South Korea's civil servants have been ordered to do their public duty by switching off the heating and donning long johns as the severe cold puts a strain on power resources, according to officials.
In an emergency energy savings plan, all ministries and state-run companies have been told to turn off the heating from 11:00 am to noon and 5:00-6:00 pm, the Knowledge Economy Ministry said.
Government buildings have to keep the office temperature below 18 degrees Celsius (64 degrees Fahrenheit) and state employees are encouraged to wear thermal underwear to battle the cold, it said.
"Offices will be quite cold under the required temperature, so state employees, whether encouraged or not, will end up wearing thermal underwear anyway," a ministry official, Roh Keon-Ki, told AFP.
Officials will patrol state buildings to check the temperature, he said.
"We're trying to set an example because the country may face a severe electricity shortage if the current pace (of heating consumption) continues."
Knowledge Economy Minister Choi Kyung-Hwan warned last week of possible blackouts after electricity demand soared to record highs this winter.
Sunday's temperature in Seoul fell to a 10-year record low of minus 17.8 degrees Celsius. Large parts of the Han river that bisects the capital are frozen over.
The temperature in the southeastern port of Busan sank to minus 12.8 degrees Sunday, the lowest level in 96 years, causing the death of a homeless man.
Water supplies in the southeastern city of Gimhae were cut off Sunday after pipes burst.