On over 85 per cent of days in a year, enough sunlight is produced between the hours of 8 a.m. and 5 p.m. for it to be directed inside buildings and provide perfectly adequate lighting. Daylight structures are the best systems for such purposes as they guide light into the room from above and fully exploit the position of the sun. Interiors are thus brightly lit using daylight in a particularly harmonious and uniform way.

Numerous calculation methods have proven that energy costs for electric lighting can be greatly reduced if natural light is used.

Example:
According to DIN 5034, a hall which covers an area of 800 square metres and is 8 metres high has 101 square metres of overhead rooflight space at its disposal (12.6 per cent of its total roof surface). Without daylight systems, energy costs in such a hall total 6,000 Euros per year. If such systems are used, costs can be brought down to 1,800 Euros a year.
(Source: FVLR – German Daylight and Smoke Protection Trade Association)