Thermally Anisotropic Composites for Improving the Energy Efficiency of Building Envelopes

Abstract

This article describes a novel application of thermal anisotropy for improving the energy efficiency of building envelopes. The current work was inspired by existing research on improved heat dissipation in electronics using thermal anisotropy. Past work has shown that thermally anisotropic composites (TACs) can be created by the alternate layering of two dissimilar, isotropic materials. Here, a TAC consisting of alternate layers of rigid foam insulation and thin, high-conductivity aluminum foil was investigated. The TAC was coupled with copper tubes with circulating water that acted as a heat sink and source. The TAC system was applied to a conventional wood-framed wall assembly, and the energy benefits were investigated experimentally and numerically. For experimental testing, large scale test wall specimens were built with and without the TAC system and tested in an environmental chamber under simulated diurnal hot and cold weather conditions. Component-level and whole building numerical simulations were performed to investigate the energy benefits of applying the TAC system to the external walls of a typical, single-family residential building.

Opaque Envelopes: Pathway to Building Energy Efficiency and Demand Flexibility: Key to a Low-Carbon, Sustainable Future

“…For TAMs, the high-conductivity layer(s) must be connected to a heat sink or source; for example, a heat sink could be a plumbing loop with circulating water [48]. These systems have anisotropic thermal transport properties because the high-conductivity layer(s) are the least resistive paths for heat transfer, thus helping reroute heat flow through the envelope to the connected heat sink or source.…”

Special Issue “Building Thermal Envelope”

“…Biswas et al [12] investigated the application of thermally anisotropic composites (TACs), composed by alternate layers of rigid foam insulation and thin and high-conductivity aluminum foil, for improving the energy efficiency of building envelopes. The TAC was coupled with copper tubes with circulating water, which acted as a heat sink and source, and the system was applied to a conventional wood-framed wall assembly.…”

An Assessment of the Thermal Behavior of Envelope Surface Coatings with Different Colors

“…In this way, attempts to minimize heat loss in rooms are more and more effectively separated from external weather conditions, which can often lead to the deterioration of the microclimate inside the building. Another way to save energy is to improve the existing design and material solutions [ 7 , 8 , 9 , 10 ] and to look for alternative solutions, e.g., using renewable energy (such as solar radiation [ 11 , 12 ]; wind, water, geothermal energy [ 13 , 14 , 15 ]; or biomass). In energy-conscious (solar) building design, attention is paid to many elements—finding solutions regarding the structure, shape, construction, and location of the building, including carefully selected parameters for the partition, facilitating the possibility of using solar radiation energy, which can significantly improve the heat balance of rooms in the building [ 16 , 17 , 18 , 19 ].…”