ᐅ Exhaust hood with external ventilation for KfW55 standard

I want to build a single-family house according to the KfW55 standard. These houses are absolutely airtight, and the airtightness is verified with a blower door test. Is it allowed to operate a range hood in exhaust mode? For the exhaust, a duct with a diameter of 150 mm (6 inches) leading outside is required. Wouldn't this area then no longer be airtight?

I don’t know if this has changed. But at least last year, any KFW classification was just smart calculation.
If something didn’t fit, then use a different brick, or different windows, or a different heating system, or better insulation of the foundation slab or the roof, etc.
In the end, only the overall package matters. Or has that changed?

I would prefer to find out whether an extraction system is required, or if a recirculation hood would be sufficient. The difference in terms of functionality is actually quite small. The disadvantages, besides the poorer energy efficiency, are mainly the noise that is transmitted into the house. At least in our current apartment, you can already hear the wind, and there is also a slight draft around the stove.

Of course, KfW55 standard and exhaust air for the range hood are possible. For this, a thermal box is required, like the one offered by the company Naber (a quick online search will help). We installed such a model, and it works great.

Forget about recirculation; definitely go with an exhaust ventilation system.

Bookstar schrieb:

Forget about recirculation, definitely go for exhaust air.

Why, how come?
It works great here.