Автоматизация зданий: системы управления и энергоэффективность

Branch of automation
automation within commercial buildings

Building automation (BAS), also known as building management system (BMS) or building energy management system (BEMS), is the automatic centralized control of a building's HVAC (heating, ventilation and air conditioning), electrical, lighting, shading, access control, security systems, and other interrelated systems. Some objectives of building automation are improved occupant comfort, efficient operation of building systems, reduction in energy consumption, reduced operating and maintaining costs and increased security. BAS functionality may keep a buildings climate within a specified range, provide light to rooms based on occupancy, monitor performance and device failures, and provide malfunction alarms to building maintenance staff. A BAS works to reduce building energy and maintenance costs compared to a non controlled building. Most commercial, institutional, and industrial buildings built after 2000 include a BAS, whilst older buildings may be retrofitted with a new BAS. A building controlled by a BAS is often referred to as an intelligent building, a "smart building", or (if a residence) a "smart home". Commercial and industrial buildings have historically relied on robust proven protocols (like BACnet) while proprietary protocols (like X 10) were used in homes. With the advent of wireless sensor networks and the Internet of Things, an increasing number of smart buildings are resorting to using low power wireless communication technologies such as Zigbee, Bluetooth Low Energy and LoRa to interconnect the local sensors, actuators and processing devices. Almost all multi story green buildings are designed to accommodate a BAS for the energy, air and water conservation characteristics. Electrical device demand response is a typical function of a BAS, as is the more sophisticated ventilation and humidity monitoring required of "tight" insulated buildings. Most green buildings also use as many low power DC devices as possible. Even a passivhaus design intended to consume no net energy whatsoever will typically require a BAS to manage heat capture, shading and venting, and scheduling device use.

Building management systems are most commonly implemented in large projects with extensive mechanical, HVAC, and electrical systems. Systems linked to a BMS typically represent 40% of a building's energy usage; if lighting is included, this number approaches to 70%. BMS systems are a critical component to managing energy demand. Improperly configured BMS systems are believed to account for 20% of building energy usage, or approximately 8% of total energy usage in the United States. In addition to controlling the building's internal environment, BMS systems are sometimes linked to access control (turnstiles and access doors controlling who is allowed access and egress to the building) or other security systems such as closed circuit television (CCTV) and motion detectors. Fire alarm systems and elevators are also sometimes linked to a BMS for monitoring. In case a fire is detected then only the fire alarm panel could close dampers in the ventilation system to stop smoke spreading, shut down air handlers, start smoke evacuation fans, and send all the elevators to the ground floor and park them to prevent people from using them. Building management systems have also included disaster response mechanisms (such as base isolation) to save structures from earthquakes. In more recent times, companies and governments have been working to find similar solutions for flood zones and coastal areas at risk to rising sea levels. Self adjusting floating environment draws from existing technologies used to float concrete bridges and runways such as Washington's SR 520 and Japan's Mega Float.

Analog inputs are used to read a variable measurement. Examples are temperature, humidity and pressure sensors which could be thermistor, 4–20 mA, 0–10 volt or platinum resistance thermometer (resistance temperature detector), or wireless sensors. A digital input indicates a device is on or off. Some examples of digital inputs would be a door contact switch, a current switch, an air flow switch, or a voltage free relay contact (dry contact). Digital inputs could also be pulse inputs counting the pulses over a period of time. An example is a turbine flow meter transmitting flow data as a frequency of pulses to an input. Nonintrusive load monitoring is software relying on digital sensors and algorithms to discover appliance or other loads from electrical or magnetic characteristics of the circuit. It is however detecting the event by an analog means. These are extremely cost effective in operation and useful not only for identification but to detect start up transients, line or equipment faults, etc.

Analog outputs control the speed or position of a device, such as a variable frequency drive, an I P (current to pneumatics) transducer, or a valve or damper actuator. An example is a hot water valve opening up 25% to maintain a setpoint. Another example is a variable frequency drive ramping up a motor slowly to avoid a hard start. Digital outputs are used to open and close relays and switches as well as drive a load upon command. An example would be to turn on the parking lot lights when a photocell indicates it is dark outside. Another example would be to open a valve by allowing 24VDC/AC to pass through the output powering the valve. Analog outputs could also be pulse type outputs emitting a frequency of pulses over a given period of time. An example is an energy meter calculating kWh and emitting a frequency of pulses accordingly.

