one is probably high-R sub-slab foam. Just last week, I hears about another Passivhaus project in Massachusetts that specified R-50 sub-slab foam.
Dr. Feist has also provided a different explanation of the famous 15 kWh/m2*year target: it represents the heating level that Dr. Feist feels can be delivered through the ventilation system of a house in Central Europe. (As it turns out, cold-climate North American homes need more heat than homes in Germany, and it's impossible to deliver all of the required space heat in our climates through the ventilation duct work unless one overventilates or unless one breaks Dr. Feist's warnings on including recirculated air.) The desire to deliver space heat through ventilation ductwork seems to have been driven by Dr. Feist's desire to falsely claim that these buildings "don't require a heating system" -- using the logic that, if there is no boiler, there is no space heating system.
3. You wrote, "But because generating energy on-site demands additional systems, the price of clawing back that last 10% can double the cost of construction."
This makes no sense. How much energy is required for a Passivhaus? Let's pull some numbers out of thin air:
If a house uses 4,000 kWh per year, it needs a 4-kW PV system in a cloudy climate. That system will cost $16,000 to install.
If a house uses 6,000 kWh per year, it needs a 6-kW PV system in a cloudy climate. That system will cost $24,000 to install.
If a house uses 12,000 kWh per year, it needs a 12-kW PV system in a cloudy climate. That system will cost $48,000 to install.
In none of these cases will adding PV to your Passivhaus result in doubling the cost of construction.
Passivhaus..show some respect!
I like to use the original name " Passivhaus" . It shows respect to the origins of the work.
You should all do the same.
It's nice to read a west canadian POV on the subject! :)
I have to agree with sifu Martin, as discussed in prior threads , Passivhaus standard is not very well adapted to north american climate.
You will need to provide proofs of 10% ups to PH standard vs code, at least the numbers don't work here in easter Canada, unless of a complete DIY work.
Slapping solar panel on a building doesn't make it green.
Net-Zero means nothing, how many bad design/insulated buildings we've seen recently that just
added as many panels as required to hit the 0 .
Lastly, about the " UGLY " ...
I can't say i've seen that many attractive designed PH buildings..
I feel like most have extended their bugets to meet the PH soo much , it was impossible not to cheap out on the finish.
Status quo?
Great blog Monte,
I don't think I've seen it stated better.
This is a case where ignorance isn't bliss. It's just lagging behind and ignoring development.
achieving passivhaus in north american cold climates
is 10-50% easier than in central and northern europe - with a few, sparsely populated exceptions (fairbanks, yellowknife).
for almost all of the continental US, PGH could be a passivhaus if compact and detailed/oriented correctly.
@Joe Schmo - Generally, yes - Adam Cohen has been really good at disseminating that info as well.
Lack of Honesty.
I have to disagree with much of this article.
1. Cost at 10%: On a 4 million dollar home the added cost might be 10%. But a 2,500 sqft house selling at $250,000 can't be converted into a passive house for $25,000. I doubt you can even by the windows for that price. Add in the cost for insulation, HRU's, certification etc.. I doubt a 2,500 sq ft home could be converted to passive house for less than $50,000. Be realistic. If I am wrong. Prove it.
2. Too Stuffy: That might be true, but you don't need to be passive house certified to get the same amount of fresh air. You don't even need an Energy Recovery Ventilator. Supply air systems can do the same job.
3. Walls too thick: Passive house walls are thicker. Deal with it. your argument that people don't use as much floor space in a standard house is laughable.
6. Too Rigid: As soon as you need to start putting in 14" ridged insulation under a floor slab, you know that the standard is too rigid. A pretty good house or BCS 5/10/20/40 home can get you 90% of the savings at a much lower price point.
7. Your sort of right on this one. But some people (not me) like complicated roof lines and multiple bump outs in thier homes. It is much harder and more expensive to meet his standard with these homes. But it can be done.
8. Payback. See argument number one. Payback is just not there compared to a "pretty good house" or a BCS 5/10/20/40 home. Also, are banks going to give you a larger mortgage for Passive house certification? doubt it.
I am not against passive houses. If I had the money I would love to build a passive house. I just hate intellectually dishonest arguments for it.
Response to Albert Rooks
Albert,
You are absolutely correct that the Passivhaus standard does not require space heat to be delivered through ventilaltion ductwork. However, there are many documents that show that the 15 kWh/m2*year standard was chosen so that this heat-delivery mechanism could be used. It's crucial to understand this point in order to understand the history of the targets that have become enshrined in the Passivhaus standard.
If Feist had chosen a larger target -- more than 15 kWh/m2*year -- space heat could no longer be squeezed through the small airflows that Feist anticipated using, while still meeting Feist's goal of "no recirculation." Ironically, while the method of delivering space heat through ventilation ducts was possible in Germany using Feist's target, the method doesn't work in Minnesota or Vermont. The space-heat-delivery method that Feist championed in the early years of the Passivhaus standard isn't used in North America.
Interestingly, European designers are, for the most part, no longer delivering space heating through ventilation ducts either.
I'll dig up some references to document what I'm explaining.
Response to Martin Holldaday - heat demand
Martin,
You sill bump up against the heat through ventilation topic. I just proof read the new 2013 v8 Passive House Planing Package (PHPP) for errors as it came back from the printer. When I ran across the attached section on just this subject I could not help but think of your issue with it.
So... here is a scan of the page. (Sorry for the quality, I'm on a train).
It clearly says that due to the lower heat demand, the required heat CAN be delivered to the rooms by the ventilation system. It doesn't 'say that it's a requirement. Sorry but this is much like the pivotal moment in Steinbeck's East of Eden where the plot pivots on the characters ability to choose. The operative word being "MAY".
Since I've got the page open, I'll add the heat load requirement sheet. You can see there there is no requirement on method of delivery, just quantity.
A further note is that I think his statement that a "conventional" heating system can be omitted: I think that is accurate. The distinction between "conventional" and "unconventional" in this case is the systems capacity. As you know when you get to these small loads it's hard to find systems that are sized for them. It's sure been my experience that the choices are in the "unconventional range" compared to what would go into the same sized code structure.
Btw... The new 2013 PHPP is available now and can be found here: http://www.smallplanetworkshopstore.com/passive-house-planning-package-2013-v8/
This year there is also an upgrade version from 2012 and a student discounted version.
