DENVER -- Xcel Energy's ( XEL) plan for providing energy through 2015 includes an aggressive energy efficiency program that could save the equivalent of a coal-fired plant.The plan approved this month by Colorado regulators calls for Xcel Energy to spend $63 million next year and $80 million in 2010 on demand-side management -- programs aimed at cutting demand by households and businesses. The utility, Colorado's largest, is spending about $20 million this year on energy efficiency. Xcel Energy spokesman Mark Stutz said Monday that the plan projects saving 694 megawatts of electricity. That would nearly be the equivalent of a new unit being built at an Xcel coal-fired power plant in Pueblo. One megawatt provides enough energy for roughly 750 households. "The energy efficiency and load management programs we plan to implement in 2009-2010 are expected to result in $450 million of net economic benefits for our customers," Fred Stoffell, Xcel's vice president for marketing, said in a written statement. Stutz said decreasing demand by increasing efficiency also pays off for the Minneapolis-based utility. "The cheapest megawatt of energy is the one you never had to build," Stutz said. Some examples of ongoing efforts are switches that turn off blowers on air conditioners at certain points to save energy when the demand is high. The utility also tunes up businesses' ventilation systems. Approval of Xcel's plan "is a historic day" for energy efficiency efforts in Colorado, said Howard Geller, executive director of Southwest Energy Efficiency Project, a Boulder-based public interest group. "Promoting greater energy efficiency is good for the economy and good for the environment," Geller said. Xcel's resource plan approved by the Colorado Public Utilities Commission also calls for adding at least 1,000 megawatts power from renewable energy. The company is on pace to get 20 percent of its power in Colorado from renewable energy sources by 2015, five years ahead a state mandatory deadline of 2020. Xcel Energy provides electricity and natural gas to about 1.3 million customers in Colorado.