Collaborative Research: Adaptive Building Enclosure Systems Using Cellular Solid-Solid Phase Change Materials with Variable Transparency

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Buildings are responsible for about 40 percent of US energy consumption; a significant fraction of this energy is consumed to counter thermal losses or gains occurring through building envelopes. Passive-solar-design seeks to balance heat loss through the building envelope with solar energy input, while also using thermal mass, shading, and/or ventilation to dampen daily thermal swings. However, implementation of current passive-solar-design tends to be highly context-specific and often entails use of costly mechanical devices and controls. This project aims to study an innovative passive solar building enclosure system that uses cellular solid-solid phase change materials (SS-PCM) with variable transparency. The system relies on passive material-enabled controls and has no mechanically moving parts or electrical components. Successful implementation of SS-PCM foam-based building envelope materials can result in low cost responsive building enclosure systems that self-regulate building thermal comfort. The outcome of this study can lead to new technologies that reduce energy use in buildings, decrease dependence on fossil fuels, and improve the economic competitiveness of the United States. This study is also expected to result in benefits to diverse industries such as building materials, construction, and energy conservation. An innovative outreach plan will be implemented in the form of a competition that engages students at various levels of education in the topics of passive solar design, energy use, and thermal comfort in buildings.The goal of this project is to uncover the fundamental principles that govern the behavior of translucent cellular SS-PCM systems used in realistic building envelopes. Fundamental insights will be gained on (1) heat transfer phenomena occurring in SS-PCM foam systems, (2) the synergistic effects occurring between three material-enabled solar-light irradiation control mechanisms, and (3) structural features and characteristics that lead to high energy-savings in buildings. This study will create enabling knowledge on thermal and optical behavior of SS-PCMs such that building temperatures can be passively regulated year-round under different climate conditions. An integrated experimental and computational program, consisting of multi-physics modeling, materials synthesis, system level integration, and building level evaluation for energy saving, will be performed to achieve the aforementioned goal. This project can transform the use of PCM by relying on radiation energy transfer processes to deliver heat, thus bypassing the low thermal conductivity problem inherent to PCMs. The low thermal conductivity of the SS-PCM foam also delays heat-loss, thus enhancing the ability of the system to remain at a desired temperature.