Block Negative Sun Energy
One more logic about effect of sun energies is if you observe our globe and the sun path. Places closest to sun full year around where the intensity of radiation is maximum e.g. equator belt you will find maximum of health problem dark skins etc and the further you go towards any pole i.e. north or south pole, people will be more fair and healthy. At Micro level, we can take e.g. of India i.e. South India to North India.
Other example of Sun energy. Changes of seasons increases and decrease our energy levels, example we feel more energetic in winter even if the temperature is 35 but in summer at 35, we feel tired very fast because sun is comparatively closer to us in summer than winter due to the changes in the tilt of the axis of the earth.
Vastushastra tenet considers the sun angles and recommends different ways of blocking negative sun energies in summer and also utilizing positive energies in affirmative ways.