The possibility of shading a room and the existence of natural lighting in it, functions efficiently in the reduction of pollution of the environment, creates a desirable lighting quality and isolates the undesirable charge of heating, in a way that it increases the energy consumption from the air conditioning installations. 

The incorporation of shading and lighting systems in buildings is based on human dimension and aims at the improvement of the thermic and optical comfort, the restriction of the direct and diffuse solar radiation imported in the building and the fair distribution of brightness derived from the sun, the sky, the buildings and the ground. Moreover, it gives solutions to the cost of energy consumption for the coverage of human needs. 

The parameters, based on which a shading and lighting system is selected are the following : 

1. The amount of natural lighting that enters in the interior of the building, 

2. Its distribution to the building, 

3. The possible existence of places of intense lighting in the room,

4. The construction and placing cost.

The planning of such systems influences considerably the Architectural planning of the building.  The openings in the facades of a building, its orientation and the internal arrangementof its rooms and objects will follow system’s possibilities.

The existence of openings in a room offers people the possibility of having a view to the surroundings of the building and consequently the possibility of conceiving the exterior conditions of brightness and temperature.

            Due to the abovementioned reason, furniture orientation in a room depends on the existence of windows in it. Therefore, the more removed the work surface is from the windows, the most efficient the work is carried out. It has been proved that the sunbeams that enter in the interior of a working place and crash into the work surface (screen of computer), become bothering creating sight problems (dazzling).  

Nevertheless, the availability of natural light which is determined by the geographic width of building’s area and the environmental conditions the (eg the presence of obstacles) should be taken into consideration during the windows planning. The climate of each region

also influences considerably the building’s planning. Thus the seasonal and prevailing climatic conditions (environmental temperatures and sunlight probability), are basic criteria in the designing of the system.

It is likely that shading and lighting systems constitute part of the building, externally or internally his facade, or in the windows, between the glass panes. In every case the solar radiation is prevented, completely or partly. The exterior shading systems are considered effective in preventing the concentration of solar profits in the interior of the building, while the internal shading systems, that use special coatings of reflective materials, can reflect solar beams and transport part from the solar profit in the interior of the room at the same time.

Finally, as far as the evaluation of these systems is concerned, most of the methods that are used are based on the calculation of solar profit in space (g - VALUE solar profits factor), the internal lighting levels ( Tvis - VALUE  solar penetrability) and the shading factor (the amount of solar radiation that is imported via the shaded glass pane).