A proposed limit on floor-area concessions for developers who put green features in their buildings will not come in earlier than April 2011 - too late to prevent more wall-like towers from springing up across the city, critics say. The government currently allows developers to build more flats in return for adding environmentally friendly features to their buildings. The measures to limit the concession will not be retrospective, so if developers submit building plans - including for the two sites to be sold in two weeks - and get them approved before April 2011, they can still enjoy the bonus floor areas for building balconies, podium gardens, wide lift lobbies and so on. Secretary for Development Carrie Lam Cheng Yuet-ngor, replying to lawmakers, said time would be needed to consult the Legislative Council, government advisers and the Professional Green Building Council in reviewing the concessions policy, which has produced tall, bulky buildings over the past decade. Public consultation has ended and results are being summarised. If legal changes are necessary, the new policy will come in even later. Lam said it was important to 'provide clarity and certainty to the market' so developers need not include a 'risk factor', which could affect the government's land revenue. There are concerns as to whether the two Tai Po sites to be sold at auction in two weeks will be affected by the new policy. If the sites can still be developed with the concessions, developers are likely to pay more. Lee Wing-tat, the Democratic Party's spokesman on development matters, said 2011 was too late. 'It only takes months for architects to draw up building plans,' he said. 'The government is now only giving developers more time to submit plans for as many sites as possible.' He said it would be quicker simply to limit the overall extra floor area, requiring only a change in administrative measures. Green Sense leader Roy Tam Hoi-pong said the date for implementation was bad news. 'Before 2011, developers could rush to apply for land sales and quickly submit building plans for approval. There will still be wall-like towers sprouting up after all.' At present, there are 39 residential sites on the land-sales list. Tam said the government should push forward the new policy, especially for MTR Corporation and Urban Renewal Authority sites.