Building automation

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Building automation is an automated centralized control of heating, ventilation and air conditioning, lighting and other building systems through building management systems or building automation systems (BAS). The purpose of building automation is to improve occupant comfort, efficient building system operations, reduced energy consumption and operating costs, and improve utility life cycle.

Building automation is an example of a distributed control system - a computer network of electronic devices designed to monitor and control mechanical safety, security, fire and flood, lighting (especially emergency lighting), HVAC and humidity control and ventilation systems in a building.

The core functions of BAS continue to build climates within the prescribed range, providing light to rooms based on residential schedules (in the absence of obvious switches to the contrary), monitoring the performance and failure of devices across all systems, and providing damage alarms to build maintenance staff. A BAS should reduce energy costs and maintenance of buildings compared to uncontrolled buildings. Most commercial, institutional and industrial buildings built after 2000 include BAS. Many old buildings have been reassembled with new BAS, usually financed through energy and insurance savings, and other savings associated with pre-emptive maintenance and error detection.

A building controlled by BAS is often referred to as a smart building, "smart building", or (if the residence) "smart house". Commercial and industrial buildings have historically relied on strong proven protocols (eg BACnet) while proprietary protocols (such as X-10) was used in homes. The latest IEEE standards (particularly IEEE 802.15.4, IEEE 1901 and IEEE 1905.1, IEEE 802.21, IEEE 802.11ac, IEEE 802.3at) and the efforts of the consortium as nVoy (which verifies compliance with IEEE 1905.1) or QIVICON has a standards-based foundation for many heterogeneous networks devices on many physical networks for a variety of purposes, and ensures proper quality of service and failover to support human health and safety. Thus, commercial, industrial, military and other commercial institution users now use a system different from most home-scale systems. See the homes for further automation of the entry-level system, nVoy, 1905.1, and major vendors are implementing or reject this trend to standard integration.

Almost all nested green buildings are designed to accommodate BAS for energy, air and water conservation characteristics. Response to demand for electrical devices is a typical function of BAS, such as more sophisticated ventilation and moisture monitoring required for "tight" buildings. Most green buildings also use as many low-power DC devices as possible. Even passivhaus designs intended not to consume any clean energy will usually require BAS to manage heat, shadow and ventilation capture, and device usage scheduling.

Video Building automation

Automation system

The term building automation system , which is used loosely, refers to the electrical control system used to control the building, ventilation and air conditioning (HVAC) systems. Modern BAS can also control indoor and outdoor lighting as well as security, fire alarms, and basically everything else electricity in the building. Old HVAC control systems, such as 24V thermostat DC cables or pneumatic controls, are a form of automation but lack the versatility and integration of modern systems.

Maps Building automation

Bus and protocol

Most building automation networks consist of primary and secondary buses that connect high level controllers (generally specific to building automation, but may be generic programmable logic controllers) at a level that lower controllers, input/output devices and user interfaces (also known as human interface devices). BACnet open ASHRAE protocol or LonTalk open protocol determines how most devices operate. Modern systems use SNMP to track events, build decades of history with SNMP-based protocols in the world of computer networks.

The physical connectivity between devices has historically been provided by special optical fiber, ethernet, ARCNET, RS-232, RS-485 or other low-bandwidth, special-purpose wireless networks. The modern system relies on a standard, multi-protocol heterogeneous network as defined in the IEEE 1905.1 standard and verified by the nVoy audit sign. It usually only accommodates IP-based networks but can use existing cables, and also integrates powerline networks in AC circuits, power over Ethernet low power DC circuits, high bandwidth wireless networks such as LTE and IEEE 802.11n and IEEE 802.11 ac and often combine them using wireless mesh standard open special building ZigBee).

Proprietary hardware dominates the controlling market. Each company has controllers for specific applications. Some are designed with limited control and no interoperability, such as a simple open roof unit for HVAC. The software usually will not integrate well with packages from other vendors. Cooperation is only at Zigbee/BACnet/LonTalk level.

The current system provides interoperability at the application level, enabling users to combine devices from different manufacturers, and to provide integration with other compatible building control systems. It usually relies on SNMP, long used for the same purpose to integrate various computer network devices into a coherent network.

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The input and output types

Sensor

Analog input is used to read variable measurements. Examples are temperature, humidity and pressure sensors that can be thermistors, 4-20 mA, 0-10 volts or platinum resistance thermometers (resistance temperature detector), or wireless sensors.

Digital input indicates if the device is turned on or off - but detected. Some examples of inherent digital inputs will be 24 V DC/AC signals, current switches, air flow switches, or voltaic relay contacts (dry contacts). The digital input can also be a pulse type input that calculates the pulse frequency over a period of time. An example is a turbine flow meter that transmits rotation data as a pulse frequency to an input.

