What is a colour temperature?Unsurprisingly, when it comes to artificial illumination, there are many different "types" of light. Many people recall that when Compact Fluorescent Lamps (CFLs) were first introduced to homes there were many complaints that the light seemed much "colder" than traditional halogens. This is because they had a different colour temperature.Colour temperature is one of the main characteristics of visible light and determines how warm or cold the light is. All colour temperatures are assigned a number called a Kelvin Rating. Colours with lower kelvin ratings are generally warmer while those with higher kelvin ratings are cooler.Warm colours are very soft with a slightly yellowy tint and are a close, but not perfect, replication of traditional halogen bulbs. Cool colours are very bright with a faint blue tint and are sometimes compared to the light given off by fluorescents.Which works well where?While colour temperature is a largely subjective matter and many customers have personal preferences to satisfy, there are a few "rules of thumb" which can help you to decide.Due to its softness, Warm White is generally better for creating ambient/general light schemes. It is also good at promoting a relaxing and comfortable environment, so should also be used in "habitat" or "living" spaces. These may include the living room, bedroom, hallways or dining room.Cool White is more commonly used in public spaces, such as offices and shopping centres. It has a tendency to be too bright for general illumination, resulting in a room aesthetic that is too clinical for some. However, it is not uncommon to find this type of light used in kitchens and bathrooms as it works well with reflective and pearl surfaces. Feature and task lighting also benefit more from the brighter cool white, particularly as it helps to promote alertness. If you have a home office you might consider using it in there to help you concentrate.Using the two colour temperatures in combination with one another can sometimes create quite spectacular results. You will find this particularly with "layered" or "dual purpose" light schemes. For instance, in an art gallery, warm white would be used to create soft background ambience while cool white LED GU10 Spotlights could be used to highlight artwork.