Greg Mitchell, head of residential development at Manchester-based planning and urban design consultancy Turley Associates, said the planning regime in England would delay plans for a swathe of homes to be built on public land by 2015.
Mitchell said the announcement by the Government will be welcomed by developers and those looking to purchase a home.
Government departments are being asked to identify surplus land around hospitals, schools, military bases and highways by autumn of this year.
Mitchell said: "Land supply is a real issue for developers and this move will be welcomed. However, the Government is rather ambitious in hoping that 100,000 new homes will be built by 2015.
"Whilst it is suggested that some sites will be sold with planning permissions attached, no doubt at a premium, developers will in the majority of cases need to apply for the relevant planning permissions, and on straightforward sites this can take up to 18 months.
"Many of the sites however will be in sensitive locations, close to military bases or on green belt sites for example, and this will undoubtedly slow the planning process down further. It is unrealistic to expect the current planning regime to approve 100,000 new homes within the 2015 timeframe.
"The Government has promised to streamline the planning system to promote growth and this is welcomed, although no detail has yet to be announced. A major shake-up of the planning regime is already underway through the Government's Localism Agenda and how this will sit with a regime streamlined for growth will be crucial. There is real potential for conflict."
Mitchell said that land will be sold at the market rate and is expected to raise up to £10bn.
Mitchell added: "The approach being suggested by the Government selling land at the full market value is also interesting. Developers are being asked to shoulder all risks, and they will want assurances that planning permissions will follow rapidly."
The Government hopes that the first homes will be built within two to three years.