More for Albert Rooks
Albert,
As evidence of my point on the origins of the 15 kWh/m2*year limit, here is the definition of a Passive House, from the Passipedia Web site -- a site maintained by the Passivhaus Institut in Darmstadt, Germany:
“A Passive House is a building for which thermal comfort (ISO 7730) can be achieved solely by post-heating or post-cooling of the fresh air mass [ventilation air] which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air. ... All airtight buildings (any low-energy building needs to be airtight) require the use of an efficient ventilation system. In Passive Houses this system is also used for heating purposes, without the need for additional ducts, major technical interfaces, auxiliary fans etc. … The way to go therefore involves cutting back on one of the two systems: either on the ventilation system, e.g. by installing an exhaust system only; in this case the building will become a low-energy house with conventional heating; or on the heating system by using the ventilation system for heating as well – in this case the building will become a Passive House. This heating concept automatically implies extremely low energy consumption. After all, using the fresh ventilation air for heating without an additional heating system can only work in buildings with minimal net losses.”
This definition appears to have been translated from German by an online robot, but here is the gist of it: a passive house, by definition, is a house which can be heated by supplying all of the space heat through ventilation ductwork, with 100% outdoor air and no recirculation. A house with an exhaust-only ventilation system may be called a low-energy home, but such a home cannot be a passive house. If space heating is delivered through ventilation ductwork, then it is a passive house."
Response to Frank R
Frank,
Just to pick up a couple of these points:
Yes the walls are thicker and yes we deal with it. The reduction of loads has to come from somewhere. It's either better windows, thermal bridge reduction, earth connection., or walls,. Or... all of the above. Your choice.
Your BSC format is fine. It's just going to have a higher heat demand. You won't know what it is until after construction. The point of of the requirements is hitting the required load targets. Not just "approximating" them.
I don't think the PH standard is too rigid, I think we are too loose in our acceptance that we can change our situation. If you come at it from the point of view of that we can't reduce our consumption because it's just too big of a change, then yes... It's too rigid for that kind of thinking.
Where as if you come from the point of view that the planet will not be livable if we don't drastically reduce our heating loads, then 14" of insulation on a wall or a roof seems like sanity to me.
The payback can depend on too many variables. There are many cases where it proves itself to be an economical decision. However I think relying on a payback to justify it is a mistake. While Passive house can be an economical move when view from long term operational costs, the point of load reduction isn't money, it is very much environmental. It's adoption into code requirements in the "smarter cultures" was to create a situation where climate change can be averted and supply can be made by a majority of renewables.
And Still more for Martin
Martin,
However a designer chooses to ventilate, (Hopefully it's with the Zehnder systems that are sold by The Small Planet Workshop!), the designer has, at his or her disposal, an annual heating/cooling load budget of 15kwhrs/m2. Use it how you will in "conventional" ways or not!
Response to Albert Rooks
Albert,
You wrote, "Your BSC format is fine. It's just going to have a higher heat demand. You won't know what it is until after construction."
No matter what specifications we choose -- whether recommendations from the Building Science Corporation or recommendations from the Passivhaus Institut -- we all depend on energy modeling to guess at what our actual energy consumption will be. PHPP is a pretty good modeling program, and anyone can use it if they want, whether or not you are building a Passivhaus. (The modeling program is really intended for superinsulated houses, however, so it's not a good choice to model a code-minimum house.)
And you know what? Even if you use PHPP to model the energy of a new Passivhaus, you can be way, way off. You know why? Occupant behavior matters more than building envelope specifications.
For an example of what I'm talking about, check out this article: Occupant Behavior Makes a Difference.
heat system notes
Sure boilers are cheap but getting that heat moved around a typical house gets costly whether it's baseboard, hot air or radiant. plus the fuel you have to put into a boiler is not cheap and it's an ongoing expense. A well designed house whether it meets the P.H. standard or Pretty good house principles can do away with all or most of that distribution and most of the fuel. I like the point on the graph where you suddenly don' t need that expensive distribution system. That's where going the extra distance on the building envelope can end up costing less than standard code min. construction.
I think most certification standards get bogged down a bit by having to choose rigid numbers when the reality is very different case by case and very occupant behavior driven. I applaud the Passive house approach - I am a certified Passive House consultant myself - it represents good solid building science, very much in line with what we discuss here on GBA and very much based on simplification. (heat delivered using an appliance vs a heating system is a good example of simplification) I base all my own work on these principles but worry very little if my buildings do not meet the specific criteria for certification. Maybe someday I will have a client to whom that is important.
Dr. Feist is in Portland, Oregon
Albert Rooks just sent me this photo by e-mail, taken today in Portland, Oregon. It was taken at a groundbreaking ceremony for a Passivhaus co-housing project. Dr. Wolfgang Feist is the guy in the white shirt.
.
100,000 Btu Boiler,
Why does this House need a 100,000 Btu Boiler?
Response to Reiner Hoyer
Reiner,
Great question. Here's my guess: most of the capacity of the boiler is needed to supply domestic hot water, not space heating.
Here's a quote from building scientist John Straube, during a presentation on heating systems for low-load houses; the topic was tankless water heaters: “If you have two hot-water fixtures on at the same time, that’s in the range of 2 to 3 gallons per minutes combined,” said Straube. “If the temperature of the incoming cold water is 40 or 50 degrees F, now you need a large heating appliance — about 75,000 Btuh minimum. But you might only need 25,000 Btuh for space heat. If you install a tankless heater with a capacity of 90,000 to 125,000 Btuh, which is typical for Americans in a northern climate, you end up with an appliance that is four times the capacity of your space heating needs.”
passivehaus advisor costs
I was quoted 18,000$ for using a passivehaus adviser during our new home construction. I read the course work, went to seminars, and did the design myself as well as the construction myself. 18,000$ buys quite a bit of new furniture so that is what we have. Plus I think we did a pretty good job getting close or past the standard. But my proof is in our comfort and costs of running the house. So far it runs at about 1/4 the costs of our old standard built house in NY. It is also Bigger (2000' went to 2700 sq').
Response to Mark Dickerson
Mark,
Thanks for sharing your story of your $18,000 quote for a Passivhaus consultant.
I'll quote Lloyd Alter's comment on the Park Passive project in Seattle: "The Park Passive is a good example. Outside of NK Architects and their usual engineering sub-consultants, we have Rob Harrison as a Passivhaus consultant, Bronwyn Barry doing detailed THERM analysis, with it all certified by the Passive House Academy out of Ireland. ... Perhaps one reason that there is a cost premium on Passivhaus is that there are so many mouths to feed."
You're all missing the point.
