Kitchen: convection or exhaust air - what's better?

Kitchen: convection or exhaust air - what's better?

If you are planning a new kitchen, you should also think about the extractor hood. Recirculation or exhaust air have advantages and disadvantages.

When installing or remodeling the kitchen, homeowners inevitably come up with the question of which type of extractor hood is the better option. Whether circulating air or exhaust air, is also related to technical aspects. Not in every kitchen are both systems possible. For some systems, the landlord must be asked for permission, as a wall opening is required.

Extractor, recirculation or exhaust air? - Functions of the various exhaust air systems

The so-called extractor hood serves to absorb cooking fumes in the kitchen. This prevents odors from the kitchen from spreading throughout the home. The system of an extractor hood also ensures that small droplets of grease are captured so that no greasy film is deposited on the furniture, floors or walls. This saves a lot of sticky dirt, which should not only be removed regularly on the hood, but spread throughout the kitchen.

A circulating hood is in principle a box in which a fan sucks in the air from below and ejects it upwards , The air flows through a grease filter, where the fat sucks. Depending on the model, the filter is a fleece, which must be replaced from time to time. But there are also models that have a metal sieve that can be cleaned in the dishwasher. Behind this grease cutter is usually an activated carbon filter that absorbs odors, so that the room air is spared from cooking odors. These filters are exhausted and should therefore be replaced after a few months.

Exhaust hoods operate on a similar principle, but transport the intake air through a duct to the outside. A grease filter prevents grease settling in the channel. Activated carbon is not necessary, as the system distributes the odors in the ambient air of the house.

Detailed view of circulating air in the kitchen

The advantage of an extractor hood with circulating air is first and foremost the ease of installation. An exhaust hood can be attached to any wall and only needs a socket near the hood. Structural changes are not required and the costs are usually not more than 100 euros. If homeowners would like a particularly beautiful hood made of precious material, this of course costs a little more.

Since these designs merely circulate the air in the room, they can not remove moisture from it. Thorough ventilation with a wide-open window during or directly after cooking is therefore essential with these hoods.

In addition, there is another disadvantage: The hood is all the more effective the more power the blower has. Unfortunately, the volume increases with the performance of the fan. Some extractor hoods with circulating air generate a sound pressure level of more than 80 dB at the highest level. They are as loud as a passing truck. The reason is, among other things, the position of the blower at head height, just above the stove.

The noise generated by powerful blowers makes it impossible to use powerful fans. The hoods are therefore not able to circulate large amounts of air. The manufacturers usually only state the sound pressure level at the lowest level. In this stage, the hood is quieter than the sound of sizzling in the pan, but hardly circulates air.

Advantages and Disadvantages of Exhaust Air

The disadvantages of one system are inevitably the advantages of the other. Hoods, which are connected to the exhaust air, can be operated by motors that suck outside the room through the air duct, the air above the stove. Higher performance with less noise is possible. Of course, it is also superfluous because the humid air does not remain in the room.

In the past, the iron rule was that exhaust ventilation in extractor hoods in the kitchen is always superior to recirculated air. Only the required wall breakthrough, which usually costs about 1,000 to 2,000 euros with the exhaust ducts, was a disadvantage. Today it looks a bit different.

Due to the dense windows that are common today, exhaust hoods can create a negative pressure. Therefore, a regulated supply air makes sense. This in turn leads to problems in the low energy house and the passive house. Since in the latter the waste heat from cooking also serves for heating, an exhaust hood is difficult to realize in this type of house. In the low-energy house, it is not advisable to switch from recirculating air to exhaust air, because the type of extractor has been planned by the architect into the ventilation system of the house and can not be easily undone.

Modern air-conditioned fireplaces such as fireplaces or gas-fired heating use combustion the oxygen in the room air. Legislation therefore requires forced ventilation in order to prevent negative pressure in the house.

The exhaust air systems in direct comparison

Problem area

Circulation air

Exhaust air

Exhaust air duct with wall opening or roof outlet

Not required

Absolutely necessary. Homeowner must agree

Room Air Dependent Fireplace

No Problem

Forced Ventilation is Required

Supply Air

Not required

Negative Pressure May Lead to Problems

Low Energy House

Always Possible

Must enter Ventilation system can be planned

Passive house

Always possible

Not useful, usually not possible

External fan to reduce noise emission and / or increase power

Not possible


Ventilation after or during cooking


Not required

Activated carbon filter


Not required


Approximately 100 Euro

Over 1,000 Euro

An exhaust hood provides better for fresh and clean air as a recirculation hood. But it is more expensive and needs to be planned carefully.

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