The government began a nationwide Warm Biz energy-saving campaign Tuesday, encouraging workers to fend off the cold with warm clothes from fall through winter rather than using more electricity to warm up rooms.

Under the campaign, running through the end of March, the government urges people to set air conditioners at 20 C across the country. Some Environment Ministry officials came to the office wearing cardigans and stoles amid relatively cool and rainy weather in Tokyo.

"Setting the temperature of air conditioners 1 C lower will greatly help save energy and electricity costs," Katsutoshi Ito, the head of the ministry's division for promoting the campaign, said.

Industry bodies for department store, supermarket and convenience store chains are also cooperating with the ministry's energy-saving campaign by setting their air conditioner temperatures lower and using less lighting.

The ministry first proposed Warm Biz in 2005, calling for wearing thermal clothing and asking people to spend time with family members or others in a single warm room, an initiative it called "Warm Share." It also urges people to eat foods such as root vegetables that give warmth to the body.

The government is targeting a 26 percent reduction of greenhouse gas emission in 2030 compared with the 2013 level, with households and offices aiming for a 40 percent cut.