this post was submitted on 07 Aug 2023

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TIL about “passive houses,” building that are airtight and require barely any energy to heat or cool (en.m.wikipedia.org)

submitted 1 year ago by [email protected] to c/[email protected]

22 comments fedilink hide all child comments

More info here: https://www.wsj.com/articles/passive-home-design-massachusetts-2c89a18d

all 23 comments

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[–] [email protected] 42 points 1 year ago (1 children)

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.

[–] [email protected] 14 points 1 year ago

Pfft you'll get accepted into journalism school with that attitude

[–] [email protected] 34 points 1 year ago (3 children)

To people who says "they aren't airtight" are not correct. Living in a country where building houses like this is the norm I can say that they are build to be as airtight as possible to keep in humidity and thereby heat inside. What makes them livable and not a humid moldy plastic bag is a well tuned mechanical ventilation system with a heat regeneration system (air cross flow system, really simple actually) that recovers most of the heat. The ventilation system runs 24/7 and keep the air fresh, more fresh than most conventional houses in fact if it's tuned correctly that is. But yes the house is as airtight as posible and they pressure test them to ensure they meet the standards. The biggest issue with it is actually cooling them. We have issues here in summer because no method of removing heat is properly implemented yet. But in winter it's awesome. My heating bill is practically 0.

[–] [email protected] 4 points 1 year ago

I moved into one of these buildings about 1.5 years ago and it's indeed awesome. We also have no gas and tons of solar panels on the roof so last year with the insane energy prices in the whole of Europe I spend €2,83 for all my energy including heating for 8 months, and I'm easily cold so I always have the heating on. The only problem is as you say to get rid of heat in summer, but they opted for smaller windows than is standard so less heat is getting in in the first place. And because of the great insulation you also have pretty much no traffic noise from outside. The only complaint I have is that the mechanical ventilation can get quite loud when it's windy outside, but the benefits are so overwhelming I can't be that bothered by it.

[–] [email protected] 3 points 1 year ago (1 children)

Genuine question: if they're airtight, how do oxygen and CO2 levels remain livable? Spacecraft and submersibles require oxygen supply and CO2 scrubbers to keep occupants alive.

[–] [email protected] 14 points 1 year ago (1 children)

how do oxygen and CO2 levels remain livable?

The ventilation system was explained.

[–] [email protected] 3 points 1 year ago (1 children)

I suppose what trips me up is that my brain sees the concepts of "airtight" and "ventilated" to be in conflict and I am seeking further clarification than what has already been provided.

[–] [email protected] 5 points 1 year ago (1 children)

The idea is that air exchange mostly happens through a heat exchanger, so the air leaving the house warms up the air that is entering the house, for this to actually work all other parts of the place need to be airtight, because otherwise your heat escapes.

[–] [email protected] 2 points 1 year ago (1 children)

I guess this is just a looser interpretation of "airtight" than what I've previously experienced in life. In my experience, "airtight" means "zero exchange of air in or out", but this setup is a controlled process where the only place air exchange occurs is through the heat exchanger. However, from these descriptions, it's not the same sort of "airtight" as what I'm accustomed to. Not trying to say that anyone is incorrect, just that it's different from what's familiar to me and that's why I was confused.

[–] [email protected] 1 points 1 year ago

At least In NL, what you can do for cooling is to have cold water run through your in-floor heating. Brings things down to about 2-3C under ambient, so not perfect by any means, but a lot more pleasant than without it.

Unfortunately it's considered an optional upgrade that you can only really get when buying a newly built home and most people skip it in favour of things like a fancier kitchen.

[–] [email protected] 5 points 1 year ago (2 children)

I live and own a passive house: Feel free to ask questions :)

[–] [email protected] 3 points 1 year ago (1 children)

Can you address any of the intuitive concerns around the air freshness and getting enough O~2~ and removing enough CO~2~ ?

How much is the air exchange process a complex active process that you need to monitor and maintain, or is it pretty basic and "just works"?

[–] [email protected] 1 points 1 year ago

I would say "Pretty basic just works" it was adjusted during construction of the house and as long as you don't do any fundamental changes to ventilation system there is no need to readjust.

[–] [email protected] 0 points 1 year ago (1 children)

Does being airtight mean it's significantly easier to keep out pests (rodents, insects)?
Ever since I'd first heard of airtight houses (and figured I'd fit nets on all the windows) my arachnophobic ass has been fantasising about a spider-free house..

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

In the ventilation system there is filter for the incoming air and I always find some insect in them but they can't get through. I the only way for insects to get in is through the front door, for the garden door I have a net.

[–] [email protected] 2 points 1 year ago

Thanks for the answer, just makes me want an airtight house even more!
Shame I could never even afford a draughty old dump, let alone anything nice, but a girl can dream lol

[–] [email protected] 2 points 1 year ago (2 children)

Do the windows not open? Sounds like a good candidate for “sick building syndrome”.

[–] [email protected] 10 points 1 year ago

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.

[–] [email protected] 8 points 1 year ago (1 children)

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.

[–] [email protected] 3 points 1 year ago

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.

[–] [email protected] 2 points 1 year ago

Just wait until you learn about active houses.

[–] [email protected] 1 points 1 year ago

My house was built like that. There is an air intake in the basement and there are ventilation fans that always run on low in bathrooms on the 1st and second floors. They pick up speed when the light is turned on.