Controllers are essentially small, purpose built computers with input and output capabilities. These controllers come in a range of sizes and capabilities to control devices commonly found in buildings, and to control sub networks of controllers. Inputs allow a controller to read temperature, humidity, pressure, current flow, air flow, and other essential factors. The outputs allow the controller to send command and control signals to slave devices, and to other parts of the system. Inputs and outputs can be either digital or analog. Digital outputs are also sometimes called discrete depending on manufacturer. Controllers used for building automation can be grouped in three categories: programmable logic controllers (PLCs), system/network controllers, and terminal unit controllers. However an additional device can also exist in order to integrate third party systems (e. g. a stand alone AC system) into a central building automation system. Terminal unit controllers usually are suited for control of lighting and/or simpler devices such as a package rooftop unit, heat pump, VAV box, fan coil, etc. The installer typically selects one of the available pre programmed personalities best suited to the device to be controlled, and does not have to create new control logic.

Occupancy is one of two or more operating modes for a building automation system; Unoccupied, Morning Warmup, and Night time Setback are other common modes. Occupancy is usually based on time of day schedules. In Occupancy mode, the BAS aims to provides a 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 sub system) than users on the opposite side. A temperature sensor in the zone provides feedback to the controller, so it can deliver heating or cooling as needed. If enabled, morning warmup (MWU) mode occurs prior to occupancy. During Morning Warmup the BAS tries to bring the building to setpoint just in time for Occupancy. The BAS often factors in outdoor conditions and historical experience to optimize MWU. This is also referred to as optimized start. Some buildings rely on occupancy sensors to activate lighting or climate conditioning. Given the potential for long lead times before a space becomes sufficiently cool or warm, climate conditioning is not often initiated directly by an occupancy sensor.

Lighting can be turned on, off, or dimmed with a building automation or lighting control system based on time of day, or on occupancy sensor, photosensors and timers. One typical example is to turn the lights in a space on for a half hour since the last motion was sensed. A photocell placed outside a building can sense darkness, and the time of day, and modulate lights in outer offices and 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 DR incentives and savings. In newer buildings, the lighting control can be based on the field bus Digital Addressable Lighting Interface (DALI). Lamps with DALI ballasts are fully dimmable. DALI can also detect lamp and ballast failures on DALI luminaires and signals failures.

Shading and glazing are essential components in the building system, they affect occupants’ visual, acoustical, and thermal comfort and provide the occupant with a view outdoor. Automated shading and glazing systems are solutions for controlling solar heat gains and glare. It refers to the use of technology to control external or internal shading devices (such as blinds, and shades) or glazing itself. The system has an active and rapid response to various changing outdoor data (such as solar, wind) and to changing interior environment (such as temperature, illuminance, and occupant demands). Building shading and glazing systems can contribute to thermal and lighting improvement from both energy conservation and comfort point of view.

Dynamic shading devices allow the control of daylight and solar energy to enter into built environment in relation to outdoor conditions, daylighting demands and solar positions. The common products include venetian blinds, roller shades, louvers, and shutters. They are mostly installed on the interior side of the glazing system because of the low maintenance cost, but also can be used on the exterior or a combination of both.

All modern building automation systems have alarm capabilities. It does little good to detect a potentially hazardous or costly situation if no one who can solve the problem is notified. Notification can be through a computer (email or text message), pager, cellular phone voice call, audible alarm, or all of these. For insurance and liability purposes all systems keep logs of who was notified, when and how. Alarms may immediately notify someone or only notify when alarms build to some threshold of seriousness or urgency. At sites with several buildings, momentary power failures can cause hundreds or thousands of alarms from equipment that has shut down – these should be suppressed and recognized as symptoms of a larger failure. Some sites are programmed so that critical alarms are automatically re sent at varying intervals. For example, a repeating critical alarm (of an uninterruptible power supply in 'bypass') might resound at 10 minutes, 30 minutes, and every 2 to 4 hours thereafter until the alarms are resolved. Security systems can be interlocked to a building automation system. Buildings can be exploited by hackers to measure or change their environment: sensors allow surveillance (e. g. monitoring movements of employees or habits of inhabitants) while actuators allow to perform actions in buildings (e. g. opening doors or windows for intruders). Several vendors and committees started to improve the security features in their products and standards, including KNX, Zigbee and BACnet (see recent standards or standard drafts). However, researchers report several open problems in building automation security. On November 11, 2019, a 132 page security research paper was released titled "I Own Your Building (Management System)" by Gjoko Krstic and Sipke Mellema that addressed more than 100 vulnerabilities affecting various BMS and access control solutions by various vendors.

Room automation is a subset of building automation and with a similar purpose; it is the consolidation of one or more systems under centralized control, though in this case in one room. The most common example of room automation is corporate boardroom, presentation suites, and lecture halls, where the operation of the large number of devices that define the room function (such as videoconferencing equipment, video projectors, lighting control systems, public address systems etc.) would make manual operation of the room very complex. It is common for room automation systems to employ a touchscreen as the primary way of controlling each operation.