Pendle Borough Council has rejected the application to build a wind turbine at Marsden Heights Community College in Pendle because of concern for the local bat population.
The 15m-high structure was planned for the college site in Brierfield, where the school opened three years ago under the Government's Building Schools for the Future scheme.
The six-kilowatt wind turbine was turned down as it was too close to the Edge End conservation area, home to wildlife including a large number of bats.
In response to the application, Catherine Lewis, environment planning officer for Lancashire County Council, held three bat surveys in the area.
She said: "Recorded areas of activity and flight lines indicate that the risk of injuring or killing bats (would be) at its highest. As bats are a protected species, to wilfully injure a bat is a criminal offence." GL.