Thermal resilience

The increasing severity and duration of climate change is that extremes – notably heatwaves, increases the risk of human thermal stress in indoor environments where people spend most of their times. Recent field measurements have demonstrated significant overheating in the EU building stock in the EU, characterized by well-insulated and air-tight envelopes. This exposes vulnerable communities to increases mortality risks that is bound to only get worse with an ever-worsening climate warming.

The commitment to improving the energy efficiency of buildings by 2030, with the goal of achieving carbon neutrality by 2050, has been triggered by environmental challenges and the increasing scarcity of energy resources. To this end, European countries are adopting stricter regulations on building energy consumption, as illustrated by the EPB system in Belgium. 
Considering the increase in extreme weather events, the intensity and frequency of heatwaves in many regions of the world, it is essential that buildings are able to adapt to extreme events. 

Climate change has exacerbated the summertime overheating in buildings, necessitating resilient adaptation strategies. Based on our previous work, which introduced a Thermal Resilience Index (TRI) ranging from Class F to Class A+ using a concept of resilient trapezoid framework, this study explores unit-level retrofit strategies for high-rise long-term care buildings.

Airtight, highly insulated, and passively cooled buildings in the EU are designed under typical outdoor and indoor thermal conditions. With increasing risk and uncertainty with regards to climate change and associated heatwaves(HW), the design thermal performance of these buildings is not guaranteed. It is crucial to focus on improving thermal resilience to overheating and futureproof these buildings. “Thermal resilience to overheating” is the characteristic that describes the extent to which buildings and their cooling strategies can maintain habitable conditions during or post shocks.

Overheating has become a recurring problem in airtight and highly insulated buildings even in moderate climates. This study aims to analyze thermal comfort and thermal resilience in an office building during summer and mid-seasons by means of dynamic simulations. Thermal comfort assessment shows, this office building without improvements has a ‘good’ indoor climate for 79.6% of total occupied hours.

Airtight and highly insulated buildings are subjected to overheating risks, even in moderate climates, due to unforeseeable events like frequent heatwaves and power outages. Educational buildings share a major portion of building stocks and a large percentage of the energy is expended in maintaining thermal comfort in these buildings. Overheating risks in educational buildings can lead to heat-stress and negatively impact the health conditions and also cognitive performance of the occupants.

The use of the word “resilience” has increased significantly since 2010, however, there is a lack of understanding around 1) how thermal resilience is defined (where some definitions were offered only recently) and 2) what distinguishes it from typical overheating assessments. In addition to this, there is a lack of uptake in the remote monitoring industry (which uses low-cost solutions) when it comes to typical parameters used in thermal comfort studies and there is need to demonstrate how resilience performance can be reported going forward.