Sources of renewable energy like solar, wind, biomass, fuel cells, etc. should be
utilised as for as possible.
Solar energy can be utilised in various ways to reduce usage of electricity.
Day lighting refers to the lighting of spaces using light from the sun. Light reaching a particular point inside a building may consist of:
(1) Direct sunlight
(2) Diffused light or light from skylights
(3) Externally reflected light
(by the ground or other buildings).
(4) Internally reflected light
from walls, ceiling and other internal surfaces. Louvers may be used to regulate the amount of light entering the building and permit ventilation.
Source of all above images: Handbook on Energy Conscious Buildings