An opinion piece by Fionn Stevenson, Professor of Sustainable Design, Building Performance Network (BLN)

1. Performance challenges facing industry

Currently, building activity in Europe is responsible for 36% of all carbon emissions, which is driving

forward climate change at an alarming rate in terms of increases in storm damage, flooding, overheating, wildfires, and ‘weather bombs’ generally. Despite the various policy calls for Net Zero carbon emissions from buildings, we know that buildings routinely use twice as much energy as predicted, meaning they actually create an excess of carbon emissions rather than a reduction in use. This is due to a variety of factors in our construction industry including: lack of quality control mechanisms during the design and build process, inadequate legislative requirements, lack of training for build quality in relation to new technologies and systems, and poor consideration of occupant needs.

One key factor that can help with all the above issues is the provision of building performance feedback within construction systems, to inform design and build processes from inception to demolition. Without understanding how well our design intentions are being met by our design, build and in use processes, it is simply not possible to address the above failings, because we have no feedback to tell us when and why these failings are occurring. This is where Building Performance Evaluation provides an excellent way forward to understand what needs to change, when and how, during the complete lifecycle of a building process.

2. Opportunities to address challenges

Building Performance Evaluation (BPE) can be defined as:

“… the gathering of quantitative and qualitative data that characterise the performance of a building (or separate premises within a building) and the interpretation of these data to draw conclusions regarding specific performance attributes and the overall performance of the building.” according to the new British Standard 40101 Building Performance Evaluation.

The new requirement from the latest COP26 agreement for ‘energy efficiency’ opens up a new route for BPE as a means of verifying energy efficiency in buildings and heralds a potential step change in UK government attitudes towards BPE, which has been relatively hesitant up until now. The Building Performance Network  has helped to promote the world’s first bespoke BPE Standard BS40101, which is designed to cater for all types of buildings,  including retrofit and new build. This new standard, launched at the beginning of 2022, offers three different progressive levels of entry: ‘Preliminary Evaluation’, ‘Light BPE’, and ‘Standard BPE’. This enables industry stakeholders to engage with the standard at a level which is appropriate for their circumstances. The standard also allows additional tailoring through ‘Investigative BPE’ methods which can be added onto any of the levels.

Building up capacity in the construction sector to deliver BPE remains a key challenge, given that there is no accreditation process for BPE Evaluators yet. The BPN is developing the first ever UK BPE Evaluator Register, as well as developing BPE training for potential evaluators. This will be initially focused on housing, but will be expanded to the non-domestic sector.

3. Basics of BPE

So, what do you need to do to get started with BPE?

At the most basic level, BS40101 requires a list of key building parameters, such as area, purpose, location, occupancy etc, to set the scene. A quick and simple occupant questionnaire is carried out to highlight how well the building is performing in terms of occupant perceptions.  This is followed by the measurement of overall energy use after 12 months to verify occupant perceptions and benchmark performance. Finally, a building tour is required, undertaken with client, design and management representatives, to understand the findings of the previous methods in context. No monitoring is required at this level. For the ‘Light BPE’ level there is an additional post-construction review of any documentation and testing that has been carried out in relation to regulatory requirements (airtightness, EPCs, DECs, commissioning etc), water use evaluation, as well as some basic monitoring of external temperature and humidity using existing sources. The ‘Standard BPE’ level introduces thermal imaging, energy use, temperature, humidity and internal carbon dioxide monitoring at 30 minute intervals for 12 months.

One key challenge for BPE is how to disaggregate the performance of the building fabric and services as built, from the performance of the building in use, as affected by occupant practices. Installing heat meters can partly satisfy this demand, but the best test of all is a fabric heat loss test, ideally for the whole building. There are new less intrusive methods and techniques developing all the time for these activities, one of which is highlighted below – the Smart HTC.

4. Examples of BPE delivering improvements

The top six reasons for clients and design teams carrying out BPE as a routine activity are: process and product improvement, reduced risk and hidden liabilities, reduced defects, reduced maintenance, future proofing and improved customer satisfaction, which all result in a better reputation, repeat business and increased profitability. This is demonstrated frequently, by fixing things early on, during the defects period. We call this ‘fine tuning’, where BPE really excels.

BPE testing of indoor air quality in homes in one study, revealed that only 3 out of 80 homes met requirements for adequate ventilation. Much of this was down to poor design, installation and commissioning of ventilation systems, rather than occupant practices. The identification of these ventilation faults provides a valuable learning process for the design and build team.   In one housing BPE project in Rotherham, the findings showed that electricity consumption reduced by 41% in one home simply through the correction of the controls set up.

Built environment clients and their design teams now use BPE on a regular basis to deliver organizational learning and process improvement. A good example of this is the partnership that Architype Architects develops with every client, guaranteeing that BPE will be carried out on every project, on a ‘no blame’ basis, to ensure that building performance is achieved in line with design intentions. The virtuous circle induced by this systemic BPE process has led to countless awards and repeat business.

Visit the Building Performance Network visit to download the infographic document.