In the early 1970’s, J Roger Preston Ltd was appointed as the M&E consultant for the Main Terminal/ Extension to the Kai Tak Airport which provided additional loading bays connecting aircraft by air bridges. J Roger Preston Ltd also designed the mechanical and electrical services for the Cathay Pacific training centre for flight attendants and crew, and the flight-simulator cockpit.

The increasing volume of air freight necessitated the construction of separate air cargo terminals within the airport boundary and these terminals were one of the largest in the world with a throughput of 802,000 tonnes a year. J Roger Preston Ltd designed the electrical system to provide power requirements for the mechanised container-handling system directly connecting freighter loading and unloading fingers for the first cargo terminal. With further expansion, J Roger Preston Ltd designed a new building services unit separate from, but linked to, the original air-conditioning plant. This provided a central plant housing for 500 tonnes centrifugal chillers with heat rejection through a seawater system.