Distribution systems
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Distribution systems
Air
The air distribution object contains general settings for the mechanical ventilation system. When applicable, these parameters will be referenced by the selected air handling unit. They may also be used elsewhere.
Figure 48.
Three different methods for control of supply air temperature are offered. In the last alternative, closed loop control of the return air is offered. The supply air is varied by a PI controller between the given limits in order to control the return air temperature.
Note that the supply air temperature only will reach its requested setpoint if sufficient heating and cooling is available.
Night cooling When this option is activated, the fans will start at night to cool down the building in order to save cooling during the day. Night (flush) ventilation is automatically made available during Mo-Fri, May 1 through Sept 30. Fans may operate in night vent mode between 22:00 and 07:00.
The night ventilation will be on when the following conditions are all fulfilled:
- Outdoor temperature is above 12°C
- Outdoor air is at least 2°C below return air
- Return air is above 22°C
While night flush ventilation is active, the supply air setpoint to the heat exchanger and the heating coil is lowered by 10°C. The setpoint for the cooling coil is increased by 20°C to avoid any mechanical cooling in AHU while night flush ventilation is on. Note, that the cooling setpoints of the spaces must be high enough to be sure that there is no separate room unit based mechanical cooling in spaces.
Night cycling for heating provides the option to heat the building by starting the ventilation system during the night, even if the fan operation schedule is off. The supply air setpoint is set to a higher value (modulated up to the value given by Max supply air temperature) and the fans are started when any room temperature drops below its setpoint.
Heat exchanger cooling recovery enables an air-to-air heat exchanger to precool incoming air whenever possible by using exhaust air.
Heat
The hot water distribution object contains general settings for the water based heating system. All water based heating units in the rooms will be fed with the same water temperature. A separate fixed setpoint is available for hot water to the air handling system.
Figure 49.
The Room design temperature drop is used by some room units to compute design mass flows and does not affect the control of the hot water system.
An ambient temperature limit is provided, above which the hot water circulation system is shut off. This is the mechanism to use in order to shut off room heating during the summer.
Cold
The cold water distribution object contains general settings for the water based cooling system. All water based cooling units in the rooms will be fed with the same water temperature. A separate setpoint is available for cold water to the air handling system.
The Room design temperature rise is used by some room units to compute design mass flows and does not affect the control of the cold water system.
Figure 50.
Domestic hot water
Drag a domestic hot water object from the palette to the building tab. Double click to open the domestic hot water object, Figure 51. To remove the object, click the wastebasket.
Figure 51.
Domestic Hot Water Use may be specified here using different units. Note that when a unit that includes the number of building occupants is used, the relevant number of occupants should be set here as well.
The temperature of the incoming water may be given, but a default value is computed from the yearly average of the selected climate file.
A schedule for the distribution of hot water usage over the day may be given. The total amount of hot water used is automatically calculated to match the requested Hot water use, i.e. the unit of the provided distribution schedule is irrelevant, only the shape is used.
Wise water heating/cooling systems
Main functionality
The WISE Water function connects a group of waterborne heating and cooling room units or air handling units to monitor and manage their cooling and heating demands. It calculates an average temperature setpoint based on all connected units and adapts to different building sections with varying cooling/heating needs. This ensures valves remain open as much as possible, optimizing water temperature to reduce energy consumption due to optimal conditions for the producer and to increase comfort by distributing the water to the units with an optimal supply temperature. The system supports flexible configurations and integrates seamlessly with SMART Link+ for advanced control.
Technical details
- All room units calculate their desired fluid temperature based on the demand which results in a valve opening.
- The room units are grouped and connected to one shunt group each. For each shunt group a supply temperature is calculated based on desired valve opening range, maximum temperature offset etc.
- The values for all shunt groups are compared and the highest (cooling circuit) and the lowest (heating circuit) are selected and sent to the producer with a margin (offset) of e.g.1.5 °C.
How to use wise water
Wise water controls the temperature delivered to units served by a shunt group (defined by a distribution circuit).
In the current implementation, Wise water doesn’t work well with domestic hot water since it will keep the temperature for heat generation at a high level, usually above 55 °C. The use of domestic hot water should be set to 0.
In ESBO to utilize Wise water for heating, Swegon heating units need to be used. The same applies for cooling.
Also, the air handling unit must be set to “AHU with limited capacity”.
Below is described where to find the parameters in ESBO exemplified by the heating case.
To add Wise water, go to buildings-tab and click on Wise water heating system in the palette. Click on the button Swegon below Heat in the distribution system section.
Write the same set point value in all three places at [2] for room supply temperature setpoint.
The temperature is controlled to make sure the valves controlling the room units are open in an interval of 60-80% [1] (can be altered).
In Wise water, a range for the supply temperature is given, Tmin and Tmax. However, in ESBO this is given by a setpoint [2] and a maximum offset [3], Setpoint = (Tmin+Tmax)/2 and maximum offset = (Tmax-Tmin)/2.
The offset is continuously changed with a given speed [4], 0.2 °C/min (can be altered). If all valves in the group are within the interval the offset is kept constant.
If the temperature to the shunt group for any reason is lower (heating case) or higher (cooling case) than the set point deviation [5] by default 5 °C (can be altered) the setpoint sent from wise water cannot be more than 5 degrees higher or lower than the water temperature sent to the shunt group.
For the heating system, the temperature delivered from the heating source is set as the maximum temperature requested from the shunt groups plus an offset [6]. The same type of offset can be set for the cooling system.
This offset, “increase of temperature…” [6] can be found by clicking on the advanced settings link in the bottom of the buildings-tab.