Hello everyone,
We are currently building a new energy-efficient house and are considering whether to have a core drill hole installed for kitchen exhaust ventilation. Our chosen range hood can operate either as exhaust or recirculation. The project manager recommended using the hood in recirculation mode with activated carbon filters. However, the kitchen installer advises exhaust mode, as only this option supposedly eliminates odors and similar issues effectively.
We are now conflicted and thinking about having the core drill hole made but initially not using it, operating the hood in recirculation mode instead. The core drill hole would be fitted with an external grille cover and internally closed off with a cap. If needed later, we could connect the hood with a duct and have the setup ready for that.
From your point of view, is this a sensible approach, or am I missing something? What would you recommend? Should we have the core drill hole made or rather not?
Thanks in advance and best regards
We are currently building a new energy-efficient house and are considering whether to have a core drill hole installed for kitchen exhaust ventilation. Our chosen range hood can operate either as exhaust or recirculation. The project manager recommended using the hood in recirculation mode with activated carbon filters. However, the kitchen installer advises exhaust mode, as only this option supposedly eliminates odors and similar issues effectively.
We are now conflicted and thinking about having the core drill hole made but initially not using it, operating the hood in recirculation mode instead. The core drill hole would be fitted with an external grille cover and internally closed off with a cap. If needed later, we could connect the hood with a duct and have the setup ready for that.
From your point of view, is this a sensible approach, or am I missing something? What would you recommend? Should we have the core drill hole made or rather not?
Thanks in advance and best regards
It is an efficiency house 40 with KfW funding. For our hood, we would need a 160mm (6.3 inches) core drill. With a good wall box, this should not pose any energy efficiency issues. Our kitchen installer recommended exhaust ventilation because with recirculation, the filters need to be replaced regularly, etc.
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nordanney18 Mar 2026 16:15Haus2626 schrieb:
because with recirculation, the filters need to be replaced regularly, etc. I have no idea what "etc." covers. Just today, I ordered a new filling for my Berbel for €48. The first one after about 2 3/4 years. By the way, the activated carbon only filters odors; no grease comes into contact with it.
And for those who want something really advanced, there is the permalyt filter that never needs to be refilled because it regenerates regularly. Kitchen technology has already reached this level. However, it’s not exactly cheap.
Haus2626 schrieb:
It’s an energy-efficient house 40 with KfW funding. Our hood would require a 160mm (6 inch) core drill hole. With a good wall box, this shouldn’t pose any issues regarding energy efficiency. That’s basically correct but needs to be carefully calculated. Usually, energy consultants simply recommend a recirculation hood. And if exhaust is used, then definitely with airtight (and electronically controlled) wall boxes. That way, you’ll have the fewest problems regarding funding. For example, the Naber Thermobox.
Similar discussion here
https://www.hausbau-forum.de/threads/umluft-dunstabzug-neubau-kfw40-erfahrungen.j8k3r6/
It simply does not matter what your kitchen builder considers best or what forum users subjectively think is best.
What counts is your energy demand calculation.
Also, the technology you have installed, for example the ventilation system. It is not that simple to figure out.
https://www.hausbau-forum.de/threads/umluft-dunstabzug-neubau-kfw40-erfahrungen.j8k3r6/
Haus2626 schrieb:
It is an energy-efficient house, standard 40, with KfW funding.
It simply does not matter what your kitchen builder considers best or what forum users subjectively think is best.
What counts is your energy demand calculation.
Also, the technology you have installed, for example the ventilation system. It is not that simple to figure out.
MachsSelbst schrieb:
Then it’s not 1,000 "bucks," but only 150, plus the core drilling 1. 150 EUR low-cost wall box with the risk of losing funding.
2. + 200 EUR core drilling including travel (price from 2022, so still realistic today, even if it seemed high back then)
3. + 100 EUR exhaust duct and installation materials
4. + 100 EUR additional work for the kitchen installer
5. + 100 EUR material for casing (inside and outside)
6. VAT on items 2–5 + 133 EUR
= 745 EUR. Okay, that’s not 1,000 bucks, you’re right, I concede, you clever fox.
Maybe with some compromise, it could be done for 500 EUR. But then it wouldn’t be energy neutral either.
If you want the electronically controlled insulated wall box, you’re easily over 1,000 EUR, because the wall box alone costs about 300–500 EUR. Plus the above items, plus electrician costs.
Activated carbon filters can be reactivated in the oven at least once, and grease filters can be cleaned in the dishwasher.
In the kitchen, according to the ventilation concept, we will have an exhaust fan running continuously at the lowest setting. If we decide to go for recirculation instead, I believe that would also reduce odors to some extent, right? For exhaust ventilation, in addition to the wall vent, a cover for the exhaust duct would be necessary, as it would run above the wall cabinets. Overall, I would estimate costs around 1000€.
The real question is whether we should simply stick with recirculation—we have ordered a standard range hood with a maximum capacity of 740 m³/h (435 cfm)—and whether that would be sufficient when combined with the exhaust fan.
The real question is whether we should simply stick with recirculation—we have ordered a standard range hood with a maximum capacity of 740 m³/h (435 cfm)—and whether that would be sufficient when combined with the exhaust fan.
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nordanney18 Mar 2026 22:52Haus2626 schrieb:
According to the ventilation concept, we will have an exhaust fan in the kitchen that will run continuously at the lowest setting. Who is justifying that? I rarely have seen such nonsense in a KfW40 (Passive House equivalent) standard.
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