Validation of the Heat3D System for Mapping U-Values in Homes Through a Two-Phase Winter Field Trial

Effective evaluation of building fabric is essential to understanding building performance. Traditional methods, such as ISO 9869-1, provide point U-values but do not always capture the complete picture, and new measurement-led approaches are needed to support building retrofit. Heat3D is a novel iOS application that performs rapid U-value measurements of building elements by mapping thermographic images from a mobile infrared camera onto an augmented reality (AR) model of a room, from which heat flux across the element is calculated. A field trial of 22 UK properties during the 2019–2020 winter heating season assessed Heat3D’s heat flux measurements against traditional heat flux plates, with 90% of 295 Heat3D surveys falling within the combined uncertainty of the reference method. A second field trial, conducted over the 2020–2021 winter heating period, evaluated a new timelapse iteration of the method capable of measuring wall U-value within approximately 60 min; 90% of 42 Heat3D surveys fell within the combined confidence interval of the ISO 9869-1-measured U-value. These results indicate that Heat3D offers a viable, rapid alternative to traditional methods for both heat flux and U-value measurement.