A new study by Benat Arregi and Joseph Little finds increasing evidence that current mainstream guidance for assessing moisture risk of insulation retrofits in Ireland and the UK is unsuitable for traditional solidwalled buildings.This guidance is still based on simplified hygrothermal risk assessment methods, despite the availability of more advanced numerical software for two decades and a relevant standard in place since 2007, EN 15026.
Two-dimensional versions of these software applications can extend simulation beyond one-dimensional assemblies to more complex junctions. This exploratory study makes use of one of these advanced simulation tools, aided by physical measurement, to explore hygrothermal risks of solid wall retrofits at the junction with uninsulated and insulated ground floors. A brick-faced traditional dwelling in Dublin has been selected as a case study, and four scenarios have been simulated: its original condition and three retrofit approaches.
Results indicate that (a) the moisture content at the base of the wall increases in all retrofit scenarios examined, and (b) the assemblies with high vapour permeability and no membranes result in the lowest hygrothermal risk. The findings should be supported by further research and could have great relevance to guidance, specification and grant policy for energy retrofits of solid wall properties in Ireland and the UK.
Benat Arregi, Building Life Consultancy
Joseph Little, Dublin Institute of Technology