Many companies were tacitly encouraged to leave their lights on overnight because off-peak power was so cheap.
In the middle of the global argument over greenhouse gases versus nuclear power, Gilchrist says such moves could reduce power use by 70 per cent.
"Power is less than half the price at night," says Gilchrist. "Originally that was because it was so hard to turn off the coal-powered power stations, and they needed to do something with their power."
And it isn't just lights at desks that are the problem. "Lighting in lifts far exceeds the power used by them moving up and down, because those lights are on 24 hours and the lifts only run for eight hours".
"If we could capture only half of that and save 35 per cent," says Gilchrist. "This stuff should be a no-brainer, but it isn't happening."
