Thermal Insulation Materials are installed in commercial buildings owing to their sound- and heat-resistant properties

 

Thermal Insulation Materials

Thermal Insulation Materials are natural materials made of aligned nanocellulose fibers and could be a promising alternative. They are light and strong, and their anisotropic structure allows for more efficient heat conduction along the fiber direction. Moreover, their anisotropy prevents localized overheating. For instance, in May 2022, researchers at the University of Göttingen, Germany, developed wood-based thermal insulation materials to cool commercial and residential buildings.

Granular insulation consists of tiny nodules surrounded by a binder. Thermal Insulation Materials can be either loose or interconnected. Some common granular insulation materials include calcium silicate, expanded vermiculite, cellulose, diatomaceous earth, and expanded polystyrene. However, some materials have been found to be hazardous to human health. In addition, vermiculite and perlite were once common options for insulating buildings.

Natural fiberboards are another alternative for Thermal Insulation Materials. Although they are relatively light in density, wood-based fiberboards have high thermal resistance. However, their sensitivity to environmental changes makes them a poor choice for high-rise buildings. Furthermore, their internal structure is porous, allowing the thermal conductivity to increase by 50% when heated or cooled.

The NIM and ECM activities are designed to develop high-performance thermal insulation materials. These materials will feature high thermal resistance and thin insulation thicknesses. Electrochromic materials are another type of material that may be of great interest in the near future. They could provide smart windows by regulating solar radiation throughput dynamically.

When tested, thermal insulation materials have shown a low thermal conductivity at ambient pressure. However, this deteriorates when pressure increases. At 50 mbar, for instance, silica aerogel has a thermal conductivity of 0.004 W/ (m.K), which is much lower than its ambient temperature. However, the aerogel's effective thermal conductivity increases nonlinearly with pressure. The study also showed that the aerogel's thermal conductivity increases nonlinearly with pressure.

While thermal conductivity can be measured in different ways, the standard ASTM C518 provides only a partial picture of the effect of insulation on building energy. The standard only provides values that have been determined under standardized conditions. In reality, the actual values vary widely; they are the exterior temperature, air velocity, and humidity. Thus, the results are not a guarantee of insulation efficiency.