Exploring the thermodynamics of vernacular architecture offers a novel perspective beyond traditional residence research, paving the way for sustainable residential development. In this context, a historic dwelling in Wentang Village, Qimen County, Anhui Province, China, was analysed. Through simulations of the dwelling's indoor thermal environment using Phoenics software, it was found that enlarging horizontal and rooftop windows can significantly boost indoor air circulation. Such alterations not only diminish the dwelling's energy demands but also elevate the indoor living conditions. The findings underscore the value of passive natural ventilation, suggesting its efficacy in addressing humidity and temperature concerns in traditional Huizhou interiors, especially when active technological interventions are disregarded. This thermodynamically informed approach to renovation, grounded in climate adaptability, furnishes both theoretical insights and practical implications for the refurbishment and design of classic Huizhou residences.