Case Middle School at Punahou School won the grand prize in Hawaiian Electric Co.'s Energy Efficiency Awards.

HECO, which presents the awards every two years for businesses that implement energy-efficient projects, also gave the Case Middle School complex top honors for innovation in design for its mix of green design and conservation practices.

"Companies that take advantage of technological advances are setting the bar for energy efficiency across the state," said Karl Stahlkopf, HECO senior vice president for energy solutions and chief technology officer.

"Their investment in upgrading their facilities has reduced their utility bills, conserved electricity and lessened the impact on the environment.

Projects recognized in the contest received HECO rebates totaling more than $1.1 million this year and are saving over $2.1 million a year in electricity bills, HECO said.

HECO added that it awarded companies more than $19.6 million in rebates during the past decade for installing a variety of energy-efficient upgrades.

Winners in other categories in this year's awards include: