9.1. Target object
The window model corresponds to the actual window used for the validation measurements of the method (see chapter 8). The model comprising the window-reveal, window-frame, triple-glazing and Venetian blinds represents a commonly used building detail of modern constructions. Despite appearing simple at first glance, the detail is, in fact, very complex from an optical point of view. The incoming direct and diffuse radiation is first scattered at the surfaces of the blinds, where a fraction
of the irradiance is reflected towards the glazing. The glazing consists of three glass panes, the first and the last of which are coated with a low-E-film on the side facing towards the inner glass pane. The entire configuration, consisting of the blinds, two coated glass panes and one uncoated glass pane, gives rise to a series of interreflections among the different layers. Finally, a significant fraction of the irradiance is absorbed in the four layers, while a part is transmitted into the interior. In order to accurately determine the total transmitted power (or energy), a detailed knowledge of these five energy flows is essential, as not only the directly transmitted irradiance but also the secondary heat flows will contribute significantly (see also section 3.1). Therefore, the model is well suited to demonstrate the advantages of the RadiCal method, which allows for accurately determining transmittance and absorptance for any parts of the target objects. The window’s specifications can be found in Table 25; a RadiCal rendering of the window is presented in Figure 116 (section 7.11).