Fig. 1: Concept of dual-mode device.
From: Integration of daytime radiative cooling and solar heating for year-round energy saving in buildings
a Annual heating and cooling degree days of 16 U.S. cities that represent the 16 climate zones. b Heating and cooling degree days over 12 months in Durham, NC, USA. c Schematic of the dual-mode device at heating (left) and cooling (right) mode. The switchable building envelope can utilize both renewable heating and cooling sources. We identify the four criteria of the dual-mode device: heating/cooling optical properties, thermal resistance, rollability, and thermal contact.
