Application developers are busy people. There are now hundreds of thousands of apps available for PCs and mobile devices, whether they’re running an Apple operating system, Google’s Android, HTML 5, or a mobile or PC version of the Microsoft platform. But just knowing there’s an app for every issue and craving doesn’t mean you’ll find it in the vast inventory of the app store.For people interested in apps that might help them reduce their electricity bills, though, the Department of Energy has tried to make shopping a bit easier by sponsoring an app-development competition and then touting the results. Called Apps for Energy, the competition features both juried and “Popular Choice” awards categories. Prizes totaled $100,000. The results of the juried contest were announced on May 22, while results from the Popular Choice voting, which ended May 31, are scheduled to be unveiled on June 6.The DOE required that each competition entry incorporate data available through Green Button, a standardized, industry-led initiative designed to allow customers access to their usage information in easy-to-understand form. Contest rules also required that each entry include a video that explains how the app works.Calculating tree unitsThe app developers took it from there. Apps for Energy’s five judges – professionals from government, industry, and technology sectors – selected an app called Leafully for Best Overall App honors and a $30,000 grand prize. Leafully’s developers, Timothy Edgar and Nathan Jhaver, both of Seattle, decided that energy use doesn’t necessarily have to be described to utility customers in kilowatt hours, a measurement standard that, while common, might seem technically dry and abstract to many people. Edgar and Jhaver decided to instead measure energy usage in terms of trees – the number of trees (presumably trees of average height and leafage) required to offset the pollution created by energy consumption, depending on the sources used to feed electricity into the grid as demand increases and decreases over the course of a day.In addition to translating Green Button energy-usage data into trees, Leafully allows users to view their historical usage patterns, develop strategies for reducing energy consumption, and calculate the potential monetary and environmental benefits – in terms of adding trees to the environment – of following through on those strategies.Leafully’s developers point out that not all energy-saving strategies reduce user expenses: the premiums paid for energy efficient “always on” appliances or renewable-energy systems, for example, might take several years to recover through reduced utility bills, although the tree rewards could be impressive over that period.Leafully users type their Facebook login on the service’s home page to authenticate their Leafully account, which allows them to tap their Green Button data. Facebook also is used to help Leafully participants to build a community of energy savers who will collaborate on energy-reduction strategies and help motivate each other to increase their aggregate tree value.Other prize winnersThe Best Overall App second prize went to Melon, an energy efficiency startup based in Washington, D.C. Melon, which won $15,000 in the contest, focuses on using Green Button data to help commercial buildings achieve Energy Star performance. Melon’s app is designed to assess a building’s energy efficiency quickly, highlight opportunities for energy savings that would bring the building to Energy Star performance, and help building managers find contractors to make improvements.VELObill, developed by software company Zerofootprint, based in New York City, took the Best Overall App third prize, $7,500, for a app that provides users with a simple format for monitoring their electricity use (as well as water and natural-gas use), ranking it against that of their peers, and developing a plan for improvements.Two winners were announced in a Best Student Apps category: wotz, submitted by a team of students at University of California at Irvine, took first place, and Budget It Yourself, a project developed by students at Case Western Reserve University and Cleveland Institute of Art, took second.Wotz combines Green Button data with data the U.S. Census Bureau and the California Energy Commission, and offers users “play,” “explore,” and “challenge” activities to help them analyze the data, which can be presented as a landscape of shapes representing various levels of energy usage. Like Leafully, wotz has created kilowatt-hour equivalents, including one that equates 1 kwH with one deluxe bacon double cheeseburger, and another that equates electricity consumed between 2 and 3 p.m. to a number of MacBook Air recharges. Wotz also includes two games whose difficulty is determined by the amount of electricity used in the household the previous day. The app also allows users to share their usage findings on Facebook.Budget It Yourself, as the name indicates, is a tool for Android smartphones that is designed to analyze Green Button data and offers guidance on how best to budget each day’s energy usage to reduce overall consumption.Building on existing app strategiesRight now, the prospects for adoption of the Apps for Energy programs are tied to the adoption of Green Button, which was launched in January and currently has commitments from enough utilities to make data available to 27 million households once the service is fully implemented. Whether consumers will take to these apps is less certain.Adoption of usage-monitoring tools offered by Microsoft and Google, for example, was too modest to keep those initiatives alive, even though they were available for free. But some systems, notably OPower, which provides information about power usage by other OPower participants in the community, have held their own.