Passivhaus comments and observations

We are nearly done with our house construction and basically done with any of the details which will affect the results of our house’s “performance” and results of our analysis using PHPP. (PHPP is the software… a gigantic excel file… used to help design and analyze the expected energy use of a planned or existing house.)

So a few comments about passive house / passivhaus.

There are some people who think the passivhaus requirements are too difficult for new england, the upper midwest, and maybe pheonix I’ve heard (on the heating end of the sprectrum). But I personally disagree. If people want to live in extreme environments, then I see no reason why they should be let off the hook.

What I would say, is that it really is quite reasonable to take an 80% or 90% approach. Well, or 50% is good too! In other words, if one can get to within 90% of a passivhaus, then gosh, that is quite an amazing house you’ve got there. Getting all the way there is trickier in harsh climates. That said, I think it is a valid complaint that there are a number of very low cost things which people can do when building or renovating a house that people just don’t do and also that one can think “I’m going to do some PH things, but not all” and think you are going to get very close (let’s say 80% there) but in reality… you are only 40% there if one ran the numbers in PHPP and monitored the actual usage. So that’s a shame too. Valid point.

And also in the US … it’s harder (more expensive) to get the HRV/ERV and windows one needs. I say that, but perhaps it’s not so bad. Maybe the high VAT (sales tax) in many European countries means that effective prices aren’t THAT much higher here for a fancy window imported from Germany for example.

However, I still wish we could do things more locally.

I guess what I’m saying is… I think there is a place for:

1. People going all out and meeting PH with imported products and maybe some non-typical building products or techniques (this helps informs builders and future custom home or renovators to what is possible) . We need people to push on the edge of what people have done before so we can learn.

2. Sticking to only what is in a typical budget but nailing all the “low hanging fruit” — the cheap stuff. It’s a no brainer and not expensive to build a tight house and one with 2-3 times more insulation (using dense packed cellulose). And there are some quite good and not that expensive triple pane windows out there (like Paradigm in ME).

3. Somewhere in between… using PHPP to analyze, and monitor the house, but don’t go all the way with imported products. This is still great because it helps to validate the PHPP software as a accurate model of “reality”.

Related:

4. The usage of a house matters a LOT. If you aren’t careful with electricity usage and hot water usage… it’s been found that people can easily use 2 or 3 times much as another similarly sized family (I’m pretty sure I’ve seen analysis of this with comparably built homes and family sizes at cohousing developments.)

5. I think of PVs (solar electric panels) as an offset. Especially if you have net-metering, it shouldn’t really impact one’s choice of how to heat the house or hot water. IOW, prices being equal… it’s not really any better to use a air-source heat pump that 98% efficient propane hot water heater for heat. That’s based on average utility company mix of using mostly fossil fuels. If you have hydro or a “green up” option on your bill, I think the balance tips to the heat pump approach.

6. Holistic thinking… OK, so nice house. Do you eat meat? What MPG does your car get and how many miles do you drive? These things matter a lot too. Especially relative to a house operating very efficiently. A vegan driving a Prius (or living in the city and walking) maybe has a smaller carbon footprint more than someone living in a small passivhaus. I don’t know! But it’s not too hard to run the numbers. Gary Reysa at builditsolar.com does this. See his “half” project. Marc Rosenabaum at energysmiths.com does this if you are designing a house or cohousing community or fixing up an office building or dormitory, etc.
If I buy a lot of stuff and fly in airplanes a lot, my passivhaus doesn’t matter so much any more.

7. Related to #5 above… I also think “Zero Energy Homes” are cool too. I mean, zero is better than not zero. A passivhaus can more easily become a zero energy home because there is less usage to offset with PVs. And not everyone has a sunny climate or a sunny lot. And insulation doesn’t break or wear out (if you build it right). Whereas solar electric panels (PVs) do.

8. Burning wood is good. Solar is better obviously, but come on… wood is very good too. So is a greasecar (modification to run any clean TDI diesel using used vegetable oil). Not as cool as a hybrid, but in the end, who is using more fossil fuel? The hybrid!

9. I’ve said this elsewhere, but we are right about at the point that without even factoring in tax credits, etc… a grid-connected solar electric system on a sunny roof is cheaper than paying electricity bills. Prices have come down quite a bit. At least in MA with net metering and high electricity prices.

10. If it’s energy independence that you care about most, improve your car first (or if you have oil heat). Coal etc is not primarily coming from other countries.

If you like math, you can compare all these things! It’s all just BTUs and KWhs and some arithmetic and adding things up! PHPP is really just an incredibly detailed version of this same thing (for just the house).

So let’s all get to 80%! That’s way better than a few going all the way and everyone else feeling put off or excluded because it’s too expensive.

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