THE Open Learning Institute (OLI) hopes to start work on its new $221 million campus as soon as possible to take advantage of a downturn in the construction market. The institute announced yesterday it had received a $71 million grant from the Royal Hongkong Jockey Club. The grant, together with a $150 million government allocation made earlier this year, will cover a new building and services for a permanent campusat Ho Man Tin. Project management committee chairman, Mr Carlos Cheung Hon-kau, said the present construction market could reduce the building estimate by $20 million. The market could be expected to remain favourable for six months, Mr Cheung said. OLI council chairman, Mr Peter Wong Hong-yuen, said the council would try to build as soon as possible to take advantage of the market, but would not sacrifice quality for speed. A project management committee consisting of OLI, Education and Manpower Branch, and Architectural Services Department representatives will engage suitable architectural and quantity surveying consultants, and monitor costs and standards. The new campus will include a 10-storey building with offices, a library, science and computer laboratories, lecture and tutorial rooms and a canteen on the present site of Lock Tao Secondary School. Construction is expected to start in September and be completed by the end of 1995. Mr Wong said the OLI would save at least $20 million a year on rent paid for its present base in Mongkok. However, it still will be supplemented by a network of regional study centres. OLI director, Professor Gajaraj Dhanarajan, said the new campus would cater for its needs for 10 years. He said the institute's ''wish list'' was that the present enrolment of 15,000 students would rise to between 20,000 and 25,000.