Studies on internal surface heat transfer in the window area

In this paper reporting preliminary results from the ongoing research, heat transfer phenomena at window surfaces and adjacent areas of the building envelopes are studied. In the first step, in-situ observation of balcony door based on indirect estimation of temperature distribution close to window surface was carried out by means of infrared imaging (IR). In the second step, more advanced full-scale experiments were performed in a well-insulated laboratory testing room with floor heating, equipped with one window, under well controlled steady-state conditions. A combination of IR with particle imaging velocimetry (PIV) was used here with extra focus on situation close to the window frame at window sill. In such areas the reduced heat transfer by convection can be observed. As a consequence, the condensation risk free situation there seems not to be always guaranteed even by high performing building components despite the results of standard heat transfer calculations used in design practice