Thermal Mass
Thermal mass is the ability of a building material to absorb, store and release heat over time, thereby helping regulate indoor temperatures and lessen the risk of overheating. In NZEBs, high insulation and airtightness can result in heat buildup due to less ventilation; therefore, thermal mass is an important factor to absorb excess heat during the day and release it at night to achieve a comfortable temperature (Karlsson, 2012),(Ozarisoy, 2022b), (Tripathi & Shukla, 2024).
Some of the recommended materials for Thermal mass to mitigate overheating are
Concrete
The high specific heat capacity and density of concrete absorb and retain substantial heat quantities, delaying temperature changes inside a building (Tripathi & Shukla, 2024).
Phase Change Materials (PCMs)
Compared to traditional thermal mass materials, PCMs absorb and release latent heat, leading to an advanced passive thermal regulation inside lightweight frameworks (Tripathi & Shukla, 2024).
Daytime: The Surroundings absorb heat
Nighttime: Surrounding release heat
Window Design
The Window-to-Wall Ratio (WWR) is crucial in mitigating overheating by balancing daylight access and solar heat gain. A WWR of 40–50% optimises energy efficiency and occupant comfort (Neu et al., 2014; Albatayneh, 2018).
Key Takeaway
Integrate building-level passive cooling strategies early in the design process to reduce overheating in passively cooled buildings and decrease energy consumption in mechanically cooled buildings.