By Chang-Ran Kim
YOKOSUKA, Japan (Reuters) - In the muggy, unlit shed next to a Nissan car factory near Tokyo, four men in polo shirts are spending their Saturday staring at computer screens, monitoring how much power the firm's plants and offices across eastern Japan are using. So far, on the first day of the working week under a new summertime schedule, there appears to be no danger of their setting off a warning alarm, triggered when near the limit on electricity use set by Japan's struggling utilities. The factory itself, which makes the Leaf electric car and Juke crossover among others, is humming with heat and activity.
For Japanese auto and auto parts makers, July 2 marked the start of a Saturday-to-Wednesday working week -- an industry move to cut power use at peak times.
The nuclear crisis that the March 11 earthquake and tsunami triggered at Tokyo Electric Power's (Tepco) Fukushima Daiichi nuclear complex has brought about a nation-wide energy-saving drive unseen in Japan since the oil crisis in the 1970s.
With the tsunami-ravaged Tepco plant still leaking radiation and public opinion likely to derail the restart of some 30 commercial reactors now shut for inspection, the government has ordered big companies to cut their peak power consumption by 15 percent this summer, starting on July 1.
Failure to comply could mean blackouts -- a disruptive, worst-case scenario that manufacturers are desperate to avoid.
"The priority is to make sure we don't impede production," Yuji Kishi, senior manager of Nissan Motor's environment and energy control group, told reporters at the Oppama factory in Yokosuka on Saturday.
"This is one way for us to help the economy recover."
At the Oppama plant, that means workers on the early shift start an hour earlier, at 5:30 in the morning, and the late shift moves back by an hour in order to ease the burden on the grid during the peak mid-afternoon hours.
Most Japanese companies entered austerity mode as soon as the disasters hit in March, switching of lights and idling elevators.
The environment ministry is setting an example by targeting an even bigger reduction of 25 percent through painstaking steps like turning off more than half of its printers during peak hours, dimming monitors, and asking workers to bring in their own cold drinks so it can unplug vending machines.
The power shortage has given birth to "super cool biz" business attire this year, taking the "cool biz" fashion adopted six years ago a step further: polo shirts are in, and button-down shirts without ties are out.
Still, the real test lies in the weeks and months ahead, as the mercury climbs to usher in Japan's infamously humid summer.
One manager at a major data management company said that with all the computers on, the temperature in the office was already rising to 32 degrees Celsius, testing workers' endurance.
"It's so hot you lose your concentration," she said, asking that she and her company not be identified.
"It can't be good for productivity. Everyone just sits there fanning themselves all day. You see people with cold towels wrapped around their necks."
Elsewhere, companies like Sony and Canon have introduced their own daylight savings, bringing forward the work shift by an hour. Japan, unlike many countries, does not adjust its clock for the summer.
Retailer Seven & I Holdings, the operator of Seven-Eleven, intends to switch to energy-efficient LED lighting at thousands of stores, set up solar panels at some, and bring in cooler uniforms.
For the car industry and other firms shifting to Saturday or Sunday workdays, saving energy will mean inconvenience, more expense for working parents with young children, and for the companies which subsidies part of the extra child-care costs.
"We're going to have to juggle between working at home and bringing our kids to my in-laws," said Toshitake Inoshita, a Nissan spokesman whose wife also works at Japan's No.2 automaker. The couple have two children, aged six and three.
"The company is being flexible, but in reality it's inevitable that productivity will not be the same at home when you're looking after your children."
Even those who expect this summer to be testing are looking with dread at next year.
"If the remaining 19 nuclear reactors that are online now are shut, we're anticipating bigger reduction requirements in 2012," Nissan's Kishi said. "I personally don't think it's impossible, but it would be very, very difficult."
(Additional reporting by Mariko Katsumura, James Topham, Isabel Reynolds, Taiga Uranaka and Yoko Kubota in Tokyo; Editing by Daniel Magnowski)