The Iowa Utilities Board has approved a five-year energy efficiency plan for MidAmerican Energy Co. to spend half a billion dollars on energy efficiency efforts over the next five years. Beginning Jan. 1, MidAmerican, which generated more than $3.24 billion in revenues in 2012, will increase its energy efficiency efforts by more than $100 million. More than 80 percent of that money will be returned to customers in the form of rebates and technical assistance to provide incentives for the purchase and installation of energy efficient equipment, the company said. Some of the new programs include a residential heating and cooling tuneup program, the addition of LED bulbs, commercial building optimization services, ongoing commercial building performance services and additional project assistance for industrial customers. If the plan's goals are achieved, MidAmerican customers collectively should save approximately 1.2 billion kilowatt-hours of electricity. The cumulative natural gas savings goal is approximately 36 million therms .Earlier this month, the utilities board approved a $400 million plan for Interstate Power & Light Co.