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A Conversation With Wolfgang Feist

Questions and answers about the Passivhaus standard

Posted on Oct 27 2010 by Martin Holladay, GBA Advisor

Dr. Wolfgang Feist, the physicist and founder of the Passivhaus Institut in Darmstadt, Germany, began his U.S. speaking tour with a presentation and panel discussion at the Boston Architectural College on October 23, 2010. Among the other speakers at the event were Katrin Klingenberg, the founder of the Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. Institute U.S. in Urbana, Illinois.

After suffering some public relations stumbles in the past, Feist and Klingenberg have polished their presentations. In Boston, they steered clear of the awkward exaggerations and red herrings that have marred previous U.S. discussions of the Passivhaus standard.

When I first interviewed Dr. Feist in December 2007, he explained, “As long as you build a house in a way that you can use the heat-recovery ventilation(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. system — a system that you need anyway for indoor air requirements — to provide the heat and cooling, it can be considered a Passivhaus.” Since this method of heat delivery has proven to be extremely difficult in the cold climates of North America, many American designers were confused by Dr. Feist’s insistence on it. Refreshingly, Dr. Feist made no mention of this method of heat delivery in his Boston presentation.

In marked contrast to claims made at the 2009 Passive House conference in Urbana, Illinois, where the keynote speaker, Günter Lang of Austria, falsely claimed that Passivhaus buildings don’t require a heating or cooling system, Dr. Feist was forthright and candid during his stay in Boston. “In the heating climates, a Passivhaus building is not a zero-energy building — you still need to heat it,” Dr. Feist told his American audience. He later explained that, if you are building in a hot, humid climate, “You will need a small cooling system or a small dehumidification system.”

The five elements of a Passivhaus building

In his presentation to the Boston audience, Dr. Feist boiled down the Passivhaus approach to five elements:
● High levels of insulation
● Reduction of thermal bridges
● Attention to airtightness
● The use of “energy-gain” windows
● Heat-recovery ventilation

This “return to the roots” approach was well received by the American audience.

A tip of the hat to superinsulation’s North American roots

Katrin Klingenberg's presentation included a welcome review of the history of superinsulated houses. She shared slides showing many recently completed Passivhaus buildings, including the Smith house in Urbana, the Waldsee BioHaus, the Passivhaus residence on Martha's Vineyard, the 2007 and 2009 Solar Decathlon winners, the Isabella Lake house, Rachel Wagner's "almost" Passivhaus, Tim Eian's House in the Woods, the Whistler Passivhaus, the retrofit in Sonoma, California, the GoLogic project in Belfast, Maine, the Bilyeu Homes project in Salem, Oregon, and the Studio 804 house in Kansas City.

Klingenberg also announced the upcoming Passive House conference to be held in Portland, Oregon on November 4 -7, 2010.

Upcoming challenges for Passivhaus proponents

I had two opportunities to interview Dr. Feist in Boston. The first occurred before the symposium began, when about 20 people gathered in a lounge at Boston Architectural College for an informal get-together.

Later, during a mid-afternoon break, I was able to ask Dr. Feist some follow-up questions. Unfortunately, there wasn’t enough time to ask Dr. Feist all of the questions suggested by GBAGreenBuildingAdvisor.com readers. However, GBA’s podcaster Chris Briley was able to snag an evening interview with Dr. Feist; Briley’s report of his interview will soon be posted on GBA.

I found Dr. Feist to be warm and eager to answer questions from American architects and journalists. The Passivhaus standard is gaining traction in the U.S., and that’s good news. Several challenges to more widespread adoption of the standard still remain, however. It seems to me that U.S. Passivhaus proponents need to focus on:

  • A correction of the small-house penalty inherent in the standard;
  • Better advice for those building in very hot or very cold climates;
  • Better answers to questions about cost-effectiveness — especially, questions about the cost-effectiveness of measures necessary to achieve a maximum annual heating energy use of 15 kWh per square meter.

The interview

Dr. Feist began by introducing himself to the people gathered in a lounge area.

Dr. Feist: I was born in Germany. I worked in physics until the early ’80s, and then worked on energy-efficient buildings.

My work was inspired by people like William Shurcliff, who has written books on energy-efficient construction. There were important papers from the late ’70s and early ’80s, when guys were working on superinsulation. We always considered this information in Europe. There were a few research groups in U.S. and Canada, a few in Europe. These researchers were in contact with each other. But at the beginning of the ’80s, there were almost no low-energy buildings in central Europe.

"...It turns out that it is like learning to ride a bicycle: When you first see it, you don’t believe it is possible, but afterward, you see that it is easy."

Then there was a research meeting in Sweden in Lund University. Bo Adamson, the professor acting as a ‘secretary of foreign affairs,’ had studied developments in low-energy construction in Vietnam and China. He came back in the middle of the ’80s from China. He wanted to build passive houses. He told me about that, and I thought, ‘Oh, he has gone crazy.’ He had seen some passive house developments in southern China.

These things got started. We did research on the early development. There was research in U.S. and Scandinavia. We designed the first project in Darmstadt, and that turned out to be successful.

Since that time we are working on dissemination. There has been a lot of development since the mid ’90s in this field. There are now initiatives in all the European countries, including Russia and Belarus, in the Baltic countries, and almost all countries on the European continent. Already Passivhaus represents 10 or 12 percent of all new construction in Austria and Germany. We have had a big influence on the development of the building sector.

The first reaction you get from building professionals is, ‘That’s impossible. That won’t work. It’s too tight. Can’t we do it less tight?’ But we insisted in these tough figures, and it turns out that it is like learning to ride a bicycle: When you first see it, you don’t believe it is possible, but afterwards, you see that it is easy. That’s how it always worked in all these countries.

At the moment, I am in two places: working as the scientific head of the Passivhaus Intitut in Darmstadt, and also working at Innsbruck University.

Are climate-specific standards in the offing?

MH: Is there any discussion now about developing climate-specific standards for very cold climates or very hot climates?

Dr. Feist: There are already some examples in really cold climates. But the conditions are grounded in a real performance standard, so this is always a tough thing to change. So at the moment we don’t think much about changing the standard.

[In different locations] there are different boundary conditions. We have to look at these conditions, and we also have to adapt the [building] components and some of our recommendations. One of the major developments is, the next Passivhaus conference [in 2011 in Austria] will be about these regional developments.

Homes without air conditioning have low energy bills

MH: In hot climates, do you think it’s necessary for the occupants of Passivhaus buildings to accept high indoor temperatures in order to achieve energy use targets? After all, you can save energy by having no air conditioning.

Dr. Feist: There is a lot of discussion about that. To be honest, I don’t believe in that [the need for high indoor temperatures]. As long as people have a choice, [they will want] to choose comfort. In that situation we won’t be able to change that.

In the heating climates, a Passivhaus building is not a zero-energy building — you still need to heat it. The same is true for hot climates and humid climates. You will need a small cooling system or a small dehumidification system. So then we should stick to the goal of providing the best possible comfort — not by avoiding the use of cooling, but by reducing the cooling load to a very low level. Depending on the climate, you may need dehumidification, and it is very important to have shading. [We are looking at] the field of humidity recovery in the humid climates.

European windows and HRVs are expensive

MH: Some U.S. builders question the need for European equipment — for example, European triple-glazed windows or European HRVs — because they are so expensive. It’s hard to justify the high incremental cost of European equipment compared to North American equipment. The energy saving achieved by upgrading to European equipment is relatively low, especially considering to the high incremental cost of these components.

Dr. Feist: The Passivhaus standard doesn’t insist of using special types of components. It’s a total performance standard. You can use any component you want to use, as long as you can achieve the performance goal.

My recommendation is not to use the imported components. You don’t need state-of-the-art components. My recommendation is not to import windows from Europe, but to foster the development of really efficient American types of equipment.

This is what happened in Europe. We have had the exact same discussion in Europe. At the beginning, the only available HRV was a Danish one, and in Germany we didn’t want to buy a Danish one. But we were able to help small enterprises in Germany, and in the end the HRVs they produced were even better than the ones from Denmark.

It’s a very interesting thing to develop these heat-recovery systems. You will need a lot of different types in different climates. In some climates you need ones with humidity recovery; all of these are different systems. It’s not so difficult to do that.

It’s a chance for small and medium-sized enterprises to get into that [manufacturing equipment]. It wouldn’t take that long [for U.S. companies] to make joint ventures with the companies that have done this work in Europe. They are small and medium-sized enterprises. This is one of the effects of the Passivhaus performance standard, it makes a point for doing that [equipment] development. This is opening the door for small and medium-sized enterprises, opening the door to better construction standards, opening the door for more architectural freedom. This is very important.

"It might not be possible to renovate all buildings to the Passivhaus standard. Some [buildings] you don’t want to change, for several reasons."

