ᐅ Controlled residential ventilation in the basement with outdoor air supplied through the roof

Hello everyone,

We are currently in the final planning stages of our house with a basement granny flat (KFW40+).

We definitely want a controlled mechanical ventilation system, but we would prefer to avoid an outdoor air intake pipe in the garden. So, the idea came up to draw the outdoor air from the roof (the attic is outside the thermal envelope and insulated with only 60mm (2.4 inches) of wood fiber board).
The exhaust air would then be vented through a light well.

Is there any reason this might not work, apart from the fact that my outdoor air intake path would be significantly longer than the exhaust air path?

Thanks and best regards

I’ll chime in here.

I have a similar idea/problem, but I haven’t found a solution yet either...

We have the fresh air intake located on the carport. It works perfectly fine so far. Occasionally, we experience slight odor issues when the neighbors have their fireplace running. However, you can also notice this by simply opening a window on the ground floor, so I assume the exact location of the fresh air intake does not make a significant difference. (?)

I would only implement this through a light well if it is completely protected from water. If heavy rain causes water to enter there, the controlled residential ventilation system will have only served its purpose for a short time.

If I could do it again, I would choose an intake pipe like this one. Preferably placed in the front yard/street side and possibly hidden with plants.

Reason: When you draw in fresh air, you also attract small animals (mosquitoes, spiders, etc.). With such a pipe, you can easily and conveniently install a weather-protected pre-filter. Not on the roof, plus long ducting, and on top of that, you risk pulling in hot air during summer.

Ok, I hadn’t considered that point yet.

Since the technical room is located relatively centrally, I would need to lay the cable about 10m (33 feet) underground to go around the corner of the house. This would also allow for relatively good air intake (it would be on the northwest side) and completely avoid any short circuit. However, I would also need a condensate drain.

Strahleman schrieb:

I would only consider installing it through a light well if it is absolutely protected from water. If stormwater gets in during heavy rain, you’ll have only had a controlled ventilation system for a short time.

That shouldn’t be a problem since the outlet is planned relatively high up in the light well. If the water level gets that high, the controlled ventilation would be my least concern.