Computational design of building envelopes as thermal metamaterials

Abstract

A metamaterial is a composite with unprecedented properties, either in nature or in the market. Specifically designed, a metamaterial exhibits either extraordinary or “à la carte” macroscopic physical properties, or allows the device made of it (the “metadevice”) to have an optimal response. In the context of the thermal performance of a building, let the metadevice be the whole building envelope, say the “metaenvelope”. Then, the metamaterial in the metaenvelope is determined in order to maximize the building energy efficiency. To this end, we apply the optimization-based metamaterial design approach, which consists in solving a nonlinear constrained optimization problem where the objective function is the energy consumption for cooling and heating, and the design variables define the metamaterial in the envelope. Particular emphasis is given to the use of NRG-foams, which are foamed concretes with embedded microencapsulated phase change materials developed within the framework of the EU H2020 project NRG-STORAGE. Finally, metaenvelopes having NRG-foams as insulation materials will be compared with a standard envelope in terms of the energy consumed by the enclosed building to keep the indoor thermal comfort.