Temperature is that one most important parameters which should be monitored and controlled for a building. Its a primary factor in a building that keeps the occupants comfortable, and thus increases their productivity.
The reason 75F persists it to keep the occupants in the building comfortable is by capturing individual preference for temperature and then strive to maintain it.
To achieve that comfortable level of temperature conditioning, the energy consumed is enormous. Whether it is heating a building in a colder region, or cooling a building in a torrid region, whether running a heat pump to generate the required heating, or running the fan to bring in more air to cool the building, a good amount of energy is consumed.
75F is committed to provide the necessary comfort conditioning, but at a much lower reduction in energy consumption. 75F introduces various types of temperatures in a building management space, which reduces the load on the HVAC equipment, by providing the comfort conditioning as a requirement by the building.
The various types of temperatures used in the 75F system are as follows.
In order to address the comfort conditioning part of the commitment, the concept of setpoint temperature is introduced.
Setpoint is a concept of knowing what a possible desired temperature would be, that might keep the occupant in the building comfortable, and defining them in advance.
It is a temperature which the occupant can set which provides the comfort levels in a building. The HVAC equipment tries to maintain the set temperature. This is called a Single Temperature Setpoint.
Single Temperature Setpoint
It is that one temperature value which can be specified as the feels good temperature e.g., 72F.
Operation Mode Illustration
This is found to be effective when the HVAC equipment is working in a specific mode (heating/cooling). However, in a equipment which is capable of both heating and cooling, and has an auto switchover feature, the equipment can lead to rapid switchover from heating to cooling and vice versa. Also there is a possibility that the adjoining spaces in the building demands for just the opposite of the conditioning.
This rapid switchover may reduce the life of the HVAC equipment, thus 75F introduces the concept of
Dual Temperature Setpoint with its related concepts to avoid the rapid switchover, thus increasing the the life of the HVAC equipment and reducing the energy consumption
Dual Temperature Setpoint
It is a range of temperature values which can be specified as the feels good temperature e.g., 70F- 74F.
Operation mode Illustration
From the above illustration it can be visualized that the dual temperature setpoint operation introduces the concept of Deadband and the Hysteresis band.
A deadband or dead-band (also known as a dead zone or a neutral zone) is a band of input values in the domain of a transfer function in a control system or signal processing system where the output is zero (the output is 'dead' - no action occurs). Deadband regions can be used in control systems such as servo amplifiers to prevent oscillation or repeated activation-deactivation cycles.
It is the space in between two control points where no control is activated, also it is the range in a process where no changes to output are made.
Below is a use can that explains the significance of the introduction of DeadBand
Suppose 2 adjoining spaces like an office and a hallway are served by 2 heat pump units. The user in the office sets the desired temperature to 74F whereas the hallway is set to 72. if the spaces are connected via the door and the space temp is 73 then the office will be calling for heating whereas the hallway will be calling for cooling.
In this case, a 'deadband' can ensure that there is a range of temperatures where neither heating or cooling occurs. In 75F's case we will use a separate heating and cooling deadband. Say the desired temperatures of 72 /74 are as in the above case but there is a 2-degree cooling and 3-degree heating deadband. No conditioning will occur for range of 69-74 for the hallway and 71-76 for the office and the space temperature is allowed to drift. This ensures that for the spaces above when the temperature is in the common deadband range of 71-74 no conditioning will occur.
The 75F BMS controls implements two types of deadbands:
- Heating DeadBand (HBD): It is the range of temperatures where no heating occurs. For example, if setpoint is 65F with heatingdeadband as 2 then range between 63 ~ 67 no heating will occur.
- Cooling DeadBand (CDB): It is the range of temperatures where no cooling occurs. For example, if setpoint is 70F with coolingdeadband as 2 then range between 68 ~ 72 no cooling will occur.
The deadbands are altered using the HeatingDeadband and CoolingDeadband tuners feature of 75F. Tuners follow a building / system / zone / module hierarchy along with log of who made . On the CCU the tuners are on the tuners page. This is reached from any of the profiles by clicking on 'advanced tuners'.
The adjustable heating and cooling deadband offer many advantages, such as:
- Eliminating short cycling to protect your unit from unnecessary wear.
- Longer runtimes and higher efficiency
- More precise comfort.
Hysteresis is the concept of creating a separate off point as compared to the setpoint.
As in dual setpoint example cooling setpoint of 74F. As soon as desired temperature rises above 74F cooling will engage. But without any added hysteresis equipment would also turn off at 74F causing short cycling.
If 1F hysteresis is added, then cooling will turn ON at 74F and now turn OFF at 73F. This gives the equipment some breathing room, so it is not constantly turning ON and OFF.
SetPoint Temperature for a Building level in CCU
The setpoint temperatures for the building level can be visualized from the Installer options screen in the CCU as below.
For more information refer CCU Master Control
Further the setpoint temperatures for the building level can be visualized from the building schedule screen in the CCU as below.
SetPoint Temperature for a Zone level in CCU
The setpoint temperature for the zone level can be visualized from the zone screen in the CCU as below
SetPoint Temperature for a Building level in Portals
The setpoint temperature for the building level can be visualized from portals as well, under the section Building schedule in the Heatmap Page as below
For more information refer to Setting Building & Zone Schedule from Facilisight & CCU
SetPoint Temperature for a Zone level in Portals
The setpoint temperatures for the zone level can be visualized under the Zone Settings section from the visualization screen in the portal, for the zones, as below.
The setpoint temperatures for the zone level can be visualized from the zone schedule section in the visualization scree in the portal as below.
For more information refer Facilisight Heatmap- Latest
In order to address the energy saving part of the commitment, the concept of setback temperature is introduced.
Setback Temperature is concept of relaxing the desired temperature when the building is unoccupied, the deadband specified is increased. This allows the temperature to drift further without turning on the conditioning equipment which saves energy.
To conserve energy when the building is unoccupied, the desiredHeatingTemperature and desiredCoolingTemperature are relaxed, i.e., the deadband between these two is increased. This allows the temperature to drift further without turning on the conditioning equipment which saves energy.
The tuner that is used to set the setback temperature is unoccupiedZoneSetback, it determines how many degrees from the desired temperature the zone will be allowed to drift during unoccupied. Different zone may have different desired temperatures leading to different setbacks .
Operation mode Illustration
|Operation modes Visualized in Portals
Below is a visualization from the the portals of 75F for the setpoint and setback modes of operation in real time.