Variations in low carbon building performance

In February 2016, the findings of an £8 million Innovate UK study were published, highlighting a significant performance gap between design and actual carbon emissions.

The Building Performance Evaluation (BPE) study monitored the operational performance of 50 non-domestic buildings and 76 residential projects for three years.

• Building Performance Evaluation report on non-domestic buildings.
• Building Performance Evaluation report on homes.

It found that nearly every non-domestic building had higher carbon emissions than predicted during the design phase. In some cases, total emissions were 10 times the Building Emission Rate calculated for Part L compliance. Although two-thirds of the buildings studied had renewable energy generation onsite, a significant proportion of these experienced problems that impacted on potential energy savings.

Of the domestic buildings studied, carbon emissions were two or three times higher than had been estimated during the design stages. One particular house that incorporated energy saving devices such as a heat pump, solar water heating and heat-recovery ventilation actually used 29 times more than the design estimate for regulated energy.

Although the study acknowledges that '...It is a little misleading to call this a ‘performance gap’, as the actual emissions include energy use from cooking and appliances', whereas building regulations calculations only include regulated energy, '...However, even allowing for this, the evidence highlights much higher actual carbon emissions than design-stage estimates.'

The conclusions drawn echo those found in earlier studies; chiefly that poor commissioning, handover procedures and problems integrating low energy systems, are working to slow down progress towards the industry’s ambitious 2025 and 2050 carbon reduction targets.

Innovate UK project manager Mat Colmer said, “Obviously it’s a challenge that the buildings aren’t performing as intended, but all of the organisations in the project have been incredibly open – including clients such as Asda, M&S, Crest Nicholson and Gentoo. They have gone through the reviews, fixed the problems, and will now be able to tell other people about it. So the news is, it’s not just a group of specialists, but it’s industry people who are grappling with it.”

He emphasised that the comprehensive scale of the study and the information generated was a cause for optimism in terms of the performance gap beginning to be narrowed.

NEF energy specialist Federico Seguro said, “The construction industry continues to wrestle with pinpointing and bridging the gap between the design of buildings and their ‘as-built’ performance; a gap that exists across all building sectors.

“Our meta-analysis of all of the BPE projects led by Registered Providers revealed the trigger points resulting in social housing projects failing to deliver on the designed performance targets, and identified a number of key issues for the future. Our research will empower Registered Providers who have the means to champion and combat the ‘performance gap’ in buildings, and allow them to apply lessons from the BPE to their new developments.”

Recommendations from the BPE study include:

• Taking thermographic images of completed buildings to detect problems with construction details.
• More efficient and simpler controls for renewable equipment such as solar hot water systems, photovoltaics and ground or air source heat pumps.
• Making it easier to commission systems and to manage controls for multiple renewables.

The data from the study is available on the Building Data Exchange platform, created to stimulate innovation and help build more efficient properties.

Simon Hart, Innovate UK's programme leader for the built environment, said: “Homes and offices are not performing as they should do. They are consuming up to 10 times the energy they should, and there are a multitude of factors behind that. The programme has amassed so much data that it’s difficult for constructors to process it. There is an opportunity now for digital businesses to create smart home or property technology that could be adopted by the construction industry and help it to tackle these issues.”

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki

• Building data exchange.
• Building performance metrics.
• Closing the gap between design and as-built performance.
• Co-heating test.
• Domestic ventilation systems performance.
• Emission rates.
• Energy performance certificates.
• Energy Savings Opportunity Scheme.
• Green building.
• Performance of exemplar buildings in use: Bridging the performance gap FB 78.
• Retrofit.
• Soft landings.
• Sustainability.
• Zero carbon homes.
• Zero carbon non-domestic buildings.