SHOPS and offices are the target of a plan to cut power consumption by introducing a peak period surcharge. Power companies say introduction of the surcharge, currently under consideration by the Government, would help achieve a more even demand for electricity throughout the day and therefore increase efficiency. But the business sector last night slammed the move, claiming it would amount to ''penalising firms for working at their optimum''. The Deputy Secretary for Economic Services, Mrs Elizabeth Bosher, said the plan was one of a number of options being considered to reduce energy wastage. The surcharge proposals were made by the territory's two power companies, China Light and Power and Hongkong Electric. Speaking after a seminar on public utilities, Mrs Bosher said that while electricity was cheap in Hongkong it was still important to encourage people to consume less power - and one way was to impose a surcharge. Top targets were commercial users, she said, since power demands from industry had dropped in recent years as more factories had moved to the mainland. ''One of the options is to impose a surcharge during peak hours. Broadly speaking that is between 11 am and lunch time although it varies with seasons,'' she explained. ''It is the time when most offices have on air-conditioners and hotels and restaurants are cooking lunchtime meals. ''The intention of the Government is not to just put the electricity bills up but to encourage people to save resources.'' She said the proposal was still in its infancy and there was no accurate categorisation of which businesses would be included. Mrs Bosher said the Government was also considering conservation measures adopted in foreign countries. But the director of the Hongkong General Chamber of Commerce, Mr Ian Christie, was stunned when he learned of the plan. ''I really cannot believe it. It must be a joke,'' said Mr Christie. ''This peak period is when firms are operating at their maximum and everybody in the office is working at their optimum. And reasonably, most people are using their computers and using air-conditioning. ''Why should we be charged higher during this time? Are we expected to turn off all the air-conditioning and work in a sweaty office?'' While admitting there was a need to encourage energy conservation, particularly in some ''over-refrigerated'' offices, Mr Christie added: ''It is a matter of education and encouragement. It is absurd to talk about imposing surcharges.'' The Consumer Council's chief executive, Mrs Chan Wong Shui, also had reservations about putting up prices to discourage demand, also saying greater education was the key. Earlier this year, the Energy Efficiency Committee suggested legislating tighter standards for building design to reduce energy wastage. It suggested smaller and fewer windows in buildings to help reduce demand for air-conditioning.