The colour of light is an important issue when selecting the lighting, which should be adjusted to the individual needs of the user, as it affects the mood and comfort of use. Cold light helps to concentrate, and with warm colours we can rest in a great way. The colour of light, which is expressed in Kelvin unit, should be adjusted to the type and purpose of the room. Warm colours are best suited to interiors such as: living room and bedroom, and cold ones to the office.