Passive House is like the north star: a beacon to wayward projects lost in a universe of standards that don't require an absolute limit on space heating and cooling demands. Typical codes (ASHRAE, IECC, Title 24--and standards based on those, like LEED) don't require a certain level of envelope performance: want to trade off smart, thoughtful design with a high-efficiency boiler? No problem. Want to design a building with non-compact geometry, which results in more surface area for heat loss? No problem- your building will be compared to the same reference assemblies regardless of how compact the shape is. In other words, those standards provide a moving target for energy performance.
Passive House gives designers an immoveable target. Regardless of how the numbers pencil out, that target gives us a firm reference point by which to assess real, absolute performance. I personally don't care much what the numbers are ("pick a number, any number")- I only care that people are starting to look at these absolute numbers and use them to optimize their buildings, understand how they really perform and indeed what's possible.
To date, no other standard has been able to accomplish this incredible change in mindset. You all can continue to debate the numbers, how cost-effectiveness varies based on climates, local utility rates, the current cost of solar etc. Good luck with that. I'll continue to educate people about the "biggest pieces of the pie" to focus on regarding their high-performance projects--which is really the point.
Response to Katy Hollbacher
Katy,
If your aim is "to educate people about the 'biggest pieces of the pie' to focus on regarding their high-performance projects," then I think we're on the same page. That's a pretty good summary of my approach when I write articles for GBA.
That focus, which we have in common, doesn't preclude ancillary discussions, including "the [annual energy use] numbers [we should aim for], how cost-effectiveness varies based on climates, local utility rates, and the current cost of solar." After all, if someone is considering spending $200,000 or $300,000 on a new house -- the biggest purchase they will ever make in their life -- then these ancillary discussions matter very much indeed. Most people can't afford to spend an extra $18,000 to $50,000 unless they know whether it makes sense.
Cost 10% to 15% more and Honesty
I am a Passive House Consultant in northern Vermont, climate zone 6 cold and wet. Our experience is that building a PH in our tough environment costs between 10% and 15%. Frank R's post 'Honesty', says you have to buy expensive windows. It is true, but you are buying windows anyway, right. It isn't a $25,000 price on top of the price of a Standard Code house. It is an extra $7,500 or so on top of the windows you were going to buy anyway but were going to be leaky and not as thermally efficient.
We have data as well that the out of pocket monthly expenses for a Passive House and a Code house are the same from day one. The extra cost of the PH with the 90% fuel savings is the same monthly cost as the same house built to Code with a lower mortgage but much higher fuel costs. As soon as the fuel you are using goes up in price you are saving money every month with a PH.
Adam Cohen, from Structures Design Build in Roanoke Virginia says that he can build a Passive House for the same cost as a Code house. But then again that is in Virginia where you can hit the standard with much less insulation.
Monte, thanks for your article. It was well written and considering the caveats that Martin mentioned I am with you 100%.
Martin is right, the Zehnder costs a chunk of change but it and the PH windows, special detailing for air sealing and extra insulation still only cost 10% to 15% more here in Vt. We are using the Zehnder in conjunction with a point source air to air heat pump as the sole heat source. The HRV is working as a distribution system in these houses. Comfort is excellent and the Indoor Air Quality is almost as good as fresh air.
Fortunately there is no reason to rely on our feelings about the PH standard. We have monitored data showing the temperatures in each room, IAQ and efficiencies of the HRV and heat pump from PH's in Vermont. They support the claims made about PH.
There isn't any question about Monte being honest. He is debunking some common misconceptions about PH that are out there.
The Pretty Good House is more efficient than Energy Star but not as good as PH. There are arguments out there that there is a point where you are putting too much into the insulation and high efficiency equipment and windows. What we have found is you can build a PH lite and get less energy savings, but why do that if the monthly out of pocket for going all the way is the same as not doing anything but what code requires? Adding more efficiency after the fact (in a retrofit) is much more expensive than doing it during construction, that is certain.
Thanks for listening to my 2 cents.
Response to Chris West
Chris,
I disagree with your statement, "The extra cost of the PH with the 90% fuel savings is the same monthly cost as the same house built to Code with a lower mortgage but much higher fuel costs."
No one has ever shown that a Passivhaus building saves 90% of the heating costs required for a new building that meets code. The claim is that a new Passivhaus saves 90% of the heating costs required for an older German building.
Building codes have come a long way. New code-minimum buildings are much better built than old German homes -- or even U.S. homes built in the 1970s. I think a more accurate estimate is 50% savings compared to a code-minimum home. That's nothing to sneeze at. But it's important not to exaggerate.
Response to Chris West
"Adam Cohen, from Structures Design Build in Roanoke Virginia says that he can build a Passive House for the same cost as a Code house."
It's including this sort of nonsense that sets back any reasonable debate on the subject. The upgrades in materials, necessity of using specialized consultants and accreditation are free?
MARTIN :
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That focus, which we have in common, doesn't preclude ancillary discussions, including "the [annual energy use] numbers [we should aim for], how cost-effectiveness varies based on climates, local utility rates, and the current cost of solar." After all, if someone is considering spending $200,000 or $300,000 on a new house -- the biggest purchase they will ever make in their life -- then these ancillary discussions matter very much indeed. Most people can't afford to spend an extra $18,000 to $50,000 unless they know whether it makes sense.
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1- biggest purchase , i agree and don't understand why we still need to point this out to some ..
2- regular folks already spend 10 thousands of their $$$ per year, on anything without value ..
electronics, luxury items, cell phones and plans ... people like to spend on stuff they can take in their hand, taste, wear ... all unecessary stuff ! Just look at women an designer clothes .:p
but yet they have hard time spending 10 000$ additional on their new life investment ( house )
even if would pay for itself and or add confort value.
Much more important to have a 25 000$ kitchen cabinetry , than speding 5 000$ on intengible , inwall ( read invisible ) insulation.
Honesty
Chris,
I am not a builder, so my quick estimate may be way off. But hear it goes: A standard pvc double pane energy star window (builder grade @ home depot) is $10 a square ft. A German Passive house window is $90 a Square foot. Assuming a 2000sqft home is 55'x35'x9' with 15% of the wall space dedicated to windows would give you about 250 sqft of window area. So about $2,500 in for a cheap us builder grade windows, The passive house windows would be $20,000 more. I know you can use the canadian windows, but as noted with other blogs on this site, the tradoff is usually a equivelent cost in insulation.
