### Setpoint Optimization The information below provides a FULL description of this microblock and all of its properties. What information you see and what you can do with it depends on your license and the application you are in, and in some cases, a controller's driver version.
Microblock family | Control microblocks
Icon and symbol |
What it does | Optimizes a single setpoint to use the least amount of energy necessary to meet the needs of the controlled equipment. You set a maximum and minimum value that the setpoint will not exceed, and you determine whether and how often the setpoint is calculated. The microblock uses requests from controlled equipment to increase or decrease the setpoint, and adjusts (trims) the setpoint with each calculation to minimize energy use. This allows you to efficiently meet the building's requirements by optimizing the setpoint according to the needs of the controlled equipment.
Click for details below How it works Inputs and outputs Properties Programming example
#### How it works When the go input is enabled, the microblock outputs the Initial setpoint. At the frequency defined by the Every value, the microblock calculates a new setpoint: New setpoint = previous setpoint + Trim by + lesser of (but do not respond by more than or (Respond by x req)) The microblock uses the Trim by value to decrease the energy consumed by the mechanical equipment when no requests are received. EXAMPLES To optimize the cooling setpoint for a VAV air handling unit receiving requests from multiple VAV boxes: If the microblock outputs 57° and 5 minutes later the req input sees 4 requests, the new setpoint is 56° = (57 + 1 + (-2)). Because (req x and respond by) = -4, the microblock calculates using the but do not respond by more than value. To optimize the heating setpoint for a VAV air handling unit receiving requests from multiple VAV boxes: If the microblock outputs 75° and 5 minutes later the req input sees 2 requests, the new setpoint is 78° = 75 + (-1) + (2 x 2.0) If the microblock outputs 72° and 5 minutes later the req input sees 0 requests, the new setpoint is still 72°. The microblock calculates a new setpoint of 71° = (72 + (-1) + 0). But the microblock will not output a setpoint lower than the Minimum value of 72°.
#### Inputs and outputs Inputs
req Number of requests | Requests for setpoint adjustment from controlled equipment. Connect to a Total Analog or other microblock with a total number of requests for an increase or decrease in the current setpoint. Common uses are heating requests for an increased heating setpoint, cooling requests for a decreased cooling setpoint, or VAV box requests for an increased duct static pressure.
go | True (on) if the control program should optimize the current setpoint. EXAMPLES Optimize the heating setpoint if the supply fan has flow. Optimize the cooling setpoint if the supply fan has flow. Optimize the duct static pressure setpoint if the fan is commanded on.
Outputs
STPT Current Optimized Setpoint | Calculated at the frequency defined in the Every field. = previous setpoint + Trim by + lesser of (but do not respond by more than or (req x Respond by))
#### Properties TIPS Alt+click any value in the WebCTRL® or Field Assistant interface to view property details, including its editing privilege and expression (location path) for use on graphics. You can right-click some properties in the EIKON® Property Editor and select Make editable or Make read-only to determine that property's functionality in your system.
Reference Name RefName | Use the default reference name unless you want a more descriptive name for graphics or network links. Limitations: lower case only limited to 40 characters cannot begin with a number must be unique within a control program
Editing Privilege | Preset - Each microblock property has an appropriate privilege or role assigned to it. You can use Global Modify in the WebCTRL® interface to find out what the actual privilege is. CAUTION If you change the Editing Privilege from Preset, the privilege you select will be used for all properties of this microblock, which is not always desirable.
Initial Setpoints
Initial | The initial setpoint the microblock uses when the go input is enabled.
Minimum | The minimum setpoint that the microblock will output.
Maximum | The maximum setpoint that the microblock will output.
Setpoint Optimization
Every | The frequency at which the microblock calculates a new setpoint. Should reflect the response speed of the control loop.
Trim by | The microblock adjusts the setpoint by this value at the frequency set in the Every field. For a direct acting loop (such as cooling) use a positive number. For a reverse acting loop (such as heating) use a negative number.
and respond by | At the frequency set in the Every field the microblock multiplies this value by the req input value, then adds the lesser of (req x and respond by) or but do not respond by more than to the (previous setpoint + Trim by value). For a direct acting loop (such as cooling) use a negative number. For a reverse acting loop (such as heating) use a positive number.
but do not respond by more than | The limit of the (req x and respond by) value that the microblock adds to the (previous setpoint + Trim by) value at the frequency set in the Every field. For a direct acting loop (such as cooling) use a negative number. For a reverse acting loop (such as heating) use a positive number.
Property Page Text
Show Property Page Text | Check to show this microblock's value on the equipment's Properties page.
Property Page Text | You can edit the microblock description that appears on the Properties page. See "Editing Properties page text using special characters" and "Formatting a microblock property" in EIKON® Help.
#### Programming example For the heating and cooling setpoint optimization microblocks' configuration, see the examples in "How it works" above. The logic below to optimize for a VAV air handling unit's supply air temperature setpoint does the following: Accepts heating and cooling requests from up to 20 zones Uses net heating and cooling requests to determine whether to use the optimized cooling setpoint or the optimized heating setpoint Uses a ramp to prevent large jumps in setpoint when switching between heating and cooling, typical of the swing seasons