I still think Passive House (PH) is a good idea because it doesn’t need replacing in 30 years
(like the PVs), but I kinda dislike the following…
1. It is hyper-concerned with hitting the heating/cooling loads 4.75 kBTU/(ft²yr)
which is impossible without quite a lot of solar in our climate. (more on solar in a sec)
But then has what I consider relatively easy to hit targets for appliance usage,
and solar hot water. And maybe one should have saved some of their money
on insulation to buy an electric car or a personal vegan chef or something?
You could say that being very strict on heating/cooling makes a lot of sense, because
“what if energy prices double or triple?” Well… the answer is… my energy will not
double or triple in cost. It’s on my roof!!! (PVs) The same essentially goes for anyone.
People will start converting to solar heating rather than pay thru the roof for oil or natural
gas for heating and electricity produced from the same sources.
And at the same time, the prices of solar PV panels keeps coming down.
OK, more on PH…
2. It’s a shame it can only model “passive” solar (more windows on S. Fewer on other orientations).
So it really impacts the design. I personally don’t want to live “inside the heat battery”.
3. It penalizes smaller homes because a small house has more shell per space inside.
So a house that is smaller than another could use less energy overall, but not qualify
4. There is no factoring of number of occupants in the house.
5. The excel files are pretty crazy. Well.. it’s very nice actually that they are transparent, but annoying
5.1. the Imperial Unit pages refer to the SI pages rather than do calculations in Imperial Units.
5.2. there are areas that are in all german with no references to the literature. Maybe
if I were certified I would have access to someone who could give more info.
5.3. I find “bugs” but no official way to report them
6. Diminishing returns. In that… one can maybe get pretty close to PH without much extra money
spent, but to get ALL THE WAY there starts getting ridiculous. So where is the point that you should
stop and use PVs and air-source heat pumps (or active solar heating/cooling) instead. Assume all
the mechanical stuff needs replacing in 30 years. Maybe use BEOpt (ask NREL if you can try it?)
7. You can say that the insulation doesn’t need to be replaced in 30 years, but the PVs do, but
7.1 PVs will be cheaper and better in 30 years when you buy new ones
7.2 The fancier windows WILL need to be replaced!
And from my calculations, the marginal difference in 30 year spending on PV electricity to power extra
heat pumps (superinsulated vs full-on PH) is about the price of the fancier windows vs the very good windows.
So you are maybe just choosing whether to spend money on human ingenuity in the form of
air-source heat pumps and PVs, or fancier windows. Perhaps the more insulation can be justified, but
from what I can tell… one needs to really get into R-113 levels in walls/roof to meet PH without increasing windows
on the S and reducing elsewhere.
Please let me know where there is fuzzy thinking.