So my very rough estimates $20,000 for windows, $10,000-20,000 for consulation fees, $20,000 for insulation, $5,000 air sealing. Heating and cooling systems are a tradeoff due to the HRU. Is it safe to say that a passive house is going to be at least $50,000-$60,000 more than a standard house? More?
My point isn't that passive house isn't great or that it isn't worth the extra money if you can afford it. My point is that the author wrote about passive house "myths"
He stated that it is a myth that passive houses are expensive. But $50-60,000 seems is expensive to the average home owner.
He wrote that the walls are not thick. But they are at least twice as thick as a standard 2x4 wall.
He wrote that passive houses are less stuffy than normal houses. But you don't need to be a passive house to have just as much fresh air.
He wrote that they are not complicated. If they are not complicated, why do so many people (like Roger Normand for example) have trouble getting there house built to that standard?
I really liked Roger Normand's articles on building a passive house. They really show the trial, tribulations and frustrations with meet this standard. It is an honest take on what he went through to get the house built. From reading other passive house blog's this seems like a typical experience. But this article sugar coats the real issues with building to the standard.
I don't understand...
Monte Paulsen wrote, "And because the Passive House is better insulated, its residents may choose to leave windows open more days per year than the resident of a code-minimum home."
I just don't follow his reasoning. Does anybody understand what he means?
Response to Charles Campbell
Charles,
Maybe Monte's comment has to do with reports of Passivhaus buildings that tend to overheat due to too much south-facing glazing. When that March sun is pouring through the south windows, it may be necessary to open a few windows -- even if it is 48 degrees outside.
LOLZ. once again, GBA failing
LOLZ. once again, GBA failing to see the forest for the trees, confusing hyperbole with facts...
Passivhaus is LEAST cost effective on single family houses. Furthermore, Passivhaus incurs even more penalties when a building is shoehorned to meet PH - which is what the majority of US projects have done (poor education, mostly). Multifamily and institutional are where it's at - both in terms of ROI and environmental gains.
Regarding Adam Cohen meeting PH for same cost as code builders - it's actually not that hard if you are smart. He doesn't need any special consultants - he IS the consultant. He gets quality PH windows that are reasonable and not really more than the products most builders use. The amount of extra insulation needed to meet PH in SW Virginia is nominal compared to code, when the building is designed properly. Hell, in some climates the amount of insulation to meet PH can be less than code (Something that could only be said for maybe Spain and St Moritz in Europe). And it's on the commercial side, where HVAC systems are routinely oversized, that PH can be built for as much, or almost as much, as code.
There are several builders meeting Passivhaus for low-average construction cost (<$140), in climates that vary from mild (Adam Cohen, Onion Flats, Jonah Stanford) to extreme (Chris Corson)
Frank,
Let's get realistic in your voodoo analysis. You're comparing cheapest, quasi-legal PVC windows with high performance, ALUMINUM-CLAD WOOD 3pane. You can get PVC PH windows for under $50/sf. BTW, with smart design you can even get north american PH-ish windows for about that much. most of the developers we've talked to can't get windows that meet code for $10/sf though. At our local big box, locally made PVC windows that meet WSEC are generally closer to $20/sf - so a REALISTIC differential for windows of same material (but not quality/performance) could be closer to: $15 difference x 250 sf = $3,750.
$20k for consultant fees is exorbitantly high in my opinion. but it depends on the house - for something over 600k in construction costs that will require constant oversight of builder, that might be appropriate. For a builder that knows what they're doing and clients who make fast, smart decisions - no where near $10k.
$5k in airsealing is also high. Sheathing costs are already included in typ. construction, so if just looking at tapes, maybe 1/3 of that. The exception would be if you went with fluid applied WRB, but then your air barrier costs are incorporated into your WRB costs, so you can eliminate housewrap (e.g. STILL not hitting $5k).
Martin, for what it's worth it was 55 today and my uninsulated SW facing sunroom got so hot I had to open windows. This isn't a problem limited to PH.
Martin - Too many mouths to feed?
Martin, you wrote:
"I'll quote Lloyd Alter's comment on the Park Passive project in Seattle: "The Park Passive is a good example. Outside of NK Architects and their usual engineering sub-consultants, we have Rob Harrison as a Passivhaus consultant, Bronwyn Barry doing detailed THERM analysis, with it all certified by the Passive House Academy out of Ireland. ... Perhaps one reason that there is a cost premium on Passivhaus is that there are so many mouths to feed."
So... Today I rode on a train with Browny Barry, Stored our luggage at the offices of NK Architects and am actually writing this response from Rob Harrison's office. Who could guess at the strange co-incidence.
I' do think I've got a little first hand knowledge on both the players and the project. Sloan Ritche's Park Passive is a dramatic project and would require plenty of consulting support regardless of it's PH status. The actual envelop is less than I expected and a new lesson on efficiency of design. (Meaning... The walls are not that thick and it's the architectural features that outshine the PH ones.
As you know this is still very much of a new frontier. Most of the issues and complaints of cost and production problems happen on your first projects. for Sloan (owner), this was his first. For Rob, not his first.
No ones is getting rich or overreaching. PH Consultants and certification are a good bargain for initial projects. For those who are their own PH consultant, the cost is saved. I guess PH education pays dividends on your own projects.
Passive House is certainly a team sport.
Response to Mike Eliason
A code minimum house by definition is as cheap as you can build, because all houses have to be built to at least that standard. Anything you add to that, whether you are smart or the increase is minimal or has some other justification still is in addition to the costs to build a code minimum house. So no Adam Cohen is wrong and believing him is wrong.
Why it matters is that a lot of us are trying to make informed choices about how we build and if people on any side of the debate won't be honest with their numbers we can't do that.
It's all in the approach
There are many ways to skin a cat when it comes to achieving Passive House standards. Depending on one’s approach, achieving PH standards can be done within a reasonable budget. There are many HRV/ERV systems out in the market and one doesn't have to purchase the most expensive system in order to achieve proper PH ventilation standards. Sure, getting a top of the line German HRV system will achieve the PH standard but those standards can also be met with many other more reasonably priced systems.
The same goes for windows. One can do some research and find windows that achieve excellent U-Value ratings of < 0.14 and excellent Air Infiltration ratings of < 0.03 cfm/ft², all without paying a premium price tag for them. Intus Windows has a uPVC triple pane window selection that can be used in a PH application and they don't carry the hefty premium many other triple pane PH windows carry. There have been quite a few homes featured both here and elsewhere that used Intus uPVC windows and achieved the Passive House standard.
