People employed in building offices have new needs in terms of comfort at the working place. To satisfy these needs, it is necessary that architects check carefully the efficiency of the corresponding new systems that they conceive in order to improve these people working conditions. This study shows that it is possible to optimize the sizing up of the different elements of an office cell front (envelope) containing, in addition to the glass wall, sun-breaker strips and an electrochromic protection. For that purpose, the inverse simulation technique was used thanks to several programs.