4.
Don't open the windows when
the AC or heat are on in the classroom, office or dorm room
This one is a no brainer! Open windows let the heat or cool air out, which means that the energy that went into heating or cooling that air was wasted. Leaving a window open can add as much as 20-25% to the heating and cooling costs of that room, which means using more resources and creating more pollution. If the room is the wrong temperature ask that someone adjust the thermostat on the heater or AC unit.
http://www.eere.energy.gov/buildings/info/homes/homerenters.html
http://www.savewithces.com/energyheatandcool.html