What is CCT?
When we speak about CCT with regards to lighting, we are referring to the colour of the white light. CCT is only applicable to white light, and is not used for colours like red, green, or blue. CCT stands for correlated colour temperature, which is how we can tell what sort of white light a product will produce. CCT is only a measurement of the colour of light, this has nothing to do with the brightness (Lumens) or light quality (CRI).
Why is CCT important?
The colour of light has been proven to have a direct effect on the human brain. For example, a warm white light (2000k-3000k) will have a calming effect, and therefor is ideal for places like bedrooms, loungerooms, & restaurants. Whereas a Cool White light (4000k-6500k) has a stimulating effect, and is therefore ideal for places of work, or where concentration is required. For example, office lighting in Australia is mostly 4000k, and many retail supermarkets use a 4000k or 6000k light source as it is beneficial to have stimulated customers or staff.
In typical day to day lighting design practice for residential and commercial lighting, you will typically only see products being used in the range of 3000k(Warm white) to 6500k(Daylight). Some specialist architectural applications where a very warm inviting atmosphere is required, you may see some products being used below 3000k. For example, a bar or restaurant may use a combination of 2700k LED strip lighting in the bar area, together with some low glare 2700k downlights to create a warm, inviting, and calm environment. You may also see some products being used above 6500k in the signage or aquarium industry, however this high CCT over 6500k will very rarely be used in architectural lighting.