In an existing building, it’s tough to achieve the standard

Chris Briley: Does that same philosophy hold true for renovation? Right now, it is very difficult to renovate and meet the Passivhaus standard, and we hear a lot of blowback. Many people say there ought to be a renovation standard with a different airtightness threshold — instead of saying, ‘This is the line in the sand. This is the brass ring.’

Dr. Feist: With existing buildings, the philosophy is a little bit different. It might not be possible to renovate them all to the Passivhaus standard. Some [buildings] you don’t want to change, for several reasons.

It is very important to get better components — for example, windows with really good triple glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill.. When it comes to cost, in Europe, they also said, ‘It’s too expensive.’ But the cost of these windows has dropped by a factor of three. Now the philosophy is, you can use these components in retrofit. Once these components are available, that will define how far you can go with the existing stock of buildings.

It is not a good idea to have a different Passivhaus standard for retrofit of existing buildings, because it might be too tough — then there will be complaints — or it might not be tough enough, so it is too easy to reach, and maybe you could do more in most of the buildings.

I think you should do what you can on a reasonable level. We were surprised in Europe to learn that a thing like the airtightness standard was possible in all the projects we have done so far. They all came under 1 ACH at 50 pascals. If you are that tight, of course you need a ventilation system.

Insulation is a different thing. With some buildings you can do external insulation. But there are lots of buildings where you cannot do external insulation. And internal insulation is much more difficult. You will never reach the Passivhaus standard with internal insulation, because of thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. .

In Europe, the surprising result so far is that almost always we were able to reduce the overall energy consumption for heating and air conditioning by a factor of three or four. All of that information is published. If you want to get that information, that is all available on the Internet. There are some Internet pages that you can log onto. One is the Passive House International site.

Questions from the crowd

Q. from the crowd: Is that information only available in German?

Dr. Feist: We need to bring this information to a Wikipedia-type structure. We just started the ‘Passipedia.’ The site is already in a state where we can gain lots of information from people’s experiences. With all of these old publications, it’s true that most of them are in German, but I hope some will be translated.

Q. from the crowd: With these retrofit projects, what percentage of energy savings are due to airtightness changes?

Dr. Feist: In an old building, the highest part of the losses are due to bad insulation — to conductionMovement of heat through a material as kinetic energy is transferred from molecule to molecule; the handle of an iron skillet on the stove gets hot due to heat conduction. R-value is a measure of resistance to conductive heat flow. and radiation. If you start with an old building, the first step is always insulation. Then the next step is airtightness. [Editor's note: Dr. Feist later clarified this statement with the following comment: “The ‘first’ was never meant to be a timeline order.” Further discussion on this point can be found in the posted comments below.]

If you have air flow through the structure, humid air flowing through the construction, you can get condensation. That is the most important reason it has to be airtight, to avoid problems due to structural damage from moisture.

The structural damage problem is the reason why the airtightness requirement is a separate number. That was one of the experiences in very early superinsulated houses — there were often problems, structural problems, from condensation. [Dr. Feist turns to me and asks me for confirmation. I agree.]

"These airtightness details are all a question of design. It’s not a question of the quality of work on the site; it is a question of design."

Condensation and rot can occur in an airtight building

MH: But it is still possible to have condensation problems in a building that is perfectly airtight. That’s what happened in Juneau, Alaska. Convective loops brought warm, humid air in contact with cold sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. , and there was rot — even when there was no exfiltrationAirflow outward through a wall or building envelope; the opposite of infiltration..

Dr. Feist: It is always a good idea to have it as airtight as possible. From a technical point of view, having a figure of .6 ACH or its equivalent in metric units will give you a good guarantee that you don’t have damage from infiltration or exfiltration. Of course the design has to be reasonable. You could have others sources of humidity, and you have to keep that humidity out of the construction as well. But concerning this part of the problem — the problems that come from infiltration and exfiltration — you can get rid of those problems if you get it really tight.

About whether to change to practices that are less airtight — lots of people think the standard is difficult to reach. But I think it isn’t. We always have that discussion. We had that discussion in Czechoslovakia. People said, ‘It’s impossible.’ But when we made some education, it became possible. We said, you might have problems at first, but then it turns out to be really easy.

The airtightness level we normally reach after building three or four houses is .2 or .4 ach50. That’s what we normally come to.

These airtightness details are all a question of design. It’s not a question of the quality of work on the site; it is a question of design. The designer must know what is the airtight layer, and how are the different parts of the structure all connected. It is not the handcraft person who achieves that — it is the designer who does that. It is quite easy to reach.

More questions from the crowd

Q. from the crowd: How do these buildings hold up over the years?

Dr. Feist: We have experience going back more than thirty years. The Saskatchewan house is still in use. It is still like it was in the very beginning. It worked really well. There are other examples from Germany that are 15 to 25 years old.

What is important is to have the philosophy — to think about how to guaranty airtightness for the lifetime of the structure, and not just the for the pressurization test. It is necessary to have those details in the design, to have that in your construction plans.

Q. from the crowd: What about best practices for vapor barriers?

Dr. Feist: We are talking now about airtightness. There is no requirement for this to be a vapor barrier. It could be but it doesn’t have to be.

The vapor barrier discussion is much more complicated. It differs depending on the climate. Nowadays we try to avoid vapor barriers. Not that vapor barriers are a big problem — a vapor barrier can work if it is done the right way. But much more important than the vapor barrier is the air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both..

If the vapor barrier is not airtight you really run into problems. So the latest developments in Europe go in the direction of avoiding a vapor barrier, but having a vapor retarder on the warm side of the structure, to allow it to dry out if there is any moisture.

Q. from the crowd: Where can I get more information?

Dr. Feist: Passipedia.org has a part that is open to the public, to help answer the frequent questions, such as, ‘Can we open a window?’ — it seems we always have this discussion. Then there is another level [of the Web site] only open to members of the Passivhaus associations worldwide.

The idea is to share solutions, so you don’t have to reinvent all these things over and over again. That’s the concept of the Passipedia, so you can get ideas from countries with different climatic conditions, you can see some clever solutions they have invented in Korea that could be useful at your place as well.

We will provide a thorough scientific check of the information as well, because there is a lot of nonsense everywhere, a lot of these myths about damage from very tight construction, and bad advice — for example, that you are not allowed to use wooden construction. So we will check the information all the time from a scientific point of view. Sometimes information changes, because we reach a new state of knowledge. It’s important to know that. We try to follow this scientific approach. I think this is very important to follow the process of science.

It’s important to remember that there are more built passive houses than certified passive houses. Certification is important, especially for the first project. For the first project you need that quality assurance. The only way to prove a concept is to check it. But now in Europe there are architects who are building their 150th passive house, and they don’t certify every building. So certification is not at the center of our work. The center is the outlook, not the certification.

Data input woes

Later, I spoke with Dr. Feist during a break in the conference.

MH: Some people who have completed the PHPP training are still frustrated by the amount of data that has to be entered into the PHPP software. There are so many inputs, especially for windows that are not certified, and also for thermal bridging. Is there any way to simplify the number of inputs? Although we know it is technically excellent, is there a way to make it more user-friendly?

Dr. Feist: I completely agree with you. This is what we are aiming to do for the next step. To make it simple for the user is the most important thing. You have to have such a program, and we want to do that. The concept is, like it is already seen there, that you choose, say, a component, and you get all the data inputted. That is the concept that we want to follow.

MH: But we will not get Passivhaus-certified windows produced in the United States for many years.

Dr. Feist: Oh, I don’t agree. I think that will happen early. Because it’s just a question of whether this is asked from the market. If it is asked from the market, I’ve seen now that this is coming, there will be — like it happened in Europe. You know the first Passivhaus in 1991, there was no window. Nothing. There was nothing on the market. We built it just by handicraft with our own hands, and glued insulation on the window frame, and it was working. Then it took up until 1997, six years, until the first company went in. And after we had the first producer — that was the most difficult thing — after we had the first producer, there was suddenly all of the windows happening.

MH: Here in North America, we have Thermotech windows, we have Inline Windows, we have Accurate Dorwin windows. They don’t quite meet Passivhaus standards, and they aren’t certified. But for North American designers, it would still be nice if we could input the data for these windows with just one click.

Dr. Feist: You can do it. It’s no problem. The list of windows is open, and you can fill in your inputs. You only need the data.

MH: Is the data in a database somewhere that is accessible, or do you have to track it down yourself?

Dr. Feist: Of course I don’t have it. That’s a problem. That’s a thing I think is really necessary: you have to have some pressure on the producers so that they deliver the data.

MH: And it has to be accessible electronically so you don’t have to make a phone call each time.

