EOV works exclusively on the basis of the “test room” method which.
Calculate optimized values for starting and stopping air conditioning systems. Systems should start at the latest possible time and should stop as soon as possible to save energy.
There are two modes of EOV operation, heating and cooling.
This means that a room sensor is always required. “In RoomTemp” is the input for the room sensor. In addition, EOV needs a room temperature setpoint “In RoomTempSp”, the outside air temperature “In FiltOATemp”, and a datapoint assigned to the time schedule connected at the input “In Occupancy”.
When the system is in heating mode (“In OpMode” =1), EOV switches on earlier than the occupied period by the time (tVHE) to guarantee room temperature setpoint is reached by the beginning of the occupied period. The displacement of the switch-on point depends on the difference between the room temperature setpoint and actual room temperature. EOV assumes a linear room model.
Fig. 191. Optimized Start-up in heating mode
The shortest advancement of start‑up is set by Parameter P1 (lowest pre-heat). You must set this parameter to its lowest value so that the calculated start‑up point is valid. The parameter’s maximum limitation is 1080 min (18 hours).
The minimum limitation of advance time is 0 minutes. When room temperature setpoint corresponds exactly to actual room temperature, system start‑up matches the switching point in the Time Program.
Between these two limits, advancement of system start‑up (tVHE) is calculated with the following formula:
tVHE = (“In RoomTemp” – “In RoomTempSp”) * P2
The early switch-on time equals the room temperature setpoint minus room temperature multiplied by the preheat factor. The preheat factor indicates how many minutes the system requires to compensate for a deviation of 1 degree. It must be entered in Parameter P2, but EOV can independently correct it. See Adaptation of Factors in this section.
If the Time Program contains a switch point that shuts the system off while the system is in heating operation (“In OpMode” = 1), EOV optimizes this switch point, that is, EOV shuts down the system before reaching the switch point so that energy is saved. EOV calculates shutdown advance time (TVHA) the same way as EOH, using a linear characteristic curve.
EOV shuts down the system with the maximum time advance if “In FiltOATemp” is equal to the room temperature setpoint and room temperature. In this case, EOV guarantees that the room temperature setpoint is closely followed until the switch point is reached in spite of early shutdown as the heat losses from the building are zero because of “In FiltOATemp”.
EOV shuts down the system without advance when the actual “In FiltOATemp” is less than or equal to the minimum “In FiltOATemp” (Parameter P3). Between these limits, EOV calculates advance time (TVHA) as follows:
Where tcorr = (“In RoomTemp” –“RoomTempSp”) * P4
The correction factor equals room temperature minus setpoint multiplied by the optimum stop factor.
The correction factor changes the slope of the previously defined characteristic curve as a function of the control difference:
If room temperature equals room temperature setpoint, the characteristic curve remains unchanged.
If room temperature is greater than room temperature setpoint, the characteristic curve is steeper and the system is shut down earlier.
If room temperature is less than room temperature setpoint, the characteristic curve is less steep and the system is shut down later.
The following figure illustrates this relationship.
Fig. 192. Optimized shutdown in heating mode
arameter P4 (optimum stop factor) weights the influence of the control difference on the characteristic curve. If Parameter P4 is zero, EOV calculates early shutdown based on OAT only.
When the system is in cooling mode (“In OperatingMode”=0), EOV displaces switch-on point (start‑up) by time (tVKE) to guarantee room temperature setpoint is reached by start‑up. The displacement of the switch-on point depends on the difference between the room temperature setpoint and actual room temperature. EOV assumes a linear room model.
Fig. 193. Optimized start in cooling mode
The minimum advancement of start‑up is set by Parameter P5 (lowest cooling time for opt. cooling). You must set this parameter to its lowest value so that the calculated start‑up point is valid. P5 has a range of 0 to 1080 minutes. The early switch-on time has a maximum limitation of 1080 min (18 hours).
The minimum limitation of advance time is 0 minutes. When room temperature setpoint corresponds exactly to the actual room temperature, and P5 is set to 0, system start‑up matches the switching point in the Time Program.
