Mitigating the urban heat island effect in historic areas: A case study of Ulus Square and its surroundings in Ankara

As rising temperatures pose an escalating threat to heritage sites, this thesis examines the Urban Heat Island (UHI) mitigation strategies applicable in cultural heritage areas located in urban areas. Although international research on the assessment of UHI impacts within culturally protected areas, particularly in contexts constrained by conservation regulations and physical intervention limitations, scholarly work in Turkey remains limited. This highlights the urgent need to identify and incorporate key environmental factors into heritage conservation planning processes. Developing robust methodologies to evaluate UHI effects within these sensitive contexts is essential for advancing climate-responsive and resilient conservation practices. In this sense, the study first documents existing research on the impact of UHI on urban heritage zones to analyze the methods used to assess the UHI effect and then proposes mitigation studies. In line with the research objectives, this study addresses the following questions: What is the impact of the UHI effect on the urban microclimate of Ulus Square and its surroundings, and how does the UHI effect influence human thermal comfort in these areas? Which mitigation strategies proposed in the literature can be applied to reduce the UHI effect on historic Ulus Square and its surroundings, and which of these strategies demonstrate the highest mitigation potential in this context? Furthermore, how do these strategies compare to those recommended for the broader urban area of Ankara? Finally, which environmental and morphological factors should be documented, and how can they be represented in the conservation analysis of these zones? To address these research questions, the thesis adopts a case study approach. Ulus Square in Ankara, designated as a cultural heritage site, was selected as the study area. To evaluate the UHI effect, rural meteorological data were simulated under urban-specific parameters using urban climate modeling tools. These include the Urban Weather Generator (UWG), EnergyPlus Weather files (EPW), and Grasshopper/Dragonfly plugins. The simulations focused on assessing key thermal comfort indicators such as Dry Bulb Temperature (°C), Mean Radiant Temperature (MRT), and the Universal Thermal Climate Index (UTCI). Mitigation strategies identified in the literature were evaluated within the framework of national and international conservation principles, such as the Washington Charter (1987), the Valletta Principles (2011), and the Regulation on Conservation Master Plans (2005). Accordingly, four distinct intervention scenarios were developed. Due to strict regulatory frameworks and physical constraints, the proposed scenarios were limited to low-intensity measures such as increasing surface albedo, reducing anthropogenic heat from traffic, and expanding green areas. The findings indicate that small-scale interventions can yield measurable improvements in mitigating the UHI effect and enhancing outdoor thermal comfort. The study highlights the importance of considering user comfort and spatial context alongside material and energy performance in conservation analyses. This multifaceted approach is particularly crucial in historically sensitive environments when evaluating design decisions. The proposed strategies can contribute to the revision of conservation plans, site management approaches, and relevant regulatory frameworks by integrating climate-adaptive principles. In this context, the study aims to support the long-term resilience and sustainability of cultural heritage sites in the face of the growing impacts of climate change. Keywords: Sustainability, Urban heat island, Climate change, Cultural heritage, Microclimate, Numerical Model, Thermal Comfort