Here is the best comprehensive chart I could find for electrical use across sectors. This is for California in 2002. I would have to think it's probably a good representative example of roughly what you'd find in other states and roughly what you'd find in other industrial countries as well.
As you ca seen, a large portion is in areas which are just not easily addressed. Lighting makes up a decent chunk, but how much can you save with more effecient lighting? Less than 50% savings, especially considering commercial already uses mostly florescent lights.
Heating and cooling makes up a relatively small chunk, and it's unknown how much you could really save there. If you have more effecient heat management for frigdes then mabe you could save a bit. But still... no matter how generous you are, you're doing well to squeeze a few percent savings out.
California has a very efficient economy. They've kept per capita electrical demand steady for over 30 years. Their energy prices are high and as a result their industrial base is small and efficient. Ontario's industry is much larger, with 1.5% of the customers responsible for 55% of the electrical demand. It's tempting to say that we could get the kinds of cuts that California has, where all industry put together uses 20%, a walloping 35% decrease from industry alone, but I know this isn't right. While some industry in California has definitely become more efficient, some industries have simply moved away. Some may well be enjoying a carbon feeding frenzy in China.
You're right, there is a huge portion on this chart that isn't easily addressed. Mostly because it's completely undefined. Residential and industrial categories each have substantial "other" categories, which together with miscellaneous commercial and a general "other" category make up 38% of the pie. In addition there are broad categories like "agriculture/pumping" and "process" which are also difficult to attack for lack of detail, and 2% for "compressed air" which I'll admit to ignorance on, and ask anyone who knows anything about this to help me out on this tiny percentage.
That leaves 45% that really can be addressed because it's sufficiently clear. Of that 45%, space conditioning, which is the easiest thing to attack, and can be reduced by 100%, accounts for 1/3 of what we know. That's pretty good.
Lighting accounts for 24% of the total pot. As this link points out:
http://www.eia.doe.gov/emeu/cbecs/lit-type.html
electrical demand for residential lighting could be reduced by 35% if we only replaced existing incandescents that operate more than 4 hours daily with compact fluorescents. The potential is obviously higher, but that's a reduction of 3% off the total. The same article points out that demand from existing commercial fluorescents could be reduced by 20% by moving to T8 ballasts instead of the standard T12s. Commercial incandescents that moved to T8 directly could realize savings of 60%. Given their distribution for commercial as 77% fluorescent and 14% incandescent, we get combined savings of 24% from the commercial lighting sector or 3% from the big pot.
So far I'm getting reductions of 21% of only the 45% we know about. Not bad. But when it comes to lighting, we're still thinking inside the box, especially for commercial/industrial. The newest terminal of Toronto's Pearson Airport is daylit on all 3 levels, reducing daytime lighting costs to negligible levels. Retrofitting existing structures would not be particularly difficult, since most industrial and commercial facilities exist on a single level. One thing I do know about industry is that lighting can be more focused where it is needed, doing away with broad lighting across whole buildings. Much higher savings are easily achievable if we have the will.
Then we get to the last category we can address, domestic refrigeration, which accounts for 6% of the total. As this link points out:
http://www.eia.doe.gov/emeu/reps/enduse/er01_us.html
a new refrigerator in 2001 used just 38% of the energy of the average refrigerator in the US. So it's tempting to say that efficiency in domestic refrigerators could reduce the total part of the pot by a further 4%, but that would be wrong, because the chart is for California. California is singlehandedly responsible, with their refrigerator efficiency program (funding the purchase of the most efficient models every year) for driving refrigerator efficiency up across North America. They are very proud of the fact that so far, this conservation program has delivered savings in California alone equivalent to the total output of all the nuclear power plants in the United States, and at a significantly lower cost than it would have taken to build all those plants:
http://energypriorities.com/entries/2006/02/california_energy_commissioner.php
So Californians as a group already have the most efficient refrigerators. Bad news for dropping the numbers on this particular chart, but good news overall. Because across the rest of America, there are plenty of savings to be had just by adopting California standards. Another reason why this is extremely good news is that other big states and provinces can tackle other appliances. New York can tackle washing machines, Texas can do air conditioners, Massachusetts can do lighting, and so on.
Refrigerator efficiencies have improved in an almost unbelievable way. In 1972, the average refrigerator had a UEC of 1986 kWh. By 2001, the UEC was 476 kWh. That's a reduction of 76% over less than 30 years, when conservation wasn't the priority it should be now. And over that time period, average refrigerator sizes have more than doubled. If we applied this kind of program to a variety of common appliances, the savings would be tremendous.
The EIA link I pointed you to gives a breakdown of domestic electricity sources. The big enumerated ones would all benefit from being targeted for efficiency standards. A lot of the smaller ones are pretty discretionary, and could just be hit by high energy prices. We'd all have the same energy bills, because even though the cost per kWh would be higher, we'd be using fewer kilowatts. That is the point the California Energy Commission makes. Their overall energy bills are about the same as the US average, even though their unit costs are substantially higher.
I think I'll stop blathering now. I hope you get the idea.
