Enhanced Prioritization – Primary Air System Runtime Analysis

Objective/Method/Outcome

Objective: Determines if systems are being run outside scheduled hours.

Method: The Supply Fan Status, Return Fan Status, Cooling Valve Command are used to determine if it is operational outside equipment schedule. The daily Avoidable Cost is determined subtracting the actual cost and the scheduled cost and used to project potential savings.

Outcome: Triggers an insight, and calculates Potential Savings.

Description

Monitors runtime outside scheduled hours to calculate Potential Savings from excess energy consumption. This includes supply and return fan electrical consumption, cooling energy consumption, and heating energy consumption. Rule also generates meters for each of these to be used in the “Energy” view.

This rule is part of the CopperTree Standard ruleset.

Default Priority

Medium

Rule Template

Insight Type: Fault Detection

Trigger Type: Active High

Diagnosis

  1. Schedule or control outputs in manual override, at the BAS front-end or control device.
  2. Control program error. Verify equipment scheduling and sequence of operations.

Message

Primary air system has been operating outside scheduled hours. Verify equipment scheduling and sequence of operations.

Logic

Logic for Primary Air System Runtime Analysis

Inputs

InputUnitTagsDescription
Return Fan RatingHP The Return Fan Rating
Return Fan Speed%Return Air Fan VFD SpeedThe recorded return fan speed
Return Fan Status  Return Air Fan StatusThe recorded return fan status
Yearly Weeks of Cooling  The annual weeks of cooling
Yearly Weeks of Heating  The annual weeks of heating
Threshold – Potential Savings Yearly  The minimum projected potential savings that can trigger an insight
Equipment Schedule Room Occupied, ScheduleThe scheduled hours of operation for the system
Threshold – Energy Impact Weekly  The minimum energy impact that can trigger an insight
Supply Fan Speed%Discharge Air Fan VFD SpeedThe recorded speed of the supply fan
Supply Fan Status Discharge Air Fan StatusThe recorded status of the supply fan
Discharge Air Temperature°Discharge Air TemperatureThe recorded discharge air temperature
Temperatures in Fahrenheit?  This input verifies if the temperature is in Fahrenheit.
Mixed Air Temperature°Mixed Air TemperatureThe recorded mixed air temperature
Heating Valve Discharge Air Heating CommandThe status of the heating valve
Cooling Valve Discharge Air Cooling CommandThe status of the cooling valve
Fan Heat Gain Constant  The constant fan heat gain
Supply Fan Rating HP The set supply fan rating
Discharge Air Flow Discharge Air CFMThe recorded Discharge Air Flow
Rated Equipment Air Flow   
Energy Rate $/kWh The rate of energy
Coefficient of PerformanceCOP  
Density of Airkg/m3 The assumed density of air
Specific Heat Air kJ/°C The assumed specified heat air
Energy Rate$/therm The assumed rate of energy

Notes

If airflow station is not present, “0” can be entered into the “Discharge Air Flow” input. Fan speed and maximum rated flow will be used to calculate flow.

If an airflow station is present, the “Rated Equipment Air Flow” will be overridden, and the flow sensor will be utilized.

Fahrenheit or Celsius inputs can be toggled with the “Temperatures in Fahrenheit?” input block. Use “1” for Fahrenheit (default), and “0” for Celsius.

Default Values for Constants:

  • Supply Fan Rating [HP]: 20HP
  • Return Fan Rating [HP]: 15HP
  • Yearly Weeks of Cooling: 26
  • Yearly Weeks of Heating: 26
  • Fan Heat Gain Constant: 1.5°
  • Rated Equipment Air Flow [CFM]: 15000
  • CFM Energy Rate ($/kWh): $0.10
  • Energy Rate ($/therm): $0.30
  • Coefficient of Performance (COP): 3
  • Density of Air (kg/m3): 1.2
  • Specific Heat Air (kJ/°C): 1.2
  • Insight Threshold – Potential Savings Yearly [$]: $100