The students at Hillsborough County School District in Tampa, Florida, have an important assignment: save energy. The district has enlisted the right people to help the students with this work by hiring five ‘energy conservation mentors’ to teach students and faculty about energy conservation.

Hillsborough is the eighth largest school district in the country, with 230 schools serving 192,000 students. Its annual electric bill has hit $40 million in recent years, mainly from air-conditioning costs because, not sure if you heard, it tends to be hot in Florida.

Although the district has had an energy conservation program manager since the 1990s, it expanded its energy conservation efforts in early 2007 due to significant growth over the previous two decades. Part of those efforts involved hiring the energy conservation mentors. Their mission: conduct energy audits at each school by looking for leaky doors and windows and taking note of equipment that should be turned off when not in use.

According to district energy expert P.J. Crespo, on the basis of kilowatt-hours per square foot, the district’s energy use has been reduced by almost six percent since the advent of the mentor program. “On a $40 million electric bill, that’s $2.4 million of avoided energy costs,” says Crespo, who also currently directs the mentor program.

The district’s achievements are not only from energy conservation measures but also from better construction. For example, during the summer of 2012, the district’s construction department modernized the air-conditioning systems at 13 schools with the help of committed partners such as Walbridge, a general contractor performing some of the district’s HVAC projects. Most of the projects also include more efficient lighting and new lighting controls.

While the district expects to reduce energy bills, its overall approach is guided by total life-cycle costs rather than a focus solely on either initial construction costs or annual energy use. To that end, the district commissioned a life-cycle cost analysis for each of the 13 projects it worked on during the summer of 2012. “The best life-cycle cost doesn’t necessarily give you the lowest energy cost, but it ultimately saves money in the long run,” says Rory Salimbene, general manager of construction.

Students and faculty also helped after being taught by energy mentors how to conserve, and schools certainly have an incentive to do so. The district began a competition for the schools to meet their energy targets based on past usage rates. If they meet the goals, their school can share in the savings of up to $1,000 for elementary schools, $1,750 for middle schools, and $2,500 for high schools.

It’s not just energy that’s being addressed. Five years ago, few of the district’s schools recycled materials such as paper and printer cartridges. Today that’s changed, and some schools’ fourth and fifth graders are taught to read utility meters and provide results to the classroom in math-like lessons. They’re also given the power to ‘write up’ classrooms that leave lights and computer equipment on. Students can win prizes for bringing in the most recyclable materials, but there are even bigger rewards with the money collected from selling recyclable materials: field trips and other events.

“It’s all about the money,” Salimbene says. “When you can easily spend $40 million a year on energy, you have to take advantage of every opportunity to save the taxpayers’ dollars.”