ABSTRACT The path toward energy-efficient buildings with a low or zero carbon footprint, e.g. zero energy and zero emission buildings, involves the development of high-performance thermal insulation, aiming at reaching thermal conductivities far below 20 mW/(mK). Applying such superinsulation will allow the construction of relatively thin building envelopes yet maintaining a high thermal resistance, thus also increasing the architectural design possibilities. A vacuum insulation panel (VIP) represents a stateof-the-art thermal insulation solution with a thermal conductivity of typical 4 mW/(mK) in the pristine and non-aged condition. However, the VIPs have issues with fragility, perforation vulnerability, increasing thermal conductivity during time…

Abstract The potential of silver (Ag) nanoparticles as low emissivity (low-e) coating materials for window glazing applications has been discussed. Ag nanoparticles were prepared via a wet chemical method and applied on the surface of flat glass through spin coating. A mild heat treatment at 200°C was employed to achieve the low-e effect, which results in a total surface emissivity of about 0.015, compared to about 0.837 of the plain glass substrate. By applying such low-e coatings, the heat loss through a single-glazed window pane could be reduced by about 45% (U-value from 5.75 to 3.18 W/(m2K)).

Abstract Sodium tungstate (Na-WO3) nanorods with typical diameters of 10-200 nm and lengths of several microns were prepared via hydrothermal synthesis. X-ray diffraction showed that the material crystallized in a hexagonal phase (space groupP6/mmm) with unit cell dimensions of a = 7.3166(8) Å and c = 3.8990(8) Å. The as-prepared Na-WO3 nanorods showed a distinctive visible-light-driven photochromism related to a proton-electron double injection process. The involved localstructural evolutions were monitored by Fourier transform infrared (FTIR) and Raman scattering spectroscopy. One diagnostic FTIR absorption at 585 cm-1 and one Raman band at 813 cm-1 were identified and assigned to the O-W-O stretching vibration. These two modes were strongly affected by the…

Abstract Electrochromic materials (ECM) and windows (ECW) are able to regulate the solar radiation throughput by application of an external electrical voltage. Thus, ECWs may decrease heating, cooling, lighting and electricity loads in buildings by admitting the optimum level of solar energy and daylight at any given time, e.g. cold winter climate versus warm summer climate demands. It is crucial to be able to compare the dynamic solar radiation control for different ECWs and hence require specific ECW properties. The solar radiation control for ECWs may readily be characterized by several solar radiation glazing factors, where a comparison for various ECW configurations enables one to select the most appropriate ones for specific smart…

Abstract The application of superinsulation materials (SIM) reaching thermal conductivities far below 20 mW/(mK) allows the construction of relatively thin building envelopes while still maintaining a high thermal resistance, which also increases the architectural design possibilities for both new buildings and refurbishment of existing ones. To accomplish such a task without applying vacuum solutions and their inherit weaknesses may be possible from theoretical principles by utilizing the Knudsen effect for reduced thermal gas conductance in nanopores.This study presents the attempts to develop nano insulation materials (NIM) through the synthesis of hollow silica nanospheres (HSNS), indicating that HSNS may represent a promising candidate or stepping-stone for achieving SIM. Furthermore, initial…