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Parametric design and simulation of a smart façade for hot and humid climates using biomimetics, PCMs AND SMAs: a case study in İran

Ghaeili, Ardabili, Neda
Buildings consume a huge portion of energy for the provision of comforts indoor. This consume is mostly related to the performance of the façade. The bio-skin, as the emulation of nature for the design of a sustainable façade, has been considered as an efficient solution for the related energy consume by the façade. However, some solutions existing in nature are dynamic and require energy for their functioning, which is a problem for using biomimicry for the design of the efficient façade. As a consequence, the inherent feature of smart materials can be a solution for this issue, since it can convert the bio-skin into a smart one that is capable of adapting to outdoor variations with less consume energy. Based on the knowledge gained from the literature review about biomimicry and smart materials, two natural examples were selected for mimicking and two smart materials were selected as a heat exchanger and an actuator. The biomimicry principles were used to design a shading device whose movements were achieved by the NiTi50 actuator (SMA). Then the designed device was considered for designing the layers of smart bio-skin. The additional proposed layers have the function of ventilation and cooling the inlet air, and to this end, the RT-35 (PCM) was selected. Ultimately, the proposed smart bio-skin was evaluated for its impact in reducing the cooling loads and increasing the thermal comfort of occupants in August. The impact of the smart bio-skin was initially evaluated by simulating a test unit whose east and west walls were designed with the smart bio-skin. Then smart bio-skin was then applied virtually to the east and west walls of a villa in Kish Island. Results of the simulations showed that the smart bio-skin was effective in reducing the thermal loads by 42.75% while providing improved comfort conditions indoors, with a temperature of 34℃ which was 6℃ cooler than the base case scenario, while the humidity was increased an average of 50% to 70%.