We are planning a new build as an energy-efficient house according to the Energy Saving Ordinance, KfW70 standard. The developer claims that with very good insulation, solar thermal systems, and a condensing boiler, etc., this can be achieved without mechanical ventilation. A new build is sealed quite tightly as verified by a blower door test. The developer says we do not need to worry about moisture problems.
We are also used to regular manual ventilation from living in our old house... However, there the cold, fogged-up window was a reliable indicator...
The additional costs for a ventilation system would be significant...
What do the experts here think? Is it better not to forgo such a system, or does it not matter? I do not want to suffocate at night or discover mold after two years...
We are also used to regular manual ventilation from living in our old house... However, there the cold, fogged-up window was a reliable indicator...
The additional costs for a ventilation system would be significant...
What do the experts here think? Is it better not to forgo such a system, or does it not matter? I do not want to suffocate at night or discover mold after two years...
B
Bulla20001 Sep 2010 11:04I’ll join the discussion here. We have received the first drafts for our planned single-family house. Energy-wise, it is planned as a KfW70 house. It will have an indoor air-source heat pump, underfloor heating, and 36.5 Poroton T10 bricks without additional external insulation.
From what I’ve read here and what my builder confirmed, a heat recovery ventilation system (HRV) is not absolutely necessary—only for KfW55 and passive houses. However, it definitely provides a noticeable increase in comfort. According to the energy savings portal, costs for our house size of 140 m² (1507 ft²), including the basement, range from 3,000 to 5,000 euros, and with this system, the price is already entering five figures. What do you think? Is it worthwhile to include? I believe many things can be retrofitted later, but systems like this are usually difficult and expensive to add afterwards.
How does it stand regarding hygiene? What if mold develops somewhere in the ductwork or poor air quality occurs? What are the maintenance costs and how often does it need servicing? When making the decision, not only the initial expenses but also the ongoing costs matter.
From what I’ve read here and what my builder confirmed, a heat recovery ventilation system (HRV) is not absolutely necessary—only for KfW55 and passive houses. However, it definitely provides a noticeable increase in comfort. According to the energy savings portal, costs for our house size of 140 m² (1507 ft²), including the basement, range from 3,000 to 5,000 euros, and with this system, the price is already entering five figures. What do you think? Is it worthwhile to include? I believe many things can be retrofitted later, but systems like this are usually difficult and expensive to add afterwards.
How does it stand regarding hygiene? What if mold develops somewhere in the ductwork or poor air quality occurs? What are the maintenance costs and how often does it need servicing? When making the decision, not only the initial expenses but also the ongoing costs matter.
B
Bauexperte1 Sep 2010 17:39Hello,
That always depends on the point of view (professional background) of the observer.
As long as a house is built _without_ external thermal insulation composite system (ETICS) – roughly in the range of KfW 85 or 55 standards (beyond that, at least a 3-layer masonry construction must be offered, e.g., 2 layers of aerated concrete masonry with appropriate insulation in between, about 10cm (4 inches), at least in solid construction) – every homeowner can _without_ disadvantage decide against installing an air-to-air heat pump; controlled mechanical ventilation is nothing else. Mold can only develop where the outer wall does not allow for vapor diffusion. Considering construction costs in the range of EUR 3,000 up to unlimited (depending on the size of the house), you can calculate yourself when the payback period begins – regardless of the system’s benefits.
Best regards
Gartenbau schrieb:
In the long post, I can read all sorts of things, especially a lot of polemics. But not your opinion on why the ventilation system would be indispensable. What a pity...
That always depends on the point of view (professional background) of the observer.
As long as a house is built _without_ external thermal insulation composite system (ETICS) – roughly in the range of KfW 85 or 55 standards (beyond that, at least a 3-layer masonry construction must be offered, e.g., 2 layers of aerated concrete masonry with appropriate insulation in between, about 10cm (4 inches), at least in solid construction) – every homeowner can _without_ disadvantage decide against installing an air-to-air heat pump; controlled mechanical ventilation is nothing else. Mold can only develop where the outer wall does not allow for vapor diffusion. Considering construction costs in the range of EUR 3,000 up to unlimited (depending on the size of the house), you can calculate yourself when the payback period begins – regardless of the system’s benefits.
Best regards
Hello,
Well, I would think that over once again.
Regards.
Bauexperte schrieb:
....about the installation of an air-to-air heat pump – nothing else but controlled ventilation – ...
Well, I would think that over once again.
Regards.
B
Bauexperte2 Sep 2010 12:18Hello,
I am confident that you will provide a more detailed explanation.
Kind regards
€uro schrieb:
Well, I would reconsider that
I am confident that you will provide a more detailed explanation.
Kind regards
Well... an air-to-air heat pump is the same as an air-to-water heat pump, except that the heat transfer medium is not water (for example, underfloor heating), but as the name suggests, air.
This can make sense in a passive house with minimal heating demand, combined with an earth tube. However, this has nothing to do with a mechanical ventilation system with heat recovery.
The air-to-air heat pump is a heating system... the mechanical ventilation system ventilates... and ideally includes heat recovery as well as the option for humidification.
This can make sense in a passive house with minimal heating demand, combined with an earth tube. However, this has nothing to do with a mechanical ventilation system with heat recovery.
The air-to-air heat pump is a heating system... the mechanical ventilation system ventilates... and ideally includes heat recovery as well as the option for humidification.
BauLine schrieb:
Well.. an air-to-air heat pump is the same as an air-to-water heat pump.. only with the difference,.. If something is the same, there cannot be a difference!
Bauexperte schrieb:
...I am confident you will explain yourself further. Yes, as BauLine says: a controlled ventilation system ventilates, and a heat pump heats or cools!
Best regards
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