Between these two limits, advancement of system start‑up (tVKE) is calculated with the following formula:
tVKE = (“In RoomTemp” – “In RoomTempSp”) * P6
In other words, early switch-on time equals room temperature minus room temperature setpoint multiplied by the high-speed cooling factor. The high-speed cooling factor indicates how many minutes the system requires to compensate for a deviation of 1 K. It must be entered in Parameter P6, but EOV can independently correct it. See Adaptation of Factors in this section.
If the Time Program contains a switch point that shuts the system off while the system is in cooling operation (“in OperatingMode”=0), EOV optimizes this switch point, that is, EOV shuts down the system before reaching the switch point so that energy is saved. EOV calculates shutdown advance time (TVKA) the same way as EOH, using a linear characteristic curve.
EOV shuts down the system with the maximum time advance if “In FiltOATemp” is equal to the room temperature setpoint and room temperature. In this case, EOV guarantees that the room temperature setpoint is closely followed until the switch point is reached in spite of early shutdown as the heat losses from the building are zero because of “In FiltOATemp”.
EOV shuts down the system without advance when the actual OAT is greater than or equal to the maximum “In FiltOATemp” (Parameter P7). Between these limits, EOV calculates advance time (TVKA) as follows:
Where tcorr = (“in RoomTemp” – “In RoomTempSp”) * P8
The correction factor equals setpoint minus room temperature multiplied by the optimum stop factor.
The correction factor changes the slope of the previously defined characteristic curve as a function of the control difference:
If room temperature equals room temperature setpoint, the characteristic curve remains unchanged.
If room temperature is less than room temperature setpoint, the characteristic curve is steeper and the system is shut down earlier.
If room temperature is greater than room temperature setpoint, the characteristic curve is less steep and the system is shut down later.
The following figure illustrates this relationship.
Fig. 194. Optimized shutdown in cooling mode
Parameter P8 (optimum stop factor) weights the influence of the control difference on the characteristic curve. If Parameter P8 is zero, EOV calculates early shutdown based on OAT only.
For the advance calculation of the switch-on point in heating/cooling operation, EOV uses a model of controlled operation. In the heating mode, Parameter P2 (high-speed preheat factor) defines this model. The factor indicates how much time is required to overcome a control difference of 1K. In the cooling mode, Parameter P6 (high-speed cooling factor) defines this model.
The two modes require different curves because cool-down and heat-up occur at different rates. For example, in a factory, the factor for rapid cool-down is always larger than the factor for rapid heat-up because cooling down by 1K takes longer than heating up by the same amount. This effect is because the heat from machines supports heating up, while it works against cooling down.
EOV can adapt both factors automatically to the actual circumstances. This adaptation occurs when you select New start or Enable for the Factor Adaption field in the internal parameters dialog box. EOV adapts the factors with decreasing weighting, that is, the new factors calculated after the first optimization may change P2/ P6 significantly, the factors calculated after the second optimization somewhat less, and so on. After the first successful optimization, EOV sets Parameter P11 to zero. This setting corresponds to Adaption enable. You can prevent or interrupt adaptation by setting the Adaption button to disable (P11 = 1).
Time Program Preparation
When preparing the Time Schedule, set the switching points for system start/ stop to the latest possible time because EOV automatically advances these times, if necessary.
Also, you must set the Optimization variable to Yes in the Time Schedule for system start/stop.
Time Schedule Switch Point
With EOV, the Time Schedule does not use step changes in the room temperature setpoint for optimized system start/stop as is the case with EOH. Instead, the Time Schedule includes “In Occupied” status changes in the calculation of optimized start/stop time points. Therefore, you have to connect a datapoint assigned to a time schedule to the input “In Occupied.
EOV does not provide the setpoint and does not have an integrated controller. The controller application program must provide regulation during the system shutdown.
