Large-Scaled and Solar-Reflective Kirigami-Based Building Envelopes for Shading and Occupants' Thermal Comfort

Abstract

Conventional air conditioning in buildings consumes substantial energy contributing to an increase in greenhouse gas emissions, which aggravates global warming. Kirigami envelopes with reflective surfaces offer a promising option to reduce indoor heat gain. So far none has performed outdoor testing of kirigami envelopes nor numerical simulation to understand how they interact with the environment. To understand the impact of the geometric design of the kirigami shading system on both daylighting and temperature variation in the indoor environment, a series of prototypes and simulations is devised to investigate the real-time shading behavior in an outdoor environment. Large-scaled and silver-coated kirigami-based envelopes of different cut patterns and stretching ratios are fabricated and placed in front of custom-designed chambers equipped with six thermo-sensors. Simulation is performed to investigate the effect of light modulation and hence temperature inside the chamber, which corroborates with the experiments. The indoor daylighting pattern and temperature are significantly influenced by the geometry of the stretched kirigami envelope, and overall, both the indoor temperature and the spatial distribution of illuminance are more uniform compared with that without the kirigami envelope. These results indicate that the installation of kirigami envelopes can improve building energy saving and occupants' comfort. Kirigami-based shading envelopes are tested in custom-designed chambers installed outdoor to demonstrate the modulation of indoor lighting and temperature in outdoor environment. Numerical simulations are performed to study the light and temperature modulation mechanisms. Both experiments and simulation prove that more uniform light distribution is achieved using the kirigami envelopes, which can improve building energy saving and occupants' comfort.image