Integration of daytime radiative cooling and solar heating for year-round energy saving in buildings

Xiuqiang Li,Chenxi Sui,Haoming Fang,Po-Chun Hsu,Gang Tan,Yucan Peng,Ankita Nandi,Bowen Sun

doi:10.1038/s41467-020-19790-x

Abstract

The heating and cooling energy consumption of buildings accounts for about 15% of national total energy consumption in the United States. In response to this challenge, many promising technologies with minimum carbon footprint have been proposed. However, most of the approaches are static and monofunctional, which can only reduce building energy consumption in certain conditions and climate zones. Here, we demonstrate a dual-mode device with electrostatically-controlled thermal contact conductance, which can achieve up to 71.6 W/m2 of cooling power density and up to 643.4 W/m2 of heating power density (over 93% of solar energy utilized) because of the suppression of thermal contact resistance and the engineering of surface morphology and optical property. Building energy simulation shows our dual-mode device, if widely deployed in the United States, can save 19.2% heating and cooling energy, which is 1.7 times higher than cooling-only and 2.2 times higher than heating-only approaches.

Highlights

The heating and cooling energy consumption of buildings accounts for about 15% of national total energy consumption in the United States
We demonstrate the dual-mode smart heat managing device that possesses the ideal dual-mode optical properties and can achieve up to 71.6 W/m2 of cooling power density and up to 643.4 W/m2 of heating power density from experimental tests by optimizing the optical, mechanical, and heat transfer properties at various scales, ranging from nanoscale surface morphology to device-level design
Most of the solar energy is absorbed, and the radiation loss is strongly suppressed by the selective absorber, which results in high heat flux to the building envelope or the heat exchanger

Summary

Introduction

The heating and cooling energy consumption of buildings accounts for about 15% of national total energy consumption in the United States. These statistics clearly manifest the need for smart and renewable indoor thermal environmental management that can switch between cooling and heating to cope with various situations and to achieve higher energy saving all year round. The map shows our dual-mode device outperforms the solar-heating-only and radiative-cooling-only devices, which can save 19.2% of building heating and cooling energy on average

Methods

Results

Conclusion