The Electrical & Mechanical Services Department has conducted about 230 energy audits over the years on major public buildings to identify and implement energy- saving measures, Secretary for the Environment, Transport & Works Dr Sarah Liao says.

Dr Liao told lawmakers today energy-efficient fluorescent tubes and electronic ballasts have replaced less efficient lighting devices in almost all government premises.

"Whenever technically feasible, energy-efficient water-cooled air-conditioning systems are gradually replacing less efficient air-cooled ones.

"Variable-speed drives are also widely adopted in air-conditioning plants to reduce energy consumption under partially-loaded conditions," Dr Liao said.

"Occupancy sensors and timer switches are also installed in some offices to automatically switch off lights and air-conditioning when not in use."

Dr Liao said departments have also been implementing energy-conserving housekeeping measures, such as switching off lightings and computers when not in use, maintaining air-conditioning temperature at 25.5�XC and switching off some lifts during off-peak hours.

To monitor the energy-saving performance, Dr Liao said it is better to analyse the energy-consumption figures of the same buildings in different periods, provided that there are no major activity changes in the buildings across the periods.