Do high energy-efficient buildings increase overheating risk in cold climates? Causes and mitigation measures required under recent and future climates

Contradictory findings are reported in the literature showing that high energy-efficient buildings have either higher or lower overheating risks compared to old buildings. A methodology is developed using the Global and Local Sensitivity Analysis to quantify the contribution and correlation of individual building envelope parameter to the change in indoor operative temperature. This methodology is applied to an archetype Canadian detached house as a case study to evaluate its overheating risk. The building envelope thermal characteristics studied represent houses built in different periods from 1950 to high energy-efficient buildings in Montreal under different weather generations: typical historical (1961-1990), recent observational (2016), and typical future years 2030 (2026-2045) and 2090 (2080-2099) generated based on RCP-4.5 and 8.5 scenarios. The results showed that the high energy-efficient buildings can be more resilient to climate change than old buildings if adequate ventilation is provided, where the decrease of window and wall U-value, and SHGC all contribute to the decrease in indoor temperature. While without adequate ventilation, the overheating risk in high-energy-efficient buildings can be higher than old buildings, where decreasing wall and window U-values and infiltration rate has a greater contribution to the increase of indoor temperature, while decreasing window SHGC has a lower contribution to the decrease in indoor temperature compared to the case with adequate ventilation. The results also showed that natural ventilation in the high energy-efficient buildings is sufficient to reduce the overheating risk under the current climate but will require additional interior and exterior shading under future climates.

Automated summary

Contradictory findings exist regarding the overheating risks of high energy-efficient buildings compared to old buildings. A methodology is developed to assess the contribution and correlation of individual building envelope parameters to indoor temperature change. The results show that high energy-efficient buildings can be more resilient to climate change if adequate ventilation is provided. However, without sufficient ventilation, these buildings may have higher overheating risks. Additionally, natural ventilation is currently effective in reducing overheating risks, but additional shading measures will be required in the future.