Advanced control of electrochromic glazing

Funding: Swiss Federal Office of Energy (SFOE)
Duration: 2009-2012

Electrochromic (EC) glazings might be used as an alternative to conventional mobile solar shadings or solar protection glazings, which are not well suited to most weather conditions and as a rule not efficient enough against overheating. The EC glazings currently available have a radiation transmission variation range large enough to offer a good protection against overheating, although the protection against visual glare still remains to be improved. EC glazings have until now essentially been actuated manually by the users. Some elementary control schemes have also been proposed, but the time characteristics of these glazings have not been considered: EC glazings take some time to change from the dark state to the bleached state or inversely, typically 5 to 15 minutes. Therefore, a predictive algorithm, like those used for controlling building services, taking into account the thermal inertia, may bring some advantages with regard to user comfort (both thermal and visual). The project includes the development of an adequate control strategy, and the experimentation of this strategy in an office room of the LESO building, with real persons.