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How NABERS will transform the performance of UK office buildings

Sirius House, Canberra. The first office to achieve a NABERS 6 Star Energy rating. Can its success be mirrored in the UK? Photo: MIRVAC

A scheme to create an investment grade rating that reflects building performance based on the Australian NABERS energy rating scheme is in development in the UK. The hope is to bridge the performance gap between design and actual performance of office buildings. But a new report shows the UK lags 15 years behind Australia.

According to Sarah Ratcliffe, program director of the Better Buildings Partnership (BBP), which is spearheading “British NABERS” “the project is based on more than 10 years of work within the Partnership to help members improve the sustainability performance of their real estate assets.

The Partnership has 31 members.

“During this time, an independent and trusted measure of buildings’ operational performance has been elusive. The BBP looked at best practice around the world to try and identify a solution,” Ratcliffe said.

It found NABERS. “NABERS was clearly a standout example of a rating scheme, based on performance outcomes that has led to a major market transformation” 

The BPP’s version is called Design for Performance (DfP)

“This project is focused specifically on the new-build market, the idea being that if performance is difficult to measure in existing buildings, then new buildings could lead the way by using a rating scheme that could, in-time, also be used for existing buildings,” Ratcliffe continued.

Thirteen new partners have joined the DfP project this week: developers Derwent London and Stanhope and 11 leading engineering and building consultancies: AECOM, Arup, Atkins, Built Physics, BuroHappold Engineering, Cundall, Hoare Lea, KJ Tait, Ramboll, TFT and Watkins Payne.

Each have committed to advocating DfP to their clients, supporting the development of the initiative and upskilling their teams to be able to support developers delivering energy performance outcomes for new offices.

The Crown Estate has also committed to trial the DfP approach on (at least) one new office development.

The announcement is accompanied by the launch of a new report, Design For Performance: a new approach to delivering energy efficient offices in the UK. The report outlines the key learnings and progress to date, including a road map outlining the governance structures, market demand and industry skills necessary to deliver a design-for-performance approach in the UK.

Addressing the “performance gap”

The UK commercial office market targets theoretical performance to comply with Building Regulations. An energy performance certificate (EPC) rating, determined by a theoretical calculation, is used to communicate an existing building’s energy efficiency.

Sarah Ratcliffe

This results in a “design for compliance” culture, with empirical evidence suggesting the EPC rating correlates very weakly with actual operational energy use – the “performance gap”.

By contrast, in the Australian commercial office market, there is a focus on performance outcomes. This is supported by NABERS, which is a scheme to rate the operational energy efficiency of the base building.

It has transformed the energy efficiency of buildings and become a KPI influencing investment decisions for existing and new buildings, sales and purchases.

Since NABERS was introduced in Australia, buildings with better energy efficiency ratings now enjoy lower voids, increased rents and enhanced asset values, thereby producing higher income and capital yields.

Design for Performance and NABERS have signed an MOU

The BBP and NABERS have now formalised their relationship.

“Last week we were delighted to announce a partnership between NABERS and the BBP, underpinned by a Memorandum of Understanding that will see the two organisations working together to develop the scheme infrastructure for the UK,” Ratcliffe said.

Ratcliffe believes that in light of the UK government’s newly announced commitment to net zero carbon emissions by 2050, “DfP provides a tangible and practical market-based response to the performance gap, enabling building owners to deliver better buildings that can secure significant improvements in energy efficiency and provide a genuine pathway to zero carbon offices in the UK.”

In 2015, the BBP commissioned a feasibility study, supported by UK office developers, industry bodies and sustainability bodies, that looked at key success factors of the NABERS rating scheme and the “Commitment Agreement Protocol” process used for new developments. This was followed by a pilot program on six live major office developments.

“The findings of the feasibility study and pilot projects demonstrated that not only are there no technical reasons why such an approach would not be possible in the UK, but that there is an urgent need for a scheme that encourages a focus on energy performance outcomes,” Ratcliffe said.

“The delivery of DfP will, of course, hinge on the embedding of performance outcomes throughout the project life-cycle and with all major stakeholders. In the coming months, the initiative will also be looking to engage with other stakeholders including architects, contractors and managing agents,” Ratcliffe said.

The BPP is integrating Design for Performance principles into key industry standards

DfP is supported by a wide range of industry bodies and is being integrated into key industry standards including The British Council for Offices “Guide to Specification 2019” which includes a new section on “Designing for Operational Performance”, BRE’s new Construction Update 2018, CIBSE’s Metering Guidance (TM39) and BSRIA’s Soft Landings program.

Supporters also include The British Property Federation, The Usable Buildings Trust, RIBA and the UKGBC.

“The Design for Performance initiative is market led and backed, provides an approach that will secure energy performance in use and encourages much needed industry collaboration to deliver better buildings,” Ratcliffe said.

Key barriers

The new report contains a number of lessons for the future based on case studies.

In office block construction, the use of shell-and-core fit-outs, common practice in the UK in at least the upper part of the office market, is “a significant impediment to energy efficient performance outcomes,” it says.

The use of fan coil units, closely linked to shell-and-core, is also not the most energy efficient solution to airconditioning in the UK.

Furthermore, the fact that British designers work within highly prescribed boundaries of industry expectation – which are not conducive to efficient design – creates limitations on design thinking.

There is also a significant skill gap in the UK design consulting community in producing good quality advanced simulations that can accurately model HVAC plant and controls.

This puts the UK 15 years behind the Australian market now, showing how far it has to go to catch up.

As for post-occupancy monitoring and the ability of the design to achieve efficiency goals, the report’s key recommendations are that it is essential for the ability to conduct these to be present in the original brief to ensure enforceability throughout the construction process.

And it is common for the specifications for lighting to lag behind the most efficient new industry developments on the market (LEDs).

In one particular building studied, there was no capability to efficiently adjust core services’ response to variable thermal and occupancy loads. Neither could the chief building tenant, Transport for London, secure a contractual obligation from the developer for the building to achieve the energy performance goals it had.

All of this shows just how far there is to go in the UK.

Building Performance Hierarchy

Arup has encapsulated these technical challenges involved in a “Building Performance Hierarchy”. For a building to deliver good performance in operation, all the layers of the hierarchy need to be in place.

[insert hierarchy.png]

So a building must be designed to be operated effectively with these features in place:

  • data on performance needs to be readily available to the facility management team;
  • controls interfaces need to match the maintenance skill set, easy to use for operators and building users;
  • construction and commissioning need to be completed effectively, for base build and fitout;
  • commissioning, particularly of the BMS and EMS, must be done without delay;
  • care must be taken to prevent tenant fit-out works adversely affecting base building operation;
  • a process of continuous commissioning needs to be undertaken in the first 1-2 years of operation and completed within the defects liability period, to identify any residual defects;
  • maintenance needs to respond directly to building performance data and needs access to sufficient skill levels in the team for the building systems present.

Read the detailed technical report on the Pilot Programme.

David Thorpe is the author of Passive Solar Architecture Pocket Reference, Energy Management in Buildings and Sustainable Home Refurbishment.

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