Love this. So great to see others picking up the comfort conversation, running with it, and taking it even further. “Are we comfortable with the standard of buildings we’re designing & constructing, and the contribution they make to climate change?” is a great question.
We've been saying and teaching this for >40 years in the superinsulated buildings sector. Sell comfort, durability, health and safety, and resource efficiency has to follow. That ad campaign looks great!
Note that, at least in the cool humid climates like mine in new England, these buildings shift from heating dominated to cooling dominated. My opinion is that the German PH software hasn't kept up with this - I saw a presentation of a skyscraper in Boston with about 20 stories of PH offices - where the German PH analysis showed a cooling load of 2,700 sf per ton (14W/m2). I asked the PH presenter how their mechanical engineer felt about this (unattainable) load, and the response was, oh, he does his own loads.
I would suggest that the US PH standard is more realistic about cooling than the German one, and it should be used in the US. Full disclosure - I went to Europe in 2000 to view Passive Houses and other leading edge buildings, and returned to become one of the first certified PH consultants in the US. I was a Founding Board Member of PHIUS. My concern is that Passive Houses really deliver their promise across all scales and building types, and it seems pretty obvious in a country the size of the US that the hugely varying climates require varying criteria, which PHIUS incorporates.
Finally - early adopters of PH in the US were often 5,000 sf luxury homes, which even at PH standards used more resources than a code-built 1,400 sf ranch. One of the things I advocated for PHIUS as it separated from PHI was to convert the Primary Energy Criterion from a per unit area to a per occupant metric. This happened, and now smaller, more densely occupied buildings are favored rather than penalized. Lloyd, you should appreciate this! I also advocated to change th3 air tightness criterion from Air Changes Per Hour, which again favors larger buildings, to Air Flow Per Unit Area of Thermal Enclosure, which normalizes infiltration across all building sizes, Tiny Houses to Walmarts.
I didn’t know that PHIUS did a per occupant metric, I have been complaining about this forever as a serious problem. I will have to look at this right now!
I am embarrassed, when I spoke recently at the Passivhaus conference in Innsbruck I included a call for looking at this for PHI, not knowing that it was already being done in PHIUS.
Early on, when I became involved with PH, I had many discussions with Katrin Klingenberg, who brought PH to North America, about what I felt were critical deficiencies in the PHI approach.
1) One size fits all metric across all climate zones. I heard Dr. Feist state that the PH standard was the economic optimum anywhere in the world. That's absurd for any number of reasons.
2) Penalizing smaller and more densely occupied buildings by basing everything on unit area (and a freakin' arcane way to calculate that :-) and by setting the air tightness standard based on ACH50 instead of CFM50/sf of thermal enclosure.
3) Not incorporating solar electric production, which led to a serious over-investment in insulation vs. renewables.
When PHI and PHIUS separated, PHIUS set about rectifying these issues and I am pleased to say adopted versions of everything I had advocated for. There are still stalwarts of the German standard in the US, mostly where it's easier to achieve - warm dry climates like CA and in quite large buildings, as noted in my comment about the Boston skyscraper. Architects and engineers are now wrestling with a new energy code in MA where I live, where unrealistic energy demand targets for large buildings (>20,000 sf) have been set by a US consultant using the German standard. At last week's Westford Symposium on Building Science a presenter showed a school in design with really excellent specs that couldn't meet the code heating requirement. I was the performance and systems consultant on the Kern Center at Hampshire College, the seventeenth certified Living Building Challenge project worldwide. The architect for that proven net zero building, superinsulated, very airtight, told me he'd run it through the new code metrics and thought it wouldn't meet code.
So there are very clear differences between the two standards. Lloyd, maybe you could interview Kat Klingenberg for a future blog post? I'm excited with the progress they've made in many areas, especially in affordable multifamily projects.
I can fully confirm these results: We are comfortable living in a passive house for 33 years now - in winter (it can get quite cold outside here) as well as during summer heat waves (like the one we are currently experiencing): The indoor climate is always in the ISO7730-A rating - and that does NOT require much energy (electricity). At the moment: 150 watts of electrical power for a 156 m² apartment with 3 people; this can be easily covered by the PV system; and it's still less than the electricity consumption of other household appliances such as refrigerator, computer, dishwasher, ...
Great column, Lloyd. Thanks so much! Passive House is not only an effective Comfort and Efficiency standard but also a Hygiene and Electrification standard too. We'll be elaborating on all that moving forward. The international Passive House Standard has proven itself effective globally and we look forward to building capacity so everyone can enjoy its many fundamental benefits. Cheers!
This succinct article neatly spotlights most of the topics I cover in a new class on health & resiliency in clean-energy homes. Including the same references to our esteemed Bean & Bailes. Comforting affirmation!
