They aren’t “airtight”, that would awful. They are well-insulated and designed to take advantage of passive solar heating and air exchange cooling. The way roofs and windows and orientation on the land is usually done for western homes is just terribly inefficient for capturing and releasing heat in the right ways. Just some thick walls, a bank of windows facing the sunrise ,and some proper roof vents that can be opened when it’s hot is all most passive houses really are.
They literally need to meet airtightness requirements to meet the Passive House standard. It’s tested with a blower door test to check the air exchange rate at a prescribed negative pressure. You may be referring to a loose definition of passive house, instead of the standard, though. Airtightness is not “awful” as you suggested - mechanical ventilation provides fresh air
Yes, they certainly have to meet requirements for air exchange. And if you define “airtightness” as that, then yes, the ones that met that definition met that definition. What they are not is the common definition of airtightness, as in a sealed glass jar, steel can, scuba tank, or submarine, which if you look at the comments here was what was confusing a lot of people. I don’t think anyone was contending that there aren’t tests that these houses have to pass, just that the word airtightness, as understood by laypeople, isn’t an accurate term to describe these homes.
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Airtight isn’t really the best way to describe it. Rather it’s controlled air exchange, this way instead of 1000 tiny leaks all over you have a central controlled means to exchange air.
Passive home typically have ERVs or HRVs (Energy/Heat Recovery Ventilators) to achieve this, they can control the heat/humidity in the air.
Has to be some kind of air exchanger
Here is a schematic I found on the Swedish version of this article: https://upload.wikimedia.org/wikipedia/commons/0/00/Passive_House_scheme_1_multilingual.svg
I suspect not all passive houses are built in this except way though.
The WSJ article has a diagram explaining the air stuff
Do the windows not open? Sounds like a good candidate for “sick building syndrome”.
Most passive houses I’ve seen have windows that open, but they are typically double/triple glazed (depending on climate) and are casement style instead of the more typical (and inefficient) double hung. They also typically feature a ventilation system to manage air movement precisely to prevent the issues you’re concerned about.
According to the article the windows do open.
And of course they do. The building is designed to be well insulated, not to make you comfortable.
If the owner wants to let air in or out, of course they should be allowed to do that.
You never know. A lot of modern buildings (at least in the US) do not have windows that open. It’s a pet peeve of mine. Modern public school buildings are particularly poorly designed in this regard.
As a firefighter, Airtight sounds like a bomb if there’s ever a fire.
If there is a fire in in a air tight room and you close the door and stop the ventilation, wouldn’t the fire die out because of the lack of oxygen?
In an airtight room when there is a fire it consumes the oxygen and becomes ventilation controlled the room gets hotter and hotter and the combustible solids in the room continue to pyrolyze into flammable gasses but can’t burn because there is no oxygen. Then a firefighter opens the door…
There’s actually a vacuum in the room, it sucks fresh air in and all those flammable gasses and smoke ignite and explode.
It’s called a backdraft. It only happens when there is a tightly sealed home/room.
