Building Performance Evaluation

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. Below our Technical Director, Dr Sarah Price 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. At QODA, we collect 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 and 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 and Building Performance Evaluation

In the vast majority of new build and retrofit projects, we only tend to see this 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.

Research Developments

A new good practise standard on building performance evaluation has just been published by the BSI, BS40101:2022 “Building performance evaluation of occupied and operational buildings (using data gathered from tests, measurements, observation and user experience)”.

We are also learning what we can from government-funded innovation projects and utilising this information within 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.

Written by Dr Sarah Price