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A kitchen hood is often an impressive and decorative element in the kitchen design. However, we primarily purchase it for practical reasons. Effectively and quickly removing odours from the kitchen is crucial—especially in modern apartments where the living room and kitchen are combined into one space. However, developers sometimes impose restrictions on the efficiency of installed hoods when selling new properties. Why does this happen, and how does it affect the daily use of the kitchen?
What is hood efficiency?
Hood efficiency is measured in m³/h and indicates the amount of air a hood can filter per hour. It is generally accepted that a well-functioning hood should filter the air in the kitchen 6 times per hour. Therefore, the efficiency you need depends largely on the size of your kitchen.
So, how do you calculate the optimal hood efficiency for your kitchen? The first step is to calculate the volume of the room. If your kitchen has an area of 8 m² and a height of 2.5 m, its volume will be 20 m³. You should multiply this value by 6. In this example, you will get a value of 120 m³/h, which is the minimum efficiency needed for effective air filtration in your kitchen. Of course, you can opt for a hood with slightly higher efficiency, but there’s no need to exceed the calculated value by a significant margin.
Hood efficiency limitations in new apartments
In single-family houses, there are generally no restrictions on the efficiency of kitchen hoods, as the entire ventilation system is typically designed from scratch for the specific building. The situation may differ in the case of multi-storey and multi-family buildings. Sometimes, developers or building managers specify the maximum hood efficiency allowed to be connected to the ventilation ducts in the property regulations and user manuals. This limitation might be, for example, 200 or 250 m³/h.
What causes such limitations? High-efficiency kitchen hoods connected to ventilation ducts can cause a disruption of the proper functioning of gravity ventilation in the apartment. A powerful hood may result in fresh air being drawn into the apartment through the ventilation ducts, which are supposed to exhaust air, not introduce it. This is why adhering to the limitations set by developers (or only slightly exceeding them) is entirely reasonable. It’s also important to remember to slightly open a window or vent when using the hood to ensure proper ventilation flow. Otherwise, you may experience a reverse airflow in the ventilation duct. If this occurs occasionally, it won’t harm the residents. However, if it happens frequently, it could eventually lead to negative health effects for the inhabitants. Ventilation ducts often accumulate dust, mold spores, and bacteria, which can be drawn into the apartment along with the air, potentially bringing in exhaust fumes and smoke from above.
When is it impossible to install a hood?
There are also situations where installing an exhaust hood is prohibited by regulations. What situations are these?
The first is when there is a gas boiler in the kitchen that draws air for combustion from the room. In such kitchens, hoods operating as exhausts cannot be installed (similarly, this applies to bathrooms with gas heaters).
Exhaust hoods also cannot be connected to ventilation ducts if they serve more than one apartment. In new buildings, each apartment must have a separate duct, but in older buildings, it still happens that several apartments share one duct. Connecting an exhaust hood to it would cause odors from lower apartments to be pushed into the units on higher floors.
In such cases, a good solution is to install a recirculating hood with a carbon filter, which will safely and without bothering the neighbours eliminate unwanted odors.
Choosing a kitchen hood should be a well-considered decision. The steps that will help you select the right model for your kitchen are, first, calculating the optimal performance for your kitchen, and second, reading the property regulations and usage guidelines.