Make sure that simultaneous heating and cooling does not occur - verify proper operation of valves, dampers, and controls. Set back heating and cooling temperatures 30-60 minutes before the end of the day. Make sure ductwork is completely sealed and well insulated. Lighting Change out incandescent exit lights with 3 - 7 watt LED exit lights. These lights last 25 years, reducing maintenance costs.
Many areas have more lighting than is required for current tasks.
Measure current lighting levels and reduce excess lighting by using power reducers, multi-level switching, or simple removal of lamps and ballasts. Note that some ballasts continue to use some energy even when lamps are not operating. In most cases, use task lighting rather than ceiling fixtures. Replace halogen torchiere floor lamps with compact fluorescent models that use a fraction of the energy. Ask janitorial services to only light one area of the building at a time rather than having the entire building brightly lit until midnight.