B.P. Jelle, T. Gao
Norwegian University of Science and Technology (NTNU) / SINTEF Building and Infrastructure,
Norway
Keywords: aerogel, thermal conductivity, transmittance, lightweight, solar radiation, multi-functional, building envelope
Summary:
In the world of today there is a growing focus on and demand for energy-efficient materials and systems for the building envelopes being developed, e.g. exemplified through zero emission buildings and energy-producing buildings. One of these promising materials and systems is represented by aerogels. The aerogel material achieves its very low thermal conductivity through a highly porous and air-filled low-density silica skeleton with a typical air concentration as high as 95-99 vol%. Furthermore, the aerogel material exhibit the unique feature of being able to be produced as either an opaque, translucent or transparent material, thereby enabling a large range of applications which thus already are and will be utilized beneficially in existing and upcoming building envelopes. These aerogel-incorporating building envelopes may hence exploit the very low thermal conductivity of aerogels, the lightweight properties due the air-filled low-density aerogel structure, and the possibility of utilizing solar radiation as a daylight and heat source through the translucent and transparent material versions of aerogel. This study is presenting miscellaneous experimental investigations of different aerogel materials and systems intended for application in building envelopes. A new lightweight and more thermally insulating aerogel glass material has been synthesized. Aerogel granules have been applied in various translucent window panes and solar walls. Moreover, different mixtures of cement recipes and aerogel granules have been fabricated into aerogel-incorporated concrete with reduced thermal conductivity and hence increased thermal resistance. These aerogel systems may also become part of the future multi-functional building envelopes utilizing various technologies, including both passive and active/dynamic ones, the latter comprising adaptive and controllable ones, like e.g. passive systems like super insulation materials such as nano insulation materials, adaptive technologies like phase change materials, controllable technologies like smart windows utilizing e.g. electrochromic materials, and solar cell systems like building integrated photovoltaics. That is, miscellaneous materials and technologies incorporated and utilized in the advanced and multi-functional building envelopes of tomorrow.