A mobile app that helps people perform their own home lighting audits is the winner of a U.S. Environmental Protection Agency “Apps for the Environment” challenge.

Light Bulb Finder was created by a Milwaukee, Wisc., app developer called Eco Hatchery. Co-founders Adam Borut and Andrea Nylund learned they won the challenge last week, and on Tuesday they’ll be in Washington, D.C., to accept the recognition.

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Borut and Nylund started out in 2007 making home energy-saving kits that came with an online tool for tracking projects. As mobile phones grew in popularity, they realized that “mobile phones are really the perfect platform for people to do their own home lighting audits,” Borut said in an interview.

The app was released for iPhone and Android in late 2010. It lets people walk around their home and use icons to identify the type of bulb currently used in each light fixture. After entering a zip code and the estimated daily hours of use for each bulb, the app suggests more efficient replacement bulbs, as well as a detailed projection of savings, in dollars and carbon emissions.

“We want to provide people with meaningful, individualized feedback so that they can make the smartest decision based on their priorities,” Borut said.

Users can then email themselves a shopping list, or order the bulbs directly through the app. Eco Hatchery gets a small commission on each bulb shipped. It also earns revenue through partnering with utilities and municipalities to promote local energy-efficiency programs and rebates. Madison residents, for example, will receive additional information about financing for home energy retrofits through the Green Madison program.

The app has been downloaded more than 100,000 times and used to replace more than 41,000 bulbs. The savings from those bulbs is collectively worth nearly $500,000 a year and annually reducing carbon emissions by about 5,325,000 pounds. The average user replaces about six bulbs, although some people have used it to switch out several dozen bulbs. If a typical household replaced the most used incandescent bulbs, it could save around $120 on their electricity bills each year, Borut said.

The challenge called for developers to submit apps that pull in information from EPA databases. Light Bulb Finder uses EPA data on the carbon footprint of electricity by zip code to calculate the emissions savings from changing out older bulbs.

The free app is available in the Android Market and App Store.