It takes some planning and research to achieve Passive House on a budget. The main point is that it can be done but it requires thinking outside of the typical “building box” that is so common here in the USA. Passive House is a great standard to try and achieve. In the long run it will be better for the occupants of the home in terms of energy savings and better for our planet.
To clarify "opening windows"
Charles and Martin,
The open window comment is based on the fact that there is less heat loss in the overall enclosure in a PH. With the low variance in surface temps the enclosure takes far longer to lose heat and that translates to longer comfort when you leave a window open on a cold day. When the window is open, the only heat loss is in the heated air. Since people feel heat in radiation inside the enclosure, and the enclosure is not losing heat to thermal bridging, the house remains comfortable because the heat loss via air is such a minimal amount since it is not compounded by cold walls, and floors and poor quality glazing and frames.
Like a good down jacket that is partly unzipped... The rest of the jacket is good quality and the small opening is so marginal, the effect is not felt.
malcolm,
care to try again?
malcolm,
care to try again? most energy codes (they're not all equal) allow for spray foam. if the intent of code minimum was to be, 'as cheap as you can build' - then why spray foam as compliant w/ prescriptive path?
furthermore, there are several ways to construct the same house that meets the minimum requirements for energy codes. a multitude of wall assemblies, with a multitude of implications (performance, cost, durability).
furthermore, prescriptive paths aren't the only path forward. some states have progressive building codes that allow an applicant (w/ an energy model) to show how a proposed building exceeds a code minimum baseline (usually prescriptive path). through this route, looking at the whole building instead of disparate parts (hey, kind of like Passivhaus!), it is entirely possible AND legal to build a house that not only has LESS insulation than prescriptive path would require - but (whoa!) costs less too (e.g. less stringent windows/doors than prescriptive requirements).
furthermore, energy codes allow a variety of options for 'code minimum' ventilation - all with different corresponding costs, performance levels and IAQ implications.
furthermore, there are numerous PH projects featured on this blog that were built for about same cost as typical construction in that region. in some instances (MoSA in santa fe, onion flats in Philly) building Passivhaus at the same cost/sf of typical 'code minimum' construction for their locations. superior comfort and quality, lower energy bills - same effing price. I'm not sure why that's difficult to comprehend. are there others that cost more? yeah, and?
i've worked on million dollar projects with 'code minimum' assemblies, windows and doors that were TRIPLE the price of the slickest, best performing passivhaus windows ever conceived. adam's not wrong, your definition of 'code minimum' is. no one is trying to hide or fudge the numbers on this, no one's been dishonest and, frankly, the accusation isn't warranted.
martin, maybe it's time for a 'misconceptions about code minimum' post?
Wanting to hate the Passive House Standard
When I read the posts I get the impression that some people just aren't open to believing that the Passive House approach has any value at all.
I beg to differ on many of the criticisms. A few facts, largely from a real world project in New Brunswick (www.nauglerhouse.com).
1. We have a similar climate to Vermont here in New Brunswick - maybe colder.
2. The house is 100% heated through the ventilation system and the house is NOT over-ventilated to achieve this.
3. Additional mortgage is less than saved energy costs. This was only made possible with constant collaboration between builder and Passive House designer/consultant as well as sub-trades and building officials. Cost effective solutions can be found with creative thinking outside of the box.
4. Heating cost is $70 per year or <$8 per year.
5. Passive House is (I believe) a better approach than Net-Zero but harder to articulate. See point 6.
6. Passive House aims at greater comfort, greater health and greater durability. I guess this could be three points. This needs to be considered in the cost analysis for those who value these. Comparing a basic house to Passive House is like comparing a 1980's vehicle to a current one. The older one may be more cost effective up front but it doesn't include air bags, anti lock brakes, fuel injection or automated climate control (to name a few) and it will use more fuel and create more pollution. Generally the Passive House (although not something everyone will appreciate) is a superior product. Net-zero may simply be adding renewables and other technology to a basic house. This does not make it a better house but just one that produces as much energy as it consumes.
7. Passive House is an approach that aims to build houses for many generations and not just one. This house locks in energy prices to a degree that no other approach does. The approach provides insurance against rate shock if energy rates skyrocket in the future. There are very low maintenance and equipment replacement costs with fewer moving parts in the Passive House system.
8. Like any technology in it's infancy building a Passive House will be more expensive. As components are developed and built in North America the cost will come down. I thank all the believers and pioneers for investing in building a better house that is built to last.
9. Building to the Passive House standard is also an investment in the local community. More local labour and local materials translates into real and useful local jobs. These jobs likely create less pollution than the energy needed with extra energy production. High quality components create high quality jobs as we develop these components in North America.
10. Well, it is just the right thing to do in the age of climate change - sometimes the best things do cost more.
11. You can really use more space if you use Passive House windows. In the Naugler House the first place kids go is straight to the window sills. I have lived in several houses with bay window seats that never get used in the winter because it is just too cold to be comfortable. A Passive House has these features built in and they actually serve the intended purpose.
12 ...
13 ...
14 ...
People will not agree with everything - this is a fact of life - but I get tired with arguments that simply seems dismissive and negative. The Passive House approach is a scientific well proven standard that many, many people are very happy with. Like I said, it is not the solution for everyone - just like not everyone will be happy with a Prius - but I love mine!
And thanks for all the great posts!
Response to Mike Eliason (Comment #29)
Mike,
I agree with you that the Passivhaus standard makes more sense for multifamily buildings than it does for single-family homes. A Passivhaus multifamily project is more likely to save money on the heating system than a Passivhaus single-family project.
You're also right that some Passivhaus designers have done a good job at lowering the cost of Passivhaus construction. Here are some of the ways they do it: they build a simple, boxy shape, often with a shed roof. They design simple interiors with an open floor plan. They shop for the least expensive windows they can find that meet their performance specifications. They do their own PHPP calculations to reduce the cost of hiring consultants.
These tricks are all good. Many builders use similar tricks when building a conventional code-minimum house, of course -- thereby bringing down the cost of construction for the code-minimum house. If you can pare down the cost of a Passivhaus, you can also pare down the cost of a code-minimum house -- even lower.
No matter how you perform your cost calculations, triple-glazed windows cost more than double-glazed windows. A fully ducted HRV system costs more than exhaust-only ventilation. Thick walls cost more than conventional walls. And most Passivhaus jobs require the builder to hire a Passivhaus consultant, which costs thousands of dollars.
