ᐅ Controlled ventilation system in a bungalow: Is it necessary to lower the ceiling?

Hello everyone,

We are currently finalizing the building permit / planning permission application for our construction project (a bungalow with 135 sqm (1453 sq ft)). We would like to have a ventilation system installed in our bungalow. In this context, our general contractor (GC) recently approached us and said that the ceiling would need to be lowered to install the ventilation system. This means we would have to increase the room height, and this must be taken into account in the building permit / planning application.

There are several issues with this whole process:

• The GC’s subcontractor installs only Zewotherm systems; the cost estimate is 18,000 euros. On top of that, there would be additional costs for increasing the room height. From what I read here, in other forums, and hear from acquaintances, the cost for a ventilation system (e.g., Zehnder or Vaillant) including installation is more around 12k. (We originally thought we would have to build a one-and-a-half-story house; in that case, the Zewotherm system was even offered to us for 23k.)
• We do not want a Zewotherm system but prefer Zehnder (Vaillant would also be possible) – so now we have to find a suitable contractor ourselves who installs Zehnder systems.
• We don’t understand why the ceiling must be lowered to install a ventilation system in a bungalow. Has anyone had experience with this? Is it always necessary to lower the ceiling? What if the system is installed in the floor? Would the floor then need to be raised? I’m afraid our GC simply doesn’t really know much about ventilation systems... but maybe I’m wrong.

So: Has anyone installed a ventilation system in a bungalow without lowering the ceiling?

Yes, it is probably due to a lack of experience. Have your roof insulated and install all the piping and the system in the attic. This would likely be the simplest and most cost-effective option.

Mycraft schrieb:

Yes, it’s probably a lack of experience. Have your roof insulated and install all the piping and the system in the attic. That would likely be the simplest and most cost-effective solution.

We are building with a cold roof – as far as I understand, this means the ceiling is insulated, not the roof itself. Would that not work then? And if we were to insulate the roof (which would probably involve additional costs and is therefore unlikely), would the pipes just be left in the attic? So, could the attic still be used as a storage space or for other purposes?

A controlled ventilation system does not work with a cold roof design because that would cause condensation to occur in the rooms below. So, either all the pipes and the unit need to be well insulated on the roof, or the roof structure itself has to be properly insulated.

Of course, this involves additional costs, but overall it will be the simplest and most economical solution.

- since you don’t have to install any drop ceilings.
- you can use any device you prefer, your favorite model.
- you can hire an external company to handle the installation (which may be done even after the house handover).

How the ductwork is arranged will need to be planned when the time comes.

But it would look something like this:


or like this:



Since you also have a bungalow, part of the pipes could be routed through the non-accessible areas of the roof. These are typically the outer 1–2m (3–6 feet).

So the general contractor is right after all: with a cold roof, the ceiling has to be lowered to install a ventilation system!? Then I need to get a cost estimate comparing lowering the ceiling versus insulating the roof.

The pipes can also be installed in the ceiling.