Abstract Public libraries have important functions as information hubs and cultural institutions, drawing a variety of user groups. As user experience, contentment and general productivity are greatly improved by the thermal comfort of interior spaces, libraries are committed to providing suitable temperatures for both human thermal comfort and for preserving books. The standards for the handling and care of library resources established by the International Federation of Library Associations in 1999 specify the need for constant temperature and humidity in the safekeeping of library items. The recommended temperature range for sedentary activities including reading, is 20-22 °C, comfortable for people in cold regions. Hot climates prevalent in Middle Eastern nations, challenges achieving thermal comfort for library visitors. According to ASHRAE Standard 55 (2020), the most comfortable temperature in hot and humid environments is 24°C, +/- 1°C. Three methods were used in this study. First, this study gives an overview of the history of libraries in Middle East regions, and analyses the development of design elements in controlling temperatures and book preservation of this region’s libraries before and after air conditioning. Second, comparative case studies of Qatar National Library and King Fahad Library showcase differing thermal comfort approaches. Third, interviews with the two libraries users and administrators. Interior temperature, design choice and clothing preferences of patrons are examined in relation to thermal comfort in libraries. The results show that public libraries in hot regions often struggle to provide the temperatures needed to give user comfort and preserve books. This study identifies factors and design approaches to improve the thermal comfort and sustainability of Middle Eastern libraries, intersecting quantitative factors (air temperature and flow) with qualitative factors (colour, material finish and architectural and interior design). It exposes tensions between these approaches to book conservation and user comfort, to develop guidelines for effective design strategies in libraries.