Dreamed up by Sydney practice Johnson Pilton Walker, the gallery received the 2009 Sir Zelman Cowen Award for Public Architecture, and another award for interior architecture.

The awards were presented in Melbourne last night, and a diverse range of buildings by Australian architects were recognised.

Among them were the ivy bar on Sydney's George Street, the Sussan Sportsgirl headquarters in Melbourne, and the ''red steps'' in Times Square, New York.

But the portrait gallery was the big winner of the night, and jury chairman Howard Tanner sang its praises yesterday, describing it as ''smaller, more precious'' when placed beside the concrete edifices of the High Court and the National Gallery.

''It is actually a most wonderful set of spaces,'' he said.

''It's beautifully articulated, and it is a very carefully considered vehicle for portraiture, because portraits are not usually huge items. The building has a very nice human scale, which gets bigger in the sort of public spaces and then more intimate in the other spaces. We were very impressed with that.''

He said the choice of materials used on the building timber, polished concrete, terrazzo and stainless steel had also played a part in the jury's decision.

''It's a very calm and serene building, and really I think it shows the wonderful competence of Richard Johnson, who's the key architect for this building. He is really a very calm and considered person, and that shows through in the work.''

But Mr Tanner added that while it was an architectural triumph, the gallery was too small for its public role and purpose.

''I don't think the authorities in Canberra really understood what a popular facility or cultural institution this would be,'' he said. ''It strikes a chord. Everybody relates to something in the gallery and there's something there for everyone, and I think they didn't realise that in due course it would be, quite possibly, something to rival the National Gallery and the War Memorial as an attraction in Canberra.''

He said this was reflected in the numbers of visitors who had been through the gallery's doors since it opened in December, which had far exceeded expectations. ''It's a very beautifully resolved building, but I think we'll find it having to move to the next stage very quickly, and just reflecting on government not perhaps really foreseeing the future and the importance of these buildings for Australia.''