(Clean-energy is the current generic term I'm using as it seems to resonate with homeowners as meaning efficient and beyond. & no mention of bodybuilding, I only thought of that today : ) Hello Marc!
Passive House is great. But I have two issues with Passive House. It's costly to get certified. And in order to meet the standard, sometimes you need to add something expensive with marginal benefit. Here's an example:
Ten years ago, we were in the design process for a new house. Someone close by was in the same situation. We opted for a "Pretty Good House." She opted for PH certification. So we put 4"/100mm of recycled XPS foam under the slab. She put 14"/350 mm of virgin foam under her slab because she needed the extra insulation to meet the standard. I doubt her house is any more comfortable than our house.
Lloyd's emphasis on comfort is important. Windows obviously require a tradeoff between comfort/efficiency and the need we all have to see the outdoors. The most common efficiency code in the US is a version of the International Energy Conservation Code (IECC). From the 2015 code and newer, windows in most of the US must be U .30 or better. But in a very cold climate, that's not good enough to allow someone to sit near a window on a very cold day. Using PH level windows, at U .15 or better, will result in comfort which is hard to measure, but really noticeable. I can sit in a T shirt a few feet from our triple pane, PH certified windows when it's minus 20°C and be quite comfortable.
Another important benefit to PH, certified or not, is the required level of airtightness. Not only is heat loss minimized, but a tight house with good windows is quiet. The IECC requires airtightness at 3ach50 or better. PH requires .6 ach50. Both standards require mechanical ventilation. But the PH level means significantly better efficiency.
I believe that the foam under slab thing has been resolved; people kept turning that dial to compensate for not hitting the numbers elsewhere. I would have to defer to a PHPP pro on this one
Partially resolved by varying the targets by climate. We were seeing a foot of foam beneath huge slab areas here in the Northeast. One example was a one story 10,000 sf school. I asked the architect if he'd modeled the benefits of the additional 8 inches of foam (80,000 board feet) vs. the same investment in solar electricity. He sheepishly admitted he needed the 12 inches to meet the heating standard. Note that a great deal of work had been done in North America around heat loss to the ground prior to this. It's pretty clear that in the middle of a 10,000 sf floor plate that extra foam isn't doing very much!
Love this. So great to see others picking up the comfort conversation, running with it, and taking it even further. “Are we comfortable with the standard of buildings we’re designing & constructing, and the contribution they make to climate change?” is a great question.
We've been saying and teaching this for >40 years in the superinsulated buildings sector. Sell comfort, durability, health and safety, and resource efficiency has to follow. That ad campaign looks great!
Note that, at least in the cool humid climates like mine in new England, these buildings shift from heating dominated to cooling dominated. My opinion is that the German PH software hasn't kept up with this - I saw a presentation of a skyscraper in Boston with about 20 stories of PH offices - where the German PH analysis showed a cooling load of 2,700 sf per ton (14W/m2). I asked the PH presenter how their mechanical engineer felt about this (unattainable) load, and the response was, oh, he does his own loads.
I would suggest that the US PH standard is more realistic about cooling than the German one, and it should be used in the US. Full disclosure - I went to Europe in 2000 to view Passive Houses and other leading edge buildings, and returned to become one of the first certified PH consultants in the US. I was a Founding Board Member of PHIUS. My concern is that Passive Houses really deliver their promise across all scales and building types, and it seems pretty obvious in a country the size of the US that the hugely varying climates require varying criteria, which PHIUS incorporates.
Finally - early adopters of PH in the US were often 5,000 sf luxury homes, which even at PH standards used more resources than a code-built 1,400 sf ranch. One of the things I advocated for PHIUS as it separated from PHI was to convert the Primary Energy Criterion from a per unit area to a per occupant metric. This happened, and now smaller, more densely occupied buildings are favored rather than penalized. Lloyd, you should appreciate this! I also advocated to change th3 air tightness criterion from Air Changes Per Hour, which again favors larger buildings, to Air Flow Per Unit Area of Thermal Enclosure, which normalizes infiltration across all building sizes, Tiny Houses to Walmarts.
I didn’t know that PHIUS did a per occupant metric, I have been complaining about this forever as a serious problem. I will have to look at this right now!
I am embarrassed, when I spoke recently at the Passivhaus conference in Innsbruck I included a call for looking at this for PHI, not knowing that it was already being done in PHIUS.
Early on, when I became involved with PH, I had many discussions with Katrin Klingenberg, who brought PH to North America, about what I felt were critical deficiencies in the PHI approach.
1) One size fits all metric across all climate zones. I heard Dr. Feist state that the PH standard was the economic optimum anywhere in the world. That's absurd for any number of reasons.
2) Penalizing smaller and more densely occupied buildings by basing everything on unit area (and a freakin' arcane way to calculate that :-) and by setting the air tightness standard based on ACH50 instead of CFM50/sf of thermal enclosure.
