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Henry Gifford

Hi Marc –

I like everything you say here.

I like your proposal to report more than air tightness. Reporting site and primary energy should be standard for any building claiming anything. And, yes, of course it gets reported annually, and the plaque gets attached with removable screws.

I like your push to stop rewarding large homes. Maybe 10 years ago a standard would catch on better if it encouraged adoption in luxury homes, but we are past that time now, even if it was only maybe a good idea then.

A new leed certified building went up a few blocks from me, complete with a Whole Foods, and has PV panels installed vertically, facing North. I’m sure they are a good investment financially, when my April 15th contribution is added in. I suspect this is at least part of why PH does not allow energy to be simply offset by PV, as the financial situation for PV is similar in Europe. At NYC prices, the highest in the US outside of Hawaii, the payback is approximately twice the equipment life for a perfect installation, much longer of course for vertical or North installations. Payback would be much longer at New England’s electricity prices, thus a standard that encouraged PV would simply shift energy bills to my tax bill, away from conservation, which I am not a fan of.

Yes, a superinsulation standard somewhat less than PH has the potential to really, really change how thousands of houses are built very soon, those that are now being built to code minimum, or just a bit better than code minimum. I’m a big fan of a “PassivHaus Light” standard, or whatever can encourage that change now.

Henry Gifford

Andrea Lemon

Very interesting. I'd certainly rather build or purchase a house that met a rigorous local standard rather than a rigorous-but-not-always-relevant international standard. If Passive House New England were certifying houses right now, I'd probably want to go with them, assuming we'd qualify (would we?).

I've read a lot of complaints about the "watering down" of the Passive House standard, and I am sometimes inclined to agree with them. But tailoring the standard to different regions could make the Passive House brand stronger, not weaker, particularly if it addresses issues like overheating and house size.


Great work Marc!

I resonate mostly with the effort to make Passive house a thoughtful tool to enhance lifestyle awareness. To that end I agree with that the follow through (in the form of ongoing reporting) is key and I also agree with Henry re: PV. I feel that the emphasis should be primarily on lowest consumption and that PV - and even solar thermal- should be extra's. Gravy. Highly applauded, but 'also's'.

From working a lot with LEED for Homes I find that if something is easy to achieve simply by purchasing it (like getting a net zero house by purchasing a field of PV but otherwise not reducing consumption)then that is what (my wealthy) clients go for. That mind set does a good deal less to change lifestyle, values and overall consumption of the user then actually having to re-think the size and construction of your house, and thus re-arrange your world view of what it means to live in a house and consume energy and material goods.

If we all want Passive House to be different than/ better than LEED (not that we really even care to compare!) then I feel that lifestyle awareness and on going reporting/ follow through should be the main goals. And each -obviously -go hand in hand.

And the 'thoughtfulness' of this effort is such a no brainer- to do the above , plus to reward the smaller size of house (rather than larger), and to tailor to local climate. I think the bigger question is not should we put this amendment into play but why didn't PH adopt these goals form day one.

Marc Rosenbaum

Henry - thank you for your comments. I know you've thought deeply about how to show that buildings either are or aren't performing.
Andrea - I hope this proposal won't be seen as watering the standard down, but rather re-focusing it on what matters, especially primary energy.
Elizabeth - I've limited the "countable" PV energy to what I estimate is actually used onsite as it is produced. The rest is gravy, as you term it, although I think it does yield a societal as well as an individual benefit. The concern about purchasing the certification by well-heeled clients will go away once you really look at how hard it will be to meet primary energy when it is limited by occupant instead of floor area!

Peter d'Entremont


This is a reasonable and thorough proposal. It addresses the principal shortcomings of the PH standard and sort of raises the bar in terms of thinking about what is appropriate per capita resource intensity. Thank you.

Peter d'Entremont
Knight Associates, Architects

Michael LeBeau


Nice work. I need to study the proposal more carefully but have a few questions for now:

1. Have you run any projects through PHPP both ways and can you share the comparisons? My interest is very cold climate applications.

2. Would a certification program based on such revisions be named in a way to minimize confusion with other efforts called PH?

