Cooking Without Steaming Up Your Home

The water you boil never disappears — it just moves into your air. One dinner with a simmering pot, a steaming pan and a kettle can release a fair fraction of a litre of water as vapour, and all of it has to land somewhere. Usually that somewhere is your windows and your coldest walls.

Where cooking steam actually goes

Steam is only visible in the plume above the pot. Once it mixes into the room it becomes invisible water vapour, drifting through the open kitchen door and spreading into every connected room. Air can only hold so much water at a given temperature, so when that moist air touches a cold surface — window glass, an uninsulated corner behind a wardrobe — the water comes back out as condensation.

That is why a big cooking session shows up as fogged windows the same evening, and as black spots in cold corners months later. The kitchen is one of the main moisture sources in a home, alongside showers, indoor laundry and simply breathing — together a household releases roughly several litres of water per day into its own air.

Cut the vapour at the source

The cheapest moisture you’ll ever manage is the moisture you never release:

• Put a lid on it. A covered pot loses far less water to the room — and reaches the boil faster, on less energy.
• Simmer instead of rage-boiling. Pasta cooks at a gentle boil just as well as at a rolling one; the extra bubbling mostly converts your tap water into room vapour.
• Use less water. A half-filled pot has less to evaporate than a brimming one.
• Run the hood — if it vents outside. An extractor hood that ducts to the outdoors removes steam for real. A recirculating hood only filters grease: the water sails straight through the filter and back into your kitchen.

Contain it, then vent the kitchen only

Shut the kitchen door while you cook. It sounds trivial, but it keeps one room’s problem from becoming the whole home’s problem: the vapour stays where the extraction is, instead of migrating to the bedroom where it will meet a cold window at 2 a.m.

Then air the kitchen itself — short and wide, not long and tilted. A few minutes with the window fully open swaps out the humid air without cooling down the walls, the same logic as the German Stoßlüften method. Do it while cooking or right after, while the vapour is still airborne and hasn’t soaked into surfaces.

The window trap: check what the outdoor air holds

Opening while you cook is the right move most of the time — but not always. The catch is that relative humidity lies. Warm afternoon air at 35% RH can carry more actual water, in grams per cubic metre, than cool air at 90% RH, because warm air can hold far more water in the first place. The honest comparison is absolute humidity, not the percentage.

If the air outside holds more water than the air inside — a muggy summer evening, say — opening the window imports moisture faster than your pot produces it. On those days, the lid, the ducted hood and the closed kitchen door do the heavy lifting, and the wide-open window waits for drier outdoor air.

Let the app watch for you

Comparing indoor and outdoor absolute humidity before every pasta night is nobody’s hobby. Open/Shut does the comparison continuously and tells you when opening the window actually dries your home — and when it would quietly do the opposite. Free, private, no account.