Turning off the lights after leaving the room. Opening windows instead of turning on the air conditioner. Going outside to play instead of watching television.

These simple changes were among the energy-saving practices many Mililani Mauka Elementary School students and their families adopted, helping the school win the state Department of Education-Hawaiian Electric Co. Home Energy Challenge and a $10,000 check.

The Home Energy Challenge, sponsored by the DOE and HECO, is designed to teach students easy and inexpensive ways to conserve energy at home. The idea is to instill energy-saving habits in children, who also will remind their parents and grandparents to conserve electricity.

"Kids have a fresh mind, and they're willing to look at this not as a sacrifice in their lifestyle, but as what's the right thing to do," said Robbie Alm, HECO executive vice president of public affairs. "We want them to practice that but in the meantime, they can get us old guys to be better about what we do. It's harder to turn down our children and grandchildren."

Thirteen O'ahu elementary schools participated in the pilot program, which included six months of energy conservation education through materials and activities such as hands-on displays, guest speakers, conservation workbooks and a video.

As part of the challenge, some students' families also allowed HECO to track their home electricity use through their utility bills for six months and compare it with the same period the year before.

More than 180 Mililani Mauka students' families participated and collectively saved $5,000 on their home electricity bills over the six-month period.

The more than 1,100 participating families among the 13 schools saved more than 178,000 kilowatt hours and $45,900, said Kaiulani de Silva, Hawaiian Electric director of education and consumer affairs. The average saving per household over the six-month period was about $41.

Other schools whose families saved electricity won $1,000 Home Energy Challenge prizes.

Mililani Mauka Elementary fifth-graders Samantha Alvarado and Jason Yuh said their families began turning off lights when not in use and took steps to avoid energy sneakers, or phantom loads, by using power strips to turn off computers and chargers. They also opened windows instead of turning on the air conditioner. Their families still exercise those habits.

"We used to use the AC a lot," said Alvarado, 11. "We cut down a lot. We went from using it almost every night to using it once a month for a party.

"It took a little getting used to, but knowing that we're helping to save the planet, that helps a little bit. And also, if you open the windows and turn on the fans, usually it's just as good as turning on the AC."

Arlene Yoshimura, the Mililani Mauka Elementary science resource teacher who coordinated the energy challenge program for the school, said she heard from some parents that their children have become very mindful of saving electricity at home.

"One of them said her son is the electricity police," Yoshimura said. "He'd say, 'Mom, you didn't turn off the light. Mom, you have to turn off the TV if you're not watching.'

"I think the children are becoming conscious of their energy use and trying to do their part. ... Parents do listen to their children, so that is really, really important."

Applications for the Home Energy Challenge will be sent to all O'ahu public elementary schools this summer. For more information, visit www.heco.com.