Numerical investigation of the effect of vacuum insulation panels on the thermal bridges of a lightweight drywall envelope

This paper addresses the thermal bridges issues of a two storey lightweight steel framed envelope in which the VIPs are placed in an inner “protected” layer of the external walls. This configuration provides “protection” for the VIPs, allows flexibility in installation of façade elements and at the same time permits interventions and modifications (e.g. drilling, installation of appliances) on the internal side of the wall. The envelope is extensively analyzed in terms of all the different types of thermal bridges utilizing commercial computational tools and standardized methodologies and their effect on the overall thermal performance is evaluated. A total improvement of 33% on the heat transfer coefficient of the building is estimated. Results indicate the junctions between the external and internal walls, the external walls and the ceiling, the internal walls and the roof and the internal walls and the floor, respectively, as the most crucial thermal bridges. Different design modifications and solutions are assumed in order to further reduce the impact of the most crucial thermal bridges. The implementation of the modifications resulted to a further reduction of the overall thermal losses by 27.5%, leading to an overall thermal loss reduction by 60.5% when compared to the reference building.