Dow Chemical Company is one of the best examples of how exhaustible energy efficiency can be as a a resource.   The energy manager, of twenty something buildings of Dow in 1982 came up with a contest to find the most energy-saving projects.

The first year their was twenty-seven winners, with an average annual ROI of 127%.  Then in 1983 they had thirty-two projects requiring a total investment of $2.2 million with an average annual ROI of 340%.  Which end up saving the company $7.5 million the first year, and every year after.  Even six years later in 1989, the contest continued, with thirty-six projects winning.  The contest was its highest ever that year, costing $7.5 million and saving the company $37 million a year, an eleven week pay off.

Energy efficiency, the low hanging fruit that grows back