Development and experimental validation of a heat, air and moisture model for metal-clad roofs
Year: 2025
Type: article
Abstract: Accurate hygrothermal models of roofs are needed to predict the impacts of changes in construction practice, e.g. decreased roof solar absorptance, increased ceiling insulation, and modified roof ventilation details, on: i) roof thermal performance, and ii) the risks of condensation, water damage and mould growth.In this study, we developed and validated a new heat, air and moisture (HAM) roof model. Novel aspects of the model include: the ability to model several interconnected air spaces (e.g. roof and above-membrane spaces), a model to predict the onset and magnitude of condensate runoff, and the use of different external convective heat transfer coefficients to previous models.Experiments were run using a well-instrumented test building with gable roof, exposed to outdoor conditions. Four configurations of ventilation openings leading to the roof space were tested. Extensive measurements were taken of temperature and humidity throughout the roof structure, ventilation rates using tracer-gas, and ambient weather conditions.Validation of the new model revealed relatively close agreement between simulated and measured temperatures (mean absolute error 1.0 °C), humidity (mean absolute error 0.57 g / kg dry air), and ventilation rates.A sensitivity analysis is also presented, with the following findings: timesteps up to 30 min did not impact the accuracy of the model; an appropriate model for external convective heat transfer coefficients is identified; an airflow network allowing air movement between the roof and above-membrane spaces improved temperature predictions; and modelling the roof space as well-mixed produced the most accurate results.
Source: Building and Environment
Authors: Alan Green, Steven Beltrame, Georgios Kokogiannakis
Institutions: Australian Research Council, University of Wollongong
Language: English
Subfield: Building and Construction
Field: Engineering
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $4,280
Funder: Australian Research Council
OpenAlex ID: W4417537426