Ask the Optimization Expert: BAS Controls

Question: How can I improve the energy efficiency of my building automation systems or BAS controls?

Answer: BAS controls issues, which include problems with thermostats and temperature control, can take several forms. A building energy audit will typically identify energy inefficiencies in one or several of the following areas:

  • Thermostats on heating/cooling units are vulnerable to occupant adjustment
  • Space temperatures are higher or lower than thermostat settings
  • Thermostat settings have not been adjusted for change in seasons
  • Control devices are not inspected on a regular basis
  • Building temperatures are not adjusted for unoccupied periods
  • Unoccupied or little used areas are heated or cooled unnecessarily
  • Heating/cooling equipment is started before occupants arrive and/or is operating during last hour of occupancy

The suggested operations and maintenance improvements and facility improvement measures will vary based on your facility’s unique mix of inefficiencies, but what follows are some general guidelines.

Suggested BAS Controls Operations and Maintenance Improvements:

  • Reset thermostats to correct settings. Thermostats should be set to 68 degrees Fahrenheit in heating season and 78 degrees Fahrenheit during cooling season.
  • Install or replace locking screws to prevent tampering.
  • Install tamper-proof locking covers on thermostats.
  • Recalibrate thermostat.
  • Blow out moisture, oil and dirt from pneumatic lines (for pneumatic systems); clean contacts if electrical control system.
  • Recalibrate controllers.
  • Ensure that control valves and dampers are modulated properly.
  • Ensure that heat generating device is producing heat and that heat distribution to the space is unobstructed.
  • Make sure that air intake volume is not excessive.
  • Change the location of thermostats from areas subject to extreme temperature fluctuations, such as next to a window, or over a heating or cooling unit.
  • Routinely check all time clocks and other control equipment for proper operation, correct time and day and for night and proper programming of on-off set points. Protect from unauthorized adjustment.
  • Reduce thermostat settings by a minimum of 10 degrees Fahrenheit at nights, for weekends and holidays during the heating season, but maintain ventilation.
  • Shut down air conditioning units at night, on weekends and holidays.
  • Reduce winter thermostat settings to 55 degrees Fahrenheit and increase summer thermostat setting in unoccupied areas. Where possible, turn off heating systems completely in these areas if nothing in the space can freeze.
  • Use spot heaters/coolers in large spaces with low occupancy.
  • Experiment with start-up times and duration of operation to determine satisfactory comfort levels for occupants. Reduce or turn off heating and cooling during the last hour of occupancy, allowing the building to “coast.”

Suggested BAS Controls Facility Improvement Measures:

  • Install pre-set solid-state electric thermostats, which do not require calibration, if existing controls are electric.
  • Relocate thermostats in return air ducts where they will be inaccessible to occupants.
  • Replace existing thermostat with a thermostat which has a separate setting for cooling and a separate setting for heating or use one thermostat to control heating and one thermostat to control cooling.
  • Install automatic controls such as time clocks or install an automated energy management system that will reduce heating/cooling.

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