Generations of students have called it the ugliest building on campus, but the School of Molecular Bioscience at the University of Sydney can now add another worthy title to its concrete walls — heritage-listed.

The building, also known as G08, has been listed on the National Trust's heritage register for its "monumental streetscape significance", architectural and historical significance.

In its November report, the National Trust approval board noted that "it was one of the first and largest schools in Australia devoted to research and teaching in the areas of microbiology, biochemistry, molecular biology and genetics, cell biology and human nutrition".

G08 is also considered one of Sydney's iconic examples of brutalist architecture with its stark exterior, concrete columns and slab frames.

"Well I never thought it was ugly, I quite like geometry," Philip Kuchel, professor of biochemistry, said.

"It's a lovely building to work in.

"We realised that millions of dollars had been spent in the last 15 years in getting several labs up to speed with modern compliance, so it's quite a good operational building."

New plans for G08

Professor Kuchel, who has worked in G08 for more than 30 years, was one of three staff members who made the heritage submission to the National Trust.

He said they were inspired to do so following rumours earlier this year that the university had plans to demolish the building.

At the time, a spokesperson for the university acknowledged the building was "an old building" but denied the rumours and said "no decision" had been made regarding renovation or demolition plans.

The rumours were fuelled by plans to move several departments to a new science building on City Road which has yet to be approved by the Department of Planning and Environment.

The labs in G08 have been upgraded in the past 15 years. ( Supplied: Philip Kuchel )

The University of Sydney is undergoing significant upgrades as part of its Campus Improvement Program and 43 buildings were proposed for demolition between 2014 and 2020 to make way for new facilities.

In an internal email last week, staff were told the Pharmacology Department of about 60 people were going to be moved into G08 in 2017 due to the demolition of the Blackburn building.

Professor Kuchel said it meant the building would continue to be useful for several years.

"We think that's fantastic because it will get us biochemists closely in touch with people in the Faculty of Medicine doing biomedical research," he said.

"By heritage listing it ... if they [University of Sydney] really do want to knock it down, they've got to come up with a jolly good reason for doing so."

Preserving Sydney's historic architecture

The National Trust is a community-based, non-governmental organisation that recommends heritage listings to local councils and the New South Wales Government.

While its heritage listings have no legal ramifications, buildings that are state heritage listed are protected from demolition.

Graham Quint, director of advocacy at the National Trust, said the organisation worked hard to preserve modern buildings and significant architectural styles.

The continuous strip windows and blank planar walls was a typical building design in the 1970s. ( 702 ABC Sydney: Amanda Hoh )

"We don't have a good attitude to recognising our fine architecture," Mr Quint said.

"In the 1940s there was a move to sweep away Victorian-style buildings and there was a move by City of Sydney council that there be no buildings older than 50 years old.

"Sydney seems to be a city which clears away buildings to make way for new developments."

The School of Molecular Bioscience is the third brutalist-style building the National Trust has placed on its register.

Also recommended for protection is the St Leonard's Centre and the Sirius building which was denied heritage listing by the State Government in August.

"It's a strange thing for a university that teaches architecture to be a leader in demolishing leading styles," Mr Quint said.

"[Brutalist buildings] is really catching on now — it's a pity if we keep demolishing them because we won't have many left."