Saving energy has evolved from a moral calling to a financial imperative for businesses that have broadened the concept of energy efficiency to one of sustainability.

Just look at Principal Financial Group, where employees are using less paper. Or the University of Iowa, where power bills have been cut by $1.5 million a year. Or Van Meter Industrial in Cedar Rapids, where new high-efficiency warehouse lights will pay for themselves in a year and a half.

(READ the full story at the Des Moines Register)