Control systems
A large variety of glazing or selective coatings is proposed by the manufacturers, some of them devoted to protect internal spaces from excessive light, reducing the brightness glare of the glazing and heat with respect of luminous performance.
Three innovative trends are particularly attractive :
an active control of transmittance, an angular selective coating, obtained thanks to anisotropic coatings, a light scattering or deviation surface e.g. prismatic surfaces which displace the incident light sideways, arrays of microlens which act as controlled diffusers, etc.
An important advantage of fixed shading devices is that they are passive or self operating. However they have an impact on the aesthetic of the facades and must be robust enough to resist snow loading.
Orientation, inclination and geometry of fixed overhangs and fins must be carefully analysed .

Movable shading control systems are more responsive than the fixed shading devices, but their movement mechanisms can present installation and maintenance problems.
For external ones, weather implies some robustness constraints and sometimes some control implications.
Combination of a movable outdoor shading device and an indoor light blind offers best opportunities to control solar gains all year long.