The government on Thursday mapped out a set of measures to ensure stable electricity supply for this winter including mandatory usage cuts for large firms and maximum temperature limits for commercial buildings.

The package is aimed at coping with demand spikes during the winter months and averting the recurrence of nationwide blackouts that battered Korea in mid-September amid an unseasonable heat wave.

Knowledge Economy Vice Minister Kim Jung-gwan said his agency will be struggling to maintain sufficient reserves of 4 million kilowatts, forecasting rock-bottom levels between the second and third weeks of January.

“We are facing daunting problems this winter,” Kim told reporters at a briefing. “For the peak season, we estimate supply levels at as low as 530,000 kilowatts, or the reserve ratio of lower than 1 percent, which is far exceeding the 4 million safety threshold.”

Under the plan, a total of 14,000 businesses consuming more than 1,000 kilowatts a month will have to curb their peak demand by 10 percent compared with last year’s levels. If they fail, they would face a fine of up to 3 million won ($2,600), Kim noted.

The ministry also plans to cap the maximum indoor temperature at 20 degrees Celsius for the country’s 47,000 large commercial buildings and to sustain the 18 degree ceiling for some 19,000 central and provincial government agencies.

In addition, businesses in the service industry will be banned from putting up neon signs from between 5 to 7 p.m. from Dec. 5 to Feb. 29., and able to use only one billboard during peak hours.

Kim also said the ministry will extend intervals between subway trains by one to three minutes every day between 10 a.m. to noon as to keep public inconvenience minimal.

To drum up participation from households, Kim added the ministry will lay out power-saving campaigns nationwide and send alerts via television networks, social networking sites and text messages if the reserves drop below 4 million kilowatts.

Details on these measures are to be nailed down by early December, the ministry said, after consulting with related agencies, civic organizations and industry officials.

By Shin Hyon-hee (heeshin@heraldcorp.com)