AHU static pressure setpoint reset control is poor

Objective/ Method/Outcome

Objective: Determines if static pressure setpoint reset control is inefficient.

Method: The VAV damper positions are compared to determine if the they adhere to the Trim and Reset Setpoint Logic.

Outcome: This rule creates an insight.

Description

Reference: ASHRAE36-5.16.1.2

Trim & Respond Set-Point Reset Logic can be applied for static pressure reset. It reduces the setpoint at a fixed rate until a downstream VAV damper is nearly fully open and send a request of more airflow. When a sufficient number of requests are present, the static pressure setpoint is increased in response. In other word, There is always an opportunity to reduce static pressure setpoint when the maximum downstream VAV damper position is not fully open.

This rule is part of the CopperTree Standard rule-set.

Default Priority

Medium

Diagnosis

1. Reset duct static pressure by associated VAVs damper performance.

Message

Duct static pressure could be reset based on valve position.

Rule Template

Insight Type: Energy

Trigger Type: Active High

Notes

1. Expected values for “Supply Fan Status or Command” inputs are “0” or “1”.

2. Expected values for “Supply Fan Speed” inputs are “100” if they are constant speed fans or not available.

3. The input(s) that is(are) not used should be set to “0”.

4. The equations used in the rule were generated from the following article’s graph:

https://control.com/textbook/control-valves/control-valve-characterization/

Default Values:

Const. – Target Maximum Damper Position [%]: 85

Const. – Supply Fan Rating [hp]: 10

Const. – Threshold for Faulty Daily Hours of Valve Position [hrs]: 2

Const. – Energy Rate [$/kWh]: 0.1

Const. – Weeks of Operation [weeks]: 52