Techno-economic and environmental evaluation on radiative sky cooling-based novel passive envelope strategies to achieve building sustainability and carbon neutrality

As the pursuit of carbon neutrality gains momentum, retrofitting high-performance buildings with novel, energy-efficient passive envelope systems has emerged as a promising pathway towards building sustainability. To this end, this study aims to propose, evaluate, and optimize such envelope systems considering varying climate patterns in China by incorporating state-of-the-art passive cooling strategies into buildings. Comprehensive techno-economic and environmental evaluations were conducted on a standard-compliant three-story typical commercial building, considering newly proposed passive approaches. The energy performance evaluation reveals that the super-cool white roof corresponds to annual cooling electricity savings of 2.5–6.1% for the entire building and 7.0–17.1% for the top floor in response to varying climate patterns. By contrast, the radiative cooling red and yellow walls exhibit cooling energy saving rates of 1.4–1.9% and 1.9–2.6%, respectively. The insulated grey clear double-glazing window can garner even greater cooling energy savings of 2.6–13.5%. It is highlighted that for the cities located in cold regions, the thermal improvement in windows offers a significantly greater opportunity for cost savings and carbon reduction compared to retrofitting roof and wall surfaces. To maximize net savings, the optimization scheme can achieve cost savings in hot-summer cities ranging from 859.1 to 1835.1 $/year, with an average of 1151.2 $/year, and from 784.4 to 1076.5 $/year, with an average of 658.8 $/year for cold cities. To minimize carbon emissions, the optimal design approach can reduce carbon emissions by 18,093.6–37,526.6 kg/year, with an average of 22,745.0 kg/year, in response to varying climate patterns. Overall, this study sheds light on the state-of-the-art passive envelope strategies that can achieve energy-efficient carbon-neutral buildings for a variety of climates in China. The optimization scheme proposed in this study provides a useful framework for designing passive envelope systems that are tailored to specific climate patterns.