Overall energy usage in the city grew at a slower pace than the average economic growth in the 10 years to 2013, new data shows.
And from 2012 to last year, consumption of electricity alone fell 1.1 per cent.
One green group welcomed the official figures as a sign that the city was getting serious about saving energy. The statistics reflected public awareness of reducing energy consumption, Edwin Lau Che-fung, head of advocacy and education at Friends of the Earth, said.
"The slight drop is in a positive direction," he said. "It reflects a power-smart attitude among consumers and businesses."
The city recorded an overall energy balance last year of 300,284 terajoules, down from 322,938 terajoules in 2008, the Census and Statistics Department said in its annual report.
During that period, imports of electricity from the mainland decreased 5.2 per cent.
The energy balance is the sum of energy input - mostly imports of coal, oil and electricity - minus output, when these resources get transformed into energy.
Electricity generation made up the bulk of the balance, while the rest came from gas.
Commercial users remained the top guzzler of electricity last year, consuming 66 per cent of energy used. Households came second, despite falling three percentage points to 26 per cent. Industrial users consumed 7.3 per cent of electricity.
Overall energy usage rose 2.5 per cent from 2003 to 2013. Over the same period real GDP grew at an average of 4.5 per cent a year.
Environment officials have floated a pair of options on the future of Hong Kong's energy mix. One proposal involves drawing a third of the city's electricity from the mainland power grid.
Under fuel-mix proposals for 2023, mainland company China Southern Power Grid may export up to 15 billion kilowatt-hours a year to Hong Kong - an option that Secretary for the Environment Wong Kam-sing claims can help the city outperform its targets of cutting carbon emissions.
Higher electricity bills are in store no matter which option is chosen, Wong has warned.
Lau, a former member of the government's advisory council on the environment, said tougher energy and carbon reduction targets should be imposed on the city's two power suppliers.
"The government should also explain more about the two fuel-mix options," he said. "We need to know how much more electricity prices will go up and why.”