Thermal comfort evaluation in the adaptive reuse of historic industrial buildings: An empirical study of two renovated factories in Hefei

With the progression of urban renewal, the functional transformation of numerous old industrial heritage buildings has imposed new demands on their indoor physical environments. This paper focuses on the adaptive renovation of thermal environments in old industrial buildings, using two case studies: Welding Workshop (Before Renovation) and the Cylinder Casting Workshop (After Renovation) of Hefei Motor Factory and Diesel Engine Factory. By integrating on-site thermal environment measurements and subjective thermal sensation questionnaires, we employs statistical regression methods to analyze the relationship between operative temperature and actual thermal sensation (MTS) and subjective thermal discomfort. The study identifies the acceptable temperature range and duration proportion in old industrial buildings, and further compares objective and subjective differences in human thermal comfort between summer and transitional seasons in the same workshop. Based on the acceptable duration proportion, a quantitative relationship between subjective sensations and operative temperature is established. These findings offer theoretical and empirical support for green renovation strategies of existing industrial buildings and design optimization of new constructions. Practical application This study provides empirical, decision-support evidence for the green renovation of industrial heritage. At its core, it establishes operative temperature as a critical design parameter and adopts the acceptable duration proportion of thermal comfort as a quantifiable target—thereby translating comfort needs into actionable design language. The data support a practical approach combining enhanced building envelope performance with flexible indoor environmental adjustments to balance heritage preservation and thermal comfort improvements. This research framework can be integrated into the design justification, scheme comparison, and post-occupancy evaluation processes of similar projects, offering a scientific and operational reference for enhancing environmental performance in the adaptive reuse of industrial heritage.