Space Functions

Non-Residential space functions

Schedules characterizing the hourly profiles for thermostat setpoints, HVAC operation, and internal loads listed below are described in Schedules.

Each thermal zone in a building model is assigned a space function that characterizes design occupancy, ventilation, domestic hot water, exhaust, and internal load assumptions for the zone. Space functions are defined in ACM Reference Manual Appendix 5.4A.

Internal Loads

Design internal loads include:

  • Lighting power density (W/ft2)
  • Equipment power density (electric & gas) (W/ft2)
  • Occupant density (People / 1000 ft2)
  • Occupant sensible and latent heat gain (Watts per person)


Ventilation requirements include:

  • Minimum ventilation per area for design sizing (CFM/ft2)
  • Minimum ventilation per area for demand-controlled ventilation systems (CFM/ft2)


Exhaust requirements include:

  • Minimum exhaust flow per area (CFM/ft2)
  • Exhaust fan coupling with supply system fan (True/False)

Domestic Hot Water

Domestic hot water (DHW) assumptions include:

  • DHW flow per zone area (GPM/ft2)
  • Water heater fuel type (Electric or Natural Gas)