In 2018, Chinese central government defined the route and strategic goals for rural revitalization in the “Opinions on Implementing Rural Revitalization Strategy”, which marked the new era for Chinese rural development [1].With the development of China's rural revitalization in recent years, the quality of life of rural residents has also been improved, and residents have higher requirements for indoor thermal environment [2][3]. According to data released by the National Bureau of Statistics, about 39 percent of China's population still lives in rural areas [4], and the living environment and quality of life of rural people are receiving increasing attention [5][6].
Limited by economic conditions, the indoor thermal environment of vernacular dwellings in cold areas of China is generally poor in winter, which often cannot meet the needs of residents for thermal comfort [7][8][9]. There is a big gap between the income of Chinese rural residents and urban residents [10], and the living service facilities of rural residents are far behind those of urban residents [11]. Some studies have pointed out that the high initial cost is the main factor affecting the indoor thermal environment of vernacular dwellings [12]. The construction cost of vernacular dwellings is usually lower than that of urban dwellings, which leads to poor air tightness and thermal insulation of the envelope of vernacular dwellings [13][14], resulting in an uncomfortable indoor thermal environment [15][16][17]. However, relevant studies have shown that rural residents tend to show stronger environmental adaptability than urban residents [18][19]. Therefore, in-depth understanding of the actual thermal comfort range of local rural residents can be more targeted to improve the indoor thermal environment, and at the same time is conducive to energy conservation.
China's cold climate zone has a vast area, among which Shandong Province is the largest agricultural province in China (Fig. 1), with a vast rural area, which has very important research significance [20]. The rural economy of Shandong Province is relatively undeveloped, and the overall income of farmers is low [21]. According to the data released by the National Bureau of Statistics, the per capita disposable income of rural residents in Shandong Province in 2021 is 20,800 CNY (2985 USD), and the per capita income of rural residents in 16 cities is all less than 30,000 CNY (4305 USD) [4]. Therefore, improving the thermal environment of vernacular dwellings in Shandong has a great social value and demonstration significance for rural areas in cold regions of China.
Linyi is the largest and most populous city in Shandong Province, and its rural economy is relatively weak. The per capita disposable income of Linyi ranks third from the bottom in in Shandong in 2021, which results in a large outflow of young people and an increasing proportion of the elderly. Linyi is the focus of rural revitalization in Shandong Province. This paper takes the vernacular dwellings in Linyi, Shandong Province, China as the research object (Fig. 2), and conducts an investigation on the vernacular dwellings in each district of Linyi, focusing on the indoor thermal environment of vernacular dwellings and the actual thermal comfort range of residents. This paper analyzes the indoor thermal environment of vernacular dwellings in Linyi from the perspective of users, and analyzes the problems of indoor thermal environment of vernacular dwellings in Linyi based on the actual thermal comfort temperature range of local residents. The research results of this paper have guiding significance for the renovation of rural dwellings and the optimization of indoor thermal environment in Linyi.