It would mean that commercial and residential sites for more than 50 dwellings would all be sold via tender rather than an auction, ACT Greens planning spokeswoman Rebecca Vassarotti said.

The major sites would be reviewed and design, environment and social outcomes would be set before the site came to market.

The policy was pitched as part of the ACT Greens proposed planning policy ahead of next month's election, released on Thursday.

Ms Vassarotti said it would aim to introduce the change within one year.

"Our understanding is legislation would be required to do this and we would need to do some consultation with industry but that could probably be implemented within a 12-month period," she said.

Ms Vassarotti said tender criteria would be developed with a "holistic" approach to the value of money. This would be in cases where a preferred developer could not meet a reserve.

"When we build in the criteria we actually look at what we are trying to achieve on particular sites, it's about having a holistic view about what value for money is," she said.

"We do need to look at insuring we do get appropriate value for land but in terms of longer term outcomes ... a vigorous process that looks at those design criteria and has an appropriate way of valuing what is important."

READ MORE:

Last year, the former Northbourne Flats in Braddon and Turner were pulled from the market after a tender process as the preferred buyer could not meet the reserve price. The Braddon flats have since sold for $28 million.

When asked if there was a concern the process could blow out development timeframes, Ms Vassarotti said well-designed projects were more likely to be supported by the community and would avoid appeals processes via the ACT Civic and Administrative Tribunal.

"We do see projects really hampered under the current rules and we would really hope good planning up front would make it a much smoother process once we get that green light," she said.

As part of its planning policy, the ACT Greens also announced it would include a 'showcase' development each year as part of the territory's land release program. The party said one the showcase developments it would seek to provide, via an expression of interest, is a residential development in the inner city with no car park.

Labor planning spokesman Mick Gentleman said the Suburban Land Agency already considered a range of factors beyond price when selling land.

"The current requirement for land sales to meet market value doesn't mean all sales go to the highest bidder," he said.

"When selling land, the Suburban Land Agency seeks the 'highest and best use' and considers a range of factors in addition to price."

Mr Gentleman said the Greens had copied measures from Labor and that some of the party's new ideas opened the planning system up to "negative consequences".