Japan reduced energy usage fairly significantly in the summer following 3/11, to cope with the energy shortage from the missing nuclear plants. Remember, they started with rolling blackouts, and eventually got things to the point where they could cope without them.
They did this using a lot of the simple things you suggest, turning off stuff (many places got downright dim), reducing cooling, people wearing less clothing, reduced train frequency, etc.
Unfortunately this summer they seem to have given up all of that, and are simply burning a lot more oil generating electricity. I'm not sure why they didn't try to maintain the "save electricity" campaigns, because they actually were effective (some of that, no doubt, due to the implied threat: "if you don't, back to the rolling blackouts!").
[I think the "Japanese heating is inefficient" is a bit misleading -- Japanese houses are traditionally pretty poorly insulated, but they're also not very large, and tended to use localized heating (everybody huddling around a heater) instead of keeping the whole place toasty. The ultimate expression of this, of course, is the kotatsu, which reduces heating needs to a well-insulated 0.2 m^3 space focusing on everybody's feet! :) Newer buildings tend to be better heated, and hopefully they can match that with better insulation.]