SCIENTIFIC REPORT

Aerogel Glazing Systems: A Tentative Performance Assessment

Abstract

This paper reports the study of thermal and optical properties of innovative transparent insulating materials (TIM) for glazing systems: silica aerogel (pane and granular) and capillary geometric media. Twenty-one samples were assembled with several kinds of glasses in various combinations with TIM. The better performance was given by the monolithic aerogel both for light transmittance (0.58 in interspaced between two 4mm float glasses) and thermal insulation (U¼0.63W_m_2 _ K_1). The solar factor was 0.70. The results showed a very promising behavior of TIMs, in fact a 60% reduction in heat losses with respect to a double glazing with a low-e layer was achieved, with only a 27% reduction in light transmittance. For the granular systems, a U-value little higher than 1W_m_2 _ K_1 with the same total thickness was obtained, even if the light reduction was about 66%.

Aerogel Glazing: Transparent Insulating Materials

Introduction

In the 90s, various research on silica aerogels have been conducted to improve the performance of glazing with reinforced insulation (VIR), as part of the thermal regulations. To make insulating glass, the most common solution to this day was to trap air dried between two glasses. Today a new track is given with the development of transparent insulation materials: silica aerogels. Consisting of glass microspheres based porous amorphous silicon dioxide, these gels have a density only slightly higher than a cloud of fog. To get them, we first produced a gel that is structured in a network. Then the gel is dried to form pores filled with air. This gives an aerogel made ??of 99% air for 1% of material with a density of 25 mg/cm3 (Baetens, 2011, 761). These materials can increase their insulation performance being partially emptied below 0.01 atm. Nevertheless, progress to the level of transparency of this type of glazing, but current research, including CSTB, should overcome this disadvantage. When implemented with a low-E glazing, aerogel that can significantly reduce - at least 2/3 - energy losses compared to a conventional double glazing (K = 1.1 W/m2 ° C). But given their reduced transparency, applications of this type of glazing for the moment confined to the domes, glass roof or staircases where the transparent qualities of glass are not essential (Anderson, 2009, 101).

Aerogel in the windows of the twenty-first century

Another highly promising way to improve the insulating properties of glass is the use of translucent insulation of silica air gel as a space filling mezhstekolnogo glass. Silica aerogel is composed of small spheres of amorphous silica, connected to each other in a chain, forming a three-dimensional grid, whose pores are filled with air (AbuBakr, 2008, 720). Aerogel is composed of more than 96% of the air and has pores (average size from 10 to 20 nm) is smaller than the mean free path of air molecules. The remaining 4% - a thin matrix of SiO2 - the main raw material for the manufacture of glass. Aerogel has a specific density of ...