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Sadly it looks like that idea is not that sustainable. A Passivhaus (well, every current Niedrigenergiehaus, actually) is a very complicated matter and comes wi
by choeger 7y ago
Sadly it looks like that idea is not that sustainable. A Passivhaus (well, every current Niedrigenergiehaus, actually) is a very complicated matter and comes with some intrinsic problems:
> Airtight design resulting in draught free construction
That airtight design leads to problems with mold if you have any cold spots. These spots can occur due to construction faults, material faults, or any kind of acquired damage. For instance, you might not even notice that your windows do not shut exactly as they were supposed to after a few years.
In the end, the repair of such a complicated design is again very complicated (especially after a decade or two have passed and technology has again advanced), expensive, and error-prone.
So for me, I'd rather prefer to take an existing, robust and dry building, insulate it somewhat (especially roof and windows) and put in a regenerative heat source (wood, electric) but not to focus too much on the actual energy needed.
- sourcesmith 7y agoThe mechanical ventilation with heat recovery deals with the humidity problem.
- Gibbon1 7y agoWhat if I don't want to live in a plastic box?
- sourcesmith 7y agoWhat plastic box would that be?
- Gibbon1 7y agoAll the closed cell plastic foam needed to meat passive house requirements. A point. All the energy savings disappear the moment you open a window.
- sourcesmith 7y agoI think this has already been addressed by the sibling comment to my question. Insulation does not have to impermeable. Its purpose to prevent the loss of air carrying heat with it, not the transfer of moisture/humidity.
- Gibbon1 7y agoIf it's permeable then water will condense inside it and it will develop mold and deteriorate. That is the fate of all of these passive houses.
- throw0101a 7y agoNot necessarily. Mold grows in certain conditions: food availability, right temperature, water/moisture. Ideally you would want your insulation outside of vapour barrier: * https://www.buildingscience.com/documents/insights/bsi-001-the-perfect-wall https://www.buildingscience.com/documents/insights/bsi-001-t... * https://www.youtube.com/watch?v=rkfAcWpOYAA&t=22m58s https://www.youtube.com/watch?v=rkfAcWpOYAA&t=22m58s * https://www.youtube.com/watch?v=hTwq-qUnr9I https://www.youtube.com/watch?v=hTwq-qUnr9I
- myspy 7y agoBecause we stood in front of the same decisions this year, I can only recommend to use wood not stone as building material. And wood fiber insulation. Building techniques in that area are pretty advanced. (At least I hope so, let's talk about it in twenty years again :D )
- deleted 7y ago[deleted]
- Tomte 7y agoAnd introduces its own mold problem.
- sourcesmith 7y agoFor properly commissioned systems?
- Tomte 7y agoMore important is properly maintained. People tend to forget to change filters. Those are a prime breeding ground for mold, and your central ventilation distributes the spores throughout the house.
- myspy 7y agoThat's why people should change the filter and have a yearly inspection, just like for cars. But the filter is on the ingoing side and not on the outgoing side, so no moisture from the inside can aggregate there. Only the humidity from the outside but we've never had problems with that.
- Tomte 7y ago> But the filter is on the ingoing side Okay. I guess I have been wrong.
- blacksmith_tb 7y agoMy HRV has filters for both inbound and outbound airflow. I do change my filters regularly, but even in the rainy Pacific NW I haven never seen any mold growth on either filter, and I have an RPi logging air quality data with a decent sensor, so I can see my PM2.5 and PM 10 are both near-zero.
- supermatt 7y agoIn the passivhaus definition, air-tight doesn't mean hermetically sealed - it means draft free. They are still breathable (vapour-permeable).
- myspy 7y agoA good way to solve that problem is building a house made of wood which has no diffusion barrier and additionally putting clay on the inner walls. There are a couple of interesting solutions. And the ventilation system takes care of the rest of humidity, especially after taking a shower or when cooking. The price is right too.