Sustainable regeneration of waste polystyrene foam as cooling coating: Building cooling energy saving, CO2 emission reduction and cost-benefit prospective

Abstract

Passive radiative cooling technology provides a green and energy-free approach for large-scale building cooling. Developing low-cost raw materials, green production process and entire-process evaluation is keys for the commercialization of cooling materials. This work proposes quickly converting abundant waste polystyrene foam into cooling coating via closed-loop solvent extraction strategy to satisfy scale and clean production requirements of building cooling envelope. Residential building thermodynamic model and outdoor cooling experiment are established to evaluate the application in building energy-saving and CO2 reduction. In addition, this work conducts a full lifecycle assessment to explore the advantages and disadvantages of the coating. Results demonstrate the coating has a randomly porous structure thus reflecting ∼97% solar radiation and emit ∼94% thermal radiation. About 8 °C of net and ∼7.5 °C/1000 cm3 building space cooling capacity can be achieved even under ∼1500 W/m2 of solar radiation. The coating is evaluated to reduce 5.09 kW h·m−2 electrical energy and ∼2 kg/m2 CO2 emission annually in Nanjing. Benefiting from the low-cost raw materials and closed-loop preparation process, the payback time and total environmental impact are reduced 54.96% and 28.29%–54.19% compared to commercial one, respectively. This work will effectively inspire the development of large-scale and low environmental impact building cooling envelopes.