The workshops formed part of the Total Environment Centre’s “Existing Buildings Project”, in which a number of commercial property trusts undertook to significantly improve the emissions performance of their existing office buildings portfolios by the year 2012.

The trusts involved together hold about 80 per cent of Australia’s investment grade office building stock.

This final workshop had an international focus, exploring the state of climate change policy in key international markets. Speakers included Andrew Beatty, a partner in Bakers’ Sydney environment and environmental markets practice, and Pete Richardson, who is currently in Sydney on secondment from Baker’s climate change practice group in London.

Beatty and Richardson spoke about the international regulatory environment for climate change, while Nicholas Morris from energy and water economics consultancy IPA spoke about the potential effect of climate change and climate change policy on electricity prices worldwide.

A key talking point of the evening was the relative strengths and weaknesses of the various green building rating systems — a discussion sparked by the presentation by Chris Bloomfield of energy efficiency consulting firm, Exergy. Bloomfield analysed the features of the two key systems that currently exist internationally — design ratings, such as Green Star, and performance ratings, such as the Australian Building Greenhouse Rating system (ABGR) in Australia.

Design ratings, explained Bloomfield, are based on the specific green features and design of a building. Points are awarded on the basis of a broad range of factors, for example, the building’s proximity to public transport, the use of low volatile organic paint on surfaces and having separate light switches for individual work spaces.

However, no assessment is undertaken of the building’s actual emissions performance and therefore they rely on the assumption that green features will necessarily lead to green outcomes. In addition, because it is heavily prescriptive, Green Star has been criticised for being time consuming and expensive to comply with.

Performance ratings such as ABGR, on the other hand, look at a building’s actual emissions performance, but are not prescriptive about how specifically this performance is achieved. The actual building, as Bloomfield put it, is “a black box”, and only the final emissions outcome is considered. For this reason, design ratings require less documentation and compliance is, therefore, likely to be less costly for building owners.

However a downside of performance rating tools, at least as far as building owners are concerned, is that because emissions performance varies from year to year, buildings can easily be downgraded, while design ratings are more permanent.

From an environmental viewpoint, Bloomfield said that ABGR has also received criticism for being misleading in some cases. He gave the example of a new complex near the Canberra airport which received a strong ABGR rating, despite the fact that it can only be viably accessed by car.

However the overall success of Australia’s ABGR, said Bloomfield, has come from the fact that it has essentially attained real market value. For example premium tenants, such as governments, will often now only consider buildings that have obtained a particular ABGR rating.

For this reason ABGR has been used as a template for performance rating tools being developed internationally. It has also now been incorporated into National Australian Built Environment Rating System (NABERS), which measures a building’s overall environmental performance during operation, with emissions being just one element of this.

According to Bloomfield, very little research has been done to date on relationship between design ratings and performance ratings, however the UK’s EP Label, which is currently being drafted, is attempting to combine elements of both.