The Green Building Council of Australia's Sydney headquarters, its iconic GreenHouse, has achieved a five-star energy-efficiency rating from the National Australian Built Environment Rating System (NABERS).

The NABERS ratings measure the operational energy of office space and are administered on a national basis by the NSW Department of Environment, Climate Change and Water (DECCW). Coupled with the GBCA's 5 Star Green Star - Office Interiors rating, NABERS illustrates how design excellence can make a difference to a building's performance.

"Our performance rating was only achieved because of our 5 Star Green Star - Office Interiors rating and the innovative work of our design partners at BVN Architecture, WSP Lincolne Scott, and Schiavello. The result is an existing office space that is not only energy efficient, but also provides our staff with a productive workplace which allows them to perform at their peak," said Romilly Madew, GBCA chief executive. "It is important that an organisation like GBCA, which encourages sustainability in the development of buildings, can also set an example from an operational perspective."

The timing of the rating could not have been better with the recent federal government announcement that from the second half of 2010, all commercial building owners will be required to provide up-to-date energy-efficiency information - including a NABERS rating - when they sell or lease office space covering more than 2,000 square metres.

Madew said the federal government was to be applauded for its firm stance on improving the environmental performance of Australia's commercial buildings.

"A large proportion of Australia's greenhouse gas emissions comes from the office buildings in our cities, so making energy-efficiency ratings transparent for buyers and tenants is a big step forward," Ms Madew said. "It will challenge owners and tenants to find ways of adapting their offices and buildings through the use of sensible, sustainable design practices.

DECCW manager for Built Environment, Matthew Clark, said the five-star ratings achieved by the GreenHouse showed how the NABERS and Green Star ratings could be used together.

"This highlights how NABERS and Green Star can work in harmony, with Green Star to assist with innovative design ideas and NABERS to provide feedback on the actual environmental impact of the premises," Clark said.

"The NABERS five-star rating achieved by the GreenHouse shows how the two systems close the loop on a building's environmental rating process."

The GBCA's commitment to sustainability in the workplace was also confirmed recently when it became a signatory to the CitySwitch Green Office program. This program is a growing national partnership between businesses and local government. It works with offices wanting to make a positive contribution to the climate-change campaign by improving their energy efficiency.

Ms Madew said signing up for the program was a further commitment towards the ongoing environmental performance of the GreenHouse.

"The CitySwitch Green Office program assists office tenants in finding ways to cut their carbon emissions," she said. "We fully support the program's goal of an intelligence-sharing partnership between business and government."

The retro-fitted office space of the GreenHouse was a commended finalist in the National Interior Design Award for Environmentally Sustainable Design earlier this year, and was rewarded with the 5 Star Green Star - Office Interiors rating in July.

The fit-out at the Elizabeth Street head office took less than five months to complete and was delivered on a budget of just over $1.3 million, demonstrating that even small and fast fitouts can achieve high environmental standards and a productive, healthy working environment for employees.