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
Just checked:
[from outside to inside:]
5mm (0.2 inches) diffusion-permeable fine plaster
60mm (2.4 inches) thermal insulation board (extruded polystyrene)
13mm (0.5 inches) wood-based panel
160mm (6.3 inches) solid timber stud frame with 160mm (6.3 inches) sound and thermal insulation (mineral wool)
0.2mm (0.008 inches) vapor diffusion retarder
13mm (0.5 inches) wood-based panel
9.5mm (0.4 inches) natural gypsum board
Total wall thickness 26cm (10.2 inches).
[from outside to inside:]
5mm (0.2 inches) diffusion-permeable fine plaster
60mm (2.4 inches) thermal insulation board (extruded polystyrene)
13mm (0.5 inches) wood-based panel
160mm (6.3 inches) solid timber stud frame with 160mm (6.3 inches) sound and thermal insulation (mineral wool)
0.2mm (0.008 inches) vapor diffusion retarder
13mm (0.5 inches) wood-based panel
9.5mm (0.4 inches) natural gypsum board
Total wall thickness 26cm (10.2 inches).
Whether prefabricated or solid construction does not matter. A properly built house, according to current standards, is airtight, and air can (AND MUST) only be exchanged through controlled residential ventilation or intentional openings (often, for example, the window rebate). Ventilating every few hours is rarely feasible and, as far as I remember, is also not sufficient on its own.
S
Sebastian798 Jun 2015 11:25Yes, it is permitted – a mechanical ventilation system with heat recovery is not mandatory.
It is allowed to involve the operator of the system in the ventilation concept. If it is clear that the operator can ensure moisture protection by ventilating independently, this is sufficient for the concept. However, they must be explicitly informed that without their active participation, the concept cannot be implemented. No designer would implement such a concept because, in case of damage, disputes are almost inevitable. I personally do not design a system solely with the operator or owner of the property.
Nowadays, it is rarely possible to ventilate intensively about 4 to 6 times a day.
Therefore, it is practically no longer feasible to do without a ventilation system.
Nowadays, it is rarely possible to ventilate intensively about 4 to 6 times a day.
Therefore, it is practically no longer feasible to do without a ventilation system.
We are also facing the decision of whether to install a mechanical ventilation system with heat recovery or not. We can achieve KfW70 standard through solar thermal energy, which already adds over €8,000 in extra costs. A mechanical ventilation system would cost an additional €12,000.
We often read that all rooms need to be ventilated multiple times a day...
Is it really that strict? What about people who work full-time or are away for several weeks? Not all houses without mechanical ventilation develop mold, and hardly anyone sets an alarm to remind them to open a window, right?
We often read that all rooms need to be ventilated multiple times a day...
Is it really that strict? What about people who work full-time or are away for several weeks? Not all houses without mechanical ventilation develop mold, and hardly anyone sets an alarm to remind them to open a window, right?
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