Summer overheating: Understanding the ‘oven effect’ in homes

The ‘oven effect’ describes a phenomenon where buildings overheat during summer due to heat accumulation in structures like uninsulated roofs, sun-exposed walls, and large glass surfaces. This trapped heat is released slowly, causing indoor temperatures to remain high even during cooler evening hours.

Experts note that thermal phase shift—the delay in heat passing through building materials—is a key factor. A high thermal phase shift can help move heat entry to the night when it is easier to dissipate. High-risk structures include top-floor apartments with poor roof insulation and homes with single-sided window exposure that limits airflow.

In response to energy efficiency upgrades that have made buildings more airtight, new decentralized heat recovery technologies are being introduced to manage indoor humidity and air quality without the need for invasive centralized systems.