Why is my kitchen or bathroom so cold?

What this usually means

Kitchens and bathrooms are the homes of moisture, so they have the strongest extract ventilation — cooker hoods and extractor fans — to remove steam. While that ventilation is essential, it also pulls warm room air out and, unless balanced, draws cold replacement air in from outside and the rest of the house, so the room cools whenever the fan runs and cold air is felt entering. In a leaky home this make-up air arrives as draughts through gaps, chilling the room directly while the warm air it replaces is lost.

These rooms are also full of cold, hard surfaces. Tiles, glass, mirrors, worktops, baths, basins and toilets are all dense, conductive materials that quickly take on the room temperature and feel cold to the touch, and — being cold surfaces — they draw heat from your body by radiation, so the room feels colder than the air temperature suggests. Stepping onto a cold tiled floor or sitting in a hard bathroom amplifies that sensation, which is why these rooms can feel chilly even when nominally heated.

On top of this, kitchens and bathrooms often have little dedicated heating relative to their heat loss — a small radiator squeezed between units, or a single towel rail — and are frequently located on external corners of the house with two or more cold external walls and a window. So the cold is typically a combination: ventilation removing warmth and admitting cold air, many cold surfaces, modest heating, and an exposed position. The remedy addresses each part — balancing the extract and sealing draughts so make-up air is controlled, warming the surfaces with insulation and warm floors, and providing adequate heating — rather than assuming a single fault.

Common causes

Signs and symptoms

Extract ventilation removes air from a room, which must be replaced by make-up air drawn from outside or adjacent spaces. The extracted air is warm room air, so its loss is a direct heat loss, and the incoming make-up air is cooler, so the room's temperature falls while the fan runs. In a leaky home this make-up air infiltrates through gaps as cold draughts, adding a felt chill; in a controlled home it can be supplied deliberately and, with heat-recovery ventilation, pre-warmed, which removes both the draught and much of the heat loss.

Comfort in these rooms is strongly influenced by radiant exchange with their many hard, conductive surfaces. Tiles, glass, ceramics and stone have high thermal effusivity, so they feel cold to the touch and equilibrate with the room temperature, presenting large cold radiant surfaces to the body. Because comfort depends on mean radiant temperature as well as air temperature, a room full of cold surfaces feels colder than its air reading, which is why a tiled bathroom or hard kitchen can feel chilly even when heated — and why warming the surfaces, for example with underfloor heating or insulation, improves comfort markedly.

The heating provision and exposure complete the picture. Kitchens are often heating-poor because wall space is taken by units, and bathrooms may rely on a single towel rail, so installed output can be low relative to a room that loses heat through several external walls, a window and strong ventilation. The building-physics remedy is therefore multi-pronged: control and, ideally, recover heat from the extract ventilation; raise surface temperatures through insulation and warm floors; provide heating matched to the actual heat loss; and seal uncontrolled leakage so make-up air is not an icy draught. Measuring the room's heat loss and ventilation shows how to combine these for a comfortable kitchen or bathroom.

How to warm a cold kitchen or bathroom

Address all the causes together: balance and ideally recover heat from the extract, warm the cold surfaces, seal draughts, and provide heating matched to the room's losses.

1. 01

   Balance the extract ventilation

   Ensure make-up air is controlled, and consider heat-recovery ventilation to remove moisture without the chill.

2. 02

   Warm the surfaces

   Use underfloor heating or insulation to raise the temperature of cold tiled floors and walls.

3. 03

   Seal uncontrolled draughts

   Seal gaps so the air replacing extracted air does not enter as cold draughts.

4. 04

   Provide adequate heating

   Fit heating matched to the room's actual heat loss, not just a token radiator or towel rail.

5. 05

   Insulate the external walls

   Insulate the room's exposed corner walls to cut heat loss and warm the surfaces.

6. 06

   Verify comfort

   Check the room stays warm in use, including while the extractor runs.

How to prevent it coming back

• Use heat-recovery ventilation to extract moisture without losing warmth.
• Warm cold floors and surfaces with underfloor heating or insulation.
• Provide heating sized to the room's real heat loss.
• Seal draughts so make-up air is controlled, not an icy draught.