Chapter 1: Building automation

The automatic centralized control of a building's electrical, lighting, shading, access control, security, and other associated systems is known as building automation (BAS), sometimes known as building management system (BMS) or building energy management system (BEMS). Improved occupant comfort, effective building system management, lower energy consumption, lower operating and maintenance expenses, and better security are some goals of building automation.

The BAS may monitor performance and device failures, maintain a building's climate within a certain range, give light to rooms based on occupancy, and alert building maintenance staff to malfunctions. In comparison to a facility that is not managed, a BAS strives to lower building energy and maintenance expenses. While older structures may be retrofitted with a new BAS, the majority of commercial, institutional, and industrial buildings constructed after 2000 feature a BAS.

It's common to refer to a building controlled by a BAS as an intelligent building, "smart building," or (if it's a home) a "smart home." Historically, BACnet and other reliable, strong protocols have been utilized in commercial and industrial facilities, whereas residences have used proprietary protocols like X-10.

Almost all multi-story green buildings are built to support a BAS for the features of energy, air, and water conservation. Demand response for electrical devices and more complex ventilation and humidity monitoring needed for "tight" insulated buildings are typical BAS functions. Most green structures also make use of as many low-power DC appliances as they can. The management of heat collection, shading and venting, and scheduling device use will often necessitate a BAS, even in a passivhaus design that aims to consume zero net energy.

Large projects with sophisticated mechanical, HVAC, and electrical systems frequently use building management systems. Typically, systems connected to a BMS account for 40% of a building's energy consumption; when lighting is taken into account, this percentage approaches 70%. A key element in managing energy demand is BMS systems. According to estimates, improperly constructed BMS systems consume 20% of the energy used in buildings, or around 8% of the nation's total energy consumption.

BMS systems occasionally link to access control (turnstiles and access doors regulating who is allowed access and egress to the building) or other security systems like closed-circuit television (CCTV) and motion detectors in addition to managing the environment inside the building. Elevators and fire alarm systems are occasionally connected to a BMS for monitoring. Only the fire alarm panel has the ability to close ventilation system dampers to stop smoke from spreading, turn off air handlers, turn on smoke evacuation fans, send all elevators to the ground level, and park them to prevent anyone from using them in the event of a fire.

Disaster-response methods (such base isolation) have been included into building management systems to protect structures against earthquakes. Recently, businesses and governments have started attempting to create comparable solutions for coastal areas at risk of increasing sea levels and flood zones. The self-adjusting floating environment is based on the technology already in use to float concrete runways and bridges, such as Japan's Mega-Float and Washington's SR 520.

A variable measurement is read using an analog input. Thermistor, 4-20 mA, 0-10 volt, platinum resistance thermometer (resistance temperature detector), or wireless sensors are some examples of temperature, humidity, and pressure sensors.

A device's status can be determined by a digital input. A door contact switch, a current switch, an air flow switch, or a voltage-free relay contact are a few examples of digital inputs (dry contact). Pulse inputs, which count the pulses over time, could likewise be used as digital inputs. A turbine flow meter that transmits flow information as a frequency of pulses to an input is one example.

Nonintrusive load monitoring

A device, such as a variable frequency drive, an I-P (current to pneumatics) transducer, a valve or damper actuator, is controlled by an analog output's speed or position. A hot water valve opening up 25% to maintain a setpoint is an example. A variable frequency drive ramping up a motor gradually to prevent a harsh start is another illustration.

Relays and switches, as well as driving a load when instructed, can all be opened and closed using digital outputs. One illustration would be to illuminate the parking lot when a photocell detects that it is dark outside. Another example would be to enable 24VDC/AC to flow through the output powering the valve in order to open it. Pulse outputs, which generate a frequency of pulses over a set amount of time, can also be classified as analog outputs. An energy meter that calculates kWh and emits pulses at the appropriate frequencies is an example.

In essence, controllers are miniature computers with input and output capabilities. These controllers are available in a variety of sizes and have the ability to manage sub-networks of controllers as well as regularly encountered building devices.

A controller may read inputs to determine the temperature, humidity, pressure, current flow, air flow, and other crucial variables. The outputs give the controller the ability to communicate commands and control signals to other system components and slave devices. Analog or digital inputs and outputs are also possible. Depending on the manufacturer, digital outputs are also sometimes referred to as discrete.

Programmable logic controllers (PLCs), system/network controllers, and terminal unit controllers are the three types of controllers commonly utilized in building automation. However, a separate device can also be present to link external systems (such a standalone air conditioning system) into a centralized building automation system.

A package rooftop unit, heat pump, VAV box, fan coil, etc. are just a few examples of the simpler devices that can be controlled by terminal unit controllers. Instead of having to develop new control logic, the installer often chooses one of the pre-programmed personalities that is most suited for the device to be controlled.

One of two or more operating modes for a building automation system is occupancy. Other typical modes are unoccupied, morning warmup, and night-time setback.

The majority of the time, occupancy is determined by scheduling. When a building is in occupancy mode, the BAS aims to provide a comfortable environment and adequate lighting. This is frequently accomplished through zone-based control, which allows users on one side of the building to have a different thermostat (or other system, or subsystem) than users on the other side.

The controller receives feedback from a temperature sensor in the area so it can supply heating or cooling as necessary.

When activated, the morning warming (MWU) mode runs before a room is occupied. The BAS attempts to get the building to setpoint just in time for occupancy during morning warmup. To maximize MWU, the BAS frequently takes into account outdoor conditions and past performance. Additionally known as an optimum start.

Occupancy sensors are used in some buildings to turn on the air conditioning or lights. Climate control is not frequently started directly by an occupancy sensor due to the potential for lengthy lead times before a place is appropriately cool or heated.

With a building automation or lighting management system, lighting can be turned on, off, or dimmed depending on the time of day, as well as based on occupancy sensor, photosensors, and timers. One common practice is to illuminate a room for 30 minutes after the last motion was detected. In order to adjust the lighting in the exterior offices and the parking lot, a photocell put outside the building can detect nighttime and the time of day.

Demand response is also a natural fit for the lighting industry, since many control systems allow users to dim (or turn off) lights to benefit from DR incentives and cost savings.

The field bus Digital Addressable Lighting Interface may be used as the foundation for lighting control in contemporary structures (DALI). Fully dimmable lamps have DALI ballasts. On DALI luminaires, DALI can also detect lamp and ballast failures and signaling failures.

Glass and shading are crucial elements of the building system, they affect occupants' visual, acoustical, and thermal comfort, as well as giving the tenant a glimpse of the outside.

It speaks about the application of technology to manage external or internal shading elements (like blinds), or the glazing itself.

The system responds quickly and actively to a variety of changing outdoor data, including solar, alterations in the inner environment (such as temperature changes and wind), illuminance, as well as occupant needs).

Systems for building shading and glazing can improve thermal conditions and lighting from an energy-saving and comfort perspective.

According to external conditions, daylighting requirements, and solar locations, dynamic shading systems allow management of daylight and solar energy into constructed environments.

There is less requirement for temperature and humidity conditioning because most air handlers combine return and outdoor air. By utilizing less chilled or heated water, this can reduce costs (not all AHUs use chilled or hot water circuits). To maintain a healthy indoor environment, some outside air is required. Demand control (or controlled) ventilation (DCV) modifies the volume of outside air based on recorded levels of...