Lord mayor Gordon Bradbery received the Green Building Council Australia (GBCA) award at a ceremony on Thursday.

The building has undergone 10 years of upgrades and management practices to improve its level of sustainability. Ageing equipment has been replaced to meet modern building-compliance standards.

Upgrades in lighting and water systems have resulted in energy efficiency gains of 55 per cent and water efficiency improvements of 85 per cent, saving the council $200,000 a year.

GBCA chief executive officer Romilly Madew applauded the city council for having taken the lead.

"No other building from the 830 that we have certified has achieved a rating like this. It is the first regional building in Australia as well as the oldest to achieve five stars," Ms Madew said.

"The unique aspect of the council's administration building is that they did not start from scratch. They have gone through a cycle of upgrade, and efficiency has been taken into consideration. A lot of leadership is happening with local governments and in Wollongong itself there are currently eight Green Star projects under way."

Management, water quality and emissions were the council's highest rating achievements, with lower scores recorded in transport and materials.

Council sustainability officer and Green Star certified professional Dr Carl Hopley was pleased with the results, considering the obstacles his team faced.

"Transport in and around the city does not facilitate connectivity at this stage," Dr Hopley said.

"With materials, we received marks on paper supply. However, building materials were a difficult area to improve because we have never rebuilt any part of the building."

The council is now developing a sustainable building strategy designed to improve 750 buildings in the Wollongong area.

"There are 14 buildings in Wollongong that are responsible for 80 per cent of electricity and gas consumption. These are high-priority buildings where we can achieve significant energy reductions," he said.

"It is important to take what we have learnt in this building and apply it to others throughout the city. The community will only benefit from the savings."