Home Lighting: Colour Temperature, Brightness and Getting It Right

Lighting is the cheapest change that alters how a room feels, and the one most often got wrong — usually by treating a single ceiling fitting as the whole plan.

The numbers that replaced watts

• Lumens measure brightness. This is what replaced watts as the useful figure.
• Watts now measure only energy used, which with efficient bulbs is a small number and tells you nothing about output.
• Kelvin measures colour temperature. Lower numbers are warm and yellow; higher numbers are cool and blue-white. Around 2700K is the familiar warm domestic light; daylight-white options sit considerably higher.
• Colour rendering index describes how accurately colours appear under the light. Higher is better, and it matters in kitchens, bathrooms and anywhere you look at fabric, food or your own face.

Match colour temperature across a room. Mixing warm and cool bulbs in one space looks like a mistake, because it is one.

Layering

A single overhead light produces flat, unflattering light and heavy shadows. Rooms work when light comes from several places at different heights.

• Ambient — the general fill. Ceiling fittings, or uplighting.
• Task — where you actually do things. Reading, cooking, working. Brighter and directed.
• Accent — the layer that makes a room feel considered. Lamps, shelf lighting, anything low.

Two or three lamps on a switched circuit will improve a living room more than replacing the ceiling fitting.

Room by room

• Kitchen — bright, with high colour rendering, and task lighting under wall units so you are not working in your own shadow.
• Living room — warm, layered, dimmable.
• Bedroom — warm and low, with a reading light at the bed that does not disturb another person.
• Bathroom — high colour rendering, light at face height beside a mirror rather than only above it, and fittings rated for the moisture zone they sit in.
• Hallways and stairs — even, with no dark patches on steps.

Dimming

Not every efficient bulb dims, and those that do need a compatible dimmer switch. A mismatch causes flicker, buzzing or a bulb that only dims part of the way. Check both the bulb and the switch, since this is the most common lighting complaint after replacing older bulbs.

Smart bulbs

Useful for changing colour temperature through the day and for scheduling, and they add a dependency: they need power at the fitting, so a wall switch turned off makes them unreachable. Consider a smart switch instead where a room has several bulbs, which is usually cheaper and keeps normal switching working.

Before you order

Check lumens rather than watts, and keep colour temperature consistent within a room. Check the fitting type and the physical bulb size, since some fittings will not accept a larger bulb. Check dimmer compatibility if the circuit is dimmed. And check the moisture rating for bathroom fittings, which is a regulated requirement rather than a preference.