Dr. Feist: And another problem is, it has to be trustable. That’s the reason that we started the certification. Very often a producer claims to have something that is really woo-woo-woo, and when you look, well… That was one of the most impressive situations that we have had — with the first mechanical ventilation with heat recovery system. They claimed to have 85% [efficiency], but when we did the measurements in a real building, it was 62 or something. That’s a big difference. So that makes it necessary to have somebody doing test measurements.

MH: The trouble is, even if there are forty Passivhaus projects in the pipeline, it’s not enough. The manufacturers won’t care. It’s not a market yet.

Dr. Feist: I know all that, because the history in Europe was the same. It was the same thing. The interesting thing is, and that’s why it can work, is that you are not dependent on the big manufacturers. You can work with a small or medium enterprise, and there are lots of them everywhere — and in the U.S.

That’s what I think we need most to motivate these guys to do that. Because it’s not only the Passivhaus market — imagine you have a window with these properties, and have it available on your market. It can be sold for refurbishment, for retrofit, and it could be used by other people who don’t build passive houses but just want to have a good window.

MH: We’re headed in that direction, but it will take a while.

Dr. Feist: The same like it was in Europe. We are not at the end in Europe now. There are still some big players on the market who don’t like it. That’s the next step that happens. Some big players don’t like it, who want to sell their old stuff. So they are blocking on the lobbyist level. That’s what’s happening now.

Do Passivhaus buildings have lower budgets for HVAC equipment?

MH: When I see this chart showing how the cost of HVAC equipment drops off suddenly when you improve the envelope — because you ‘don’t need a heating system’ — I’m not yet convinced. I haven’t yet seen it. If you still need an HRV, an air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps., or whatever your heating system is, and sometimes a solar hot water system — is it cheaper than an American heating and ventilating package? Not yet.

Dr. Feist: To be honest about that — You can’t look in the [rear-view] mirror to save that. This is what the development can do.

MH: You’re saying, we hope it will happen some day.

Dr. Feist: No, it’s not just a hope. If you look at the example in Lafayette [Louisiana], for example. They have just one split air conditioner unit for the whole house, where you normally use three or four. And that might be the right system for such a climate, because you have a solar warm water system. In this climate, maybe 85% or something is what you get from solar, and only a small amount [of water] you have to heat with electricity. Everything else you need is dehumidification and cooling, and that can be done with such a split unit, and the split units are quite inexpensive. And so this can be done with just one unit for the whole home. And this will be very cheap, of course.

MH: But it hasn’t quite reached the point where there is a savings for hardware — not yet.

Dr. Feist: At the moment. But I think the direction is the right direction. To invest a little bit more in the envelope in order to reduce these technical costs, and that will reduce all the costs in the supply line.

MH: In America, the most economical package of HVAC components are not being put together by Passivhaus builders, but by energy-efficient builders using mini-split heat pumps and either an exhaust or supply ventilation system with one Panasonic fan that draws only 11 watts. These systems have low development costs and good energy performance — just not Passivhaus performance.

Dr. Feist: Surely you will agree that the HRV — the plate heat exchangerDevice that transfers heat from one material or medium to another. An air-to-air heat exchanger, or heat-recovery ventilator, transfers heat from one airstream to another. A copper-pipe heat exchanger in a solar water-heater tank transfers heat from the heat-transfer fluid circulating through a solar collector to the potable water in the storage tank. is not a very expensive a thing. This is just $200 or $300. If you calculate that back on an energy cost comparison, you will see this is a very cost-efficient measure.

MH: But in America, an HRV costs $2,000 to install.

Dr. Feist: It may not be available now at the price we need on the market. There I agree. This is again a thing — we have to put some pressure on the market to make these things available at a reasonable cost. It will take some time. It’s important to go that direction. It will reduce the overall electricity you need.

MH: It may or it may not. It will slightly lower your heating cost. But the HRVs use more electricity than a Panasonic WhisperGreen fan.

Dr. Feist: The efficiency of the heat-recovery system, using ECM motors, has increased very much. The systems we have now in Europe on the market, there is no question, they have a much higher efficiency than any heat pump could have.

MH: I’m not talking about heat pumps. I’m talking about ventilating a house. A supply or an exhaust system is much cheaper than a heat-recovery system, because you only need one fan.

Dr. Feist: It may be at the moment. You may be right, for the situation in the U.S. But the advantage of the heat-recovery system is in a cold or a hot and humid climate. It is a question of where you are. If you are somewhere in between, we can question whether heat recovery pays off. But if you are in a cold climate, there is no question, it pays off. And if you are in a humid climate, you have the possibility of dehumidification as well with a heat-recovery system.

MH: Not dehumidification. You can lower the humidity load caused by ventilating the house. It doesn’t provide dehumidification.

Dr. Feist: Yes, of course. What I also see, which has been proven to be a very good concept in Europe, that is the combination of the heat-recovery system with the heating or cooling supply. To have one box with everything integrated. It’s a better concept.

MH: The magic box.

Dr. Feist: You can call it a magic box. What is really important is, we all shouldn’t stick to just one kind of technology. What is important is the performance. The overall performance is what we need. Of course, we agree that we need ventilation for indoor air quality. Then there is of course the question of whether supply or exhaust alone will work. Maybe in some climates it would.

Last week’s blog: “Navigating Energy Star’s Thermal Bypass Checklist.”


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  1. Martin Holladay

1.
Wed, 10/27/2010 - 14:48

great questions
by mike eliason

Helpful? 0

great questions, martin. i'm wondering if your thoughts on PH have shifted at all based on this, or if you still have the same reservations?

my one critique is that 'EU windows are expensive'. compared to wood windows mfr'd in the US, they're really not - especially when you take quality and performance into account. but comparing to fiberglass, high performance wood windows from the EU will be pricier. i've worked on a number of homes with window packages @ $100/sf+, for double pane windows that weren't the tightest construction. i don't see how a client wanting attractive wood windows that perform really well is any different from a client wanting well designed plumbing fixtures or high quality finishes.


2.
Wed, 10/27/2010 - 17:27

Internal Insulation
by Pat Murphy

Helpful? -9

Feist notes re air tightness for retrofitting "I think you should do what you can on a reasonable level. We were surprised in Europe to learn that a thing like the airtightness standard was possible in all the projects we have done so far. They all came under 1 ACH at 50 pascals. If you are that tight, of course you need a ventilation system."

And then says "Insulation is a different thing. With some buildings you can do external insulation. But there are lots of buildings where you cannot do external insulation. And internal insulation is much more difficult. You will never reach the Passivhaus standard with internal insulation, because of thermal bridging."

That seems like a bold statement to make. I can think of some ways to insulate to the inside that would minimize thermal bridging. What do you think Martin? There are people who are trying this.


3.
Wed, 10/27/2010 - 18:01

Passivhaus retrofits with interior insulation?
by Martin Holladay, GBA Advisor

Helpful? 1

Pat,
I haven't done it -- nor have I run PHPP on an existing building. So I don't know. But I have no reason to doubt Dr. Feist.

Surely it depends on the climate: in Italy or California, interior insulation may be enough to bring an existing building into compliance with the Passivhaus standard. But certainly in a cold climate, it would be tough to reach Passivhaus performance without insulating the outside of the shell.

If the floors are framed with wood joists, then embedding the ends of the floor joists in insulation puts them in danger of rot, because the ends of the joists are now cold.

If the floors are concrete slabs, the slabs will remain brutal thermal bridges that rob your building of heat.


4.
Wed, 10/27/2010 - 19:01

What is the PassivHaus "standard" now?
by Richard Ugarte

Helpful? 7

I thought the Passivhaus standard was quite simple: if you can meet your heating and cooling loads by heating and cooling only the required ventilation air, as your forced air system, then you have a Passivhaus. It was expected that to accomplish this "standard," you will in all probability need to be below a certain ACH of air tightness and above a certain R-value for the enclosure, but these will vary by location - the standard is the same: fit it in the ventilation requirement of a dedicated outside air system. From what I read, this was claimed as the defining feature that made the Passivhaus standard different from just saying it was a low energy house at an arbitrary level: condition the ventilation air and if that is sufficient for comfort, you have a Passiv house.

Did I misunderstand the standard? Is this no longer the standard? Is Passivhaus just 'really low energy use house' now, one of many? I don't see in the interview that Dr. Feist defines the standard, but simply emphasizes "good performance."


5.
Wed, 10/27/2010 - 20:44

Response to Richard Ugarte
by Martin Holladay, GBA Advisor

Helpful? 0

Richard Ugate,
An outline of the requirements of the Passivhaus standard can be found in my previous blog, Passivhaus For Beginners.

Here are the most important points: To meet the standard, a house needs an infiltration rate no greater than 0.60 AC/H @ 50 Pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 watts per square meter and windows with a maximum U-factor of 0.14.

