The Iowa Utilities Board has approved a new five-year energy efficiency plan for Alliant Energy Corp.'s Iowa operations, the company announced. Alliant, which operates in Iowa as Interstate Power & Light Co., said it will invest more than $400 million in energy efficiency programs over the next five years, similar to the investment it made in its current plan that ends Dec. 31. The plan includes the most popular energy efficiency programs from past plans, including home energy audits and insulation rebates, heating and cooling program offerings, new construction programs, and commercial and industrial custom rebates. Items added to the plan are expanded energy-use assessment options, increased LED lighting options for homes, businesses and farms, as well as new rebate opportunities for small businesses. A full list of programs will be posted at by Jan 2.