Impact of Climate Change on High-Performance Belgian Houses: Thermal Comfort, HVAC Energy Performance, and HVAC GHG Emissions

Abstract

Climate change arising from natural and anthropogenic sources affects the built environment in several ways. One of the major impacts of climate change is the increase in average air temperatures that can lead to more intense, severe, and prolonged heatwaves. This study is developed to project the effect of such warming weather conditions on Belgian high-performance houses and provide an idea of mitigation strategies. The study consists of three main parts (Part I, Part II, and Part III). In Part I, the study investigates a large number of thermal comfort/overheating evaluation methods to find a fit-to-purpose and appropriate method. It then provides a critical and qualitative review of resilient cooling strategies that can be applied as mitigation strategies. In Part II, a comprehensive simulation-based methodological framework is introduced to assess and compare the resistivity of buildings and their cooling strategies to the overheating impact of climate change. This part also provides an extensive weather dataset to estimate the changes in weather conditions and heatwaves in Belgium by the end of the century under different emission scenarios. In Part III, numerical studies are performed to predict the changes in thermal comfort conditions, HVAC energy performance, and HVAC Greenhouse Gas (GHG) emissions in Belgian high-performance houses due to climate change. This part includes the evaluation of a set of active and passive cooling strategies based on uncertainty analysis, sensitivity analysis, and optimization techniques.

The following presents a summary of essential practical information and recommendations obtained from the research:

• In conducting thermal comfort analyses for building designs, it is crucial to utilize asymmetric indices to effectively identify and address potential issues related to overheating and overcooling discomfort. To ensure comprehensive protection against overheating, it is recommended to incorporate both short-term and long-term criteria into the design process, considering not only specific heatwave events but also year-round warm discomfort. As a practical recommendation, this research proposes the use of three valuable indices for overheating assessments in the context of climate change: Indoor Overheating Degree (𝐼𝑂ℎ𝐷), Ambient Warmness Degree (𝐴𝑊𝐷), and Climate Change Overheating Resistivity (𝐶𝐶𝑂𝑅). These indices can be calculated using the following fomulas:

• When integrating cooling systems into buildings, it is important to prioritize resilience alongside energy efficiency, sustainability, and affordability. Relying solely on energy efficiency might compromise a building's ability to handle extreme events. To ensure resilient cooling, it is important to consider the four criteria of absorptive, adaptive, and restorative capacities, as well as recovery speed from the initial design phase. Combining multiple cooling strategies with different capacities might be necessary, as no single strategy can fulfill all requirements. The most suitable cooling approach can vary depending on the climate.

• For effective building performance simulations in major cities of Belgium, it is highly recommended to utilize the novel meteorological dataset presented in this thesis. This specialized dataset is thoughtfully designed to cater to the unique requirements of such simulations. By incorporating both historical and future weather data on an annual basis, including Typical Meteorological Years (TMYs), Extreme Meteorological Years (XMYs), and detailed information on three types of heatwaves (based on intensity, duration, and highest temperature), this dataset offers invaluable support for accurately assessing and optimizing building performance under various climatic scenarios.