Although the Passivhaus standard has never required space heat to be delivered through ventilation ductwork, Dr. Feist has muddied the waters considerably by telling many journalists, designers, and builders that Passivhaus buildings must do exactly that. When pressed, the Passivhaus Institut has replied that in fact space heat may be delivered by any means you want -- electric resistance baseboard heaters, gas space heaters, pellet stoves, furnaces, or boilers -- in spite of what Dr. Feist said.


6.
Wed, 10/27/2010 - 23:05

Much appreciated article
by J Chesnut

Helpful? 1

Much appreciated article Martin and Chris.

I think we can all agree on the 5 elements of Passivhaus and I agree with your list of challenges that PH proponents face. I'll look forward to 2011 when regional differences will be addressed. I still don't understand how the 15kWh/m2 was arrived at and if it makes sense for all climates.

One surprise for me was Dr. Feist's remark that when retrofitting old building he puts the priority on insulation before air tightness. This may be the most expedient way to address heat loss but it seems more prudent to tackle the air tightness to avoid moisture concerns in the assembly.

Martin I think your point about economical HVAC packages is worth further debate. I think spending an additional $5K-$10K is worth the reduced energy consumption though I am not as knowledgeable about all the alternatives and their performance comparisons.

Recently a PH standard for retrofits was distributed. I don't have the manual with me but it includes less rigorous ACH and heat energy use standards than the new construction targets. I'm confused why Dr. Feist didn't mention this and in fact this wasn't a good idea to have a separate standard.


7.
Wed, 10/27/2010 - 23:05

Heating systems in passive houses
by Wolfgang Feist

Helpful? 0

Really do not know what is creating such a confusion. The definition never changed - it's a performance standard, it never was different - 15 KWh/m² Heating / 15 cooling, 120 primary energy for residential buildings. And: It was always open which systems to use. Although, there is a motivation to use these figures: the 15 & 15 is such a low requirement, that heating/cooling is no longer a big issue. The compact systems (Martin calls "magic boxes") become possible. I'm still convinced, that this is one of the best and most economic solutions - never claimed it's the only one.


8.
Wed, 10/27/2010 - 23:29

"You Don't Need a Heating System"
by Kevin Dickson, MSME

Helpful? 1

Martin,

You say you haven't seen it, but the H4H NREL house in Arvada proved it with off the shelf equipment, installed, for about $1000. The heating system in that type of house would normally cost $6k.


9.
Thu, 10/28/2010 - 01:13

The challenge of a hot climate
by TJ Elder

Helpful? 0

Wherever a building is located there will be some degree of solar heat gain plus incidental sources of heat from appliances and bodies. In a cold climate these heat sources subtract from the space conditioning energy demand, whereas in a hot climate they add. This simple fact challenges the strategy of achieving very low energy use through superinsulation. In a hot climate the indoor temperature could rise above the outdoor ambient when windows are closed and A/C is not running, reversing the delta-T. Of course with A/C running (and a positive delta-T) the insulation does reduce heat gain through the enclosure. However in hot areas it is necessary to address internal gains, and some will be unavoidable (human activity). For some areas / occupancies it may be impossible to achieve PH energy targets while actively space cooling.


10.
Thu, 10/28/2010 - 01:27

Another unavoidable heat source
by TJ Elder

Helpful? 1

Also on the list of unavoidable and unhelpful sources of heat is lighting, either through windows or artificial. Even with appropriate glazing and efficient lighting design, light = heat. If every watt of light becomes work for the air conditioner, window sizes and locations must be strategic. It could come down to choosing larger windows and leaving them open rather than smaller windows to reduce cooling load.


11.
Thu, 10/28/2010 - 04:48

Response to J Chesnut
by Martin Holladay, GBA Advisor

Helpful? 0

J Chesnut,
I agree with you. I was also surprised at Dr. Feist's retrofit advice: first add insulation, then address airtightness. That is the opposite order from the way that weatherization workers have been approaching buildings in the U.S. for the last 30 years. Here in the U.S., the order of the retrofit work is always: start with airtightness, then address insulation.

The classic problem would be in an attic. If you install lots of insulation in an attic before sealing the ceiling plane, you've made a mistake.


12.
Thu, 10/28/2010 - 05:00

On economical HVAC equipment
by Martin Holladay, GBA Advisor

Helpful? -1

Kevin Dickson and Dr. Feist,
Kevin, the house your are referring to -- the Habitat for Humanity house in Wheat Ridge, Colorado -- does indeed have a very low cost HVAC system. But it's not a Passivhaus building.

It is one of the houses that I was thinking of when I pointed out that the most innovative thinking on low-cost HVAC equipment is coming from builders outside of the Passivhaus community. I'm also a big fan of Carter Scott in Massachusetts, who is heating his houses with ductless minisplit units (one outdoor unit, two indoor units, $5,000 installed cost) and ventilating them with a single Panasonic WhisperGreen fan (11 watts, about $120). Like the Habitat house in Colorado, Carter Scott's homes are not Passivhaus buildings.

Katrin Klingenberg did a good job keeping the equipment costs relatively low for her first house -- except for her HRV, which was imported from Germany at great expense.

Dr. Feist keeps returning to the idea of the "magic box." When I wrote an article on these devices, I tracked down how much they cost. According to Barry Stephens, a Zehnder ComfoBox costs about $18,000 in Europe — not including the ground loop for the ground-source heat pump, which can easily cost $10,000 or more. A magic-box appliance from Drexel und Weiss costs about $25,000 in Austria. So it appears that the Europeans haven't yet figured out how to solve the cost problem yet.

I don't want to beat up the Passivhaus people too much on this issue; I think eventually we'll come to a consensus on this, and designers will find clever ways to address this. Here's my prediction on the consensus:
-- Heating and cooling with a Japanese or Korean ductless minisplit.
-- A very simple ventilation system, with or without heat recovery.

Unfortunately, some of the Passivhaus designers have been led astray by the lure of the best, state-of-the-art European equipment, which is extremely expensive. I was glad to hear Dr. Feist say that it's not necessary to go down that road. We can find our own North American solutions to these problems.


13.
Thu, 10/28/2010 - 05:23

Response to Thomas Jefferson
by Martin Holladay, GBA Advisor

Helpful? -1

Thomas,
You have very clearly explained the great challenges facing designers of hot-climate Passivhaus buildings.

Most hot-climate buildings with a slab-on-grade foundation don't include any insulation under the slab, because ground coupling lowers cooling bills. That's one example of a part of the shell that clearly doesn't benefit from insulation in a hot climate.

The traditional tropical solution to this problem was:
-- Put the house on stilts;
-- Build a massive roof with very wide overhangs for shading;
-- Open the house to any available wind by providing large openings without any glazing.

In other words, you don't want a superinsulated building. Of course, you still have an indoor air temperature which equals your outdoor air temperature. So if it's 100 degrees outside, it's 100 degrees inside.

If you want your interior temperature to be 72, then you need air conditioning, and the design challenges increase tremendously. You've got a refrigerator, a kitchen stove, a water heater, lots of lighting, a television, and several computers. As you point out, all of these internal heat sources help you in Minnesota but hurt you in Phoenix.


14.
Thu, 10/28/2010 - 08:08

air tightness AND insulation
by Wolfgang Feist

Helpful? -1

Have I said insulation "first"? :-) Can't be true, because that has again always been clear from the very beginning and well presented:
- Yes, in most cases insulation is more important than airtightness (with respect to the energy balance). That is why we superinsulate (all adapted to the climate)
- AND: In order to avoid structural damage an exterior component HAS TO BE airtight. Period.

You do that together, that is what we have done (in practize, not just in theory) and it is what we recommend - and that was my statement, you can read it everywhere on passipedia because that is just very simple building physics. Martin, we should not confuse people with respect to this. May be, a controversy (you like controversies?) is a tool to make these topics interesting - so, if that’s your goal, thank you.


15.
Thu, 10/28/2010 - 08:16

Response to Wolfgang Feist
by Martin Holladay, GBA Advisor

Helpful? -9

Dr. Feist,
Thanks for your clarification; I appreciate it.

I stand by the accuracy of my reporting, however.

I think this was a simple misunderstanding. When you said, "If you start with an old building, the first step is always insulation. Then the next step is airtightness," the meaning was, "Most of the heat loss is due to low insulation levels. The second most important heat-loss factor is air leakage."

Again, thanks for clarifying.


16.
Thu, 10/28/2010 - 08:30

air tightness AND insulation
by Wolfgang Feist

Helpful? 1

Good that we agree again - the "first" was never meant to be a timeline order. Our language is sometimes not accurate - but we both know, what the science behind it is.
AND: There might be a difference between Europe and the US - old buildings in the US are sometimes extraordinarily untight (because most Central European constr. is masonry with plaster, these ones "start" with n50 in the range of 3 to 6 ACH - not so bad, but still by far not good enough.


