What do we mean by interior design?  Well it is the absolute difference between outside, garden design from that needed for the exterior area of the house.  Once inside, there is a need to take into account who is going to be living there – age group, number of folk etc.  Light requirements often get overlooked but are critically needed.   It’s no good allowing windows to exist but not be of great benefit to the residents.  If you look around a room and maybe sit on the sofa reading at various times of a normal day, it’s very obvious that some times of the day it will be difficult to read and work without artificial light.  However if the room is designed in such a way that all the light available is used more effectively, then it is instantly more successful.   Light will bounce off walls and ceilings.  So there are times when using curtains and window blinds.  The optimum colour is that which warms the room when cold, cools the room when hot and is kind on the eyes.