Americans who receive meter data on their home energy use reduce consumption on average by 1.8 percent after the first year.

That's according to a study of 750,000 households of varied demographics in six states conducted by energy-management software company Opower and sponsored by the Environmental Defense Fund (EDF). The study followed homes enrolled in various utility programs that provided home usage data via Web portal, text, or paper reports mailed to consumers' homes.

The figure may not sound like much. But if every home in the U.S. reduced energy consumption by 1.8 percent, nationwide energy usage would drop by more than 26,000 Gigawatt hours per year--enough to power all the homes in Colorado and Utah combined, according to the EDF.

Such a reduction would also curb CO2 emissions by 8.9 million metric tons annually in the U.S., according to the EDF.

Usage data was gathered and shared--via 11 gas and electric utilities servicing the meters--for a minimum of 12 months. The data showed that homes saved between 0.9 percent and 2.9 percent annually and that the average savings was 1.8 percent.

"The programs in the sample serve urban and rural areas, the geography spans East Coast, West Coast, and Midwestern states, and the service providers include from investor-owned utilities, coops, and municipal utilities," according to the report.

OPower is a start-up founded in 2007 that offers software platforms for utilities that allows customers to access smart-meter and home-energy consumption data from a portal on a utility's Web site. OPower garnered attention in November when it snagged $50 million in venture capital from Kleiner, Perkins, Caufield & Byers and Accel Partners, among others.

Correction 9:57 a.m. PT: This story had incorrectly stated the type of electricity meters involved in the study. It included both smart and regular utility meters.