To better understand the per model and national energy use of modems, routers, and other such devices – and how much could be saved by more efficient designs – NRDC and its consultant Ecova measured the power use of 60 models in the field and laboratory using a simplified version of the ENERGY STAR test method. Measurements and modeling estimated that small network equipment in America's homes consumed more than $1 billion worth of electricity in 2012, equivalent to the output of three large (500 MW) coal-fired power plants. This resulted in 5 million metric tons of carbon dioxide emissions, which represents the annual tailpipe emissions of 1.1 million vehicles.