By the Numbers: Energy-efficiency investments would pay huge dividends, says McKinsey & Company report

$1.2 trillion

Amount U.S. consumers and businesses could save by 2020 by boosting their energy efficiency, according to " Unlocking Energy Efficiency in the U.S. Economy," a new report from management consulting firm McKinsey & Company. (The report covers nontransportation energy use.)

Under current conditions, the United States wastes more energy each year than Canada consumes. Our nearly 130 million homes, many of which lose energy to leaky ductwork, underinsulated attics, and inefficient appliances, account for roughly 35 percent of the potential energy-efficiency gains, says the report. (You can make your old windows less drafty by caulking gaps, as shown. And use a programmable thermostat to boost your household-energy savings.)

As the report details, an initial investment of $520 billion would be needed to reduce annual energy consumption by 23 percent by 2020, which translates into $1.2 trillion in savings and an end-use reduction of 9.1 quadrillion British thermal units.

Those savings are key, because worldwide energy use is projected to soar over the next two decades, according to the U.S. Department of Energy's Energy Information Administration. The EIA says energy use will reach 678 quadrillion Btu in 2030.—Daniel DiClerico | e-mail | Twitter | Forums | Facebook

Essential information: Pinpoint the biggest energy savers and energy hogs in this report on residential energy use. If you're in the market for new appliances, use our free buyer's guides to find the most-efficient washing machines, dishwashers, refrigerators, and air conditioners in the Consumer Reports ratings. And learn more about weatherization.