Citation: Liu, C.; Ma, W.; Hao, J.; Luo, D.; Zuo, J.; Zhang, C. Energy Retrofitting Assessment of Public Building Envelopes in China’s Hot Summer and Cold Winter Climate Region. Buildings 2022, 12, 1866. https://doi.org/10.3390/ buildings12111866 Academic Editor: Rafik Belarbi Received: 20 September 2022 Accepted: 31 October 2022 Published: 3 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). buildings Article Energy Retrofitting Assessment of Public Building Envelopes in China’s Hot Summer and Cold Winter Climate Region Changchun Liu 1,2 , Wenting Ma 3 , Jianli Hao 2,3, * , Daiwei Luo 1 , Jian Zuo 4 and Cheng Zhang 3 1 School of Architecture and Urban Planning, University of Suzhou Science and Technology, Suzhou 215009, China 2 Jiangsu Provincial Construction Carbon Neutral Technology Engineering Research Center, Suzhou 215009, China 3 Department of Civil Engineering, Xi’an Jiaotong-Liverpool University, Suzhou 215000, China 4 School of Architecture and Built Environment, The University of Adelaide, Adelaide, SA 5005, Australia * Correspondence: jianli.hao@xjtlu.edu.cn Abstract: The retrofitting of existing public buildings to save energy and reduce carbon emissions is a priority for China’s building sector. Accordingly, the Chinese government requires all public buildings to be energy retrofitted based on the Design Standard for Energy Efficiency of Public Buildings GB50189-2015. However, few studies have been conducted to assess the energy efficiency of this design standard in the hot summer and cold winter (HSCW) climate region of China. The aim of this study was therefore to provide sensitivity analysis for the thermal properties of the envelope of a typical public building energy retrofit in China’s HSCW climate region. The results show that the thermal performance of the existing envelope of the sample building was very poor, with heating and cooling energy consumption 18.94% higher than the GB90189-2015 baseline model. It was found that better optimized parameters could reduce the heating and cooling energy load by 28.26% compared with the parameters of the sample building. The findings from this study provide valuable references for local governments and practitioners eager to improve the energy efficiency of existing public buildings in China’s HSCW region. Keywords: building energy retrofit; energy efficiency design standard; building envelope thermal property; hot summer and cold winter; building energy simulation 1. Introduction The energy consumption of the building sector accounts for around 40% of final energy use and 25% of total carbon dioxide emissions globally [1,2]. With continuous economic development and improving living standards, the energy demand of the building sector in China has been steadily growing since the beginning of the 21st century [3]. Since the end of 2015, all newly designed buildings in urban areas have been required to implement the government’s building energy-saving standard. Public buildings have the highest energy use intensity among all building types [4]. A huge number of existing public buildings in China were designed before the end of 2015, most with very high energy consumption [5]. Retrofitting existing buildings is recognized as the most feasible and cost-effective way to achieve green buildings, and it has less environmental impact than demolishing and reconstructing a new building [6]. Energy retrofitting existing public buildings is a priority for energy saving, mitigating the environmental impact of the building sector, and sustainably developing China [7]. Energy retrofitting existing buildings employs efficient energy-saving measures to reduce energy consumption while meeting the thermal comfort needs of people [8]. Since [9] China has a very large land area with distinct regional climates, bespoke measures are needed in different climate regions to meet the thermal comfort and living habits of the residents [9]. Building retrofit measures in China vary according to the five distinct climate Buildings 2022, 12, 1866. https://doi.org/10.3390/buildings12111866 https://www.mdpi.com/journal/buildings