Open kitchen, strong smells: why the cooker hood is not enough

You fry fish, the hood hums away on full power, and yet the smell sits in the sofa, the curtains and sometimes the bedrooms by the evening. Many people decide the hood "doesn't pull enough". That is rarely the whole story.

In an open-plan kitchen, three things overlap and interfere with each other: the kitchen hood, the flat's ventilation system, and the paths where fresh air comes in. As long as those three roles are blurred, people keep changing appliances without touching what actually moves smells through the dwelling.

Hood, ventilation extract, air supply: three different jobs

In a dwelling designed to Belgian standard NBN D50-001, an open kitchen connected to the living room should have a dedicated mechanical extract of 75 m³/h. That airflow is there for continuous background ventilation, not for the short, intense burst of steam and grease when you sear a steak.

The cooker hood sits directly above the hob and tries to catch those plumes at source. It may discharge the air outdoors or send it back into the room after filtration. Finally, fresh air has to come from somewhere: trickle vents in window frames, a mechanical supply system, or simply leaks in older joinery.

When those three functions are confused, people expect the hood to do the job of general ventilation. It cannot: it acts too locally, and only when you choose to switch it on.

Why a recirculating hood lets moisture and smells spread

A recirculating hood does not throw air outside. It sends it through a grease filter, sometimes through a charcoal filter, then straight back into the kitchen. The grease droplets are trapped, part of the odour molecules are adsorbed, but the water vapour stays in the air.

Cooking is largely heating water and fats. The added moisture mixes into the air of the living space. In an open plan, that warm, humid air naturally drifts towards cooler areas: hallway, bedrooms, storage. It carries with it the fraction of odours that escaped the charcoal filter or for which no filter is fitted.

You can have a correctly installed recirculating hood with new filters and still end up with a persistent "cooking" smell in the whole flat. Moist air expands and moves; the hood has no way of stopping that, because it never actually removes that air from the dwelling.

Smell of cooking in the whole flat: what the airflow is doing

While you cook, temperature and humidity rise around the hob and then in the living area. Warm air is lighter, so it lifts towards the ceiling, then flows out over the room and towards circulation spaces.

At the same time, the flat's ventilation keeps extracting in the kitchen, bathroom and WC. Fresh air is often supplied in living rooms and bedrooms. The effect is this: you push fresh air into living spaces and you pull odour-laden air towards the extract vents, which means it has to cross the living area first.

With an open kitchen there is no closed door to limit that movement. Even with the hood running, a significant share of emissions is never captured at the canopy, mixes into the room air and simply follows the pressure pattern towards the nearest extract grille.

Weak hood or too airtight flat: the modern open kitchen problem

In many recent Brussels, Flemish Brabant or Walloon Brabant flats, windows and doors are very airtight and unplanned leaks are small. An externally vented hood still has to throw a volume of air out and have it replaced by new air. If there is not enough inlet area, the negative pressure increases.

The hood then mostly churns the air above the hob without reaching its nominal airflow to outside. Smells and steam bypass the capture zone and spill into the room. Side effects can appear: doors that slam when the hood starts, or combustion appliances nearby whose flue draft is disturbed.

Turning to an even more powerful hood in that situation increases the under-pressure without solving the missing air supply. The issue is not the fan alone, but the overall balance between extracted air and incoming air in the flat.

Open kitchen, strong smells: what you can actually do

The priority is to understand where air comes in and where it leaves. As long as extraction and air supply are not coherent, "cooking smell in the whole apartment" will return as soon as you do more than reheat a plate.

Some practical levers, to be adapted to each dwelling:

• Create a gentle cross-flow while cooking: an air inlet on the opposite façade, a tilt-and-turn window cracked in the living room, an internal door slightly open towards extract rooms.
• Limit how much you emit into the room: lids on pans, slightly lower temperatures, avoiding long grilling sessions that extend beyond the hood's capture area.
• Check the regulatory kitchen extract: presence of a dedicated extract in an open kitchen, condition of the grille, and that the airflow is not strangled by a closed damper or blocked cover.
• For a ducted hood, verify that the external discharge is not obstructed and that there is a real air supply route, rather than relying only on random leaks in the building.

These measures do not turn a hood into a whole-flat ventilation system, but they cut down how much greasy, smelly, humid air is left free to drift and settle in neighbouring rooms.

Recirculating or ducted hood: what is realistic in an existing flat

In many Brussels apartments under renovation, a recirculating hood ends up being the only realistic option because no suitable duct is available. This avoids cutting a new hole in the façade or disrupting an existing ventilation unit, but it means accepting that moisture and part of the smells remain in the living volume.

A ducted hood does remove some stale air from the dwelling, but only if the discharge duct is properly designed and if air can enter elsewhere to compensate. If not, the real airflow drops and the nuisance stays, with the added discomfort of under-pressure.

In an existing flat, the useful question is therefore not only "recirculating or ducted?", but also: what ventilation is already installed, where are the air inlets, and how can you avoid the open kitchen acting as a diffuser that perfumes the rest of the apartment after every meal.