Transparent active envelopes are nowadays widely used. As their thermal and fluid dynamics behaviour is very complex, it is very important to obtain more detailed knowledge about their performances through laboratory measurement campaigns, where test conditions and operative parameters can be controlled and changed over a wide range of values. For this reason, an experimental test facility (TWINS - Testing Window INnovative Systems) was designed and built at the Department of Energy at the Politecnico di Torino in 2004. TWINS allows measurements in continuous, thanks to about 70 sensors connected to a datalogger, of the energy consumption, indoor air temperatures, heat fluxes, surface temperature distributions, air temperature distribution and air flow rate of two transparent façades (one used as a reference) with various glazing and shading devices mounted and managed according to different ventilation strategies. In this paper the monitoring activity and the first results are presented.