17.
Thu, 10/28/2010 - 11:32

I was a bit surprised by your
by Pat Murphy

Helpful? 0

I was a bit surprised by your comment on the ends of the floor joists getting cold. I had not though of it. There is a pattern here now to close off the vents to avoid moisture and then spray or insulate the joists at the mud sill. Won't this popular technique make the joist ends colder.?

Dr. Feist noted: "Good that we agree again - the "first" was never meant to be a time line order. Our language is sometimes not accurate - but we both know, what the science behind it is" AND "There might be a difference between Europe and the US - old buildings in the US are sometimes extraordinarily untight (because most Central European constr. is masonry with plaster, etc."

There are close to 120 million homes that are going to need retrofitting since I don't think we can replace them with passive homes. It seems very important to figure out how to bring them near the passive performance level. One thing that I am only beginning to understand is how important air tightness is to the structural issue rather than just the air quality issue. I think when we understand more about this, that retrofitting solutions may be discovered.

These dialogs between you and Feist are very valuable. I hope he follows and participates in the thread throughout his visit.

Pat.


18.
Thu, 10/28/2010 - 11:39

Damp joists
by Martin Holladay, GBA Advisor

Helpful? -1

Pat,
The problem with cold joist ends that get damp and rot is most severe with old masonry buildings that have joists that sit in beam pockets. If the building is uninsulated, there's a lot of heat flow through the bricks, and the joists stay dry. Once insulation (especially fibrous insulation like fiberglass batts) is installed on the interior of the building, the ends of the joists are cold.

If indoor air (that is, warm humid air) filters through the fiberglass insulation and contacts the cold masonry beam pocket, you've got rot. That's one example of how interior insulation can take a building without structural problems and turn it into a building with structural problems.


19.
Thu, 10/28/2010 - 11:41

principles vs certifications
by kim shanahan

Helpful? 7

I was heartened to read Dr. Feist believes the principles of the the Passive House have more importance than the certification. With the dominance of ResNet and HERS ratings in our American market, especially as they relate to tax credits and protocols like Energy Star, it will be quite some time before builders switch to Passive House certifications. In the meantime, we have much we can learn and experiment with. Attention to the envelope, sensible design, and energy efficent air-exchanges are clearly the low-hanging fruit. The efficacy of the individual components will come in time, and as Dr. Feist points out, they should come from small and medium sized entrepenuers who devlop their products first and get their certications second.
Great article and great interview.


20.
Thu, 10/28/2010 - 12:09

Response to Dr. Feist
by J Chesnut

Helpful? 1

Thank you for your contributions and clarifications to this discussion.
I lived a couple of years abroad and understand the need to understand each other rather than hold each other to rigidly to the words we use.

I am excited about the availability of a energy modeling tool such as the PHPP that includes the ability to factor passive solar gains into the design. The Passivhaus discussions in the US have been very productive.

To Martin's defense, it isn't a matter of creating controversy around the subject but taking the introduction of the PH standard here seriously and scrutinizing it in order that we who are using it accurately understand it rather than uncritically stand behind the cache of the latest label on the green scene.

PHIUS could use a regular web presence like Martin to elucidate the finer details of the energy modeling capacity of PHPP. I think it is important too to offer the translations of the German DIN references in the PHPP user manual or point to equivalent American standards.

I don't know if the priority should be to make the PHPP easier, but instead to offer support so that users are confident they are using the software 100% correctly.

Thanks again and I welcome the introduction of the PH standard to the US.


21.
Thu, 10/28/2010 - 12:25

Interior Retrofit
by Pat Murphy

Helpful? -1

Thanks for your comment re masonry pockets.

To continue the dialog (or start it) on super-insulating to the interior, I noted that in your Oct 10 commentary on History of Superinsulated Houses in North America you used a graphic from The Super Insulated Retrofit Book so obviously you are familiar with that work. The 30 page chapter entitled Interior Retrofit has a myriad of details re thickening walls to the interior including ways of installing vapor barriers and dealing with the joists. This was a Canadian book which may give it some more credibility. Do you think these are valid approaches? Do you think a room by room retrofit over many years is a possible approach to the existing stock? Are you familiar with Linda Wiggington's Thousand Home Challenge and do you think it has potential?


22.
Thu, 10/28/2010 - 12:28

Response to Kim
by J Chesnut

Helpful? -1

Yes I think we can all agree on the 5 elements of a Passivhaus Martin bullet points in this blog.
Martin blogged recently about the historical debate between superinsulation versus passive solar.
Now that these concepts are married I think the debate will move to 'how fine tooth a comb'.

ResNet and HERS ratings are less sophisticated than the PHPP in terms of accurately modeling the energy use of new construction. The real advance of the PHPP is that it is a design tool that informs the design of a building a the critic stages of schematic design. Leveraging passive solar gains can be optimized and the thermal envelope and mechanical can be fine tuned to achieve even greater levels of energy reduction potential.
The most vocal opponents to PH don't comment on this aspect. They instead point to the air tightness levels, argue the arbitrariness of the standards energy use requirements and warn against overuse of petrochemical insulation.
Its the PHPP that coordinates the 5 elements of Passivhaus into an optimized whole and makes the performance of the whole system more significant then the performance of the components.


23.
Thu, 10/28/2010 - 12:37

More on interior insulation for Pat Murphy
by Martin Holladay, GBA Advisor

Helpful? -10

Pat,
I've already written a blog on this topic for next week, titled, "How Risky is Cold OSB?"

Dr. Feist and I agree that exterior insulation is the best retrofit strategy.

Adding insulation to the interior of a cold-climate house is risky, because you are making your sheathing colder, and therefore raising the risk that your sheathing will be damp. This is especially risky if (1) you don't have a tight interior air barrier, and (2) you have a cladding like stucco that is slow to dry.

There are ways to reduce the risk. These measures include doing your best to create an interior air barrier -- an almost impossible task in a typical existing house -- and adding a ventilated rainscreen gap between the siding and the sheathing.

But if your retrofit work requires replacement of the siding, it obviously makes much more sense to install thick exterior foam, which is far less risky than thickening your walls from on the interior.


24.
Thu, 10/28/2010 - 13:40

I sometimes wonder...
by Katrin Klingenberg

Helpful? 1

Martin,
...after reading your reporting if I actually attended the same event. Not that I question the "accuracy of your reporting". Certainly you are free to put your spin on things, add and omit whatever you feel appropriate. To make it interesting :)

In 2007 our 2nd Annual North American Passive House conference was called "The path of high performance; from the 70s until now". We had invited Harold Orr to be our keynote speaker to present on his early work as well as on his ongoing deep energy retrofit in Regina. Bill Rose presented on the history of the Small Homes Council and the low-Cal house. Opening the conference I quoted William Shurcliff's press release, yes the same one that you keep quoting, I read too and own probably similar books. We then invited you last year to the PH conference to present on the history to repeat that content for those who had previously not been aware of it. If you like to put the spin on things that you educated me, that's fine if it makes you feel better :) You will find that our effort to honor those North American roots and to connect them to the ongoing advances nationally and internationally has been consistent from the beginning of our organization and will again be a topic at the upcoming conference. Your red herring issues are all issues that are documented and researched quite well. They require a more in depth discussion forum and knowledge level. An introductory presentation is aiming at a discussion on a more general level. I am stating the obvious. Maybe you should come to the conference in Portland, where those topics will be discussed in much more depth. You could get some of your questions answered.


25.
Thu, 10/28/2010 - 13:54

Katrin, My apologies
by Martin Holladay, GBA Advisor

Helpful? 1

Katrin,
I am indeed very sorry that I am unable to attend the conference in Portland. It sounds like it will be a great conference.

I'm sorry to have implied that my writings influenced your presentation. I will correct my blog accordingly.


26.
Thu, 10/28/2010 - 14:40

On red herrings
by Martin Holladay, GBA Advisor

Helpful? -12

Katrin,
I agree with you that there is plenty of research and information available on the "red herrings" issues. I do my best to contribute to educating the public about superinsulation and the Passivhaus standard. Like you, my intent is to share accurate information to help educate builders and designers.

However, there is no doubt that confusion remains. As evidence, just look at the question posted on this page by Richard Ugarte. This was Ugarte's misunderstanding: "I thought the Passivhaus standard was quite simple: if you can meet your heating and cooling loads by heating and cooling only the required ventilation air, as your forced air system, then you have a Passivhaus."

Here's another example: as recently as two weeks ago, an editor at Fine Homebuilding magazine -- surely someone who is more in the loop than the average Joe at the local lumber yard -- expressed puzzlement when I mentioned a heating system for a Passivhaus building. He said, "But I thought that Passivhaus buildings don't require a heating system."

My point is, the Passivhaus standard has, in the past, sometimes been presented in ways that have confused builders and designers. Not everyone understands the standard as well as you -- even though, as you correctly point out, these "are all issues that are documented and researched quite well."

