The Task Group received a presentation from Natural Resources Canada (NRCan), which explored using a reliability-based approach to assess overheating outcomes (or rather the cooling measures) to be required in future codes. This method is how structural requirements are set in the code. The research used the EnergyPlus modeling tool to simulate multiple climate and building metrics for a variety of housing types over the summer months. While this approach was viewed positively, concerns were raised about defining “failure” solely as homes exceeding 26 °C, without accounting for duration, consecutive hours, or nighttime recovery.

Questions were also raised about the appropriateness of using a "base of 10°C for Cooling Degree Days" (CDD10) as a primary metric for assessing high-temperature risk. The TG learned that CDD10 is used in ASHRAE calculation. CDD10 is created by totalling up for the entire summer months, the number of days where the exterior temperature exceeds 10°C with the number of degrees over 10°C for each respective day).

The TG agreed to

• collaborate with the TG on Climatic Data to consider adding CDD and 1% July Design Temperature Data to climatic data in Appendix C of the codes
• re-visit the research in a future meeting and decide how 'failure' should be defined so that the modelling could be re-run with those assumptions, and 
• to use terms “heat-gain mitigation” or “heat-gain reduction” instead of “passive cooling” which always refers to non-mechanical measures. This is to distinguish against the term or “cooling systems”  which always means mechanical system. 

The National Research Council (NRC) presented the results of a field study on existing large residential buildings showing that overheating varies significantly across buildings and units, with upper-floor corridors frequently exceeding 26 °C in summer. The study identified occupant behaviour and common-area ventilation as the biggest influencers of indoor conditions, highlighting the need for careful assumptions and further interdisciplinary input before deciding on the most effective regulatory measures.