Abstract
Reducing energy use and associated CO₂ emissions in existing buildings is a key challenge in the transition towards a low-carbon built environment. Renovation using low-carbon, high-performance envelope insulation materials offers significant potential, but reliable methods are needed to assess their performance under real-world operating conditions.
This study presents an integrated experimental and modelling framework to evaluate the thermal and energy performance of novel insulation materials under real outdoor conditions. Two parallel full-scale test cells were used to represent pre- and post-renovation configurations, enabling a direct comparison between baseline and renovated test wall assemblies. High-resolution experimental measurements were combined with transient simulations in IDA ICE and EnergyPlus to investigate a newly developed bio-based polyurethane (bio-PUR) insulation, which was integrated into one external wall and the window frame of the renovated test cell. Model validation was carried out by comparing simulated and measured operative temperatures, internal surface temperatures, heat fluxes, and heating energy demand.
Across multiple operating scenarios, the calibrated models reproduced temperature measurements with deviations between measured and simulated values generally below 5% in the heated cases, while heat-flux and heating-energy predictions showed deviations below approximately 16% and 12%, respectively; larger discrepancies were observed under free-floating conditions. Sensitivity and parametric analyses identified insulation thermal conductivity as the dominant material property influencing heat flux and heating energy demand, while air-infiltration modelling primarily affected the latter; operative and surface temperatures showed low sensitivity to material properties and infiltration modelling. The renovated test cell exhibited a 26% reduction in space-heating demand compared with the reference configuration.