If you already have a programmable thermostat, make sure the schedules and setpoints are correct, and you don't have weekend operation if you don't need it. Remind staff to watch lighting and equipment use. If you can switch part of the lights off when there is light from windows, you will save energy directly and reduce the cooling load. Keeping lights and computers turned off when the building is unoccupied will help reduce the need for cooling when the building is unoccupied. Change those air filters.
Dust clogs the filters and reduces airflow and cooling effectiveness.
Change or clean air filters at the start of the cooling and heating seasons for good system performance. Make sure the filters are the right size and are tightly installed so they do their job. Keep condensers clear. Your air conditioner cools the building by transferring heat to the outside. Most systems have air-cooled condensers with a fan and condensing coil on the roof or in the alley.