Roller shutters are characterized by a curtain made of many horizontal profiled bars (mostly made of aluminium, plastic or wood) hinged together. These can be raised to open and can be closed tightly for solar protection and darkening purposes; to some extent, roller shutters also fulfill some of the security requirements of the user. The entire curtain can be raised, for instance when there is no direct solar radiation or if free solar gains should be used. Special designs may have adjustable slats (similar to blinds) or special profiles to ensure that more natural daylight is utilized better. Roller shutters are very efficient passive shading systems that can be adapted well to the outside climatic conditions (height adjustable).
If solar radiation is too strong, more than 85% of the incident sun energy can be blocked (reflected and absorbed) from the interior of the building drastically reducing the use of active cooling systems.
During the heating period, significant solar gains can be achieved as the shutter can be deactivated (retracted).
Roller shutters, in connection with motorized drives, a well designed control system and openable windows ensure that no or only little cooling energy is required during the day, while ensuring efficient cooling at night; besides, they provide the necessary protection of the private sphere.