I hope we can agree that it's in everyone's interest to present this information to the public. Because after all, we share the same goal: to promote greater adoption of superinsulation techniques in North America.


27.
Thu, 10/28/2010 - 15:15

Agreed
by Katrin Klingenberg

Helpful? 0

Thank you!


28.
Thu, 10/28/2010 - 17:28

From the Passivhaus Primer online:
by Richard Ugarte

Helpful? 10

http://www.passivhaus.org.uk/filelibrary/BRE-PassivHaus-Primer.pdf

"To achieve the PassivHaus standard the energy required for space heating
must not exceed 15 kWh/(m2 a) – this is the overarching requirement."

Now, why this value of 15-15? The Primer says:

"1. The figure of 15kWh/(m2 a) has been arrived at from calculating the
maximum amount of heat that can be delivered using the fresh supply air at
the minimum required ventilation rate."

It seems to spell out that the 15-15 was arrived at, not by an arbitrary performance level, but by asking how much heat or coolth you can deliver with a dedicated outdoor air system (DOAS). The Primer then spells out the limits that the air itself imposes:

"It is limited to 15kWh/(m2 a) for two reasons:

1 The temperature of the fresh incoming air cannot exceed 50°C – if the
fresh air is delivered at a higher temperature than this problems can
occur with the indoor air quality (e.g. burning smells caused from the air
scalding dust within the ductwork).

2 A comfortable indoor temperature (20°C) needs to be achieved in areas
with low ventilation rates – this means that only a certain amount of
heat can be supplied without exceeding the 50°C temperature limit.

Without achieving the PassivHaus space heating requirement of15 kWh/(m2 a) or less, criteria 1 & 2 will not be achieved and thus it is not recommended to try and heat a dwelling using the fresh incoming air."

Then the Primer says how the ACH and insulation requirements simply devolve from this 15-15 requirement:

"Achieving a space heating requirement of 15 kWh/(m2 a) or less means that
the following headline features are specified:

• Super-insulation: opaque U-values must be less than 0.15 W/m2K
• U-values for windows and doors need to be 0.8 W/m2K or less (for both
the frame and glazing). This requires the window frame to incorporate
insulation and triple glazing
• Thermal bridging needs to be minimised, and ideally eliminated
• Airtightness: n50 of 0.6 h-1 @ 50 Pa or less
• Whole house mechanical ventilation with heat recovery (75% efficient or
better, with a low specific fan power)."


29.
Thu, 10/28/2010 - 17:58

On the origins of 15 kWh per square meter
by Martin Holladay, GBA Advisor

Helpful? -1

Richard Ugarte,
You're right -- that's the explanation of the origin of the 15 kWh per square meter requirement. In a sense, it is a historical curiosity, however, and is not central to achieving Passivhaus certification, because the Passivhaus standard does not require a builder to deliver heat through the ventilation system. It's a tale that is of interest to Passivhaus historians, not Passivhaus designers.

As I wrote earlier, you can design a house to deliver heat any way you want. As long as your heating load doesn't exceed 15 kWh per sq. meter per year, you are good to go.

There are many reasons why delivering heat through ventilation ducts is irrational; I have explained them in my blog, A ‘Magic Box’ For Your Passivhaus.

In that blog, I wrote, "Ventilation requires small air flows, while the delivery of space heat and cooling usually requires larger air flows — making the integration of these two functions illogical. In hopes of achieving a particular heat-delivery goal, a magic-box designer can be tempted to solve this technical challenge by overventilating. It makes more sense to optimize ventilation ducts for fresh air delivery without consideration of heating or cooling loads; combining these functions often results in technical compromises. Because of this last point, I predict that the long-touted Passivhaus recommendation to deliver space heat through ventilation ducts will eventually fall by the wayside — if not in Europe, then certainly in North America."


30.
Thu, 10/28/2010 - 19:42

Thanks
by Richard Ugarte

Helpful? -8

Thanks, Martin, that helps me understand things better. You are allowed a minisplit, but your minisplit size is pegged to the ventilation air potential heat/coolth carrying capacity, as a foreign currency might be pegged to the dollar. And you find it illogical to put a fan coil in the ventilation fan where you could have a minisplit instead, and so not combine the functions in one apparatus. What is illogical about a fan coil? Isn't this just a very small (<=0.25 ton) forced air system with a return plenum coming from outside fresh air? Is this inherently illogical? I think I'm missing something you're saying.


31.
Thu, 10/28/2010 - 20:08

On hydronic coils in ventilation ductwork
by Martin Holladay, GBA Advisor

Helpful? 0

Richard,
There's nothing wrong with putting a hydronic coil in your ventilation ductwork. If that works for you, Bless you and Godspeed. It probably means you live in a relatively mild climate, however.

Ultimate Air sells a hydronic coil designed to be installed in your ventilation ductwork. It only produces 8,700 Btu/h at full output -- that isn't much -- and even that output requires 200 cfm of airflow -- way more airflow than is typically used for ventilation. The numbers don't add up.

Most homes are adequately ventilated with about 50 cfm of ventilation air. That a small air flow, so there's a limit to the amount of BTUs that you can add to the air flow with typical water temperatures. If you live in northern Vermont or Minnesota, it's hard to make this system work. If such a heat delivery system results in 16 inches of sub-slab foam, is the investment in the foam logical?

I'm all in favor of any heating system that works. I tend to favor heating systems that are inexpensive to install, long lived, and affordable to operate. "Magic boxes" don't qualify -- yet. Some day they might.


32.
Thu, 10/28/2010 - 22:54

One step better than bath fan ventilation
by Dave Robinson

Helpful? 2

We've been getting our renovations tight enough to need "Ventilation on Purpose" . It's true, a bath fan with a controller would be the cheapest solution ... but not by much. The Panasonic ERV gives 40 cfm and costs about $300. Most importantly it doesn't introduce negative pressures. (This system isn't ducted and introduces fresh air at a single point, requiring the regular duct system to distribute the fresh air.)


33.
Thu, 10/28/2010 - 22:58

15kw Threshold
by Sean Wiens

Helpful? 0

Hi Martin,

It was good meeting you at the BC Building Envelope Council AGM a few weeks back.

Re Passive House, I believe you are being a bit misleading. You cannot choose whatever heat source you want and still hope to achieve the 120 KWh/m²/yr threshold requirement for all electricity demands. The point is, the homes are designed around being ABLE to heat them with nothing more than heating the air circulated by a high efficiency HRV with a small electric element or a brine geo exchange loop or a heat pump. This is not a pipe dream. It has been proven many times over. The rest of the requirements/suggestions just seem to be the best way to meet that requirement in a cost effective manner.

The high efficiency HRV's that meet the 75% rating are already available in N.A. and it is expected that a PH Certified HRV and a PH Certified window will be available within N.A. within the next yr (local BC firm working with window manufacturer to produce certified window units and a HRV manufacturer has already delivered his unit to a testing facility for efficiency certification). It should also be pointed out that it is cheaper to import high efficient triple pane windows from Germany now compared to buy a lot less efficient wood high 'quality' dbl pane windows from N.A.

An HRV is the only way you are going to be able to change the air enough times for hygienic reasons once you have achieved the .6 ACH and yet not pump all your heat outside as would result from any single fan system you try to install. HRV's are pretty standard on new construction in our area, so the added cost for a 'efficient' one is not substantial (<$1000??).

The real issue is that the Passive House is one of the only 'green' models I have studied that tries to reduce energy usage by a substantial factor, instead of just building our normal junk and then putting contraptions on the roof to try and generate heat and power and call it 'Net 0'. Contraptions that costs many 10's of thousands of dollars, often have a limited service life, and often do not provide the performance promised.

Anybody who builds a Passive House will easily meet the requirements of any other 'green' label you wish to throw its way and probably for a lot less money.


34.
Fri, 10/29/2010 - 04:38

State of our industry?
by Thorsten Chlupp

Helpful? -6

I was very enthusiastic about Energystar, LEED and Green build and spend a lot of my time volunteering into these programs and promoting them over the years. There was so much good initially I had seen - and still do but things have become murky over the years and there is so much green washing and political infighting going on today it is simply sad. We are missing the point - and I see the same exact trend happening with the Passiv Haus standard over the last year. There is so much misinformation being produced and so much resistance build up against this standard that I really wonder sometimes...what are we thinking? Can't we just step away from our egos for a second and try at least to look at the big picture? Do we really need to defend - our science is better than your science? I know more than you do - and we are the ones who really invented it all?

