Evaluation of the global warming impact on the cooling demand in buildings worldwide

Abstract

According to forecast statistics of the United Nations, the global population is expected to grow from 8.2 to 9.7 billion by 2050 and could approach 11 billion by 2100. The number of buildings and habitations is therefore expected to increase proportionally to the population growth. In the European Union, buildings account for 40% of the energy consumption and 36% of the greenhouse gas emissions, with HVAC systems being the biggest contributors. In the actual context of global warming, by the end of the XXI century, the global air temperature is predicted to increase up to 4.8K if global warming issues are not handled carefully regarding the greenhouse gas emissions. As a result, cooling is expected to become the fastest-increasing energy-consuming technology in buildings, making it a key focus for efforts to limit further global warming.

This thesis investigates the impact of global warming on the cooling demand of residential buildings worldwide. A dynamic thermal model was developed and validated to simulate the hourly indoor temperature and cooling loads under various climate conditions. Typical Meteorological Year (TMY) data for present (2001–2020) and future (2041–2060) periods were used to assess the evolution of cooling needs in multiple representative cities across different climate zones.

The results reveal a clear and consistent increase in cooling demand, particularly in regions already subject to warm or humid climates. Increases range from +15% to over +60% depending on the city. A sensitivity analysis was conducted to identify the most influential parameters on indoor temperature, such as solar gains, insulation levels, and internal heat sources. The simulation model was validated using real data from monitored test houses, achieving strong statistical accuracy.

In addition, several passive cooling strategies were tested in the model to assess their potential to reduce future cooling loads. Among these strategies were window shading, thermal mass enhancement using concrete layers, phase change materials (PCM), and night-time ventilation. These measures showed significant capacity to reduce future cooling loads, with combined reductions reaching up to 99% in some cases. However, their effectiveness varied by climate, underlining the need for context-specific design strategies.

This study emphasises the importance of anticipating future energy needs and rethinking building design in a warming world. While passive and active cooling solutions offer promising paths, long-term sustainability will also depend on broader changes in energy consumption behaviours and in the way our cities are designed and organised. Urban layout, building density, green spaces, and materials used play a key role in shaping the thermal performance and energy needs of buildings.