My consultant told me to think of it this way. Stand in a cluttered closet and think how that makes you feel. Now go into an airy room and feel how that feels. Besides space, energy is affected by color. For example, the psychological affect of certain colors has been documented often.
Color can definitely affect mood.
You can evoke the same feelings by adding color to certain places in a room. Color can also make a room feel large or small. Color and how it relates to certain areas of your life is as significant as how the energy flows from and around your belongings. For example, one of the three most important rooms in your home is your bedroom. Here you want soft and soothing colors.