By some accounts, the United States could stand to get twice as efficient in the coming decades, saving hundreds of billions of dollars and slashing its global-warming emissions in the process. Yet other economists have been a bit more skeptical that boosting energy efficiency is really so easy — or a surefire way of tackling global warming.
The Alliance to Save Energy has a report on how the United States could double its "energy productivity" by 2030 — that is, double the amount of economic activity generated from a given unit of energy.
The US is less energy-efficient than many other industrialized nations, including Japan, France, and Germany. Cross-country comparisons can sometimes be misleading, since different countries are in different situations with regard to their size, industrial structure, climate, and so on.
The report notes, for instance, that many buildings in the United States could employ much more-efficient lighting, insulation, roofing, and boilers to cut their energy use by up to 50 percent. But, for the most part, these readily available technologies have been slow to catch on.
Many landlords often have little incentive to buy efficient appliances for their tenants (since the tenants are often the ones paying the utility bills). What's more, under current regulations, many power companies have little incentive to promote efficiency in households.
An argument is that energy efficiency may not be as helpful for tackling global warming as often advertised. For instance, if air conditioners become more efficient and cheaper to use, people might use them more often. This is a phenomenon known as the "rebound effect" and estimates can vary. In the ASE study above, the rebound effect is assumed to be around 5 to 10 percent. But if the effect is higher, then these measures wouldn't do as much to reduce emissions
SOURCES - Vox, Alliance to Save Energy