I would have thought good ventilation would bring much colder air in from the outside thereby mitigating the benefits of good insulation. How do modern houses deal with this issue or is good ventilation much less important and I expect? (I’m in the UK so we don’t have blown air heating/cooling as standard here)
In: Engineering
Nothing to do with “modern houses”, far more to do with just understanding what we’re doing.
My previous 1930’s UK house had double-brick-wall with a gap between, vent-bricks in staggered positions on both internal and external walls, and it worked perfectly fine. For decades people lived in that house with just a coal/log fire rising up one wall and were perfectly happy.
Then we got people who started sealing up bricks “because they let cold air in”, plasterboarding the entire interior, and so on. Now the house is warm, but full of damp and mould. So then they realise that they have to vent it, so they go to extraordinary lengths to vent it.
My current house is 1960’s. It’s tiny and they put a huge concrete-tile roof on it and pathetic insulation, plus breezeblock exterior walls and then everything else was plasterboarded inside. It wasn’t well designed, because it was originally council (social) housing and was always intended to have shared heating. I know, because the shared heating pipes were still in my loft and you can see where they ran through all three house’s lofts and then down into each house. They ripped them out in the 90’s I think.
What I did with both houses was insulate it, board out the loft, seal the house properly (yes, I know! But there was no ventilation by the time I bought either of them! There were however lots of gaps around windows, lots of open vents for things like tumble dryers, lot of loosely-exiting pipes, big gaps under the doors, and so on) and put in a loft positive pressure vent system (a big fan that slowly blows air down from the loft into the house).
Both houses instantly stopped being damp/mouldy and stay warm even with a constant “draught” from upstairs (you can get heated models that even heat the incoming air, but I don’t think they’re worth it). It’s just not flowing enough to hurt anything, all it’s doing it making sure you have a little fresh air. I still haven’t turned my heating on since February. It’s 20C in my living room, and 13C outside and has been all day. That basically doesn’t change until it drops below about 5C outside.
Ventilation and insulation are not the opposites of each other. You just have to have a balance. If you insulate like mad, it’s actually WORSE because then you HAVE to ventilate. If you ventilate like mad then it’s too cold and you lose all the heat you make. You have to have a balance, like everything else. Just like venting a bathroom – if you vent too much, it’s freezing, if you don’t vent enough the walls get sodden with water every time you have a shower and you end up with damp and other problems.
And the balance is really a tiny pathetic little fan blowing air constantly down from my loft (already warmed slightly by the house) back down into the house, and then sealing my house to make it almost airtight. Or some airbricks that aren’t obstructed. Or the heat recovery systems (but they are expensive and hard to fit yourself) which basically use the heat of “exiting” air to warm up “incoming” air that they put back into the house.
My house is basically always warm except when it’s -5C outside. Then I have to put the heating on (and I only have a tiny electric heater because I really don’t need more than that!). And I don’t have damp, mould, condensation etc. anywhere near what it was when I first moved into either house.
You can’t live in a hermetically sealed box (space stations and space craft have all kinds of moisture problems they have to have special equipment to deal with), and you don’t want to be letting all your heat out. You just need a balance. Which we used to understand in home design, then totally forgot for the sake of aesthetics or doing up and selling houses on quickly, and now we’re re-learning it with some proper tech.
Humans have lived in non-sealed, incompletely insulated dwellings for hundreds of thousands of years. Because they learned that completely sealing yourself in either kills you, makes you less healthy, or doesn’t actually make anything any better (e.g. water dripping off the walls with make you colder than a small draught in one particular part of the house that you can easily avoid).
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