3) Not incorporating solar electric production, which led to a serious over-investment in insulation vs. renewables.
When PHI and PHIUS separated, PHIUS set about rectifying these issues and I am pleased to say adopted versions of everything I had advocated for. There are still stalwarts of the German standard in the US, mostly where it's easier to achieve - warm dry climates like CA and in quite large buildings, as noted in my comment about the Boston skyscraper. Architects and engineers are now wrestling with a new energy code in MA where I live, where unrealistic energy demand targets for large buildings (>20,000 sf) have been set by a US consultant using the German standard. At last week's Westford Symposium on Building Science a presenter showed a school in design with really excellent specs that couldn't meet the code heating requirement. I was the performance and systems consultant on the Kern Center at Hampshire College, the seventeenth certified Living Building Challenge project worldwide. The architect for that proven net zero building, superinsulated, very airtight, told me he'd run it through the new code metrics and thought it wouldn't meet code.
So there are very clear differences between the two standards. Lloyd, maybe you could interview Kat Klingenberg for a future blog post? I'm excited with the progress they've made in many areas, especially in affordable multifamily projects.
I can fully confirm these results: We are comfortable living in a passive house for 33 years now - in winter (it can get quite cold outside here) as well as during summer heat waves (like the one we are currently experiencing): The indoor climate is always in the ISO7730-A rating - and that does NOT require much energy (electricity). At the moment: 150 watts of electrical power for a 156 m² apartment with 3 people; this can be easily covered by the PV system; and it's still less than the electricity consumption of other household appliances such as refrigerator, computer, dishwasher, ...
Great column, Lloyd. Thanks so much! Passive House is not only an effective Comfort and Efficiency standard but also a Hygiene and Electrification standard too. We'll be elaborating on all that moving forward. The international Passive House Standard has proven itself effective globally and we look forward to building capacity so everyone can enjoy its many fundamental benefits. Cheers!
Nice article. I am definitely stealing this! : - )
Let's talk about building & body science!
No, not bodybuilding. Yep, building & body.
This succinct article neatly spotlights most of the topics I cover in a new class on health & resiliency in clean-energy homes. Including the same references to our esteemed Bean & Bailes. Comforting affirmation!
(Clean-energy is the current generic term I'm using as it seems to resonate with homeowners as meaning efficient and beyond. & no mention of bodybuilding, I only thought of that today : ) Hello Marc!
and I like clean energy as a term!
I am working on my next book and right now am in the middle of the health section! Much more to come. I wrote a bit about it here https://lloydalter.substack.com/p/how-the-built-environment-enhances
Yes I read that post (& watched your video w/ Tye) & was VERY inspired by Tye!
Passive House is great. But I have two issues with Passive House. It's costly to get certified. And in order to meet the standard, sometimes you need to add something expensive with marginal benefit. Here's an example:
Ten years ago, we were in the design process for a new house. Someone close by was in the same situation. We opted for a "Pretty Good House." She opted for PH certification. So we put 4"/100mm of recycled XPS foam under the slab. She put 14"/350 mm of virgin foam under her slab because she needed the extra insulation to meet the standard. I doubt her house is any more comfortable than our house.
Lloyd's emphasis on comfort is important. Windows obviously require a tradeoff between comfort/efficiency and the need we all have to see the outdoors. The most common efficiency code in the US is a version of the International Energy Conservation Code (IECC). From the 2015 code and newer, windows in most of the US must be U .30 or better. But in a very cold climate, that's not good enough to allow someone to sit near a window on a very cold day. Using PH level windows, at U .15 or better, will result in comfort which is hard to measure, but really noticeable. I can sit in a T shirt a few feet from our triple pane, PH certified windows when it's minus 20°C and be quite comfortable.
Another important benefit to PH, certified or not, is the required level of airtightness. Not only is heat loss minimized, but a tight house with good windows is quiet. The IECC requires airtightness at 3ach50 or better. PH requires .6 ach50. Both standards require mechanical ventilation. But the PH level means significantly better efficiency.
I believe that the foam under slab thing has been resolved; people kept turning that dial to compensate for not hitting the numbers elsewhere. I would have to defer to a PHPP pro on this one
Partially resolved by varying the targets by climate. We were seeing a foot of foam beneath huge slab areas here in the Northeast. One example was a one story 10,000 sf school. I asked the architect if he'd modeled the benefits of the additional 8 inches of foam (80,000 board feet) vs. the same investment in solar electricity. He sheepishly admitted he needed the 12 inches to meet the heating standard. Note that a great deal of work had been done in North America around heat loss to the ground prior to this. It's pretty clear that in the middle of a 10,000 sf floor plate that extra foam isn't doing very much!
Note that PHIUS is not relying on PHPP, it uses a version of a more robust analytical tool called WUFI by the Fraunhofer Institute.