The thermal influence of Urban Heat Islands (UHIs) is not limited to periods of high temperature but persists throughout the year. The present study utilizes hourly data collected over a period of one year from a network of hygrothermal monitoring stations with a high density, which were deployed across the city of Cáceres (Spain). The network was designed in accordance with the World Meteorological Organization’s guidelines for urban measurements (employing radiation footprints and surface roughness) and ensures representation of each Local Climate Zone (LCZ), characterized by those factors (such as building typology and density, urban fabric, vegetation, and anthropogenic activity, among others) that influence potential solar radiation absorption. The magnitude of the heat island effect in this city has been determined to be approximately 7 °C in summer and winter at the first hours of the morning. In order to assess the energy impact of UHIs, Cooling and Heating Degree Days (CDD and HDD) were calculated for both summer and winter periods across the different LCZs. Following the implementation of rigorous quality control procedures and the utilization of gap-filling techniques, the analysis yielded discrepancies in energy demand of up to 10% between LCZs within the city. The significance of incorporating UHIs into the design of building envelopes and climate control systems is underscored by these findings, with the potential to enhance both energy efficiency and occupant thermal comfort. This methodology is particularly relevant for extrapolation to larger and denser urban environments, where the intensification of UHI effects exerts a direct impact on energy consumption and costs. The following essay will provide a comprehensive overview of the relevant literature on the subject.

Initiatives abound for improving energy efficiency in existing dwellings stock, yet the impact in their indoor thermal comfort conditions, postretrofit performance, and comfort levels are insufficiently explored. Studies that evaluate this parameter, enabling the validation or adjustment of current policies of retrofit actions, would be essential. Thus, this paper details the thermal monitoring and behaviour of a sample of 92 dwellings with a homogeneous user profile, with the aim of identifying thermal and comfort patterns. For this purpose, continuous long‐term monitoring is proposed for the comparative analysis of time series data for different climatic periods, instead of complex and individual data collection in situ. In order to correlate the envelope’s thermal behaviour, buildings are characterised in terms of building typology and construction period, after which occupant behaviours are examined via questionnaires on self‐reported thermal sensations and adaptive actions. Key results point to a lack of relationship between the building typology and construction period and thermal performance, even after the implementation of energy efficiency improvement measures. Additionally, thermal comfort was found to be intermittent, albeit more present in winter than summer, with a marked heterogeneity when it comes to individual habits. These facts indicate that it is necessary to include additional thermal performance driving factors for determining practical comfort implications and characterising its correlation with energy efficiency.

The thermal influence of Urban Heat Islands (UHIs) is not limited to periods of high temperature but persists throughout the year. The present study utilises hourly data collected over a period of one year from a network of hygrothermal monitoring stations with a high density, which were deployed across the city of Cáceres (Spain). The network was designed in accordance with the World Meteorological Organization's guidelines for urban measurements (employing radiation footprints and surface roughness) and ensures representation of each Local Climate Zone (LCZ), characterised by those factors (such as building typology and density, urban fabric, vegetation, and anthropogenic activity, among others) that influence potential solar radiation absorption. The magnitude of the heat island effect in this city has been determined to be approximately 7 °C in summer and winter at the first hours of the morning. In order to assess the energy impact of UHIs, Cooling and Heating Degree Days (CDD & HDD) were calculated for both summer and winter periods across the different LCZs. Following the implementation of rigorous quality control procedures and the utilisation of gap-filling techniques, the analysis yielded discrepancies in energy demand of up to 10% between LCZs within the city. The significance of incorporating UHIs into the design of building envelopes and climate control systems is underscored by these findings, with the potential to enhance both energy efficiency and occupant thermal comfort. This meth-odology is particularly relevant for extrapolation to larger and denser urban environments, where the intensification of UHI effects exerts a direct impact on energy consumption and costs. The following essay will provide a comprehensive overview of the relevant literature on the subject.