Influence of Geometric Form and Size on ETFE Cushion Building Facade Characteristics and Their Implications for Thermal Performance and Energy Consumption

ETFE cushions are applied to building facades in a wide range of geometric forms and sizes. However, information on how cushion geometry and dimensions affect bulging behavior, thickness and area values, structural strength, thermal conductivity, and energy performance remains limited. Therefore, this study investigates cushion typology in eight geometries (isosceles and equilateral triangle, square, rectangle, rhombus, pentagon, hexagon, circular) with side lengths or radius values between 1 and 10 m, covering 115 variations. Geometric/physical mathematical area calculations, the parabolic dome model, elastic plate bending theory, the empirical thickness model, and thermal-resistance and degree day-based energy calculation approaches are used to obtain planar area, inflated curved surface area, maximum and average thickness, R and U values, and heating, cooling, and total energy consumption for each typology. The use of AI in numerical calculations provides fast and efficient design solutions in architecture and enables various geometric and performance scenarios to be produced rapidly. Circular, hexagon, and pentagon cushions lower U values and provide energy savings due to their high bulging capacity and deformation homogeneity; square, rhombus, and rectangle cushions show medium-level performance; isosceles and equilateral triangles limit energy savings because they produce higher U values. In conclusion, an increase in average bulging thickness and characteristic length reduces the number of cushions required to cover the facade, decreases the U value, reduces total heating and cooling energy consumption, and improves thermal performance. When a facade is covered with cushions of different geometries and sizes, it provides up to approximately 99.24% energy savings.