Colour temperature by room

A bulb is chosen not in watts (which measure consumption) nor in lumens (which measure intensity), but in Kelvin (K), which measure colour temperature.

The lower the Kelvin value, the warmer the light (pulling toward yellow and orange). The higher it is, the cooler it becomes (pulling toward blue). At 2700 K, you have candlelight. At 6500 K, you have noon daylight in summer.

Every room has its right temperature, depending on its use. Rest rooms demand warmth, precision rooms demand neutrality, technical rooms demand cool.

Living room. 2700 K for general and ambient sources. If you read a lot, add a task source at 3000 K (a reading lamp). No higher, otherwise the atmosphere tips into the clinical.

Bedroom. 2700 K everywhere. Strictly nothing above 3000 K, otherwise you disrupt melatonin production and sleep. Bedside lamps, sconces, ceiling light, all at 2700 K.

Dining room. 2700 to 3000 K, with a dimmer mandatory. A meal needs warm light that flatters faces and food. A pendant above the table at 2700 K is ideal.

Kitchen. Two distinct zones. General light at 3000 K (warm versatile). Worktop light at 3500 to 4000 K (neutral, to see food colours and work without eye strain). Dedicated strips or spots under the wall units.

Bathroom. 3000 to 4000 K around the mirror, never lower. At 2700 K, your complexion appears yellowish and you cannot apply makeup or shave properly. Elsewhere (shower, bath, general ceiling light), 3000 K is fine.

Study / reading corner. 3000 to 4000 K for direct task light. 2700 K for general ambient to avoid fatigue. The combination gives comfort over long hours.

Entrance, hallway, dressing room. 3000 K, versatile. Avoid 4000 K, which makes an arrival feel cold and unwelcoming.

Interior designers work almost always in 2700 K throughout residential spaces, except precision zones. It is the temperature that best flatters materials: patinated wood, leather, linen, stone. An open fire burns at around 1800 K, so does a candle. This warm cultural anchor is what makes 2700 K so comfortable.

CCT LED bulbs (variable temperature) now allow the temperature of the same bulb to be modulated according to the hour: 2700 K in the evening, 4000 K in the morning, in a bedroom, to respect biological rhythms. Higher cost, but useful in multi-function rooms.

Joseph Dirand sometimes pushes to 2200 K in certain living rooms, almost the colour of a candle. Very enveloping effect, but requires many sources to compensate for the perceived lack of visual intensity. Reserved for very precise atmospheres.