Fig. 195. Wire-sheet Icon
Fig. 196. Property Sheet
Fig. 197. Slot Sheet
Table 120. Inputs
Inputs |
Type |
Functional description |
In Occupied |
boolean |
“In Occupied” is the input for the datapoint connected to a time schedule that controls occupancy. This datapoint assigned to the time schedule controls the occupied/ unoccupied mode of the system. A logical 1 is occupied; a logical 0 is unoccupied NOTE: If the datapoint assigned to the time schedule is not directly connected to the control icon, the Next Schedule” icon must be added between the datapoint and the EOV. |
In RoomTempSp |
numeric |
Room temperature setpoint |
In RoomTemp |
numeric |
Room temperature sensor input |
In FiltOATemp |
numeric |
Filtered outdoor air temperature |
In OpMode |
enum |
Sets the mode of operation, heating or cooling. Heating is 1 Cooling is 0. You can set This input from a switching logic evaluation of the heating and cooling outputs from the “ZeroEnergyBand” statement. |
In Enabled |
boolean |
If the input “In Enabled” is set to false disabled in the slot sheet, the output “Out” will be disabled and is set to the value “0”. |
Table 121. Outputs
Outputs |
Type |
Functional description |
Out OnOff |
boolean |
Commands system start‑up (1) and shutdown (0). This output is mandatory. |
Out OptimOn |
boolean |
Is logical 1 during system start‑up, otherwise, it is 0 |
Out OptimOff |
boolean |
Is logical 1 during system shutdown, otherwise, it is 0 |
You can use these outputs in conjunction with an increased room temperature setpoint during the preheat phase.
Table 122. Parameter List
Description |
Value Range |
Default Value |
Unit |
Heating Case |
|||
P1 Minimum pre-heat time This is the minimum warm-up time for optimum start. This specifies a minimum amount by which to advance the scheduled start time in heating mode regardless of the actual optimum start calculation. |
0…1440 |
60 |
min |
P2 Preheat factor Warm-up rate for optimum start. When the plant is turned on for heating, this value is the number of minutes it takes to increase room temperature by 1 degree This value can be automatically adjusted if the adaptation option is enabled. |
0…∞ |
10 |
min |
P3 Optimum stop OAT low limit for optimized shutdown (heating) Minimum outside air temperature for optimum stop. When outside air temperature is at or below this value, the stop time will not be advanced in heating mode. |
-15…24 |
10 |
°C |
P4 Optimum stop factor heating Optimum stop factor. For optimum stop during cooling, this value sets the amount of influence that the difference between room temperature and its setpoint has on advancing or retarding the optimum stop calculation. The base stop time is 120 minutes before the schedule stop time. For every degree that the room temperature is above setpoint, the base stop time will be decreased by the value of this parameter. For every degree that the room temperature is below setpoint, the base setpoint will be increased by the value of this parameter. Set to 0 to make optimum stop during cooling solely dependent on outside air temperature |
0…∞ |
10 |
- |
Cooling Case |
|||
P5 Lowest cooling time for optimized cooling Minimum cool-down time for optimum start. This specifies a minimum amount by which to advance the schedule start time in cooling mode regardless of the actual optimum start calculation. |
0…2880 |
0 |
min |
P6 Cooling factor Cool-down rate for optimum start. When the plant is turned on for cooling, this value is the number of minutes it takes to decrease room temperature by 1 degree This value can be automatically adjusted if the adaptation option is enabled. |
0…∞ |
10 |
|
P7 Maximum OAT for optimized shutdown Maximum outside air temperature for optimum stop. When outside air temperature is at or above this value, the stop time will not be advanced in cooling mode. |
0…40 |
25 |
°C |
P8 Optimum stop factor cooling Optimum stop factor. For optimum stop during cooling, this value sets the amount of influence that the difference between room temperature and its setpoint has on advancing or retarding the optimum stop calculation. The base stop time is 120 minutes before the schedule stop time. For every degree that the room temperature is above setpoint, the base stop time will be decreased by the value of this parameter. For every degree that the room temperature is below setpoint, the base setpoint will be increased by the value of this parameter. Set to 0 to make optimum stop during cooling solely dependent on outside air temperature. |
0…∞ |
10 |
- |
Adaptation |
|||
P9 Adaptation (for adapting P2 and P6) 0=enable 1=disable 2=new start/enable (restarts adaptive calculations and overwrites previously calculated data and starts adapting P2 and P6 from scratch) |
0…2 |
0 |
- |