Reducing the continuously growing cooling energy demand of buildings is an important part of achieving global emission targets. Here, we present an innovative scenario of how the integration of a programmable material into a climate-adaptive building envelope (CABE) can create an energy-efficient thermal management system inherent to the material. This novel concept is based on a thermoresponsive shape memory polymer foam (SMP) and is designed to regulate the flow of ambient air through the building envelope in order to enable natural cooling of the structure. Hygrothermal simulation data obtained by the software WUFI^® Plus indicate that significant cooling energy saving potential may be accessible with this type of concept. As a possible material basis for a corresponding adaptive element, a reactive foamed polyurethane-based SMP foam is proposed, which is capable of executing a thermoreversible shape change of more than 20% while having a suitable switching temperature range. Finally, the ecological impact of such a functional foam element is evaluated in detail as well as its influence on the overall balance of a façade construction by means of a life cycle assessment (LCA).

The research project Fraunhofer Cluster of Excellence “Programmable Materials” aims to develop new materials that can change their properties according to defined boundaries. This article describes the development and use of a novel programmable phase change material (PCM) for latent heat storage applications. At the moment, these PCMs have a programmable trigger mechanism incorporated that activates the crystallization of the material as a reaction to a defined stimulus so that the stored heat is released. In future development stages, programmability is to be integrated on the material level. The latent heat storage that is based on PCMs can be recharged by using the energy of the sun. As an example, for a possible application of such a material, the use of a novel programmable PCM in greenhouses to support heating energy reduction or to reduce the risk of frost is explained. Using the hygrothermal simulation tool WUFI^® Plus, the effects in greenhouse constructions without and with commercially available or novel programmable PCMs are calculated and presented in the present article. The calculations are based on the material data of calcium chloride hexahydrate (CaCl₂-6H₂O), as this material serves as a basic material for the development of programmable PCM compositions. The results of the simulations show a positive impact on the indoor temperatures in greenhouses in view of the risk of frost and the reduction of heating energy. Thus, the vegetation period can be extended in combination with a lower energy load. By an eligible actuation mechanism, an inherent material system for temperature control can be created.