The Development Bureau's plan to tighten restrictions on the area of buildings triggered immediate opposition from Henderson Land Development yesterday. Tony Tse Wai-chuen, general manager for sales at the developer - which was embroiled in a controversy in 2006 over concessions it was granted at its Grand Promenade project in Sai Wan Ho - said the proposal was not in line with the government's policy of encouraging green facilities. Too many government restrictions might prompt developers to build fewer such facilities because of the costs involved, he said. Grand Promenade was named in the government paper, which said: 'Following from the incident on the Sai Wan Ho development ... the public's attention is increasingly focused on the fact that ... developers are entitled to enjoy various concessions in the calculation of gross floor area which directly contribute to building bulk and height.' Institute of Architects local affairs committee chairman Wong Kam-sing said: 'Developers should shoulder more corporate social responsibility.' Mr Wong supported the idea of reducing parking space, adding that the review should take into consideration the use of cars in different districts. Citing the example of Tung Chung, he said that many parking slots were vacant due to poor planning. But he commented that the proposal to impose a six-metre height limit for sky gardens would make designs inflexible, and might limit plants' exposure to sunlight. Surveyor Pang Siu-kei said the government's suggestion of including basic infrastructure in the calculation of gross floor area was impractical. 'This will especially affect small building sites,' he said. 'If you count these facilities in, the area left for residents' use will shrink.' It would be more feasible to introduce an overall cap for gross floor area, he said.