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Goldbeere26 Nov 2010 22:20Hello everyone!
I have been reading and researching online and in this forum for a long time now, but unfortunately, I’m still not much wiser when it comes to mechanical ventilation with heat recovery.
My partner and I are planning a single-family house (160 m² (1,722 ft²)) with gas and solar energy, built to the KfW-70 standard. Now we are wondering whether we should install a ventilation system.
Friends of ours have a decentralized ventilation system in their new build and are very happy with it—they can’t imagine living without it anymore.
However, in various forums, people often say that for new builds, a centralized system is better. The whole ducting, with maintenance and the potential for germs, gives me a weird feeling... I would constantly wonder what’s actually in the air inside my home. Is that a misguided concern?
And is the decentralized ventilation really that much worse than the centralized system? You hear that a lot.
What kind of costs should we roughly expect for a ventilation system? Is it true that centralized and decentralized systems cost about the same?
Thank you very much for all your advice!
Goldbeere
I have been reading and researching online and in this forum for a long time now, but unfortunately, I’m still not much wiser when it comes to mechanical ventilation with heat recovery.
My partner and I are planning a single-family house (160 m² (1,722 ft²)) with gas and solar energy, built to the KfW-70 standard. Now we are wondering whether we should install a ventilation system.
Friends of ours have a decentralized ventilation system in their new build and are very happy with it—they can’t imagine living without it anymore.
However, in various forums, people often say that for new builds, a centralized system is better. The whole ducting, with maintenance and the potential for germs, gives me a weird feeling... I would constantly wonder what’s actually in the air inside my home. Is that a misguided concern?
And is the decentralized ventilation really that much worse than the centralized system? You hear that a lot.
What kind of costs should we roughly expect for a ventilation system? Is it true that centralized and decentralized systems cost about the same?
Thank you very much for all your advice!
Goldbeere
B
Bauexperte28 Nov 2010 12:15Hello Goldbeere,
Basically, a residential ventilation system is recommended whenever the masonry construction does not allow for natural air exchange; for example, a single-family home built with external thermal insulation composite system (ETICS) => mold growth. Or when both occupants work regulated hours during the day; especially at the time when the house is newly handed over, controlled ventilation is essential and should be given top priority, regardless of the building system.
There is a distinction between:
Central systems, which have a remote installation location and operate almost silently. They have two outlets and two inlets (exhaust air is expelled outside, fresh outdoor air is supplied from outside, stale air is extracted from the living spaces, and fresh supply air is fed into the rooms). Central systems are more complex because the ventilation ducts must run from the living spaces to the central unit.
Decentralized systems (especially suitable for retrofitting) usually serve only one room each.
The installation costs of central systems are higher than those of room-based ventilation. Controlled residential ventilation with heat recovery is generally not economically justified. The debate about bacterial contamination varies and, in my opinion, is often due to a lack of understanding of new technology. As long as the manufacturer’s recommended maintenance intervals are followed, in my experience there are no problems.
Best regards
Goldbeere schrieb:
…In various forums, you often read: if it’s a new build, then a central ventilation system. However, all the ductwork along with maintenance and possible bacteria gives me an uneasy feeling... I would always wonder what might be in my air... Is that the wrong way to think about it?... Central or decentralized is supposed to cost about the same??!
Basically, a residential ventilation system is recommended whenever the masonry construction does not allow for natural air exchange; for example, a single-family home built with external thermal insulation composite system (ETICS) => mold growth. Or when both occupants work regulated hours during the day; especially at the time when the house is newly handed over, controlled ventilation is essential and should be given top priority, regardless of the building system.
There is a distinction between:
Central systems, which have a remote installation location and operate almost silently. They have two outlets and two inlets (exhaust air is expelled outside, fresh outdoor air is supplied from outside, stale air is extracted from the living spaces, and fresh supply air is fed into the rooms). Central systems are more complex because the ventilation ducts must run from the living spaces to the central unit.
Decentralized systems (especially suitable for retrofitting) usually serve only one room each.
The installation costs of central systems are higher than those of room-based ventilation. Controlled residential ventilation with heat recovery is generally not economically justified. The debate about bacterial contamination varies and, in my opinion, is often due to a lack of understanding of new technology. As long as the manufacturer’s recommended maintenance intervals are followed, in my experience there are no problems.
Best regards
Hello Goldbeere
A mechanical ventilation with heat recovery definitely has its advantages, and those who have one are usually impressed by how it works—not always by the specific device or its sometimes incorrect settings. Some units can also become quite noisy. Many systems are not properly planned and are simply adjusted via the air outlets until suitable values are reached, which is not really the purpose of the system.
This usually applies to central systems, which should ideally be installed in the warm zone due to their duct routing or be insulated accordingly.
Decentralized systems are generally more cost-effective. They require only small wall openings during the shell construction phase, or you can incorporate their sleeve pipes directly into the wall while building it up. For typical residential buildings, two units per floor are often sufficient, alternating between air intake and exhaust. This process is automatically controlled. These units are very quiet and consume very little electricity (3 watts/h), which results in an annual cost of about 50 € for the whole house—not much for clean and fresh air. These devices (e.g., Inventer) cost around 500–800 € installed.
The "eco-ventilator" might be somewhat more expensive, but for normal-sized, common houses, you only need a maximum of two units. It also has the advantage of providing humidity recovery, which is not possible with standard decentralized devices. This benefit is especially useful during the heating season when indoor air tends to be too dry.
In decentralized units, the heat exchanger is usually made of ceramic, which you can easily remove and clean in a dishwasher. This makes it clear what or through what the fresh air flows.
So—just gather information and choose the right option.