Response to Garth Hood (Comment #31)
Garth,
I understand the advantages of building a superinsulated house with a low air leakage rate. You don't have to convince me of the many advantages of this approach. You're right that using this approach can result in a house that is much more comfortable than a code-minimum house, and that the cost of the higher mortgage can often be covered by energy savings. (The same can be said about investing in a PV array, by the way.)
Like you, I'm all in favor of aiming for greater comfort, greater health, and greater durability.
I agree with you than Passivhaus construction costs are higher than conventional construction, but that some of these costs will come down as superinsulation methods become more commonly used.
Finally, I agree that it's much more comfortable to sit next to a triple-glazed window on a cold winter day than it is to sit next to a double-glazed window.
I'm all in favor of superinsulation methods and air-sealing measures. The only question I raise is whether it's necessary to hit the target numbers developed by Dr. Feist in Darmstadt, Germany. Superinsulation methods pre-dated Feist's fascination with superinsulation, and a cadre of North American builders have been using these methods continuously since 1980.
If North American builders decide that they don't need to build a certified Passivhaus, they can save a lot of money on consultants and certification paperwork. If North American builders live in a climate where HRVs aren't particularly cost-effective, why not consider a different type of ventilation system? Does it really make sense for so many New England Passivhaus buildings to have sub-slab foam that is rated at R-40 and R-60? These are valid questions -- and raising these questions is not equivalent to "wanting to hate the Passivhaus standard."
Response to Mike Eliason (Comment #35)
Mike,
You wrote, "Martin, maybe it's time for a 'misconceptions about code minimum' post?"
I'm not sure what you're saying, Mike. But it you are implying that GBA promotes code-minimum construction, that's an unfair parody of this site. GBA has a long history of advocating in favor of above-code energy specifications.
Sure Mike
Let's try again. Why not use real world examples such as the project that Monte used to illustrate this blog.
http://www.bernhardtpassive.com
The Berhardt passive home is a 3800 sf house costing $740, 500 built in Victoria British Columbia. The project team were good enough to provide a budget breakdown which includes a comparison with what a similar house would cost if built conventionally. It shows a $31,000 premium for building to passive house standards.
But let's look at their numbers a bit closer. Their conventional construction costs assume "that it is built with similar thermal comfort and air quality". In other words the comparator is Passive house standards by other means.
How does this play out? While the overwhelming majority of houses in Victoria are heated by either a gas forced air furnace or electric baseboard heaters, they chose to heat the conventional house with radiant in-slab water pipes. So the passive house mechanical systems are $18,000 while the comparator is $36,500.
Houses in Victoria are typically framed with 2"x6" studs and fg batt insulation. The Bernhardt house uses 2"x8" studs sheathed both sides and an additional 2" x4' interior wall. The cost premium on their $95,000 framing budget? $15,000.
Foundations in Victoria are typically a 30" high concrete wall insulated at the perimeter with 2" of foam. Higher end houses such as this might include 2" under slab foam. The premium claimed for increasing this to 12" foam on the wall and 16" under the slab is $15,000 on a $65,000 item.
The fees for design are $40,000 for the passive house and $35,000 for the conventional build. I'd like to find an architect in Victoria who could extract that fee from a house of this size and complexity.
What does all this lead to? That there is a premium for building to passive house standards (they admit it). And that you would have to be in a charitable mood to accept that the premium is as low as the project team claims.
So back to you Mike. Why don't you pick a passive house that has been built in one of the many regions you say they have been built for the same cost as one using conventional construction of the same size and level of finishes, and give us the budget with real numbers showing how this was done.
False Claims abound
I keep hearing the false claim that building to PH standards is only a 10% premium. This just is not true in the vast majority of cases. It is about time that we start looking at the actual build costs per square foot and verify this 10% figure.
In my region, a code min house can be built for between $80 and $130 per square foot. Building to PH standards usually works out to double this or more. For starters, PH builds almost always include an architect (someone usually not utilized on code min spec houses), you are now also requiring a structural engineer to pass off all of the locations where you are stuffing rigid foam into the structure to reduce thermal bridging, again – not a typical requirement in code min spec houses. Both of these often add up to $15K - $50K just for the professional envolvment. Finally there is the flawed claim of HVAC equipment purchase savings. Once you reduce the size of the heating plant below what is needed for a typically built small house, you are getting into specialized equipment with a much higher cost. You can buy a furnace/boiler for $1500 for a small code min house with another $1500 - $3000 to install the system, but to get a 15K BTU boiler or furnace for a high performance house is often going to be $15K or more just for the equipment.
We need to remove the hype from these projects and start accurately reporting their true cost. Then we can start looking at where further reductions in energy use may be more expensive than on site generation of energy, and start balancing the equation for a truly low impact dwelling. We are not in Germany. Our electricity costs 10 – 12 cents per kWh not the 30+ cents in Germany. Therefore the payback is not the small number of years often claimed within the PH community. It can actually be longer than the expected life of the dwelling.
Way back in response #16 ...
Reiner Hoyer asked:
"Why does this House need a 100,000 Btu Boiler?"
Bottom line, (almost) NO house needs a 100,000 BTU boiler- even code min houses!
Buffering domestic hot water loads with a thermal storage tank and going with a smaller burner makes a lot more sense. For Passive house loads that thermal storage tank with it's own burner, aka "condensing tank hot water heater". Most IRC 2009 code min houses under 3000 square feet (US-type measurement, not PHPP) will have design condition heat loads under 50,000 BTU/hr even in climate zone 7. A ~50,000 BTU boiler and an "indirect" storage tank for the hot water is a common (and goo) solution, with many vendors offering modulating boilers in that range. The 100,000 BTUhr Eco-King is the smallest boiler that vendor has, but it at least comes with a 6:1 turn down (min-fire= ~17,000 BTU/hr), but there are many many boilers with lower minimum firing rates than that, all of which would be perfectly appropriate for the application.
There is zero advantage to having the 100K high fire, or even a modulating boiler when the 99% outside design temp heat load is at or even below the min-fire output of the boiler. A simpler bang/bang single firing rate condensing burner has fewer operating or reliabity issues. The value of modulating systems is only there if they are sized and set up so that they will actually modulate, which is why ductless mini-split heat pumps and a heat pump water heater would have been both a cheaper and BETTER option in a Victoria B.C. location. (Greener too, since Victoria's local power grid is mostly hydro based, whereas the Eco-King is a fossil-burner generating greenhouse gases and other emissions.) A 3/4 -1 ton mini-split can actually modulate much of the time at PassiveHouse type loads, and better versions would deliver a seasonal average COP north of 3.5 in Victoria's temperate climate (just as they do across the strait in WA.)
my kid seemingly stuck in terminal-showering mode (with the aid of a drainwater heat recovery heat exchanger). My house clearly doesn't need a 100,000 BTU/hr boiler, and Ron Bernhardt's passive house doesn't either.
