ᐅ But should you install a controlled residential ventilation system?
Created on: 25 May 2015 00:14
U
Uwe82
Hello everyone,
We are in the final stages of planning our house; the floor plan is set, and the detailed construction planning will take place soon. It is a prefabricated house built with a timber frame construction and a prefabricated basement on a slope, meaning the front part of the basement is fully exposed above the slope.
So far, we have excluded the topic of mechanical ventilation with heat recovery, partly due to planning concerns (we are doing everything ourselves from the rough plumbing and electrical installation stages) and partly for cost reasons. However, in recent weeks, we have started to reconsider this, mainly for comfort reasons.
Long story short: Our question mainly concerns the routing of the ductwork, which would partially be installed within the floor structure. So far, we have planned for a floor buildup of 15cm (6 inches) on the ground floor. However, if we were to increase this to 18cm (7 inches) as our house manufacturer suggests, the clear floor height would decrease from 245cm (8 ft) to 242cm (7 ft 11 in) on the ground floor. This would bother me a bit. We cannot change the floor-to-ceiling height due to the zoning plan restrictions (maximum eave height fully utilized).
Now the question is: Is it really necessary to plan for 18cm (7 inches) because of duct crossings, or are there alternatives? For a suitable floor plan (here is our current one: https://www.hausbau-forum.de/threads/efh-in-Hanglage.12265/page-3#post-90366), could the ducts be routed only within the walls? And which mechanical ventilation system with heat recovery would you recommend for a living area of 180m² (1,938 sq ft)?
Thanks in advance for all the information!
Uwe
We are in the final stages of planning our house; the floor plan is set, and the detailed construction planning will take place soon. It is a prefabricated house built with a timber frame construction and a prefabricated basement on a slope, meaning the front part of the basement is fully exposed above the slope.
So far, we have excluded the topic of mechanical ventilation with heat recovery, partly due to planning concerns (we are doing everything ourselves from the rough plumbing and electrical installation stages) and partly for cost reasons. However, in recent weeks, we have started to reconsider this, mainly for comfort reasons.
Long story short: Our question mainly concerns the routing of the ductwork, which would partially be installed within the floor structure. So far, we have planned for a floor buildup of 15cm (6 inches) on the ground floor. However, if we were to increase this to 18cm (7 inches) as our house manufacturer suggests, the clear floor height would decrease from 245cm (8 ft) to 242cm (7 ft 11 in) on the ground floor. This would bother me a bit. We cannot change the floor-to-ceiling height due to the zoning plan restrictions (maximum eave height fully utilized).
Now the question is: Is it really necessary to plan for 18cm (7 inches) because of duct crossings, or are there alternatives? For a suitable floor plan (here is our current one: https://www.hausbau-forum.de/threads/efh-in-Hanglage.12265/page-3#post-90366), could the ducts be routed only within the walls? And which mechanical ventilation system with heat recovery would you recommend for a living area of 180m² (1,938 sq ft)?
Thanks in advance for all the information!
Uwe
We have been living in our (solid) house without a ventilation system since August of last year.
We air out the house twice daily. On weekends, some rooms are aired more frequently—for example, the children's room after their afternoon nap. We also often have the terrace door open, or depending on the weather, windows tilted open. To reduce and then maintain the indoor humidity after construction, this has been sufficient for us.
On the ground floor, good humidity levels were reached relatively quickly; it took a bit longer upstairs, but now the levels are also within a good range. It is important in the beginning to heat all rooms, including those not in use (e.g., guest rooms) and bedrooms. Only warm air helps to remove moisture.
In our neighborhood, there was reportedly mold behind pictures in one house. That’s why we occasionally take down large pictures.
I think that once the house has dried out reasonably well, it can be left without airing for longer periods during vacations or business trips. Besides plants, where else would the moisture come from? Right after moving in, we did go on vacation for about a week, but I was a bit worried then.
In general, a new house works fine without a ventilation system. Maybe not quite as comfortable, but it works.
We air out the house twice daily. On weekends, some rooms are aired more frequently—for example, the children's room after their afternoon nap. We also often have the terrace door open, or depending on the weather, windows tilted open. To reduce and then maintain the indoor humidity after construction, this has been sufficient for us.
On the ground floor, good humidity levels were reached relatively quickly; it took a bit longer upstairs, but now the levels are also within a good range. It is important in the beginning to heat all rooms, including those not in use (e.g., guest rooms) and bedrooms. Only warm air helps to remove moisture.
In our neighborhood, there was reportedly mold behind pictures in one house. That’s why we occasionally take down large pictures.
I think that once the house has dried out reasonably well, it can be left without airing for longer periods during vacations or business trips. Besides plants, where else would the moisture come from? Right after moving in, we did go on vacation for about a week, but I was a bit worried then.
In general, a new house works fine without a ventilation system. Maybe not quite as comfortable, but it works.
We live in a four-year-old house without a ventilation system, and both of us are away during the day. We ventilate if possible in the morning and a little in the evening. On weekends, a window or door might be left open for a longer time. Windows are (almost) never tilted open. Inside the house, we have relatively high humidity levels, clearly above 50%.
We do not have any mold. However, I believe it would have been difficult to maintain the necessary ventilation during the first year, although we were not the owners then.
We do not have any mold. However, I believe it would have been difficult to maintain the necessary ventilation during the first year, although we were not the owners then.
The question always is how airtight the house is, especially without specific KfW Bank requirements. Without proper measurements, it’s like comparing apples and oranges (whether a house achieves 0.5 or 2.5 in a blower door test makes a big difference). In my previous apartment, I never ventilated manually but still had good air quality. The necessary air exchange was provided through natural leaks. Some developers or prefabricated house suppliers install ventilation slots in window frames without planned mechanical ventilation, which may be very discreet but are still sufficient to prevent mold. To make a proper comparison, more information would be needed.
The general contractor suggests ventilating about twice a day after the drying phase, which should be sufficient. However, since our bedroom is only about 12 square meters (130 square feet) in floor area, the fresh air would be quickly used up with the windows closed... This is also why we are considering a mechanical ventilation system with heat recovery.
D
Doc.Schnaggls10 Jun 2015 10:09@Häusle77 :
I can highly recommend installing a controlled ventilation system for living spaces.
As self-proclaimed "window-open sleepers," we always struggled with stale air at night whenever we had to keep our bedroom window closed due to bad weather (in our old apartment).
Now, with the controlled ventilation system, we have both supply air (in the sleeping area) and exhaust air (in the dressing area) in the same room and sleep much better even with the window closed.
I wouldn’t want to be without our controlled ventilation system anymore, purely as a comfort feature.
Regards,
Dirk
I can highly recommend installing a controlled ventilation system for living spaces.
As self-proclaimed "window-open sleepers," we always struggled with stale air at night whenever we had to keep our bedroom window closed due to bad weather (in our old apartment).
Now, with the controlled ventilation system, we have both supply air (in the sleeping area) and exhaust air (in the dressing area) in the same room and sleep much better even with the window closed.
I wouldn’t want to be without our controlled ventilation system anymore, purely as a comfort feature.
Regards,
Dirk
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