On Tokyo Bay, at the edge of the largest urban sprawl on Earth, sits what may be an environmentalist's dream home.

Solar panels on the roof and a fuel-cell in the backyard power the family house, a lithium-ion battery stores the surplus electricity, hot water pipes double as floor heating, and good insulation saves energy all round.

But it's the little high-tech touches that give this eco-house a cutting edge when it comes to futuristic low-carbon housing.

Its maker, Panasonic, has fitted the "Eco idea house" with super-efficient and intelligent appliances that promise to save power at every turn while ensuring a comfortable lifestyle for its residents.

Sensors follow people as they move from room to room and can, for example, blast a jet of warm or cool air at a person sitting in the living room, said Panasonic group president Fumio Ohtsubo during press conference.

"If the person leaves for the kitchen, the lights there can turn on, while the (living room) lights, air-con and television all turn off thanks to sensors that detect human presence, temperature and lighting," he said.

The house also boasts a washing machine that halves water use simply by tilting its drum, and a fridge that 'learns' its users' habits and switches into sleep mode when it doesn't expect to be opened for some time.

Corporates going green

Innovations like these have made Panasonic the country's most environmentally-friendly manufacturer, according to a survey by the Nikkei business daily, ahead of Sharp, Mitsubishi Electric and NEC.

Japan's corporate giants ? from electronics makers to the big car companies ? are increasingly betting on environmental and energy-efficient technologies as they seek to dig out from Japan's worst post-war recession.

Toyota's Prius hybrid car has been the top domestic seller since the spring, followed by Honda's hybrid, the Insight. Mitsubishi Motors has meanwhile bet on electric cars and promoted its zero-emission compact, the i-MiEV.

The government, seeking to meet ambitious climate change targets along with economic recovery, has encouraged Japan Inc. to go green to get out of the red.

State subsidies have helped boost hybrid car sales, while an eco-point programme, just extended in a new stimulus package, encourages consumers to buy energy-efficient appliances such as those in the Panasonic house.

The government is also working on an ambitious programme to cover public buildings in solar panels and boost other renewable energy sources.