Mike
I admit my quick estimate was "Voodoo". For the widow, I used a 36x62 big box northern energy star PVC window at $175 or a $11sqft retail. I assumed most builders can get a better discount than retail, so $10 sqft. I can believe that the number is closer to $15-20 for a halfway decent builder. You stated that a certified window can be bought $35 sqft? From GBA blogs:
• Prepare to pay dearly for German windows — about $1,500 to $2,000 per window. Unilux windows cost about $90 per square foot. Stephan Tanner, the architect who founded Peak Building Products, said that high-quality Optiwin windows cost $100 per square foot or more, plus 6% to 10% for shipping. Canadian windows are much less expensive; according to Thompson, triple-glazed Inline Fiberglass windows cost $40 or $50 a square foot.
Great if you can get certified windows for that costs. You could use Canadian Windows to get close to $35. But as noted in other blogs, If you use non certified windows than you need to make up the energy difference by adding costs elsewhere.
Regarding the air sealing. You say it's just the tape, but look at Bernhardt passive home. They had to add OSB to the interior walls and ceilings and tape. Add in multiple blower door tests, labor etc…. $5,000 doesn't seem unreasonable.
Regarding consultants cost. See examples from Mark Dickerson. Unfortunately most home owners don't have Mark's skill or knowledge to get training. For them the only option is to work with a consultant.
I think Malcolm Taylor has the best idea of all. A real world code 2,000-2,500 SqFt minimum house vs. a real world passive house. No gimmicks in the estimate. No tradeoffs on the space, amenities etc..
Respose to Frank - Post #42
I can assure you that if you shop around and do some due diligence, one can buy triple pane energy efficient PH standard windows for $20 - $30 per sqft. You are making it sound like there are only two options; a cheapo big box window that leaks air and water and is highly inefficient or a top dollar PH certified $100 per sqft window. Intus uPVC triple pane windows are excellent high performing windows and they sell for around $20-$30 sqft depending on options. These windows achieve a U-Value of < 0.14 and the glazing units themselves are around Ug 0.08. This will more than satisfy PH standards and they have been used in homes that were awarded PH Certification.
I know quite a few people who went with the "standard" big box windows that later ended up costing them thousands and even into the tens of thousands in repair and replacement costs. As the saying goes, you get what you pay for and buying cheaply made windows will cost you later on. Compare a standard builder grade window with a European made window like Intus. It is a night and day difference in quality and of course efficiency. They close, lock and seal like a bank vault door versus closing like a barn door.
$100 per sqft for windows is not only insane but also completely unnecessary. $10 per sqft for cheaply made windows is also a bad choice in terms of energy efficiency and longevity. You will end up replacing those windows in a few years.
Peter L
Peter,
I think you miss my point. You don't have to convince me that cheapo big box windows are bad. My point was that if you go into a production builder new home, the windows will be of similar quality and construction. The issue I have been making is that the cost of an upgrade from a code minimum house to a Passive House might be 10% of the cost of a million dollar home, but it a much higher percentage for a less expensive home. In my area for example a 2,000 sqft starter home will be in the $250,000-$300,000 range (including the land). I have my doubts that the code minimum house can be upgraded to a passive house for $275,000-$330,000.
It's good to know the Intus windows go for $20-30 a sqft. With no experience buying a certified window I can only go with the statements in the blogs that I read. From Martin's previous blogs and Rogar Normands experience the passive house windows were in the $100 dollar range. If it does go for $20-30 a sqft for Intus, I stand corrected. Again, it would be nice to see a real world example of the upgrade costs without any gimmicks.
15 kWh/m2*year
Great discussion.
Based on years of experience designing, building, reviewing and certifying projects across U.S. climate zones, PHIUS agrees with the notion that one standard is not sufficient for all of the United States. PHIUS and PHIUS CPHCs (Certified Passive House Consultants) have done a lot of work on this subject and preliminary findings and recommendations will be presented at the upcoming 8th Annual North American Passive House Conference (http://www.passivehouse.us/phc2013/) in Pittsburgh.
Hope to see you there where everyone can carry on the discussion in person.
Response to Michael Knezovich
Michael,
I can't make it to the conference, but I look forward to reading about any announcements or recommendations from the committee. We will continue to report any Passivhaus news here at GBA. Thanks.
Response to Martin Holladay (Comment #37)
Martin,
I don't think I ever mentioned that I advocate that every house get Passive House certification. I doubt many in the Passive House movement would advocate for this. This is simply a client choice. and a method of third party performance verification. Of all the projects I work on less than 5% will ever get certified.
What I believe in, wholeheartedly, is the modelling and performance based process. And I also believe that a consultant, of any type, should save a client in one way or another. This can either be by saving money or by providing a superior product. And I am the first to send a client on their way if I can't offer any service of value.
I have worked with many builders. As far as i can see it is only through the energy modelling process that they can fully understand the dynamics of a balanced thermal envelope approach. A prescriptive approach will give good results most of the time. If a client is willing to have a house built by a rule-of-thumb rather than a more targeted approach then that is their choice and they take their chances that the project variables were within that prescriptive norm.
If a consultant is not providing useful information to the client, to help make informed decisions, then he/she is not doing his/her job. In every field there will be those who are in it to provide a service and others that just want to make a quick buck.
I am always happy to have a frank and open discussion about the pros and cons of any building approach. Some of the comments I have seen on GBA regarding Passive House don't seem to accept some of the facts that real world projects are bringing forward. Many dedicated builders and consultants are working hard to bring efficiencies to a new-to-us Passive House technology. None are saying that Passive House is the only way to build but it is absolutely cost effective for a client that values what it offers and wants a house to last. If all someone wants is granite and square feet at the lowest capital cost and the most corners and roof lines possible then Passive House is likely very poor value.
We also need to place a value on future proofing our buildings - or at least provide this option to the client. In this light we should build a house to last a hundred years or more with much higher energy rates coming in the future and from 100% renewable sources. I consider global warming to be a given yet even skeptics should care about air quality and industrial contamination to help move us closer to a clean energy economy that creates more quality jobs in many regions. The Passive House approach to building will increase labour while reducing energy - this is good for local economies. As we make more high quality components in North America this is good for local economies as well. We generally do not look at hidden costs in our economic system but we urgently need to find a way to quantify and value them.
