Legal regulations
The UK Health & Safety at Work Act of 1974 states that an employer has to ensure the health & safety of employees. The Act also includes a duty to provide adequate lighting to ensure work is undertaken safely. It also states that an employee's eyesight or health mustn't be jeopardised. Regulation no.8 of the Workplace Regulations Act 1992 specifically states that employers must ensure:
- Every workplace should have suitable & sufficient lighting
- This should be natural light, where possible
- Emergency lighting should be provided where needed
For complete guidance on legislation around the amount of light needed in UK workplaces within the UK, please visit the Health and Safety Executive in HSG 38: Lighting at Work website to download the full regulations.
Light colour / colour temperature
The light colour or colour temperature is measured in Kelvin (K) and describes the individual inherent colour of white light, generally perceived as "cool" or "warm". The specification of the light colour in Kelvin should not be confused with colour-changing lighting technologies (RGB), in which light can shine in red, green or blue. A rough distinction between the three light colours is:
- Warm white (<3,300 Kelvin) = cosy light for living spaces
- Universal white (3,300 - 5,300 Kelvin) = light for working
- Daylight (> 5,300 Kelvin) = bluish light for basement and utility rooms
Colour rendering / CRI
The colour rendering index (CRI) indicates how natural the colours of an object appear when a light is switched on.
A CRI of Ra 100 means that colours are reproduced as they would be in daylight. Ra >= 90 indicates very good, Ra >= 80 good colour rendering. Bulbs below Ra 80 are not recommended for living spaces, as colours can be distorted or rendered greyish.
