Learn lessons from the Grand Promenade project or repeat the farce in West Kowloon, town planning experts warned yesterday. They called on the government to be more specific in its land lease conditions on matters such as building density, land use and the calculation of gross floor area. They were speaking after legislators fiercely criticised decisions taken by former buildings chief Leung Chin-man on the gross floor area calculation for the Grand Promenade project in Sai Wan Ho - decisions said to have cost the government $125 million in land premium revenue. Hong Kong Institute of Architects vice-president Vincent Ng Wing-shun said the Buildings Ordinance, dating to the early 1950s, did not offer specific guidelines on whether certain types of public facilities could be exempted from the calculation for floor area. 'In the case of Grand Promenade, the Building Authority was given discretionary power in exempting public transport terminuses from the gross floor area calculation because the item was not covered by the ordinance,' Mr Ng said. 'A lot of the community and cultural facilities under the West Kowloon [arts hub] project do not fall under the ordinance either.' Hong Kong Institute of Surveyors spokesman Lau Chun-kong advised the government to be specific. 'The government has absolute power in drafting the land lease. It should list what facilities are to be exempted from the gross floor area calculation and what facilities are not, under the West Kowloon project.' But he did not see a need to revise the Buildings Ordinance. 'Amending the ordinance may not be the best way to cope with the rapid changes in town planning,' Mr Lau said. 'On the other hand, in recent years the government has already shown sustainable improvements in laying out specifications on gross floor area calculation exemptions in the lease conditions of new plots of land. The government must learn its lesson from the Grand Promenade project, though, and seek to avoid the same pitfalls.' Legislator Patrick Lau Sau-shing said the government had already taken enough precautions by limiting the plot ratio governing development density to 1.81 under the revised scheme for the West Kowloon project. Mr Lau, who represents the architectural, surveying and planning constituency, said the planning and lands departments should reduce the room for discretionary decisions by the Building Authority. 'If the [two departments] are more specific on building density, building height and planned land use, [the authority] will be less likely to exercise ... discretionary power,' he said.