Abstract
Shading systems are widely used, also in Nordic climates, in conjunction with glazed facade in office buildings. The primary functions of the solar shading devices are to control solar gains leading to cooling needs during operational hours and reduction of discomfort caused by glare. A secondary property of shading devices incorporated in glazing units is that they can be utilized as an additional layer in the glazing unit when the shading device is deployed. This can improve the thermal transmittance value (U-value) of the windows. It can be deployed during night-time or in periods when a blocked view does not have any consequences for the users of the building. This article presents hot-box measurements of thermal transmittance values (U-values) performed for three insulated glazing units with integrated in-between pane shading systems. The shading devices are venetian-type blinds with horizontal aluminum slats. The windows with double- and triple-pane glazing units have motorized blinds. The window with a 4-pane glazing has a manually operated blind placed in an external coupled cavity.
The measurements are compared to numerical simulations using the WINDOW and THERM simulation tools. The results showed that only minor reductions of U-values of the glazing units were obtained as function of shading system operation. It was, however, found that the introduction of shading devices in the window cavities will increase the total U-value of the window due to thermal bridging effects caused by shading device motor and the aluminium slats of the blinds. coupled cavity.
Abstract
The application of traditional thermal insulation materials requires thicker building envelopes in order to satisfy the requirements of the emerging zero energy and zero emission buildings. This work summarizes the steps from the state-of-theart thermal insulation materials and solutions, like vacuum insulation panels (VIP), gas-filled panels (GFP) and aerogels which all have various drawbacks, to our concepts and experimental investigations for making superinsulation materials (SIM) like e.g. nano insulation materials (NIM).
Abstract
Glass represents an important and widely used building material, and crucial aspects to be addressed include thermal conductivity, visible light transmittance, and weight for windows with improved energy efficiency. In this work, by sintering monolithic silica aerogel precursors at elevated temperatures, aerogel glass materials were successfully prepared, which were characterized by low thermal conductivity [k ≈ 0.17–0.18 W/(mK)], high visible transparency (Tvis ≈ 91–96 % at 500 nm), low density (ρ ≈ 1.60–1.79 g/cm3), and enhanced mechanical strength (typical elastic modulus Er ≈ 2.0–6.4 GPa). These improved properties were derived from a series of successive gelation and aging steps during the desiccation of silica aerogels. The involved sol → gel → glass transformation was investigated by means of thermo-gravimetric analysis, scanning electron microscopy, nanoindentation, and Fourier transform infrared spectroscopy. Strategies of improving further the mechanical strength of the obtained aerogel glass materials are also discussed.