A mechanical ventilation with heat recovery definitely has its advantages, and those who have one are usually impressed by how it works—not always by the specific device or its sometimes incorrect settings. Some units can also become quite noisy. Many systems are not properly planned and are simply adjusted via the air outlets until suitable values are reached, which is not really the purpose of the system.
This usually applies to central systems, which should ideally be installed in the warm zone due to their duct routing or be insulated accordingly.
Decentralized systems are generally more cost-effective. They require only small wall openings during the shell construction phase, or you can incorporate their sleeve pipes directly into the wall while building it up. For typical residential buildings, two units per floor are often sufficient, alternating between air intake and exhaust. This process is automatically controlled. These units are very quiet and consume very little electricity (3 watts/h), which results in an annual cost of about 50 € for the whole house—not much for clean and fresh air. These devices (e.g., Inventer) cost around 500–800 € installed.
The "eco-ventilator" might be somewhat more expensive, but for normal-sized, common houses, you only need a maximum of two units. It also has the advantage of providing humidity recovery, which is not possible with standard decentralized devices. This benefit is especially useful during the heating season when indoor air tends to be too dry.
In decentralized units, the heat exchanger is usually made of ceramic, which you can easily remove and clean in a dishwasher. This makes it clear what or through what the fresh air flows.
So—just gather information and choose the right option.
G
Goldbeere29 Nov 2010 15:00Hello Bauexperte,
Hello BauLine,
Thank you both for your answers!
The more I read about this topic, the more I find arguments in favor of controlled residential ventilation. Especially—as you, Bauexperte, mentioned—when both partners work full-time and cannot ventilate frequently. I also immediately thought about the period after the house handover—it seems that there is still some residual moisture in the house that needs to be removed by ventilation.
I/we definitely tend to prefer decentralized ventilation. And if about two fans per floor are actually sufficient, the costs are not too high. Better to spend this money than to risk mold later on.
I will ask my girlfriend which fans they installed.
BauLine, if only two or three fans are installed per floor, where would be the best locations? Probably exhaust fans in the kitchen and bathroom? And fresh air supply in living rooms and bedrooms?
Goldbeere
Hello BauLine,
Thank you both for your answers!
The more I read about this topic, the more I find arguments in favor of controlled residential ventilation. Especially—as you, Bauexperte, mentioned—when both partners work full-time and cannot ventilate frequently. I also immediately thought about the period after the house handover—it seems that there is still some residual moisture in the house that needs to be removed by ventilation.
I/we definitely tend to prefer decentralized ventilation. And if about two fans per floor are actually sufficient, the costs are not too high. Better to spend this money than to risk mold later on.
I will ask my girlfriend which fans they installed.
BauLine, if only two or three fans are installed per floor, where would be the best locations? Probably exhaust fans in the kitchen and bathroom? And fresh air supply in living rooms and bedrooms?
Goldbeere
Hello Goldbeere,
two questions in advance:
?
The background of my question: If you have planned a wood stove, this room usually cannot be connected to a central ventilation system. With passive heat recovery, in addition to the savings achieved by controlled residential ventilation, extra energy can be saved. More than 90% of the energy contained in the exhaust air can be recovered this way. If this is planned, only a central residential ventilation system makes sense.
Since this is a new build, there are many reasons to favor a central ventilation system. In older buildings, the decentralized option is often used for economic reasons.
Besides your online research, I would also recommend personal contact with professionals and, if possible, visiting reference projects. There you can ask users about both central and decentralized ventilation systems.
two questions in advance:
- Have you planned to install a fireplace, and
- Have you already considered heat recovery from the exhaust air
?
The background of my question: If you have planned a wood stove, this room usually cannot be connected to a central ventilation system. With passive heat recovery, in addition to the savings achieved by controlled residential ventilation, extra energy can be saved. More than 90% of the energy contained in the exhaust air can be recovered this way. If this is planned, only a central residential ventilation system makes sense.
Since this is a new build, there are many reasons to favor a central ventilation system. In older buildings, the decentralized option is often used for economic reasons.
Besides your online research, I would also recommend personal contact with professionals and, if possible, visiting reference projects. There you can ask users about both central and decentralized ventilation systems.
G
Goldbeere12 Jan 2011 11:09Erik_IEU schrieb:
Hello Goldbeere,
two questions first:
- Have you planned to install a fireplace, and
- Have you ever considered heat recovery from the exhaust air
?
The background of my question: If you plan to have a wood-burning stove, usually that room cannot be integrated into a central ventilation system. With passive heat recovery, in addition to the savings from a mechanical ventilation with heat recovery system, extra energy can be saved. More than 90% of the energy contained in the exhaust air can be recovered this way. If this is planned, only a central ventilation system is possible.
Since this is a new build, there are many arguments in favor of a central ventilation system. In existing buildings, mostly for economic reasons, a decentralized system is used.
Besides your online research, I would recommend personal contact with professionals and, if possible, visiting reference projects. There you can ask the users about both central and decentralized ventilation systems.Hello Erik_IEU!
Yes, we are planning a room-sealed wood-burning stove in the living room. If I understand correctly, the stove should get its combustion air through the chimney. Why then can a mechanical ventilation with heat recovery system not be installed or planned in the living room? I have not heard that before...
My partner is not yet convinced by the “cost-benefit calculation” of a mechanical ventilation system with heat recovery. He would rather invest the money more “sensibly” and continue to ventilate manually as before. I tend more toward a mechanical ventilation system, but without heat recovery—that would exceed our budget.
We are currently waiting for a detailed offer with the system designation, manufacturer, performance description, and so on. Then we can look into it more thoroughly.
But if a mechanical ventilation system with heat recovery cannot be planned in the living room, isn’t a decentralized solution more sensible? How else can the living room be ventilated (besides manually)?
Thank you very much for your help!!
Goldbeere
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