Displacement ventilation and natural light are combating lethargy and tiredness in the Green Building Council of Australia’s (GBCA) new headquarters, according to Robin Mellon.

Officially opened by environment minister Peter Garrett yesterday, the GreenHouse recently achieved a 5 Star Green Star - Office Interiors v1.1 rating due to its use of natural light, waste management, energy conservation, low emission paints and timber from sustainable forests.

The retrofit, by BVN Architecture, also includes a grey-water recycling system, recyclable carpets, compost systems, worm farms and an innovative substitute for air-conditioning.

“Rather than air-conditioning the space we've put in displacement ventilation across the two main work areas. Displacement ventilation means you raise the floor up about 20 cm, on a raised platform, and you pump fresh air into that space, and then you have vents on the floor by each desk," said Robin Mellon, Green Star chief executive of the GBCA.

"So all you're essentially doing is washing the working area with clean air, and then you're extracting it up at the ceiling ... it means you get a much nicer ambient temperature. You get much more fresh air, and it also saves a lot of money on not having to air-condition the whole space."

Boosting staff morale and creating a pleasant working environment were also aims of the GreenHouse's makeover. According to Mellon, one of the best ways to improve the productivity of a workplace is to surround the staff with a healthy, "green" environment.

"For the last 30 years we've concentrated on air-conditioning all our buildings and then we have to seal them so that they operate efficiently, and then we effectively create our own personal gas chambers by filling them full of materials and paints and carpets and furniture that give off pollutants. Then we wonder why we're lethargic, and we're tired, and we're not performing very well," Mellon said.

The GreenHouse's use of natural light, open spaces, fresh air and natural materials has had the desired effect on the GBCA's staff morale and work ethic, he said. "We're trying to create a space that is warm, that feels green and sustainable, but which is also a very productive space to work in. And we've noticed the difference."