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
Bulla200011 Feb 2011 10:08Hello, we faced the same issue a few months ago and then decided on a controlled residential ventilation system. While opinions vary, most homeowners today choose a controlled residential ventilation system, as do most energy consultants.
For us, the key point was that with the controlled residential ventilation system, we easily achieved energy standards well below KfW70, just above KfW55. Although this does not offer additional benefits for the KfW subsidy, the lower the energy demand, the better for the electricity bill later on. In addition, our heat pump, an AlphaInnotec fully integrated with the ventilation system (KHZ 60), increases the overall system’s coefficient of performance (COP) significantly through their combined operation.
Moreover, with a controlled residential ventilation system, it remains possible to add external wall insulation later using an External Thermal Insulation Composite System (ETICS). However, that would almost certainly require a controlled residential ventilation system.
The increase in comfort is also not to be underestimated.
For us, the key point was that with the controlled residential ventilation system, we easily achieved energy standards well below KfW70, just above KfW55. Although this does not offer additional benefits for the KfW subsidy, the lower the energy demand, the better for the electricity bill later on. In addition, our heat pump, an AlphaInnotec fully integrated with the ventilation system (KHZ 60), increases the overall system’s coefficient of performance (COP) significantly through their combined operation.
Moreover, with a controlled residential ventilation system, it remains possible to add external wall insulation later using an External Thermal Insulation Composite System (ETICS). However, that would almost certainly require a controlled residential ventilation system.
The increase in comfort is also not to be underestimated.
B
Bauexperte11 Feb 2011 10:21Hello,
You should continue negotiating with this salesperson and remove the others from your list of potential candidates.
Modern houses, built according to the latest technology standards and the requirements of the Renewable Energy Heat Act as well as the Energy Saving Ordinance, are so airtight that regular ventilation is usually not sufficient to remove moisture from the house. Keep in mind—especially if you and your husband both work full-time—when you will actually be able to ventilate.
There are many good ventilation systems available at various price levels; if a central system exceeds your budget, consider decentralized systems. The latter, for example, have the advantage that you don’t need flat ducts running under the ceiling and can selectively control the ventilation in rooms you find necessary, rather than ventilating every single room. Central systems take up significant space in the utility room, so the room should be planned with at least 8 m² (86 sq ft) if such a system is used.
Based on recent blower door test results from our new builds, I see a ventilation system not as a nice-to-have feature but rather as an investment to avoid trouble (such as mold).
Kind regards
Diin schrieb:
We have now received an offer from Company A with a ventilation system featuring heat recovery, and the salesperson also recommended it to us.
You should continue negotiating with this salesperson and remove the others from your list of potential candidates.
Modern houses, built according to the latest technology standards and the requirements of the Renewable Energy Heat Act as well as the Energy Saving Ordinance, are so airtight that regular ventilation is usually not sufficient to remove moisture from the house. Keep in mind—especially if you and your husband both work full-time—when you will actually be able to ventilate.
There are many good ventilation systems available at various price levels; if a central system exceeds your budget, consider decentralized systems. The latter, for example, have the advantage that you don’t need flat ducts running under the ceiling and can selectively control the ventilation in rooms you find necessary, rather than ventilating every single room. Central systems take up significant space in the utility room, so the room should be planned with at least 8 m² (86 sq ft) if such a system is used.
Based on recent blower door test results from our new builds, I see a ventilation system not as a nice-to-have feature but rather as an investment to avoid trouble (such as mold).
Kind regards
Thank you very much for your quick responses!
I’m generally in favor of ventilation systems. That’s why I was so confused about what the salesperson was trying to convince us of.
Of course, he immediately started badmouthing the competitor’s system (Vallox mechanical ventilation with heat recovery 090 SC) and trying to sell his own system (Helios mechanical ventilation with heat recovery) as better.
BUT I’d still rather have the Vallox system than not be able to afford the Helios one, right?
@Bulla I also think the comfort benefit shouldn’t be underestimated, not to mention that mold is the last thing I want in the new house!
The only drawback with provider 1 is that they use lightweight construction for the interior walls on the upper floor, instead of solid walls like provider 2. But I think I could live with that... they’re not going to fall down just from leaning on them.
These decisions are really tough!
I’m generally in favor of ventilation systems. That’s why I was so confused about what the salesperson was trying to convince us of.
Of course, he immediately started badmouthing the competitor’s system (Vallox mechanical ventilation with heat recovery 090 SC) and trying to sell his own system (Helios mechanical ventilation with heat recovery) as better.
BUT I’d still rather have the Vallox system than not be able to afford the Helios one, right?
@Bulla I also think the comfort benefit shouldn’t be underestimated, not to mention that mold is the last thing I want in the new house!
The only drawback with provider 1 is that they use lightweight construction for the interior walls on the upper floor, instead of solid walls like provider 2. But I think I could live with that... they’re not going to fall down just from leaning on them.
These decisions are really tough!
B
Bulla200011 Feb 2011 11:12Our DEURA builds everything entirely with solid construction. No changes were necessary, although we had to accommodate the ventilation ducts here and there, for example, on the ground floor just behind the door. The ventilation system is from Alphainnotec but supplied by Pluggit. You can also roughly estimate the costs with them.
Hello,
Ventilation systems are convenient and comfortable but are neither strictly required nor always absolutely necessary.
It is advisable to have the need evaluated beforehand before investing €4,000 to €7,000!
Modern buildings are relatively airtight, which is reasonable and necessary. However, simple window ventilation may still be sufficient for standard buildings complying with energy-saving regulations or KfW 70 standards, even though the market thrives on fear of mold. In case of doubt, this should be checked.
For buildings with very low heating demand or passive house (PH) standards, it is hardly possible to manage without a mechanical ventilation system with heat recovery. Here, controlled ventilation plays a crucial role.
Best regards.
Diin schrieb:Solar thermal systems are rarely economically viable for single-family houses but can help meet primary energy requirements.
...We are planning to build a solid-built house meeting KfW 70 standards, with underfloor heating, a fireplace, and a solar system. That is already decided.
Diin schrieb:Understandable, since they are selling it.
...
We have now received an offer from Company A for a ventilation system with heat recovery, and the salesperson also recommended it to us.
Ventilation systems are convenient and comfortable but are neither strictly required nor always absolutely necessary.
It is advisable to have the need evaluated beforehand before investing €4,000 to €7,000!
Diin schrieb:
...
My husband and I are laypersons... but my intuition tells me that the better the house is insulated, the harder it will be to remove moisture and stale air from the house, right?
Modern buildings are relatively airtight, which is reasonable and necessary. However, simple window ventilation may still be sufficient for standard buildings complying with energy-saving regulations or KfW 70 standards, even though the market thrives on fear of mold. In case of doubt, this should be checked.
For buildings with very low heating demand or passive house (PH) standards, it is hardly possible to manage without a mechanical ventilation system with heat recovery. Here, controlled ventilation plays a crucial role.
Best regards.
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