Does an Opening Rooflight Help Clear Cooking Smells?

Cooking produces two things at once above the pan: moisture, which shows as steam, and the volatile compounds that carry smell, released from oil, spice and browning food as it heats. Both are lighter than the surrounding air the moment they leave the pan, so both climb toward the ceiling together rather than settling anywhere near the floor. A rooflight opened at that ceiling gives the whole rising layer, smell included, a way out that a low-level window on a side wall rarely offers as directly.

This is the same stack effect that clears steam from a bathroom or a landing, covered fully in rooflights for ventilation: purge, trickle and stack effect. What is worth adding for a kitchen specifically is that smell does not need much moisture in the air to travel; a dry fry-up can smell strongly with barely any visible steam, and the rooflight does exactly the same job of pulling that rising air up and out whether or not it is carrying much visible vapour with it.

A cooker hood and an opening rooflight solve the same problem from opposite ends of the room, and neither replaces the other.

A hood sits directly over the hob and pulls air at the source, catching smell and grease before either spreads far from the pan. It is fixed in one position and only reaches what passes close underneath it, so smell that drifts sideways toward a dining table or a sofa in an open-plan room is largely beyond its reach. A rooflight set higher and further into the room clears that wider drift instead, working on the whole volume of air above head height rather than the column directly above the cooking surface. Fitted together, the hood deals with what rises straight up from the pan, and the rooflight deals with what has already spread into the room by the time anyone notices the smell.

In a straightforward, closed kitchen, a hood alone is often enough because there is less room for smell to spread into. The case for a rooflight grows stronger the larger and more open the room is, which in practice is exactly where an opening rooflight tends to be specified anyway: a kitchen extension built as one open volume rather than a separate room behind a door.

Peterborough's newer streets in Bretton, Orton and Werrington carry a lot of single-storey rear extensions built as one open kitchen-diner rather than a separate room, and a Fletton brick terrace extended at the back tends to follow the same pattern: a flat roof over what used to be a yard, opened straight into the original kitchen to make one long room. Cooking smell in that layout has a dining table, a sofa or a whole ground floor to spread into rather than four walls and a door to hold it back, and it will reach curtains, cushions and a sofa's own fabric well before it reaches a rooflight if nothing is drawing it upward.

An opening rooflight set into the flat roof over that kind of extension sits above the whole room rather than above one end of it, so it pulls air from wherever the smell has spread to rather than only from directly under the glass. Where exactly it should sit for that to work well is covered in where an opening rooflight should sit for airflow; for smell specifically, a position toward the cooking end of the room, rather than dead centre of the whole extension, tends to catch more of the rising air before it has had the chance to spread into the seating end.

Steam and smell behave slightly differently once cooking stops, and that difference matters for when a rooflight is worth opening.

Steam mostly stops rising within a few minutes of the pan coming off the heat, once the room's air has nowhere new to draw moisture from. Smell can linger a good while longer, held in the air at a low concentration long after visible steam has gone, and released slowly again from anything it has already settled onto: fabric, wood, even a tea towel left on the rail. That means a purge run only while the hob is on can clear the steam but leave a lower-level smell behind, one that fades on its own over hours rather than being flushed out in minutes.

A rooflight left running for a few extra minutes once the pan is off the heat, rather than closed the moment cooking finishes, clears more of that lingering stage than the same purge cut short. A wall switch or remote makes that easy to judge by eye, and a timed setting through the controller, covered in can an electric skylight be put on a timer?, can be set to run a little past the point anyone standing in the room would think to close it by hand.

Smell that is not carried out through the roof does not simply disappear. It settles onto the nearest soft or porous surface and is released again slowly over hours or days.

• Curtains and upholstery closest to the cooking end of the room
• Wooden cupboard doors and open shelving, which hold smell longer than a sealed worktop
• A sofa or rug in an open-plan room with nothing between it and the hob
• Bedding or clothes in a room directly above a kitchen extension's flat roof, if warm air finds its way up rather than out

A rooflight opened during and just after cooking reduces how much smell ever reaches those surfaces in the first place, which matters more in an open-plan room than a closed one, since there is simply more soft furnishing within reach of the rising air.

None of this asks a household to change how they cook or live in the room. It asks the rooflight to be switched on at the point it can do the most good.

A wall switch by the kitchen door, or a remote kept on a worktop away from the hob, makes opening the rooflight as easy as reaching for a light switch on the way to the cooker, and our guide to how electric opening rooflights work covers the actuator and control options in full. Every quote for a rooflight over a kitchen extension still comes with a sightline sketch, drawn from the table or the worktop, showing the view up through the glass alongside the siting and control choices that decide how well it clears the room. Our electric and opening rooflight installation service covers the sizing and siting for a kitchen extension of any layout.

Does a rooflight clear smell as well as opening a window?

A window low in a wall relies partly on a breeze to move air through it, while a rooflight at the top of the room is driven by the temperature difference between inside and out, so it keeps pulling rising air, smell included, on a still day when a low window barely moves at all.

Do I still need the cooker hood if I have an opening rooflight?

Yes. A hood pulls air and grease from directly over the hob before it spreads, while the rooflight clears the wider room once smell has drifted into it. The two are specified together in a kitchen extension, not as alternatives.

Will an opening rooflight get rid of strong cooking smells like fish or curry?

It will clear them faster than a closed room manages on its own, since the rising air carrying that smell has a direct route out at the highest point of the room. How much lingers afterwards also depends on how long the rooflight is left open, and how much has already settled into soft furnishings nearby.

Should the rooflight be left open all the way through cooking?

Running it during cooking and for a few minutes after tends to clear more of the smell than closing it the moment the hob goes off, since a fair amount lingers at a lower level once the strongest steam has cleared.