Is the Passiv Haus standard the holy grail for us to solve our problem in our building industry - I don't think so. We have a much wider spread of climates and a different culture and industry. Our building codes and regulations have a lot of issues untouched which are highly regulated and mandate in Germany. Passiv Haus can be a tremendous asset for us in regards to building highly efficient homes - but it does not help us with a much bigger problem we are still trying to tackle - unhealthy buildings. A many of common building product are very problematic. How many brand new homes we build today are still very toxic? These are the grassroot problems which led to LEED and Greenbuild - and these are very important problems to solve. Our health is priceless. We need to look at the big picture and if we want to see change we will have to stop working against each other and work together. Share and learn from each other - and not get caught up in questions of "who has the better answers".
And we will need to adapt our market and realize it's potential. Drooling over high efficient magic boxes or windows from Europe and shipping building materials halfway across the world is not the right answer. And in my opinion it is missing the core of what we are trying to do with building high efficient buildings. Conserve energy demand, reduce carbon footprints - build more sustainable.
There isn't anything sustainable about shipping windows from Germany to the States. The embodied energy in transportation costs is something we will never be able to overcome with the more efficient building we are trying to put together. It is tempting - I travel through Germany every year and visit many amazing projects and look at their newest innovative products with envy. But I believe it is crucial that we develop our own markets - in our very own communities. It might not be the easiest and fastest way to get us what we want - but we need to understand the economic importance of money spend in our direct communities and also the sustainability of the overall picture. I was able to work with many of our local vendors to produce what we need for high efficient homes right here in town or at least in state. Our small local window shop is building high efficient tilt turn windows for us now with any glassing we specify. We build our own "R-40 Arctic" entry doors with insulated fiberglass frames, VIP panels, cork laminate which are airtight and have a seven point locks system for the same amount of money it would costs to buy and ship a "Passiv Haus" door from Europe.

And we need to get real about what an efficient building truly is and what can be done with proper planning, design and modern building materials if they are put together carefully. Five years ago I was proud of myself to build high efficient, super insulated "GREEN" homes with the highest energy rating in the State. Today I am amazed to see what is even possible in our extreme cold climate (Fairbanks, AK) and how efficient homes can truly be .. and I humbly learn something new every day and try to keep an open mind. Learning from the Passiv Haus standard and realizing its potential has been a major contribution to what our company is able to do today. Once you grasp the principle there isn't anything really difficult about the standard itself. It gives you benchmarks and tools to work towards and from there on it is just a matter of good design and building practices. Achieving 0.60 n50 is not difficult once you design the air layer and your crucial window and door opening correctly - and you keep a blower door unit and an IR camera in your tool trailer with your chop saw and your nail guns and treat them as what they are - tools to get the job done right. Excessive and unrealistic air tightness? If I pick out one of the improvements in our homes I would never back off from - this may be it. It is the most inexpensive energy measure there is - and it solves so many other issues at the same token. Stop your exfiltration and infiltration and all your wall problems are solved. Ventilation - heat distribution in a controlled environment become so much easier. Not convinced? Build to the Benchmark and see for yourself. Take the time to really learn about the Passiv Haus standard before dismissing it or ranting about it as being excessive and unfeasible. By now there is a lot of good information on the web in English - at everyone's disposal for free with your simple friend Google.

Dr. Feist is here as an ambassador to encourage us to work together and even takes time to answer question here on GBA to help. I am very grateful for his willingness to spend his limited time on the road here to try to bridge the gap of misunderstanding which seems to widen instead of closing. And I don't believe he does so as a sales person - but as an individual who believes at what he is doing and is concerned with the global challenges we as humanity are faced with. From what I have seen and heard from him - as well as Katrin this is their sole motivation and they spend a lot of their personal time to stand up and make a stand. Looking at what is ahead of us in the near future is what keeps me going and motivated every day and what keeps me pushing the envelope from one project to the next. We all can make a difference - one step at a time. And it will take all of us to work together to really brings us forward...Let's build responsible, TC

PS: Martin, Dr. Feist, Katrin & Mike and the PHUIS crew - and so many other unnamed and unknown amazing individuals who contribute every day for all of our benefit - thanks for what you do.


35.
Fri, 10/29/2010 - 05:09

Response to Sean Wiens
by Martin Holladay, GBA Advisor

Helpful? -1

Sean,
You wrote, "You cannot choose whatever heat source you want and still hope to achieve the 120 KWh/m²/yr threshold requirement for all electricity demands." I didn't mean to imply that a Passivhaus designer can ignore the 120 KWh/m²/yr threshold; of course not. All Passivhaus targets must be met, including the 120 KWh/m²/yr target.

That said, I have been assured by Dr. Feist and Katrin Klingenberg that you can use any heating method you want, and any heating distribution method you want, as long as these energy use targets are met.

That's great news about Passivhaus windows -- I look forward to being able to buy these windows here in North America soon.

I'm a fan of HRVs, but I'm also paying close attention to builders experimenting with other clever ways of ventilating homes.


36.
Fri, 10/29/2010 - 05:16

Response to Thorsten Chlupp
by Martin Holladay, GBA Advisor

Helpful? 9

Thorsten,
Thanks very much for your comments; you make many good points.

I was a little lost, however, reading some of your comments -- "There is so much misinformation being produced and so much resistance build up against this standard that I really wonder sometimes." Are you referring to GBA? I hope not. If so, point out the misinformation -- because we are striving for accuracy here and will be happy to correct any misinformation.

"Take the time to really learn about the Passiv Haus standard before dismissing it or ranting about it as being excessive and unfeasible." Who's dismissing and ranting? GBA has focused its spotlight on the Passivhaus standard since this Web site was launched, and we've been promoting air tightness and thick insulation whenever the topics come up.

Like you, I'm grateful to Dr. Feist and Katrin Klingenberg for their work, and was delighted to meet with them in Boston. Their work to encourage the adoption of the Passivhaus standard is inspiring.


37.
Fri, 10/29/2010 - 12:29

CO2 and shipping
by mike eliason

Helpful? 0

"There isn't anything sustainable about shipping windows from Germany to the States. "

as long as you are only making one shipment, and not multiple trips, this is bogus.
the CO2 output of shipping windows from DE to seattle is about 600lbs
(10,465 miles x 0.0887 lbs CO2 per Ton-Mile x 2/3 tons=619 lbs CO2)

getting glass and windows that are significantly more airtight, have a better U-value, SHGC and VT than you can get in the states can easily save this - especially over 20+ years. this also means - especially here in the NW - you can get away with significantly less rigid insulation under slab and on walls. in an 800sf slab, you can save about 300 pounds CO2 for each inch of EPS i can eliminate, thanks to better glass.

you are talking about less than 1% of total CO2 emissions for construction of a new wood house (about 40 tons). that is fairly insignificant by any standard.


38.
Fri, 10/29/2010 - 12:36

Response to Mike Eliason
by Martin Holladay, GBA Advisor

Helpful? -1

Mike,
Are you sure that these European windows really save significant amounts of CO2 compared to Thermotech windows with high-solar-gain triple glazing with two low-e coatings and warm-edge spacers?

In other words, what are you comparing the performance of these European windows to?


39.
Fri, 10/29/2010 - 13:10

windows
by mike eliason

Helpful? -1

martin,
i've run PHPP on 2 projects, and in each case, internorm and optiwin windows w/ glastroesch glazing outperformed thermotech and serious windows fairly considerably, especially on the qualitative front. in both cases, this allowed for less insulation around entire envelope.

for our projects, the glazing has to be just right. thermotech's 322 gain and cardinal's LoE179#2#5 has less VT, and a much lower u-value than the glastroesch. and we don't particularly like Serious because of the color/VT issues. per PHPP, both the thermotech and cardinal glazing calculate to 18% over 4.75kBTU/ft2a. thus we'd would have to beef up wall, slab and/or roof insulation.

that's not the direction we're interested in going, and a lot of people we talk to don't want fiberglass windows. if the CO2 cost of shipping superior windows is about the same CO2 cost of additional insulation, then client is going for the better windows.


40.
Fri, 10/29/2010 - 16:17

I've been curious about this
by Jesse Thompson

Helpful? 9

I've been curious about this shipping question, so I quickly looked up some numbers on the internets. Wikipedia says 510 BTU / short ton mile for domestic water, 3,357 BTU / short ton mile for heavy trucks. These figures are probably incorrect, but that shows the huge efficiency differences between water freight and truck freight.

If we order windows in Portland ME, and they come from Ottawa, Thermotech, Loewen, InLine etc (400 miles away) by truck, that's 1.3 MBTU / short ton (whatever that is).

If we order windows from Germany (3,700 m) that ship to Boston and truck from there (100 m) , that's 2.2 MBTU / short ton. Worse, but not too bad.

If we order windows from Minnesota, Marvin, Anderson, etc (1,400 m) by truck , that's 5.0 MBTU / short ton! We've just jumped an order of magnitude.