Nonintrusive load monitoring is software that relies on digital sensors and algorithms to find other devices or loads of electrical or magnetic characteristics of the circuit. However it detects the event by analog means. It is very effective in operation and useful not only for identification but for detecting early transients, channel faults or equipment, etc.

Control

The analog output controls the speed or position of the device, such as variable frequency drivers, I-P transducers (currently being pneumatic), or valve or dampening actuators. An example is a hot water valve that opens 25% to maintain the setpoint. Another example is the slender variable slender motor drive frequency to avoid a difficult start.

Digital output is used to open and close relays and switches and move loads on commands. An example is turning on a parking light when the photocell shows it dark outside. Another example would be to open the valve by allowing 24VDC/AC to bypass the output powering valve. The digital output can also be a pulse type output that transmits the pulse frequency over a period of time. An example is the calculation of kWh energy and emits the appropriate pulse frequency.

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Infrastructure

Controller

The controller is essentially a specially crafted little computer with input and output capabilities. These controllers come in various sizes and capabilities to control devices normally found in buildings, and to control sub-network controllers.

Inputs allow the controller to read temperature, humidity, pressure, current flow, airflow, and other important factors. The output allows the controller to send commands and control the signal to the slave device, and to other parts of the system. The input and output can be either digital or analog. Digital output is also sometimes called discrete depending on the manufacturer.

Controllers used to build automation can be grouped into three categories: programmable logic controllers (PLCs), system/network controllers, and terminal controllers. But enhancements can also exist to integrate third-party systems (eg stand-alone AC systems) into the central building automation system.

The terminal unit controller is usually suitable for controlling lighting and/or simpler devices such as the roof package unit, heat pump, VAV box, fan coil, etc. The installer usually selects one of the pre-programmed personalities most suitable for the device to be controlled, and does not have to create new control logic.

Shelter

Residential is one of two or more operating modes for building automation systems. Unwanted Heating, Morning and Night-Time Heating is another common mode.

Occupancy is usually based on day time schedule. In Occupancy mode, BAS aims to provide a comfortable climate and adequate lighting, often with zone-based controls so that users on one side of the building have different thermostats (or different systems, or sub systems) of users on opposite sides.

The temperature sensors in the zone provide feedback to the controller, so as to produce heating or cooling as needed.

If enabled, the morning heating mode (MWU) occurs prior to occupancy. During Morning Heating, BAS tries to bring the building to the setpoint just in time for Shelter. BAS is often a factor in outdoor conditions and historical experience to optimize MWU. This is also referred to as optimized start. .

Override is a command that starts manually to BAS. For example, many temperature sensors mounted on the wall will have push-buttons that force the system into Residential mode for a certain number of minutes. If available, the web interface allows users to initiate remotely on BAS.

Some buildings rely on occupancy sensors to enable climate lighting or conditioning. Given the potential for long waiting times before the room becomes cool enough or warm, climatic conditioning is not often initiated directly by occupancy sensors.

Exposure

Lighting can be switched on, off, or dimmed with building automation or time-based lighting control systems, or on occupancy sensors, photosensors and timers. One example is turning on the lights in the room for half an hour since the last movement was felt. A photocell placed outside the building can sense the darkness, and time of day, and modulate the lights outside the office and parking lot.

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

In new buildings, lighting control can be based on a bus of Digital Addressable Lighting Interface (DALI) field. Lamp with DALI ballast fully dimmable. DALI can also detect lamp and ballast failures on DALI luminaires and signal failures.

Air handler

Most air handlers re-mix and outside air so less temperature/coolant humidity is required. This can save money by using less water that is cooled or heated (not all AHUs use cold or hot water circuits). Some external air is required to keep the building air healthy. To optimize energy efficiency while maintaining healthy indoor air quality (IAQ), demand control (or control) ventilation (DCV) adjusts the amount of external air based on measured occupancy levels.

Analog or digital temperature sensors can be placed in space or space, the return and supply of air ducts, and sometimes external air. The actuators are placed on hot and cold water valves, outside air and air damper back. The supply fan (and back if any) starts and stops based on time, temperature, building pressure or combination.

Unit of constant air volume handling

The less efficient type of air handler is a "constant air volume handling unit," or CAV. The fans at CAV do not have variable speed control. In contrast, CAV opens and closes dampers and water supply valves to maintain temperature in the building space. They heat or cool the room by opening or closing the cold or hot water valve that feeds their internal heat exchangers. Generally one CAV serves multiple spaces.

Unit of variable air volume handling

More efficient units are "air venting units (VAVs)", or VAVs. VAV supplies pressurized air to a VAV box, usually one box per room or area. VAV air handlers can change the pressure to the VAV box by changing the fan or blower speed with variable frequency drives or (less efficiently) by moving the guide propeller to the fan at a fixed speed. The amount of air is determined by the space requirement presented by the VAV box.

