Thermal Mass and Ground Coupling: Full scale evidence for summer and winter resilience

Thermal Mass and Ground Coupling: Full scale evidence for summer and winter resilience

This study investigates the role of structural thermal mass and ground coupling in enhancing the passive thermal resilience of single-storey residential buildings during both summer heatwaves and winter heating outages. The study compares two identical test dwellings with different constructions: a medium-weight masonry building (B1) with direct ground-floor interaction, and a lightweight timber-frame building (B2) with a fully insulated slab. Results from monitored heat events in 2018 and 2019 demonstrate that the ground-coupled, heavy structure (B1) effectively prevents overheating during severe summer conditions, maintaining safe indoor temperatures without mechanical cooling, whereas the lightweight, insulated slab building (B2) experiences significant overheating, crossing comfort thresholds for extended periods.

During controlled winter heating outages, B1 maintained habitable conditions for over 60 hours, with higher minimum indoor temperatures compared to B2, which exhibited rapid temperature declines and deeper cold stress. The findings show that structural mass and ground coupling offer passive buffering benefits throughout the year: they moderate indoor temperature swings in summer and extend winter safety periods in case of heating system failures. While lightweight insulated envelopes offer short-term efficiency for winter heating, these are more susceptible to both summer overheating and rapid winter cooling during outages, especially as climate extremes become more frequent.

The research concludes that building envelopes combining structural mass with ground-floor interaction can improve resilience to temperature extremes, reducing reliance on active systems and enhancing occupant safety under both heatwaves and heating interruptions.