Thermal performance of an electrochromic smart window tested in an environmental test cell

This paper describes the results of experimental tests and computer simulation modelling aimed at evaluating the performance of an electrochromic (EC) window with respect to solar control in buildings. The research is carried out by a test-cell equipped with a small area EC double glazing unit (EC-DGU) where one pane consists of an EC device and the other of a clear glass. The performance of the device on global light transmittance control, internal temperature control and solar heat gain control, is investigated in summer-time under real sky conditions as a function of time, test-cell orientation and switching strategies (static and dynamic). Both experiments and numerical analysis show that the decrease of the heat load affecting the test-cell, normalized respect to a clear float glass, is maximum when the EC-DGU is set to its lowest transmitting state and amounts to about 50% for west orientation and about 60% for south orientation. In this latter, thermal load reduction registered when the EC DGU is driven in the dynamic mode (31%) is similar to that of a reflective low-e glazing.