There is no substitute for a comprehensive energy audit and analysis, but as a minimum, if a small business doesn’t do anything else, here is a list of 12 “sure savers.” These are simple, high return-on-investment energy efficiency opportunities.
    1.    Turn off lights and equipment when not in use.
    2.    Buy ENERGY STAR qualified products.
    3.    Install occupancy sensors on lights in proper locations.
    4.    Make use of free “daylighting” and adjust illumination level to actual needs.
    5.    Tune-up heating/ventilating/air-conditioning (HVAC) systems with an annual maintenance contract.
    6.    Regularly change or clean HVAC filters.
    7.    Install a programmable HVAC thermostat.
    8.    Replace incandescent light bulbs with compact fluorescent lamps wherever appropriate.
    9.    Replace exit signs with LED (light emitting diode) units.
    10.    Control incoming sun through windows to lower heat gain in summer or increased heat gain in winter.
    11.    Ceiling fans: Turn on when people in the room; off when they are not.
    12.    Plug air leaks with weather-stripping and caulking.

Source: U.S. Small Business Administration