The solar-folding-shutter by hilbra after an idea of Prof. Wilfrid Balk has an energetic additional utility confirmed by model experiments which corresponds to an extension of the glas surface of about 30 percent. It is remarkable that the advantages are reached without the disadvantage of an actual extension. Since the window usually is a weekness in the thermal insulation in the outer wall this problem can be made smaller with the solar-folding-shutter. Is the solar-folding-shutter closed it reduces the -value of the window so clearely that it reaches the value of the outer wall. Regarding the termal insulation one aspekt is often neglected; the summer heat. Once the heat has entered the room it can no longer escape just as the warming energy in wintertime. As the solar-folding-shutter is casting a shadow on the window in summer a reduction of the increase of temperature in the room behind is reached. Meanwhile the planing with the sun has been fascinating the collaborators of the enterprise so that they developped the so-called horizontal-folding-shutter which is based on the system of the solar folding shutter. While for the commonly known folding-shutter the utilization is restricted to a socalled hole-facade one can realize modern architecture with the horizontal- as well as with the solar-folding-shutter. Both versions do not need a connecting lateral facade for the opening. The solar folding-shutter only need breast and lintel while the horizontal-folding-shutter just needs the area of the lintel.

Security

The design with the sun was also of high importance concerning the horizontal-folding-shutter. The segments (lamellas) are arranged in a way that the daylight can shine through the shutter when it is open in winter while they cast a shadow like a canopy in summer. In a closed condition the shutter is a protection against glances, sun, and burglary. Are there any security risks concerning these described shutters? There are in fact things to considered. The DIN EN 922 T1 and T2 have been kept aswell as the regulations of the TÜV Berlin. Concerning the electric operation of these shutters the fire protection is an important subject. With the help of a loose-function the shuters can be opened quickly in a case of power failure.