When you are shopping for light bulbs, you may see CRI on some labels i.e. the colour rendering index. Colour rendering index or CRI is the measurement of how well a lamp illuminates colour. It is not a measurement of brightness but more an indication of how sharp colours will appear under its light.
What is the CRI? The CRI must not be confused with CCT lighting which stands for correlated colour temperature. Both terms are related but represent different qualities of a lamp’s light. CCT is a measurement of a light given off by the lamp itself. When someone talks about cool white light or warm white light, then they are pointing towards the colour temperature of the light or the CCT.
The manufacturing companies make use of CRI Colour Rendering Index values to show the quality of light a bulb produces and the accurateness of the colour looks like under that light source. CRI is determined by comparing light sources of the same CCT or the colour temperature against a reference source with a CRI of 100. The testing method evaluates the light source's ability to render eight standard pastel colours.
The difference between the light reflected by the test source and the light reflected by the reference source gives the numeric CRI value. For many people, the CRI value of close to 100 indicates a better appearance of colour under it.
The colour rendering index ranges from 1 to 100 per cent indicating how perfect a particular light source is at interpreting colour when compared to a "reference" light source. The CRI of 100 is the best and that is the natural sunlight. It is how accurately it reflects the colour. The higher the CRI value, the better the colour rendering capacity. The 50 to 70 of CRI is considered fair, 70 to 80 is better and the best is between 80 to 100.
What does Colour Rendering Index mean?
The Colour Rendering Index must not be confused with the colour temperature of the light source. The colour temperature is calculated in Kelvin and shows how cool or warm the lighting is. Conversely, CRI is less dependent on such variables. For many places and people, the greater the CRI, the better the colour rendering capacity.
What is the Colour Rendering Index? CRI is the measure of how correctly the artificial light source shows the colours of the people or objects under them. With the help of a numerical scale from 1 to 100, CRI measures the colour rendition and accuracy of objects various light sources in contrast to how those objects will appear under natural sunlight or incandescent lights.
What is a good CRI value for a light source?
As we know that the colour rendering index is measured on the scale between 0 and 100. At 0 CRI, all colours appear the same while the 100 CRI indicates the actual colours of the objects. Halogen lights and incandescent lights have a CRI of 100. Generally, the light sources with s VRI values between 80 and 90 are considered as good and those having more than 90 CRI values are excellent. You can follow a simple rule i.e. the higher the CRI value, the better the colour rendering ability.
There is no link between CRI and colour temperature. Both of them are different things and are independent of each other. For instance, a 5000K fluorescent light source i.e. daylight colour temperature can have a CRI of 90 while another 5000K fluorescent light source could have a CRI of 75.
Why the colour rendering index is important?
The CRI is an important factor in almost any space ranging from your home to your office. A light source with a low CRI value will bring washed out and flat hue to the objects it illuminates. When it falls on objects, they look dull and drab-coloured. For people, it simply means sick skin tones and lifeless unappealing eyes.
On the other hand, a light source with a high CRI value can impart a vicious and exciting life in your ambience. High Colour Rendering Index will pop the colours of your clothing, furniture, food, and all other objects in the surrounding, adding a rich delicacy to the design display you have set. Light bulbs with high CRI will provide people with a glowing healthy look and rich skin tone.
A high CRI value is especially important for colour-critical environments where the presentation, visual appeal, and colour accurateness is crucial to a business. This comprises the grocery stores to help make the food look appealing, retail stores to highlight vibrant clothing, and in the real state while creating an appealing and vibrant look to the home to sell it.
CRI and LED light bulbs
Recently, the LED bulbs have gain popularity, primarily because of their energy efficiency and bright light generation. Most of the LED lights give a CRI Colour Rendering Index value of about 80 to 90 on the scale. As a result, LED creates a brighter room but with an accurate and natural output of light. Contrary to fluorescent light bulbs which can produce an unnatural look, LEDs are well suited to indoor environments. Besides CRI, the number of lumens output or real light generated plays a vital role in the overall effectiveness of the LED light bulb too.
Why Colour Rendering Index is becoming more important?
At the age of incandescent light sources, the colour rendering index was not such a great deal as the incandescent bulbs provide great colour rendering. Then the time came when incandescent bulbs start to disappear from the scene because of their poor energy efficiency. At the start, they were substituted by fluorescent lamps that are more energy efficient. Nowadays, LED bulbs are becoming a widespread alternate to fluorescent lights.
LED light bulbs have been glorified for their higher energy efficiency even in contrast to energy-stingy fluorescents. Such light sources also come with other advantages like a longer lifetime. Also, they have no harmful mercury and do not shatter. So the lighting trend is shifting from fluorescent to LEDs that is why is CRI Important in lighting.
