As well as modelling buildings carefully using accurate modelling systems, such as Passivhaus Planning Package (PHPP), Building Performance Evaluation (BPE) is a key part of our work as building physics consultants. In this blog, Dr Sarah Price, Enhabit’s Head of Building Physics & Consultancy, looks at the vital – but often-neglected – role of building performance evaluation.
Building Performance Evaluation: Cost-effective approaches
Building performance evaluation should happen routinely, but it is often value-engineered out of projects or not included in the first place due to tight budgets. However, building performance evaluation doesn’t need to be expensive. Enhabit collects energy bill data from clients pre and post-retrofit to evaluate space heating demand. The data below is from the first Passivhaus retrofit project in the UK.
Annual Space Heating Demand (kWh/m2.yr)
PAS 2035 & Building Performance Evaluation
In PAS 2035, the new retrofit standard, basic evaluation consists of a questionnaire and a walkaround to ensure that the intended outcomes have been achieved. Then, if the results of this basic evaluation show that the retrofit is not performing as intended, more advanced building performance evaluation is undertaken. This could include, but is not limited to, airtightness testing, U-value measurements, indoor air quality measurements, invasive investigations, or specialist building services inspections. The evaluation process in PAS 2035 the part of the project and the project is not complete until a successful outcome has been achieved.
Troubleshooting & Building Performance Evaluation
In the vast majority of new build and retrofit projects we only tend to see these kind of advanced building performance evaluation techniques when something has already gone wrong with the building. They may be implemented in expert witness cases, or to placate complaints, but these are still relatively rare and many people simply live with the consequences of poor building design and construction. The UK construction industry struggles to ensure compliance with building regulations, so implementing good building performance evaluation seems a long way off.
A new good practice standard on building performance evaluation is in the early stages of development with the BSI. We hope to see this published in the next couple of years.
In the meantime, we are learning what we can from government-funded innovation projects into new retrofit construction techniques. The latest of these is the social housing decarbonisation fund which requires all projects to be compliant with PAS 2035 and includes a proportion of buildings that shall undergo advanced independent building performance evaluation, even if the basic evaluation was successful.
Dr Sarah Price, Head of Building Physics & Consultancy, Enhabit
Enhabit works to ensure our new builds and retrofits do not exhibit the performance gap. We use the principles of building physics in our modelling and design work, and make sure that as many of our projects as possible are monitored post-completion. Examples of our building performance evaluation work include airtightness testing, U value measurements, and energy bill monitoring.
Enhabit is a member of the Building Performance Network (BPN), which is an independent not-for-profit organisation, working to bring together individuals and organisations with an interest in improving building performance in operation. More information: building-performance.network