Passively Adaptive Radiative Switch for Thermoregulation in Buildings

TL;DR

This paper introduces a passively adaptive radiative switch that can automatically switch between heating and cooling modes in buildings with minimal temperature change, significantly reducing energy costs.

Contribution

It presents a novel radiative switch leveraging phase-change materials to enable automatic, low-temperature-range cycling between heating and cooling states.

Findings

Reduced cooling energy cost by 3.1x

Reduced heating energy cost by 2.6x

Effective passive thermoregulation in outdoor tests

Abstract

With the ever-growing need to reduce energy consumption, building materials that passively heat or cool are gaining importance. However, many buildings require both heating and cooling, even within the same day. To date, few technologies can automatically switch between passive heating and cooling, and those that can require a large temperature range to cycle states (>15o 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 3o C. The black selective-absorber louvers induce high heat gain when closed, yet when open, expose a white, 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 3.1x and heating by 2.6x compared to non-switching devices. Our concept opens the door for passively adaptive thermoregulating building materials.