An important factor in the selection of LED lighting is CRI. CRI (colour rendering index) is a quantitative measure to define how accurately artificial lighting represents natural daylight and sunlight. CRI is not to be confused with colour temperature of the product, measured in Kelvin. It is, in fact, a separate, unrelated measure.
CRI is measured on a linear scale from 0 to 100. The higher the value, the better the quality of the colour rendering and less variance there is between the artificial lighting and natural lighting. The number is shown with the letters Ra following it. Ra is the denotation of the measure and is the average of the R values.
R values relate to individual reference colours. This is a predefined colour swatch, universally used to ensure industry consistency. A light source is measured against each of these colours with the resultant quality measured, combined and balanced to give an overall CRI value.
Products with 90Ra+ are extraordinary. They are almost as accurate as daylight in their colour rendering. Museums, art galleries and residential properties are all ideal locations for high CRI. The experience from paintings and artefacts is amplified when they can be seen in as true a reflection of sunlight as possible.
Areas that benefit from fine, precision design and close monitoring of paperwork can also benefit from 90+ CRI, to make the quality and accuracy of work output as great as possible.
All the benefits of high CRI means that shops, supermarkets and other food vendors are often places to see it in situ. Butcheries with meat and greengrocers with fruit and vegetables can all expect to make their produce look more attractive, more vibrant and more enticing to customers.
80Ra+ is high grade and a strong representation of natural colour. General lighting usage in offices and most residential applications is a suitable place to have 80Ra lighting. Under 70Ra is where lighting becomes noticeably distorted and misrepresented, in comparison with natural colour. However, there is sometimes a place for this – like in car parks and general area lighting.
Overall, CRI is an essential part of lighting selection and has a noticeable impact on the environment it’s installed into. For truer representation of natural sunlight and less noticeable shifts between daylight and artificial light, a higher CRI is the method to achieve that.