Each VAV box supplies air to a small space, such as an office. Each box has a silencer that is opened or closed based on how much heating or cooling is required in the chamber. The more open boxes, the more air you need, and the greater amount of air supplied by the VAV air handling unit.

Some VAV boxes also have hot water valves and internal heat exchangers. Valves for hot and cold water are opened or closed upon request of heat for the space provided. This heated VAV box is sometimes used only on the perimeter and the interior zone is just a cooler.

A minimum and maximum CFM should be set on the VAV box to ensure adequate ventilation and proper air balance.

Air Handling unit (AHU) Discharge Air Temperature control

Air Handling (AHU) and Roof Top units (RTU) units servicing multiple zones must vary the DISCHARGE AIR TEMPERATURE SET POINT VALUE automatically within the range of 55 F to 70 F. This adjustment reduces cooling, heating, and fan energy consumption. When outside temperatures below 70 F, for zones with very low cooling loads, increasing air supply temperatures decrease the use of reheating at the zone level.

VAV hybrid system

Another variation is a hybrid between VAV and CAV systems. In this system, the interior zone operates as in the VAV system. The outer zones are different because the heating is supplied by the heating fan at a central location usually with a heating coil fed by a building boiler. The heated air is supplied to the dual exterior duct mixing box and the damper is controlled by a zone thermostat which calls for cooled or heated air as needed.

Factory center

The central plant is required to supply air handling units with water. It may provide cold water systems, hot water systems and condenser water systems, as well as transformers and auxiliary power units for emergency personnel. If managed well, this can often help each other. For example, some plants produce electricity in periods with peak demand, using a gas turbine, and then using a turbine heat exhaust to heat water or absorptive chiller power.

Cold water system

Cold water is often used to cool air and building equipment. The cold water system will have chiller (s) and pumps. Analog temperature sensors measure cold water supply and return paths. Chiller (s) sorted and lit to cool cold water supply.

Chiller is a cooling unit designed to produce cold water (cold) for cooling purposes. The cold water is then circulated to one or more cooling coils located in the air handling unit, fan coil, or induction unit. Cold water distribution is not limited by the 100-foot separation limit applicable to the DX system, so cold-based cooling systems are typically used in larger buildings. Capacity control in cold water systems is usually achieved through modulation of water flow through coils; thus, some rolls can be served from a single chiller without compromising individual unit controls. The coolant may operate either on the principle of vapor compression or absorption principle. Vapor compression compresses may use reciprocating, centrifugal, screw, or rotary compressor configurations. Reciprocating chillers are typically used for capacities below 200 tons; centrifugal coolers are usually used to provide higher capacity; spin turns and screws are used less frequently, but not infrequently. Rejection of heat from the chiller may be through air-cooled condensers or cooling towers (both discussed below). The vapor compression cooler can be bundled with air-cooled condenser to provide the package chiller, which will be installed outside the building envelope. Vapor compression refrigerants can also be designed to be installed separately from the condensing unit; usually like a chiller will be installed in a closed center plant room. The absorption chiller is designed to be installed separately from the condensing unit.

Condenser water system

Cooling towers and pumps are used to supply cold condenser water to chillers. Since the supply of condenser water to the coolant must be constant, variable speed drivers are usually used on cooling tower fans to control the temperature. The right cooling tower temperature ensures proper cooling head pressure in the chiller. The cooling tower set point used depends on the refrigerant used. Analog temperature sensors measure the condenser water supply and return path.

Hot water system

The hot water system supplies heat to the building's air handling unit or the VAV box heater coil, along with the domestic hot water heater coil (Kalorifier). The hot water system will have a boiler (s) and pump. Analog temperature sensors are placed in hot water supply and return paths. Some types of mixing valves are commonly used to control the temperature of the heater water loop. Boiler (s) and pumps are set on and off to maintain supply.

Installation and integration of variable frequency drivers can reduce the energy consumption of building circulation pumps by up to 15% of what they have used before. The function of variable frequency drives by modulating the electrical frequency supplied to the motor under its control. In the US, the power grid uses 60 Hertz or 60 cycles per second. Variable frequency drive is able to decrease the output and energy consumption of the motor by lowering the electrical frequency provided to the motor, but the relationship between motor output and energy consumption is not linear. If the variable frequency drive provides power to the motor at 30 Hertz, the motor output will be 50% because 30 Hertz divided by 60 Hertz is 0.5 or 50%. The energy consumption of a motor running at 50% or 30 Hertz will not be 50%, but it will be something like 18% because the relationship between motor output and energy consumption is not linear. The exact ratio of the motor or Hertz output provided to the motor (which is effectively the same thing), and the actual energy consumption of the drive/motor frequency combination depends on the efficiency of the variable frequency driver. For example, since variable frequency drivers require their own power to communicate with building automation systems, run cooling fans, etc., If the motor always runs at 100% with variable frequency drivers installing operating costs or electricity consumption will actually go up with a new variable frequency drive installed. The amount of energy consumed by variable frequency drives is nominal and hardly worth considering when calculating savings, but it should be noted that the MCC does indeed consume the energy itself. Because variable frequency movers rarely run at 100% and spend most of their time in the 40% output range, and because now pumps are completely off when not needed, variable frequency drivers have reduced the energy consumption of the pump to about 15% of what they use before.

