Building Automation Systems:
– Characteristics:
– 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, increasing to 70% if lighting is included.
– Improperly configured BMS systems are believed to account for 20% of building energy usage in the United States.
– Can be linked to access control, security systems, fire alarms, and elevators for monitoring and response.
– Include disaster-response mechanisms like base isolation for earthquakes and solutions for flood zones.
– Functions:
– Improved occupant comfort, efficient building system operation, energy consumption reduction, cost savings, and increased security.
– Climate control, lighting based on occupancy, performance monitoring, and malfunction alarms.
– Infrastructure:
– Controllers are small computers with input and output capabilities.
– Controllers can be grouped as PLCs, system/network controllers, and terminal unit controllers.
Inputs and Outputs in Building Automation Systems:
– Sensors:
– Analog inputs measure variables like temperature, humidity, and pressure.
– Digital inputs indicate device status (on/off) and can include pulse inputs for counting over time.
– Nonintrusive load monitoring uses digital sensors and algorithms to identify loads from electrical characteristics.
– Controls:
– Analog outputs control device speed or position.
– Digital outputs open/close relays and switches, driving loads based on commands.
– Analog outputs can emit pulses over time, such as energy meters calculating kWh.
Building Automation for Energy Efficiency:
– Lighting:
– Controlled based on time of day or occupancy.
– Suitable for demand response to save energy.
– Newer buildings use DALI for lighting control.
– Shading and Glazing:
– Impact visual, acoustical, and thermal comfort.
– Automated systems control solar heat gains and glare.
– Air Handlers:
– Mix return and outside air to save energy.
– Demand control ventilation adjusts outside air based on occupancy.
– Temperature sensors and actuators control air valves and dampers.
Occupancy Control and Building Automation:
– Occupancy:
– Operating modes include Occupancy, Unoccupied, Morning Warmup, and Night-time Setback.
– Aims to provide a comfortable climate and lighting based on schedules.
– Zone-based control allows different settings for different areas within a building.
– Room Automation:
– Subset of building automation with centralized control in one room.
– Common in corporate boardrooms, presentation suites, and lecture halls.
Integration and Security in Building Automation Systems:
– Alarms and Security:
– Modern systems have alarm capabilities and can be integrated with security systems.
– Fire alarm panels can override building automation in emergencies.
– Buses and Protocols:
– Building automation networks consist of primary and secondary buses.
– ASHRAE’s BACnet and LonTalk specify device interoperability.
– Systems provide interoperability at the application level.
This article needs additional citations for verification. (August 2011) |
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.
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.
