ABSTRACT
The European Union promotes energy-efficient building standards, such as nearly Zero-Energy Buildings (nZEB), adapted to each country’s specific climate conditions. However, the increasing frequency and intensity of urban heat islands (UHI) and heat waves (HW) challenge traditional energy performance assessments, which are based on outdated climatic data. Conventional methods rely on historical average temperatures, failing to account for rising cooling demands due to recent extreme heat events. As a result, buildings previously classified as energy-efficient may now exhibit significantly higher cooling loads, undermining their intended performance.
This study investigates the combined impact of UHI and HW on urban building energy efficiency, particularly for structures designed to meet nZEB or Passive House standards. Through a comparative analysis of three building typologies in Timișoara, Romania, this research examines the influence of compactness, window size, and shading on cooling demand.
Furthermore, this paper explores large-scale urban cooling interventions, such as increasing vegetation coverage, implementing reflective surfaces, and integrating water bodies. The results highlight that urban planning strategies prioritizing green infrastructure can significantly mitigate the UHI effect, with tree canopies emerging as the most effective countermeasure. Given the accelerating pace of climate change, updating energy performance simulations to incorporate UHI indices and extreme weather scenarios is crucial for ensuring the long-term resilience of energy-efficient buildings in urban environments.