Alarm and security

All modern building automation systems have alarm capability. It's not good to detect potentially dangerous or expensive situations if no one who can solve this problem is notified. Notifications can be via computer (email or text message), pagers, cell phone voice calls, audible alarms, or all this. For insurance and liability purposes, all systems keep records of who is notified, when and how.

Alarms can immediately notify someone or just notify when alarms build to some threshold of seriousness or urgency. On sites with multiple buildings, instantaneous power failures can cause hundreds or thousands of alarms from equipment that has been shut down - this should be suppressed and recognized as a greater failure symptom. Some sites are programmed so critical alarms are automatically resent at various intervals. For example, a repeated critical alarm (from an uninterruptible power supply in 'cut') may resonate at 10 minutes, 30 minutes, and every 2 to 4 hours thereafter until the alarm is resolved.

Common temperature alarms are: space, air supply, cold water supply, hot water supply.
Pressure, humidity, biological and chemical sensors can determine whether the ventilation system has failed mechanically or is infected with contaminants that affect human health.
A differential pressure switch can be placed on the filter to determine if it is dirty or not performing.
Status alerts are common. If a mechanical device such as a pump is required to start, and the status input indicates it is dead, this may indicate a mechanical failure. Or, worse, an electrical fault that could represent a fire or shock hazard.
Some valve actuators have a final switch to indicate if the valve has been opened or not.
Carbon monoxide and carbon dioxide sensors can tell if this concentration in the air is too high, either because of fire or ventilation problems in the garage or near the road.
The cooling sensor may be used to indicate the possibility of a refrigerant leak.
Current sensors can be used to detect current low conditions caused by slipping fan belts, filter blockages in pumps, or other problems.

Security systems can be interlocked with building automation systems. If occupancy sensors are present, they can also be used as a burglar alarm. Because security systems are often deliberately sabotaged, at least some detectors or cameras must have battery backup and wireless connectivity as well as the ability to trigger an alarm when disconnected. Modern systems typically use power-over-Ethernet (which can operate pan-tilt-zoom cameras and other devices up to 30-90 watts) capable of charging these batteries and creating a free wireless network for real wireless applications, such as backed-up communications reserves.

The fire alarm panel and their associated smoke alarm system are usually programmed to replace building automation. For example: if the smoke alarm is activated, all outside air absorbers close to prevent air from entering the building, and the exhaust system can isolate the flame. Similarly, an electrical noise detection system can shut down the entire circuit, regardless of the number of triggered alarms or these depressed people. Fossil fuel combustion devices also tend to have their own over-rides, such as natural gas feed pathways that die when slow-pressure droplets are detected (indicating leakage), or when methane excess is detected in the building's air supply.

Good BAS recognizes this replacement and recognizes the complex failure conditions. They do not send excessive alerts, nor do they waste valuable backup power to try to revive this device that has been shut down by this safety. Bad BAS, almost by definition, sends an alarm for every warning, and does not recognize manual replacement, fire or electricity or fuel security. Thus, a good BAS is often built on safety and fire systems.

Information security

With the growing spectrum of capabilities and their connection with the internet, automated build systems are repeatedly reported to be vulnerable, allowing hackers and cybercriminals to attack their components. Buildings can be utilized by hackers to measure or change their environment: sensors allow monitoring (eg monitoring of employee movements or customs of the population) while actuators allow for action on the building (eg opening doors or windows for intruders). Some vendors and committees begin to improve security features in their products and standards, including KNX, ZigBee and BACnet (see the latest standards or standard design). However, the researchers reported some open issues in building automation automation.

What is BUILDING AUTOMATION? What does BUILDING AUTOMATION mean ...

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Space automation

Room automation is part of building automation and with a similar purpose; it is a consolidation of one or more systems under centralized control, although in this case in one room.

The most common examples of room automation are corporate boardroom, presentation space, and lecture hall, where the operation of a large number of devices that determine the function of the room (such as video conferencing equipment, video projectors, lighting control systems, public address systems etc.) the room manual operation is very complex. It is common for the room automation system to use the touch screen as the main way of controlling every operation.

Building Automation Systems | Sav Mor Mechanical

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References

Building Management System Revlight Solutions Pte Ltd - OwnSelf

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External links

v: Building Automation Providing a learning resource for professionals in this field

Source of the article : Wikipedia

Building automation

Tuesday, June 26, 2018