I also believe that an HRV, of some type, is a necessary part of a well built house in a northern climate. I would like to see the data to suggest that an HRV is not cost effective in most Canadian climates. I can't speak to warmer climates. There are new machines that do an excellent job of reducing humidity and cooling air. We will see new technologies develop as more leading edge projects are completed. Air bags or anti-lock brakes can be argued as not being cost effective yet it both are now considered an essential part of a new and safe vehicle.
And thanks to everyone for this lively discussion!
Garth Hood
Response to Garth Hood
Garth,
I agree with most of what you wrote. Whether or not a client chooses to follow the Passivhaus standard, and whether or not a house should be certified, is a client choose. If the client wants it and can afford to pay for it, it makes sense to deliver what the client wants. That's fine.
I still see no evidence to support one of your statements: "... Passive House ... is absolutely cost effective for a client that values what it offers and wants a house to last." Perhaps you meant to say, "Passive House makes sense for a client that values what it offers and wants a house to last." That is different from cost-effectiveness. The desires of the client and durability have nothing to do with cost-effectiveness. I remain unconvinced that the 15 kWh/m2*year target has anything to do with cost-effectiveness.
Finally, I agree that HRVs are cost-effective in Canada. I don't think that they are a good choice in the warmer climates of the U.S.
Response to Martin Holladay, GBA Advisor
I absolutely stand behind my comment, "... Passive House ... is absolutely cost effective for a client that values what it offers and wants a house to last," for several reasons...
First, our first house built to the Passive House standard in Fredericton New Brunswick (actually we almost doubled the standard so the next one should be even better value) has upgrade mortgage costs that are less than the energy saved costs - at current energy prices. If energy prices go up this advantage for Passive house will only increase. The cost of a renewable energy system in our market is far more than the Passive House upgrades to get to the same energy consumption level. Our data analysis was verified by a parallel economic analysis by the Canadian Passive House Institute. Hopefully a third party study will someday verify the data that the Passive House community has gathered so far.
Second, this house builds in features that will make it last longer compared to a basic house. This must have some real value for some clients even if the market doesn't recognize it. It is just a matter of when the house is sold - before or after rot is discovered in a wall or before or after windows or a heating system needs to be replaced in a poorly built code house. Not valuing durability is a fault in our current economic system that encourages building poorly. This is not cost effective for future generations.
Third, if health and comfort have no value then we may as well save some money and go back to living in a cave. Hardwood floors and granite counter tops are not cost effective yet people want them. It is difficult to quantify the value in building a better house when some of the value added features are subjective.
Maybe we need to stop talking about "cost effective" when it comes to housing. Who asks about the cost effectiveness of leather seats or air conditioning or any upgrade package when buying a car (or building a house 10 times bigger than needed)? Do people want them? Absolutely!
In the end it doesn't matter much to me whether you believe in the 15 kWh/m2a target or not but I also want to make it clear to folks out there that some designers and builders are proving there are many benefits to aim for this high standard. Passive House is a very challenging standard that has many advantages and some builders are proving it can be cost effective and at the same time they are building a better house.
This may not be the the cost effective approach for everyone but it is cost effective for the right client when built by the right builder.
Response to Garth Hood
Garth,
I'm delighted that you were able to build a cost-effective Passivhaus. That's great. Not every builder is so successful.
Of course any builder interested in energy efficiency wants to build a durable house that provides comfort to occupants and is healthy. You have set up a false dichotomy -- a choice between a code-minimum house and a Passivhaus. Those are not the only two choices. There is no reason to believe that a conscientious reader of GBA would build a house that will have "rot discovered in a wall."
You also wrote, "It is difficult to quantify the value in building a better house when some of the value added features are subjective." I agree -- which is why I strongly urge you to stop using the word "cost-effective" for the measures that fall into this category.
Location Location Location
1 - Code minimum: this is so variable! Here in Calgary the City often ignores the ability in the National Building Code of Canada to avoid the prescriptive requirements of Part 9: Residential Buildings, and appeal to Part 4: Structure or Part 5: Moisture Control and Ventilation. Parts 4 and 5 allow a novel design to meet the requirements through satisfaction of applicable standards, given appropriate professional oversight in some cases.
It's the "Plan Checker Lottery." You submit your Building Permit by waiting in line, and get sent to one wicket or another. You might get the keen young guy with a good attitude to green building - she may even "believe" in global warming! Or you might get the old grouch for whom green building is a conspiracy of anti-business communist greenies. Flip the coin. They call the shots in terms of their particular approach...
Minimum code in Calgary is still pretty poor. Small towns just over the border in B.C. have a much more flexible attitude; they are years ahead of Calgary in terms of the understanding and application of building science.
But this is Alberta, Oil Town North. There is a heavy financial incentive to ignoring the amount of gas used to heat buildings…
2 - While true that some parts of the PHPP were developed for use in Darmstadt, don't pretend that cold climates don't exist in Europe. Head up or north and don't ignore successful passive houses in Sweden and high-altitude Austria. It is true that Yellowknife may not be the best place to build a passive house. But Vermont? C'mon. Not so extreme (though this year there are sure to be folks spitting mad and cursing through cold fingers in the East… All the more reason to spend $$ on insulation rather than fuel, even if it is chainsaw gas and time to feed the wood stove…)
3 - I am designing close to passive house assemblies - we have yet to find a client who is willing to spend extra dollars when gas is at $3.00 (now $5.00 so the argument is getting better). But one note on costs: is everyone factoring in the cost of replacing an expensive heating system? Geothermal at $30K a pop is a cost that needs to be paid again… when? 10, 15, 20 years? Same with windows. Buy the standard NAm. windows with wind-up hardware. When will you be replacing them? At what cost? Factor in condensation damage at the bottom corners of the double paned glass, including damage to framing, and what is the cost of replacement?
4 - I am quoting some costs here - LOCATION! They will certainly change with yours.
5 - So what if it is easier to achieve PH in the south? Go for it! Odd that the ease of achieving the standard is used sometimes as a backdoor critique - it's just the tone of some of the posts…
Location. Don't need to say it again. Location.
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One I hear a lot with Passive House is that it's too much like being in a plastic trash bag, which couldn't be further from the truth. Built it tight and ventilate it right leads to very low energy consuming homes, exceptional comfort and often, longer lasting homes due to an added emphasis on building science details. Truly, PH is a wonderful thing, and with it becoming more and more popular, I think most folks are going to understand it better as the industry changes.
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