An innovative external wall insulation system for energy efficient refurbishment of houses

Energy use from housing contributes in the region of 27% of total UK carbon dioxide and greenhouse gas emissions. Therefore, achieving the national target of an 80% reduction in emissions by 2050 is highly dependent on the reduction of energy consumption in dwellings. Whilst progress is being made towards the improvement of the building fabric of new build dwellings, the existing building stock presents a more complex problem. The UK has over 8.5 million houses that are in excess of 60 years old, which are expected to still be in use for many years and yet need to be made considerably more energy efficient. There are limited insulation options available to those who occupy solid wall properties, making these particularly difficult to treat. Existing internal and external insulation products tend to be expensive, and installation on site can be time-consuming and weather-dependent. An innovative external insulation system has been developed, which seeks to overcome some of these barriers. The system, which consists of an uPVC shell with an insulating foam core, was designed to fit on most homes, within half the time, in variable weather conditions and using a lower level of installation skills than current systems. In this study, the authors have analysed the thermal bridging and condensation issues associated with the new product, alongside calculation of a theoretical u-value. Dynamic whole building simulation has been undertaken using a typical Nottingham (UK) property construction, with annual energy demands derived for scenarios both before and after installation of the external insulation system. The results indicate that the innovative external wall insulation panels are able to provide similar levels of improvements in u-values and energy demands/greenhouse gas emissions as compared to more conventional products. It therefore presents a viable alternative to systems that currently exist, thus expanding the number of options available for housing retrofit projects.