The goal of a building automation and control system (BAC system) is to achieve and maintain an optimum level of comfort and the lowest possible energy use. The classical building automation and control system is divided into three levels (even when using a standardized communication protocol BACnet):
- Management level
- Automation level
- Field level
In a Desigo system, this can be described in greater detail through functions and applications.
Plant scope
Here is where the automation stations are located that take over control of primary plants such as air handling units, heating circuits, and cooling circuits to supply the rooms or heating or refrigeration plants.
The plants are always demand-controlled over the supply chain, in other words, heat or cooling demand occurs in a room that is forwarded to the applicable generation or over the heating or cooling circuit.
Floor scope
This is where rooms and room segments are controlled - energy-efficient HVAC functions, but also lighting and shading systems ensure optimum room conditions.
In an HVAC environment, we have radiators, and/or heating/chilled ceilings, but also fan coil units as well as variable air flow systems. On primary plants, hot or chilled water, but also treated air, is provided based on demand and is treated in the room segment by radiators, heated/chilled ceilings, heating or cooling coils. Blinds control can be used in addition to daylight or indirect lighting to heat and cool the room. Lighting control is also integrated to provide optimum lighting, together as well with blinds control.
Central functions specify, from the superposed location (Building Scope), for example, the room operating mode as well as room setpoints for the room or a group of rooms. The room user can also intervene with local room operator units and adapt room conditions to his or her needs.
Building Scope
Superposed central functions, e.g. a weather station, can generate setpoints for assigned rooms based on the outside air temperature. A scheduler can form and distribute a room operating mode for assigned rooms in a building section or floor. Moreover, lighting and blinds components can be deployed to a defined state via protection, service, or emergency functions. Demand signals from the rooms (Floor scope) are evaluated here and compiled and forwarded to the primary plants such as central air handling, heating or cooling circuits (located in the Plant Scope).
The following image illustrates the devices and functions located in different scopes and how the communication paths are defined. It illustrates that the floor scope does not require interaction to another floor scope nor permits and supports interaction; conversely, functions and applications communicate in the building scope with floor and plant scopes. The plant scope processes the information (forced and demand signals) from the building scope.
You can set in detail that a floor scope encompasses a floor or floor segment with a maximum of 250 participants. The floor scope can comprise multiple floors (with a total of max. 250 participants), i.e. the floor scope stands for a zone with a max. 250 IP-capable devices or room automation stations.
Central functions and flexible room management plays an important role in the design of BACnet and IP networks.
Central functions
Central functions are based on the concept of group manager and group members.
Room operating modes, room setpoints, and operating modes for lighting or blinds groups are flexibly distributed from a group manager over group members whose group membership is typically set during commissioning, but can also be changed later during operation using a management platform, e.g. Desigo CC. Multiple group members can be located on a room automation station by discipline. This includes, for example, lighting groups by floor, building section or building or blinds group by facade or over a facade segment.
Commanding | Designing a system |
|---|---|
Distribution/commanding of group managers to group member | Restricted to max. 500 group members |
Moreover, the same concept can be used to compile demand signals for chilled water, hot water, or for air handling. Demand occurs in room segments assigned to a group; it is collected, evaluated and transmitted to generation via the applicable group manager.
Concentrate data | Designing a system |
|---|---|
Collecting data from the group members via the group manager | Restricted to max. 250 group members |
A group member is not the same as a room segment. A room segment can include multiple group members.
Central functions can be directly designed in an easy-to-understand manner. In a multi-story building, rooms are rented on a floor-by-floor basis to various users. A central function exists by floor for each room operating mode, room setpoints, lighting, and shading. All lighting and shading is switched from a central location for each floor.
Emergency, service, and protection functions act on the entire lighting control and shading systems in the building.
Tenant | ||||
|---|---|---|---|---|
Retail mall Ground floor | Tenant A, 1st floor | Tenant B, 2n floor | Tenant C 3rd floor | Tenant D, 4th floor |
Businesses and public areas | Offices and hallways | Offices and hallways | Offices and hallways | Offices and hallways |
All central functions can be interconnected to meet the advanced requirements on mid-size to large projects.
If a tenant uses, for example, two floors, a central function can individually act on the given floor, that acts for its part on an additional, superposed central function, on both floors. The example of lighting or shading provides a good illustration of this.
Tenant | ||||
|---|---|---|---|---|
Retail mall Ground floor | Tenant A, 2nd floor | Tenant A, 3rd floor | Tenant B, 4th floor | Tenant B, 5th floor |
Businesses and public areas | Offices and hallways | Offices and hallways | Offices and hallways | Offices and hallways |
For separate IP networks on both floors, the building and cross-floor functions are mapped in the building scope and the floor functions in applicable floor scope.
Flexible room management
The functions are divided up: The room coordinates HVAC, lighting, or blinds functions as the shell and generates the resulting operating modes, setpoints, etc.
In the room segment, components and aggregates such as radiators, chilled ceilings, lighting, or blinds actuators are controlled per the operating mode set in the room.
One or more room segments can be assigned to a room. The room segment is flexible, since it can be reassigned by the management platform (by the user) under certain circumstances without an engineering tool. The ABT engineering tool is used to regroup in the event that buttons are used for lighting and blinds.
