How to keep cool with the engine off

A system that switches off a car engine automatically while leaving the air conditioning running on electricity may be the answer to sweltering heat in vehicles during summer, though it won't come cheap.

The locally developed system comes as the city's ban on idling engines kicks in this week.

'Passengers won't feel the air conditioner has stopped,' said Productivity Council consultant Kenny Wong Siu-wai, who was in charge of the system's development.

It might cost HK$20,000 to HK$30,000 to install, though owners could enjoy petrol savings in the long run, the council said.

The system, which can work on all cars, involves installing a lithium-ion battery in the boot, an electric motor in the front, and a control device and panel on the dashboard.

It stops the engine when the car comes to a standstill, with its gear shifted to neutral or parking, and the handbrake pulled. The battery then starts up to support the air conditioner, which normally runs on petrol when the car is moving.

The air conditioner can run on the battery for at most an hour.

Developed at a cost of HK$3 million, the system is pending patent registration and approval from the Transport Department on the structural changes required for use on cars. After that, the council will license the sales and production to car-parts manufacturers.

Despite the cost of installation, the system could save 5 per cent of petrol in summer and 7 per cent in winter, the council said. Technology development director Joseph Poon said this could in turn save drivers HK$8,000 to HK$9,000 a year.

The council is testing a more advanced system for taxis, with a larger battery that can last for two hours. It is working on equipping a taxi for a road test in two months.

Wong Wing-chung of the Northwest Area Taxi Drivers and Operators Association said it was impossible for taxi owners to pay that much for the system. He suggested the government subsidise three-quarters of the cost. The association would road-test its first electric taxi next week.

Raymond Tang, sales executive at car dealer Richburg, also expected lukewarm response from car owners.

'It's too expensive for average drivers. For cars of commercial use, owners might install it if the government was to subsidise part of the costs.'