When talking about comfort and security in industrial, commercial and tertiary buildings, both new and to be recovered, one of the greatest problems is to guarantee a good natural illumination of interiors.

In such buildings it is seldom possible to provide a good illumination exploiting just the external vertical walls.

As a consequence the daylight can be collected from the roofing just through systems, which do not suit the same roofing or do not guarantee its waterproof; in addition many problems can arise from the heat loss or, on the contrary, from the entrance of excessive heat caused by solar radiation.

The more one allows natural light to penetrate into the buildings, the more one lets sun radiation and UV rays enter the internal rooms, causing excessive heating and making the rooms unbearable to live in. This problem can be solved just by air conditioning systems with increased performance and power. On the contrary, limiting the openings towards the outside to cope with the excessive sun radiation, it is inevitable to have environments constantly lit by electric lighting, even during daytime.

Such systems for the design of natural lighting are by now obsolete and have shown the direct and indirect damages they cause to man and the environment. To correct these alterations the newest architectural laws require buildings not to be just casings designed to be lived in, but also casings designed not to disperse natural energies or those produced for their own utilization; these recent buildings are partially or totally self-sufficient in energy production they need to be lived in.

Unfortunately any source of alternative energy causes an unavoidable environmental impact, hence the need for an integrated planning to foreseen, before any energy source, A REAL SAVING OF THE ENERGY NEEDS.

The exploitation of a natural lighting system, rather than an artificial one, provides considerable physical, mental and economic benefits, other than a significant energy saving and a reduction of environmental emissions.