Yahoo Mail users will spend $110 more this year on electricity compared to Gmail users according to Opower, the global leader in energy information software for the utility industry. Based on the company's cutting-edge behavioral science and patent-pending data analytics, Opower found that, on average, Yahoo Mail users consume 939 kilowatt-hours (kWh) more than Gmail users, or about 11% more electricity per year - a sizeable, statistically significant difference in usage.

By analyzing consumer energy information derived from their work with more than 70 utility companies - including 8 of the 10 largest in the U.S. - and containing data from 40 million homes, Opower looked at the correlation between email address and electricity usage across 2.8 million American households around the country. About 1.15 million of those households are Gmail or Yahoo users, and are spread out across 23 states and several distinct climate zones.

According to Opower, the reason Gmail users consume less energy than those with Yahoo Mail has to do with the users themselves. Opower's data indicates that Yahoo Mail households are more likely to live in larger residences and also use more electricity per square foot.

In contrast, Gmail users tend to live in cities, where dwellings are often more compact and energy-efficient. In addition, Opower found that Gmail users are more likely to sign up for an in-depth analysis of their home energy usage.

While Yahoo Mail users cannot simply switch email accounts to reduce their energy consumption, they can adopt simple ways to cut back - such as turning off computers at night, getting a programmable thermostat, or upgrading a heating system - to make an impact on their utility bills. Opower's products, which include easy-to-understand, printed Home Energy Reports delivered with monthly utility bills, have helped consumers save more than $100 million to date.

"Making energy consumption relevant to consumers is something that Opower strives to do every day," said Opower President Alex Laskey. "We hope that by analyzing the data that we have on over 40 million homes and providing insights about how Americans are using electricity, we can make the topic interesting and inspire people to make changes in the way they consume energy."

The correlation between email address and electricity usage is the inaugural topic to appear in Opower's new corporate blog, "Outlier," which will provide unique insight into how Americans use energy.