Throwing a guess out there... I think this applies more to Air Conditioning usage in the US. I'm an expat in MA, my company sends out a few emails in the summer along the lines of 'we are reducing our energy consumption at the request of the power provider, all non essential lighting will be turned off and cooling systems tuned to 'optimal' temperatures'

this is to avoid brownouts. If I recall, the same does no happen in the UK other than everyone making a cuppa at a break in coronation st. (o;