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!
B
Bauexperte23 Oct 2013 01:32Hello,
You have the option to install a central or decentralized ventilation system – you should decide on one of these. Keep in mind that with both options, you will have to accept compromises regarding your likely preferences.
Regards, Bauexperte
kleineelfe schrieb:Isn’t it (almost) a bit too late to consider this now? By the way, I would recommend increasing the ventilation interval frequency to 5 times per day during the first year after moving in.
We are building a KfW 70 house with a timber frame construction and an air source heat pump, without any solar gain [...]
However, we don’t know how to realistically manage the "simple thrice-daily airing." Apart from the temperature drop in winter, we simply don’t have the time. We are both working and don’t want to become slaves to ventilation.
Are there no practical, less demanding alternatives?
You have the option to install a central or decentralized ventilation system – you should decide on one of these. Keep in mind that with both options, you will have to accept compromises regarding your likely preferences.
Regards, Bauexperte
K
kleineelfe23 Oct 2013 01:39It is never too late for something like this.
Why increase to five times air exchange by opening windows briefly, and how is that supposed to be seriously implemented, unless you get up at night to ventilate?
What do you suggest as a decentralized solution?
Why increase to five times air exchange by opening windows briefly, and how is that supposed to be seriously implemented, unless you get up at night to ventilate?
What do you suggest as a decentralized solution?
K
kleineelfe23 Oct 2013 10:10We have already considered both options, but aren’t these significant thermal bridges?
klblb schrieb:
It’s all a matter of trade-offs. Ventilating sharply 5 times a day will also make your house cold, and you will have to reheat a lot of air... Who claims that ventilating sharply 5 times a day is actually necessary? On what measurements are such statements based? Could one ventilation be enough, or are as many as 10 needed? How does an exceptional case (building drying) compare to permanent, normal occupant behavior?
Energy loss is proportional to the actual amount of air exchanged as well as the temperature difference throughout the year down to the heating limit!
With exhaust air only, without heat recovery ventilation, this is an energy loss. How high is it actually (annual balance)?
With central heat recovery ventilation, the supply air flow for each room is indirectly heated centrally, so that, for example, at -14°C (7°F) outdoor temperature, the living room is ventilated with 12 to 15°C (54 to 59°F) instead of -14°C (7°F). This definitely affects the room heating demand. The heat generator is relieved in terms of output!
Who weighs these factors, especially how and according to which standards/criteria?
Best regards.
R
Rowley65123 Oct 2013 13:20Hello, I just want to quickly join the discussion since we are currently facing the same question about whether to install a mechanical ventilation system with heat recovery—yes or no.
Basically, I am against it for the reasons already mentioned several times. In addition, for our building project (KfW 70 standard, hollow brick walls WITHOUT additional external insulation, gas heating plus solar, underfloor heating, and a wood stove in the living room), I believe that disciplined “shock ventilation” (opening windows fully for short periods) is enough to remove moisture from the house. What are your thoughts on this?
Unfortunately, expert opinions differ widely about the necessity of mechanical ventilation to prevent mold growth...
Basically, I am against it for the reasons already mentioned several times. In addition, for our building project (KfW 70 standard, hollow brick walls WITHOUT additional external insulation, gas heating plus solar, underfloor heating, and a wood stove in the living room), I believe that disciplined “shock ventilation” (opening windows fully for short periods) is enough to remove moisture from the house. What are your thoughts on this?
Unfortunately, expert opinions differ widely about the necessity of mechanical ventilation to prevent mold growth...
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