Now someone just has to figure out how much energy a short ton of windows saves... Of course, it's a lot longer to go from Germany to Seattle, and they better not put them on a truck in New York.


41.
Sat, 10/30/2010 - 07:15

"State of our Industry?"
by John Brooks

Helpful? -1

I have been reading GBA since day one.
Before that JLC Building Science Forum and before that FHB Breaktime.
I think that Thorsten's recent post is the best post ever.

...what are we thinking? Can't we just step away from our egos for a second and try at least to look at the big picture? Do we really need to defend - our science is better than your science? I know more than you do - and we are the ones who really invented it all?

It is a shame that Thorsten barely posts here because I think he has a lot to share.
Thorsten, I hope you are working to publish more articles.
As winter approaches I hope you will post here more often and try to ignore the "dark side"
I want to hear more about your experiments.

Our industry is in a "Sad State" and we are wasting a lot of time by not working together.


42.
Sun, 10/31/2010 - 17:01

European PH windows
by mike eliason

Helpful? 1

martin/jesse:

took a stab at better numbers on how much EU windows could save. IF shooting for passivhaus, they could save as much as six tons of CO2:
http://bruteforcecollaborative.wordpress.com/2010/10/30/can-european-win...


43.
Sun, 10/31/2010 - 18:42

Window shipping Bogus
by Thorsten Chlupp

Helpful? 0

Embodied energy is something very hard to truly quantify - if it is in manufacturing or transportation. I agree with that my argument may be bogus if you could ship directly from place of origin to your project directly as calculated in Mikes post and blog. If you're working on one pet project a year I also may agree. However, if this is simply becoming the way you build - and you build more than 10 "Passiv Homes" a year the dynamics change. Long lead and shipping times will become a road block on your projects. There will be shipping damages, mishaps on the job, warranty issues to deal with. Someone will need to respond and timing will be of essence. And it quickly becomes not feasible - and not sustainable in my humble opinion at least. If we want to be real about building homes to this standard then we will need to create our own market right here and we will need start now. We can easily manufacture windows of equivalent quality and efficiency in North America. The only reason that they are not being built right now is that there simply was never a demand for them from our industry.
Economics: Being a small Builder we still easily spend 200K on windows per season. That is an insignificant amount for a bigger manufacture but it is a considerable amount of money for a small window shop. And even more important - it is a lot of money being circulated in our community, which is quickly multiplied, creates jobs and opportunities and is after all the basic foundation of economic growth and stability in our neighborhood. I personally at least believe that in these changing economic times focusing on localized growth and investment will be key.
As any good designer of efficient buildings knows windows are the weakest link in your chain and therefor the most single important factor. They have a multitude of functions starting with essential day lighting, comfort and ventilation to the more complex function of providing the only free heat we ever get through solar heat gain if the glassing is appropriate (in a heating climate of course). So yes - it is very, very tempting to order better performing windows from Europe right now...and I struggled with this for some time. In the end I decided for myself that it is more important - and more sustainable to develop our own market which takes time, money and lots of effort but seems to be in the long run the better choice. Being at the end of the road in a very extreme climate might influence this choice maybe different - but at the end of the day I still believe we need to focus on the big picture. And part of this picture should be that any new home we build is at least 80% more energy efficient - everything else is IMO simply "bogus". The first thing we need for this step to take place in North America is - manufacture better windows :-)
FYI - in my 14000 HDD climate it takes a window with a SHGC of 0.68 with U-0.072 to get to the magic Passiv# of 4.75 KBTUs(ft2/yr). - no amount of insulation anywhere else in the assembly can bridge this thermal weak point. One of the reason the Scandinavians bumped up there Passiv Haus numbers for the northern regions to 9.5 kBTUs(ft2/yr). Climate has a huge impact on your numbers - take your PHPP and change your climate to the included set for Yellowknife/Canada to see what I mean. With our current windows I hit 9.18 kBTUs(ft2/yr.), but that is as low as it gets until new glassing technology is developed. Otherwise it takes an R-20 shutter figuring in a 58% utilization factor of the shutter and a window with a high SHGC of min 0.54 - better above 0.60...Being the stubborn German as I am I overcame this hurdle (maybe!) on my latest project with R-20 to R-40 Thermal shutters on all windows. Typing this I can hear Martin already cry out "but they don't work!". Yup, I know it all has been tried before - but I guess some of us just don't listen. After I spend all year modeling and playing around with 4-5 ply glassing configurations to get up to R-14 glassing values I concluded that at today's technology we cannot build windows efficient enough without limiting the one factor which is IMO the most important of them all in a heating climate - the solar heat gain coefficient. I simply don't like to use anything below 60% on south facing windows anymore...free heat just can't be beaten in this day and age where nothing else in life comes for free anymore. And once a window is installed you can't change your SHGC - but you can cheat your U-values with a thermal shutter. That's my theory for now and something which was for me at least worthwhile to explore further. Come spring I will have a more educated opinion and a pile of data and firsthand experience to see if it is a feasible means to higher performance buildings Far North - or a simple dead end. Anyways, enough of my ramblings. TC


44.
Sun, 10/31/2010 - 19:06

Response to Martin
by Thorsten Chlupp

Helpful? -7

Martin, I don't see where I pointed fingers at you or GBA in my post. I thanked you for your contributions at the end. I am sometimes simply frustrated to see our industry go backwards. How you present your information is not up to me and you have to be the judge of your writings and your style. How others read and interpret this information will always vary and be personal. And as long as discussions are constructive and on topic they are very valuable. However at least in my opinion discussion here on GBA often times just turn into personal vendettas and get way out of hand. Something I personally don't need to be part of in my very limited spare time. All of which of course has nothing to do with this particular discussion about your interview with Dr. Feist.


45.
Mon, 11/01/2010 - 05:48

Response to Thorsten
by Martin Holladay, GBA Advisor

Helpful? -1

Thorsten,
Thanks for the clarification, Thorsten. I appreciate it, and I agree.

Your advice that we should all try to work together is very valuable. How to manage a Web-based forum so it is open, inclusive, supportive of free speech, and still avoids the "personal vendettas" you mention is a tricky balancing act; here at GBA, we're still imperfect. We're trying, however.


46.
Mon, 11/01/2010 - 09:02

Thorsten - Shutters?
by Simon Hare

Helpful? -1

Thorsten - Could you share a brief description of your shutter detail? We're developing custom thermal/aesthetic shutters for a project in a "neighborhood design district" in Boston to satisfy both history buffs and us energy geeks. Always eager to read about others' experiences with shutters in cold climates, and especially on cost and construction side of things. (I grew up in the middle east, where thermal shutters are the norm).

Thanks.


47.
Mon, 11/01/2010 - 11:55

Shutters/ windows
by Mark Klein Gimme Shelter

Helpful? 0

Thorsten I look forward to hearing more about your local window initiative, also your shutter report, we have found that nicely finished shutters or insulated shades that work add a lot to our window cost. That reality is one of the things that has pushed us in the direction of more aggressive use of active solar thermal systems.


48.
Mon, 11/01/2010 - 13:31

Local Doors & Windows
by Jesse Thompson

Helpful? -8

This local small door & window manufacturing facility you described, Thorsten, seems to be a big cultural gap between the EU and US, but one that could easily be bridged by innovative small manufacturers. We're far too dependent on the big national companies changing their offerings, but cold climate windows are such a small market in their mind, it's just not happening.

I get the sense there is a world of small scale digital milling machines out there that would enable a smart & small wood based facility to turn out extremely sophisticated windows and doors: http://www.weinig.com/C1256F98005C541E/CurrentBaseLink/W2697LJ3150ALPAEN

This would shift the embodied energy in the direction it needs to go. Glazing would be produced nationally, windows locally. Who wants to start the first one in New England for us?


49.
Mon, 11/01/2010 - 14:03

Response to Jesse
by Martin Holladay, GBA Advisor

Helpful? -2

Jesse,
Then there's the issue of glazing. Mike Eliason wrote, "For our projects, the glazing has to be just right. Thermotech's 322 gain and Cardinal's LoE179#2#5 has less VT, and a much lower U-value than the Glastroesch."

When I've researched the topic, I've gotten conflicting answers. Pinning information down is tricky because window testing standards in Europe differ from those in the U.S. Here's what I want to know: why can't Cardinal and Pilkington produce and sell better glazing to North American manufacturers, so that Thermotech can match the performance achieved by European window manufacturers?


50.
Mon, 11/01/2010 - 14:35

Glazing
by Jesse Thompson

Helpful? 0

Personally, I'd be quite happy if we could purchase a locally made (250 mile radius?) wood window with a thermally broken frame and thicker than 3/4" glazing units with glass from Cardinal and Pilkington.

Glastroesch might be a notch better than US glazings, but it's the good wood frames (better than 0.15 U frame or so) that are the weak link for us, not the glazing.


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