Current functions of building automation

A modern building automation system has several functions that seek to facilitate and comfort the lives of future residents. In a properly automated building, we can find some of the following functions in effect:

Controllers

Controllers are basically small computers, built specifically with input and output capabilities. These controllers come in a variety of sizes and capacities and can control devices commonly found in buildings in addition to controlling subnets of other controllers.

Inputs allow a controller to read temperature, humidity, pressure, current flow, air flow and other essential factors. Outputs allow the controller to send command and control signals to slave devices and other parts of the system. Inputs and outputs can be digital or analog. Digital outputs are also sometimes called discrete, depending on the manufacturer.

Controllers used for building automation can be grouped into three categories: programmable logic controllers (PLCs), system/network controllers, and terminal unit controllers. However, an additional device may also exist to integrate third-party systems (eg a standalone AC system) into a central building automation system.

Terminal unit controllers are generally suitable for controlling lighting and/or simpler devices such as a package roof unit, heat pump, VAV box, fan coil, etc. The installer normally selects one of the available pre-programmed options best suited to the device to be controlled, and does not need to create new control logic.

Occupation

Occupancy is one of two (or more depending on the situation) operating modes for a building automation system. Unoccupied, Morning Warm Up, and Night Retreat are other common modes.

Occupancy is generally based on times of day. In occupancy mode, BAS aims to provide comfortable climate and adequate lighting, often with zone-based control so that users on one side of a building have a different thermostat (or a different system or subsystem) than users on the opposite side. .

An in-zone temperature sensor provides feedback to the controller so it can provide heating or cooling as needed.

If enabled, morning warm-up mode (MWU) occurs before occupancy. During morning warm-up, BAS attempts to bring the building to the setpoint before occupancy. BAS generally takes into account external conditions and historical experience to optimize MWU. This is also known as optimized start.

Some buildings have occupancy sensors to activate lighting or climate conditioning. Given the potential for long wait times before a space gets cold or warm enough, climate conditioning is often not initiated directly by an occupancy sensor but by pre-set automatic programming.

Lighting

Lighting can be turned on, off or dimmed with a building automation or lighting control system based on time of day or occupancy sensor, photosensors and timers. A typical example is the lights going out in a certain space about half an hour since the last movement was detected. A photocell placed outside a building can detect darkness and time of day and control lights in outside offices and in the parking lot.

Lighting is also a good candidate for demand response, with many control systems providing the ability to dim (or turn off) lights to take advantage of light incentives and savings.

In newer buildings, lighting control can be based on the fieldbus called Digital Addressable Lighting Interface (DALI). Lamps with DALI ballasts are fully dimmable. DALI can also detect lamp and ballast failures in DALI luminaires and signal failures, making maintenance of thousands of lamps, for example, simple and practical.