Hello everyone,
We are currently starting to deal with the technical aspects of our single-family home.
I haven’t found a thread discussing whether a ventilation system generally makes sense or not. So here is a general discussion thread on the topic:
At first, we looked into various timber frame construction providers, which made us quite sensitive in this area. Naturally, a ventilation system is quite important due to the tighter building envelope, which I can completely understand. However, everything is also marketed accordingly...
Since we have now decided to go with a regional solid construction company, completely different questions arise:
I currently have a detailed offer from a solid construction company:
- $10,000 additional cost for thermal insulation measures
- $13,000 additional cost for a central ventilation system or $9,000 additional cost for a decentralized ventilation system
--> So the repayment subsidy of $18,000 is of little use to me; on the contrary, I am even paying extra for this (of course, I get a “better” house in return).
Key Data:
- Single-family home city villa, 150m² (1,615 ft²) with basement
- Air-to-water heat pump
- Building material: brick
The questions I am now asking myself:
1. Is a ventilation system even necessary to achieve KfW 55 standard?
2. If yes, would it maybe make more sense to go for KfW 70 and forget about the subsidy?
3. Is a ventilation system really that great? There are many reports about noise, high maintenance, etc.
4. If yes, in our building project would a decentralized or central system be better? I have read a lot of positive things about decentralized systems, so central ones might not be an option? Is that correct or not?
5. Is it even possible to reach KfW 55 standard otherwise? Do you really have to ventilate every 2 hours? Are there any experiences?
6. Is the additional $10,000 cost for KfW 55 without a ventilation system justified? Are the prices for the ventilation systems justified?
I know this is an endless debate and there are clearly two opinions here. However, we find it really difficult to make a decision. Maybe a few discussions and information here will help us make up our minds.
We are currently starting to deal with the technical aspects of our single-family home.
I haven’t found a thread discussing whether a ventilation system generally makes sense or not. So here is a general discussion thread on the topic:
At first, we looked into various timber frame construction providers, which made us quite sensitive in this area. Naturally, a ventilation system is quite important due to the tighter building envelope, which I can completely understand. However, everything is also marketed accordingly...
Since we have now decided to go with a regional solid construction company, completely different questions arise:
I currently have a detailed offer from a solid construction company:
- $10,000 additional cost for thermal insulation measures
- $13,000 additional cost for a central ventilation system or $9,000 additional cost for a decentralized ventilation system
--> So the repayment subsidy of $18,000 is of little use to me; on the contrary, I am even paying extra for this (of course, I get a “better” house in return).
Key Data:
- Single-family home city villa, 150m² (1,615 ft²) with basement
- Air-to-water heat pump
- Building material: brick
The questions I am now asking myself:
1. Is a ventilation system even necessary to achieve KfW 55 standard?
2. If yes, would it maybe make more sense to go for KfW 70 and forget about the subsidy?
3. Is a ventilation system really that great? There are many reports about noise, high maintenance, etc.
4. If yes, in our building project would a decentralized or central system be better? I have read a lot of positive things about decentralized systems, so central ones might not be an option? Is that correct or not?
5. Is it even possible to reach KfW 55 standard otherwise? Do you really have to ventilate every 2 hours? Are there any experiences?
6. Is the additional $10,000 cost for KfW 55 without a ventilation system justified? Are the prices for the ventilation systems justified?
I know this is an endless debate and there are clearly two opinions here. However, we find it really difficult to make a decision. Maybe a few discussions and information here will help us make up our minds.
I need to follow up again, this time regarding the ventilation system in general. Meanwhile, the main contractor has come up with a solution using a ventilation system from Alpha Innotec combined with a heat pump from the same manufacturer.
The reason I want a ventilation system at all is, on one hand, heat recovery during winter and, on the other hand, protection against moisture damage. At some point, I started wondering what happens in summer when the outside temperature is above 21°C (70°F) — meaning it’s warmer outside than you’d want inside the house. I asked the energy consultant about this, and he told me: Option A: turn off the ventilation system during the day in summer and turn it back on when you come home. Option B: keep the ventilation running and live with high indoor temperatures.
Seriously? Especially in summer, humidity is usually quite high, so ideally the system should keep running. But you also don’t want 30°C (86°F) inside the house when it’s really hot outside… I brought up the term “ground heat exchanger” with him. He advised against it (condensation issues?), and besides, it would cost a few thousand euros more.
How have you solved this problem?
The reason I want a ventilation system at all is, on one hand, heat recovery during winter and, on the other hand, protection against moisture damage. At some point, I started wondering what happens in summer when the outside temperature is above 21°C (70°F) — meaning it’s warmer outside than you’d want inside the house. I asked the energy consultant about this, and he told me: Option A: turn off the ventilation system during the day in summer and turn it back on when you come home. Option B: keep the ventilation running and live with high indoor temperatures.
Seriously? Especially in summer, humidity is usually quite high, so ideally the system should keep running. But you also don’t want 30°C (86°F) inside the house when it’s really hot outside… I brought up the term “ground heat exchanger” with him. He advised against it (condensation issues?), and besides, it would cost a few thousand euros more.
How have you solved this problem?
T
T_im_Norden30 Jul 2020 20:48Heat recovery works in both directions; if the mechanical ventilation system allows it, the incoming outside air can be cooled. However, since indoor temperatures usually rise due to a lack of shading rather than ventilation, the effect is not very strong.
T_im_Norden schrieb:
A heat recovery system works both ways; if the mechanical ventilation with heat recovery supports it, the incoming outside air is cooled.How is that possible?
I think it’s unavoidable that even with a bypass, there will be times in summer when you turn it off during the day and on at night. But since we don’t have any experience yet, we’ll only know once we’ve moved in and the first heat wave hits us. My feeling is that it won’t be worse than now, with outside temperatures around 35°C (95°F) and indoor temperatures of about 27-28°C (81-82°F). It can only get better from here.
T
T_im_Norden30 Jul 2020 21:29Physics.
A heat exchanger works because heat flows from warmer to cooler areas.
In winter, cold outside air comes in and warm air goes out, so heat flows from the exhaust air toward the supply air.
In summer, warm outside air comes in and cooler indoor air goes out, so heat flows from the supply air into the exhaust air.
A heat exchanger works because heat flows from warmer to cooler areas.
In winter, cold outside air comes in and warm air goes out, so heat flows from the exhaust air toward the supply air.
In summer, warm outside air comes in and cooler indoor air goes out, so heat flows from the supply air into the exhaust air.
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