Relative carbon intensity of buildings in the Sydney CBD

19 June 2014 — A report by Flux Consultants has found carbon intensity may be a better metric than NABERS ratings for benchmarking performance and driving sustainability improvements in buildings.

Beneath the Stars: Data Empowerment for the Next Generation of Sustainable Property, authored by Flux Consultants director Ché Wall, co-founder of the Green Building Council, and sustainability consultant Siân Gibbons, takes recently released data on the Commercial Building Disclosure program and analyses it to assess how to guide best practice in low carbon policy for the buildings sector.

The data set, the report authors said, was considerably larger than any other commercial office energy efficiency data made available in Australia to date.

“Until now, only limited, and often distorted, energy and carbon efficiency data has been available,” they said, “so the release of the comprehensive CBD data set, including the underlying annual carbon footprint of buildings in our cities, provides an unprecedented basis on which to properly understand operational energy and carbon performance in Australian office buildings and to recalibrate our understanding of best practice.”

Relative carbon intensity of Melbourne CBD buildings

The analysis found that a building’s NABERS rating was often not a good indicator of its carbon performance.

“The use of star rating tools has driven transformation across the commercial property sector, but our analysis showed that star rating and underlying carbon intensity are not the same,” the authors said.

“Simplifying performance to a star rating metric conceals the underlying true carbon footprint of the building, which is the most useful data for investment and policy purposes.”

The report stated that true carbon intensity was a key metric for investors and financiers seeking to invest in low carbon assets, as well as for developers pursuing high performance, carbon neutral developments.

Relative carbon intensity of Sydney CBD buildings.

The report identified that while there was a definite market need for an asset rating tool like NABERS, there was also a growing need for “transparent carbon accounting and market benchmarking, particularly for those who seek to direct capital or policy toward low carbon outcomes that can be aggregated, pooled and verified”.

The next wave of innovation in building performance would be enabled by “simplicity and transparency and relative performance being judged against a peer group”, the report authors suggested.

“Our analysis of the CBD data set concludes that the actual underlying annual carbon intensity of buildings – the data ‘beneath the stars’ – provides a more reliable way to benchmark relative performance of an asset than the associated simplified star rating, and this data could inform city-centric common baselines that could unlock capital flows.

The data could be used to develop the next generation of performance metrics to “drive world-class energy efficient buildings as well as to attract a new audience of institutional investors”, the report stated.

Other key conclusions of the report included:

The dataset provides insight into correlations – data analysis revealed a number of correlations that appeared to contradict the current understanding of energy and carbon in buildings as assessed under star rating tools, including moderate to strong correlations found between area and greenhouse gas intensity, but little to no correlation observed between hours and greenhouse gas intensity

Boundary setting is important for fair comparison – a limitation in the CBD dataset was observed in the handling of energy boundaries and separation of landlord and tenant energy, and, as a result, buildings striving for best practice outcomes might be discouraged

Comparing well internationally, but room for improvement — the CBD program performed well against the New York City Local Law 84 program, but the comparison highlighted the need for the program to be extended to additional buildings types, to adopt annualised reporting regardless of a sale or lease trigger, for extensive year-on-year reporting of trends and observations, and the use of a common reporting period

The CBD program is scheduled for review in 2015.

Read the full report.

4 replies on “Report: look beneath the NABERS stars to drive building sustainability”

  1. Extremely interesting article and associated report. Thanks for the links

    As others have said, NABERS Energy’s intent was to be a simple tool. The argument was that it needed to be simple at the time if it was going to be the subject of Commercial Building Disclosure legislation which has been incredibly important and transformative for our industry (even it just meant that it was put onto the radar of FMs and building owners). I think many of us have been surprised as to how the NABERS Energy rating can be so influential in decision making. This influence is problematic if we fail to consider the original intent and simplicity of the tool.

    I completely agree that we need to look beyond the stars. But we also need to look beyond the Energy tool as well. Sustainability is more than energy. NABERS is more than energy.

    It took CBD legislation to drive the uptake of the NABERS Energy tool. The market is starting to see the value of Water, Waste and Indoor Environment. It would be good to see building owners and tenants who are truly interested in sustainable performance measurement adopt the other NABERS tools, as well as analyses of carbon intensity as outlined in the report, without legislation necessarily forcing them too.

  2. I was at a interior design awards tonight held at Interface office in Sydney. What amazes me is at this function of some 150 people how many are really passionate about making our cities sustainable. From Architects, Interior designers, builders, publishing and editors. In fact everybody there that I spoke to had reasons to want to make our cities sustainable.

    I spoke to an engineers from Cundall, A very well known architect in Sydney and many other people in the sustainable space and the most common component of conversations was that people are being left out of the equation in the design process.

    When are we going to get it right. We are designing for living breathing people. They are the ones who have to live in the spaces that are built up around codes regulations, certifications and certification When are we going to design for real people.

    The only organisation that comes close to include people in the design process in the” Living Futures Institute”.

    Remember this, our world is all about people.

  3. The original concept of NABERS was inclusive of a full range of sustainability indicators – the version of NABERS that’s been adopted was massively watered-down thanks to industry lobbying. Rolling out the original NABERS would be a real contribution to a systemic shift to something approaching real ‘sustainability’.

  4. This report makes some important points. NABERS has been developed on a very limited knowledge base, and it was originally developed as a voluntary and simple tool. Indeed, both residential and commercial building energy rating in Australia has been developed on incredibly small budgets with tiny resources compared with some other countries. So it’s remarkable that we have developed useful tools.

    However, I am nervous about making changes on the basis of even this improved database. For example, the R2 values for trend lines related to hours of operation are close to zero. Perfect correlation has an R2 value of 1, and no correlation has an R2 of zero. So even this larger dataset is so scattered that clear conclusions can’t be drawn. It may be that if we engaged some hotshot statistical mathematicians, they could use more advanced analytical tools to extract meaningful trends. But this is tricky work.

    This report is a great first step, and it raises a lot of important issues. Who will fund the next step?

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