Passively adaptive radiative switch for thermoregulation in buildings
Charles Xiao, Bolin Liao, Elliot W. Hawkes
Abstract
Using building materials that passively heat or cool will reduce energy consumption. However, many buildings require both heating and cooling, even within the same day. Currently, few technologies can automatically switch between passive heating and cooling, and those that can require a large temperature range to cycle states (>15°C), making them ineffective for daily switching. We present a passively adaptive radiative switch that leverages the expansion in phase-change energy storage materials to actuate the motion of louvers and can cycle states in less than 3°C. The black selective-absorber louvers induce high heat gain when closed, yet when open, expose a white, infrared-emissive surface for low heat gain. During an outdoor test in which temperature was held steady, our device reduced the energetic cost of cooling by 3.1× and heating by 2.6× compared with non-switching devices. Our concept opens the door for passively adaptive thermoregulating building materials.