Hello everyone,
maybe someone here can give us a good tip, as we are quite uncertain about a ventilation system.
We are planning to build a house (solid construction) according to KfW 70 standards, with underfloor heating, a fireplace, and a solar system. That much is already decided.
We received an offer from Company A for a ventilation system with heat recovery, and the salesperson recommended it to us.
At Company B, the ventilation system is significantly more expensive, and the salesperson told us that since the house is so well insulated, moisture would not be an issue... where would it come from? The rest could be regulated by normal airing anyway.
(I also think he realized that his ventilation system would have blown our budget and now I worry that he advised us against it just for that reason!)
My husband and I are laypersons, but my instinct tells me that the better the house is insulated, the more problems I would have getting rid of moisture and stale air inside the house, right?
After all, a blower door test does show that there is very little air circulation.
Am I completely wrong?
We are a bit torn now, since such a system is not exactly cheap! But is it necessary, or just a nice extra?
Thank you very much for your help!
maybe someone here can give us a good tip, as we are quite uncertain about a ventilation system.
We are planning to build a house (solid construction) according to KfW 70 standards, with underfloor heating, a fireplace, and a solar system. That much is already decided.
We received an offer from Company A for a ventilation system with heat recovery, and the salesperson recommended it to us.
At Company B, the ventilation system is significantly more expensive, and the salesperson told us that since the house is so well insulated, moisture would not be an issue... where would it come from? The rest could be regulated by normal airing anyway.
(I also think he realized that his ventilation system would have blown our budget and now I worry that he advised us against it just for that reason!)
My husband and I are laypersons, but my instinct tells me that the better the house is insulated, the more problems I would have getting rid of moisture and stale air inside the house, right?
After all, a blower door test does show that there is very little air circulation.
Am I completely wrong?
We are a bit torn now, since such a system is not exactly cheap! But is it necessary, or just a nice extra?
Thank you very much for your help!
We also have a KFW70 house. (Although it was not officially certified, it was built to that standard.) It does not have a mechanical ventilation system. There are two of us, both working full time. We ventilate once in the morning and then just live normally throughout the day. The house was empty for 3 years, and we have been living here for 9 months now. So far, there has been no mold. I monitor the humidity levels quite closely. In winter, it was around 40% humidity, and now in the transitional season it is about 60%. I believe as long as this value does not increase further, there is no risk of mold. It seems to be possible to have a KFW70 house without a mechanical ventilation system...
B
BauProjekt1410 May 2014 15:30Just because it is KfW 70 does not mean it was built airtight. From KfW 55 onwards, on-site supervision is mandatory.
Was a blower door test conducted? Were you present?
Was a blower door test conducted? Were you present?
Soroka schrieb:
If you mean me, I suggest you read the headline again... This has nothing to do with completely leaky buildings without blower door tests... whether the insulation was installed according to KFW 70 standard or if the construction is airtight enough are two different matters – here it is specifically about how well the workers carried out their tasks.
Saruss schrieb:
This has nothing to do with completely leaky buildings without a blower door test... whether the insulation was installed according to the KFW 70 standard or whether the building is airtight enough are two different things – here, the focus is especially on how well the construction workers carried out their work. Exactly… (I was also referring to the expression about the two different things)
Soroka schrieb:
..... It therefore seems possible to achieve KFW 70 without mechanical ventilation with heat recovery... That is not just a possibility but a fact. Property developers, general contractors, and mechanical ventilation with heat recovery vendors obviously see it differently. I have been involved in several construction projects without mechanical ventilation with heat recovery. To this day, there has been no mold, even though ventilation does not occur every 2 hours! Strange?
New builds are often occupied hastily and prematurely, without a complete drying of the structure having actually taken place. If this is not ensured, even standard mechanical ventilation with heat recovery won’t help.
Drying the building before occupation can sometimes incur significant kWh costs, but a lot can be done in advance to keep these within limits.
Influence can be exerted already at the construction stage. Why a 1.5 g single-family house is often built so expensively is a mystery to me.
Best regards.
Similar topics