Design and Testing of Climate-responsive Ventilated Building Façades

Abstract

Enhancing building performance has become a focal point in reducing the environmental impacts of the built environment to address climate change. Considering the highest share of comfort-related energy use in buildings, and the importance of indoor environmental quality (IEQ), a balance between energy conservation and IEQ provision is required. Building façades are the primary boundary that control mass and energy flow in buildings. Dynamic façades are potential alternatives to existing high-performance façades to improve IEQ in buildings, as they change their functionality with time, in response to changing environmental loads. This study aims to design and develop a multifunctional climate-responsive façade (CRF) in a continental climate. First, the literature review presents CRF theories and technologies. To design the CRF conceptually, a performance-based design framework was developed. This tool can be used in the initial decision-making stage of CRFs to conceptualize them based on case-specific performance metrics. The design of the conceptual CRF was optimized using CFD simulations in the climate of Toronto, Canada. The façade is a multifunctional, integrated, climate-responsive, opaque and ventilated (MICRO-V) façade, which regulates heat, air, and moisture flow into buildings. MICRO-V comprises a pre-conditioned cavity with phase change materials, and an adjustable insulation system integrated with a bi-directional ventilation module with heat recovery. The design of the MICRO-V was finalized by selecting the best-performing configuration of geometry, material properties, and operation. The results showed a 77% pre-conditioning efficiency of air in the ventilation module. Also, the thermal transmittance of the insulation could change from 0.05 to 0.5 W/m2.K with airflow variation. The simulations showed the interactions between the MICRO-V components, leading to the façade prototype. The performance of this prototype was evaluated using experimental tests in the BETOP test cell in Toronto. The results demonstrated the performance of the façade under different operation scenarios, and its ability to pre-condition fresh air while controlling thermal exchanges in the room. The experimental tests confirmed an agreeable compatibility with the simulation results. In this study, a design process from concept generation to prototype development of CRFs was presented that could be expanded and used in future research. MICRO-V is a CRF with decentralized ventilation that could be adjusted to different building contexts and climates.