South Korea's president has turned down the thermostat in his office and donned warmer underwear to save energy, he said Monday, urging fellow citizens to do the same to avoid a supply shortage. The warmer underwear was initially uncomfortable, Lee Myung-Bak disclosed in a fortnightly radio address. "But after a while, I got used to it, and now I am very warm and comfortable wearing it," he said. Lee said the country faces an uphill battle to meet fast-rising electricity demand and could face an emergency this winter. He urged South Koreans to turn down the temperature in homes and offices, switch off unnecessary lights and use high-efficiency appliances. In September, unseasonably high temperatures caused brief but widespread rolling blackouts which hit more than two million homes or other premises. Officials said they had to cut off supplies because electricity reserves were too low. This month, the government announced a series of power-saving measures to take effect during Korea's normally severe winter. Big consumers will have to cut power consumption by 10 percent compared to a year earlier during peak days which will be announced later. Some 19,000 government offices will have to keep the indoor temperature below 18 degrees Celsius (64 degrees F), while 47,000 private buildings that use less than 1,000 kilowatts a month must keep it below 20 degrees. Analysts say successive governments have kept electricity prices artificially low to appease voters, encouraging overuse.