Replacement infill panels for historic timber-framed buildings: measured and simulated hygrothermal behaviour

The historic built environment has a fundamental role to play in the future of our cities. It has been recognised to be instrumental in achieving social, economic, environmental, and cultural sustainability. However, operational carbon emissions must be reduced, and further research is required to achieve this. This paper presents the ongoing research by the authors, evaluating the energy retrofit of historic timber-framed buildings in the UK. The paper focuses on a funded research project where monitoring of replacement infill panels under real climatic conditions, and digital dynamic hygrothermal modelling, are utilised to determine the thermal performance of four infill materials, the hygrothermal conditions within and around the panels, and assess associated risk to the historic timber frame from moisture accumulation. The four materials monitored are traditional wattle-and-daub, expanded cork board, a composite detail of woodwool and wood fibre boards, and hempcrete. The results show wood fibre as the most susceptible to moisture accumulation. The use of impermeable perimeter sealants should be questioned; however, this requires further research. The results from simulations corroborated these main findings, however interstitial condensation was predicted at the inner face of the wood fibre insulation, which to date has not been measured. The monitoring is ongoing. KEYWORDS: Heritage Retrofit, Hygrothermal Monitoring, Hygrothermal Simulation, Timber-Fram