Quality and performance

Initial performance monitoring work

Pioneering studies by Leeds Beckett University from 2005 revealed that there was a significant performance gap – the difference between actual as-built performance and the design target – for energy use in new homes, sometimes more than 100%.

The GHA explored these problems through a number of performance monitoring studies, working with Leeds Beckett University, Oxford Brookes University and UCL, and funded by the Department of Communities and Local Government (DCLG), Energy Saving Trust and NHBC Foundation:

Phase 1: Fabric testing – Provision of technical support for GHA Developers in monitoring the fabric performance of their dwellings
Phase 1A covers 4 dwellings on 3 sites, all using different build systems (e.g. SIPS panels or thin joint masonry) and built to different standards, including Code 4, Code 5 and Ecohomes Excellent. Phase 1B has extended this monitoring to cover 4 further dwellings, including Code 4, Code 5 and Passivhaus schemes, and built using timber frame, Hemcrete and other systems.
Phase 2: In-use monitoring and post occupancy evaluation – Extension of the above monitoring on each site, to measure energy and water consumption, indoor air quality, humidity and thermal comfort, and occupant feedback.

The following projects were used as case studies:

Subsequently, numerous other studies have shown that the in-use energy performance gap is a significant problem across the industry, particularly the Zero Carbon Hub reports on closing the gap between designed and built performance and on Understanding the performance challenge, plus the Innovate UK Building Performance Evaluation programme reports.

Other studies have also shown significant performance gaps associated with ventilation, indoor Air Quality and overheating/summer comfort.

Performance delivery – LowCarb4Real

Following the initial monitoring research, the GHA worked with Leeds Beckett University and UCL on the LowCarb4Real project sponsored by UrbanBuzz, to gather evidence and good practice about how to deliver low carbon homes. Drawing on detailed academic studies at Stamford Brook along with GHA member experience, the GHA and its partners helped to implement this learning by providing education and technical support to GHA Developer members and others.

As a result of this work, GHA members were able to improve the performance of their schemes such that they encountered a performance gap of only 5-20%, significantly better than the figures being achieved on other sites elsewhere.

Information about how to achieve good performance on sustainable housing projects was then collected and a number of detailed case studies were created, including:

The GHA was also involved with a number of performance monitoring studies, as part of the Innovate UK (then Technology Strategy Board) Building Performance Evaluation programme, which showed that the energy use performance gap could be significantly reduced:

Subsequently, a number of organisations (including several GHA members) have developed tools/guidance to address the energy performance gap, including:

The Assured Performance Process (APP) created by the NEF
The Building Energy Performance Improvement Toolkit (BEPIT) managed by BioRegional
Zero Carbon Hub reports

Performance gap campaigns

As a result of this research, the GHA led a campaign for the house-building industry to address the energy in-use performance gap and for housing performance to be based on measured as-built performance, rather than design targets/intent. This challenge was adopted by the Zero Carbon Hub, which developed a working group that discussed how performance measurement could be included in the Building Regulations.

After the Zero Carbon Hub was closed in 2016, there was a hiatus in the industry’s focus on as-built performance until the publication of the new Industrial Strategy in 2017, when the need to radically reduce CO2 emissions was recognised once again.

Subsequently, a number of initiatives have started to address the energy use performance gap, including:

The Building for 2050 research project, funded by BEIS
The BEIS Buildings Mission to at least halve the energy use in new buildings by 2030, and the response from the Green Construction Board about how this could be achieved
The proposed BEIS Future Homes standard, which is currently the subject of an ongoing consultation.

However, there has not been a similar focus on the need to address the ventilation & indoor air quality (VIAQ) and summer comfort (overheating) performance gaps. Indeed, recent Government-funded research on ventilation and overheating has confirmed that these problems are still prevalent. These topics therefore remain a focus for GHA campaigning activities.