3. Would you anticipate any flack from PHI for modifying PHPP and presumably distributing the results?

Mike LeBeau

Marc Rosenbaum

Thanks Peter and Mike
1 - The bottom line is you still have to make the primary energy limit. Where you are in Duluth you'd need to make your own adjustments, because heating is going to be a higher percentage of the total energy usage than it is in New England. I'm aiming at removing the focus on the annual heating demand criterion and re-focusing on primary energy because I believe that in New England climates the existing standard is forcing investments in envelope well past the point of investments in, for example, lower hot water energy.
2 - No new name, but rather as an amendment to the existing standard, just as jurisdictions adopt codes with their own amendments.
3 - I don't intend to modify PHPP at all. The current version still calculates what we need, we just change inputs (such as changing 6.6 gpd hot water use to 10 gpd) or we look at different outputs (such as design heat load before internal and solar gains are calculated).

BTW - you might look at the criteria I have proposed, particularly the 30W/sf design heat loss, and decide it isn't low enough for Duluth.

Bob Lemaire

At the recent NESEA conference, Michael Blasnik summed up the state of affairs pretty well with the old adage: “The perfect is the enemy of the good”. IMHO making programs like PH more a function of the problem than a stand alone solution is a step in the right direction. What you lose in one-off efficiency with a more pragmatic standard can be made up in volume if the result is improved affordability. In the end, economics drives all major change. Witness the history of CAFE standards for automobiles.

Right now in New England there is an opportunity to influence the approach to dealing with what is generally considered an unavoidable continued rise in oil prices. You have shown that a decent house can be made much more efficient with a modest investment in existing technologies. I disagree with the disqualification of unsubsidized PV because of the cost-payback equation. The same argument can be made against the incremental cost of most deep energy retrofits. The difference is that both the absolute and relative cost of PVs are trending down while the cost of labor and materials of super-insulation will continue to rise.

Marc Rosenbaum

Bob, thanks for your comment. I'm not sure I understand the sentence about unsubsidized PV. My point in allowing only a portion of the primary energy to be met with PV isn't about payback, it's about having PV cover for a not good house.

Bob Lemaire

Marc, I don't know enough about PH to comment on the merits of PV in accomplishing it's goals. You have a better handle on that. I was referring to the first comment, where the example is abuse of the subsidies. That's a separate problem and I don't think it should disqualify this improving technology from being a reasonable part of the long term solution.

Michael LeBeau

Without taking this too far off topic I want to weigh in on the PV issue a bit. Rebate programs in general are a pain in the ass and the pv ones are no exception. They have done almost as much harm to the industry as they have done good. However, that has nothing to do with the technology itself and what it has to offer to the built environment and to society. There is no other energy generating technology I know of that offers such an elegant, durable and clean end result. To diss it simply because of the bad handling of a few programs and various specific stupid applications is just the result of not looking close enough to understand the potential. We would do well if we invested some of our remaining fossil resources in building out a backbone of distributed energy that will keep paying back for several decades. This technology fits in perfectly with the concept of long lasting super efficient buildings.

Tom Bassett-Dilley

Hi Marc,
It's great to see this concrete proposal--thank you for putting it out there! I've got a question that's been bugging me about PE, and your proposal puts it in perspective. If a particular region has a low PE value (say they have a lot of wind or hydro power), might their buildings might have much poorer envelopes than, say, ours in Chicago where PE factor is high? I don't have a sense of how your DHD limit translates (in addition to the PE value), but that seems to be the logic of AHD in addition to PE.

Regarding house size, this makes a lot of sense to me--I suspect the variation in dwelling size in Europe is less varied (and on average much smaller) than ours, making it a more "American" problem.

Marc Rosenbaum

Tom -
Thanks for your comments. I don't think that the primary energy factor for grid energy is going to affect the envelope much, because the design heating load criterion I advocate is tough. It's a great discussion about whether regions with better or worse grid PE factors should be aiming at the same or different total primary energy consumption limits. I don't have an opinion as yet.


Interesting proposal. Not sure I like the concept of local revisions calling it Passive House but the concepts are great.

Might want to add some language for non-residential use such as schools, offices, etc. I know that the energy budget per workstation at NREL in 65W. Maybe 40W per person per occupied hour for offices and 30W per person per occupied hour for schools?

I've considered building a tiny-house passive house and ran into wall thickness issues - these changes would "fix" that problem as well.

Marc Rosenbaum

Because the US is so large, we need local revisions. It's analogous to European countries like Sweden adapting the PH std - and even Sweden, as I understand it, has two climate zones and two house sizes, with altered criteria for each.

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