Following the PAS 2035 standard for retrofit projects can help to avoid the impacts of “bad retrofit”, as recently reported following a National Audit Office (NAO) report. Done well, retrofit of existing homes can lead to significant reductions in residents energy bills as well as CO2 emissions from the dwelling.
The NAO report found that 98% of retrofit projects that had external wall insulation installed had issues that could lead to damp and mould if left unaddressed, and needed remedial work. Trustmark had reported that these works had not been installed in line with the PAS 2035 standard.
PAS 2035 sets out a process for retrofit projects that aims to improve quality and avoid unintended consequences, such as mould. This process includes:
- Take a “whole dwelling” approach to retrofit – historically, improvement measures were done in isolation (e.g. external wall insulation), without considering how this would interact with other elements of the building. For example, cold bridging around windows or reduced airflow through the dwelling as a result of the added insulation.
- Improve accountability – the standard requires a qualified Retrofit Coordinator on all projects, and any contractors working on the project have to be registered with Trustmark.
- Improved monitoring and evaluation – every PAS 2035 project has at least a “basic evaluation” within 3 months of completion. This aims to review if the retrofit has delivered planned benefits. If any issues are identified, they can be addressed before any major consequences (such as mould) occur.
Improving the energy efficiency of existing buildings will be essential in meeting the UK’s commitment to achieving net-zero by 2050.