How Building Automation Systems Work
Building automation systems are like one-half of a building’s brain. They’re the part that tells equipment around the building what to do, the same way that your brain tells your fingers what to do. (The other half of the brain, the part that handles incoming sensory information, is analogous to an energy management system.)
Most people who are unfamiliar with the commercial real estate world think of buildings as static objects. That makes sense: They don’t see the living, breathing routines that make up the daily life of a commercial property. In an average day, lights go on and off, heating and cooling systems adjust the temperature, vents decide how much air to let it, and countless other processes happen that have to be controlled.
A building automation system operates the controls of a building from a central hub, though many modern systems can be remotely controlled through a digital platform or app. The software at the heart of this type of system operates using a logic algorithm to manage controls according to direct inputs and preset conditions, giving rise to the term “smart building.”
A building automation system, or BAS as it is commonly abbreviated, networks and controls almost every major element of a space. A short list of systems automated in the typical smart building might include the following:
- Lighting and other electrical systems
- Plumbing systems
- HVAC systems and rooftop units
- Fire alarms and other emergency systems
- Elevators and other mechanical systems
- Surveillance cameras and other security systems
- Vents and exhaust fans
- VAV Boxes
What does a Building Automation System do?
When it is being used correctly, a smart building is greener, more user-friendly, and less expensive to operate than a regular building.
Some of the ways that this works are obvious. A BAS can be configured to reduce heating or cooling use after tenants go home for the day, for example.
Other uses are a little bit more sophisticated. Some modern building automation systems use machine learning to predict when a room or unit will be out of use and adjust HVAC use accordingly. In large buildings, a BAS can be configured to stagger its daily powering-on program in order to reduce peak load, and as a consequence, energy bills.
Large retail spaces often employ light sensors to detect the level of sunlight entering from rooftop windows, allowing their BAS to adjust their interior lighting use accordingly. Offices may connect simple motion sensors to their BAS to detect when a room is not in use and turn off the lights to conserve energy.
Experts in building automation are finding new areas for resource savings all the time by making use of increasingly sophisticated logic algorithms, better metering and sensors, and novel building design techniques.
What isn’t a Building Automation System?
It’s pretty common for a BAS to be used in conjunction with some form of smart metering or energy management software, but they are not the same. By itself, a BAS provides building management staff with the tools to control a building, but no information about what is going on in that building.
Perhaps the easiest way to understand the difference is to think of your building as a car. An energy management system is the dashboard of your car: it allows you to see all the controls and understand how all components are operating. With this high-level view, you accurately direct your car.
That’s when the building automation system comes in. BAS acts as the steering wheel: you can direct the car by telling it what to do. You can set it on “cruise” mode to drive on autopilot, but you’ll still need to run frequent, necessary checks to make sure everything is working properly.
Your building operates the same way. An energy management software provides an overview of your building operations, with the option to explore a potential problem before it happens. A good EMS is more than a dashboard. It provides you with in depth analytics, real-time alerts and reports, in-software collaboration tools, and advanced customization options. You then use this information to set your building automation system to run most efficiently.
To really get the most out of a BAS, it is important to invest in a diverse array of smart meters and sensors to detect resource use and other relevant data points in real time. The more access a BAS has to data, the better it can fine tune resource allocation in the building throughout the day.
What are the benefits of a Building Automation System?
A modern BAS equipped with appropriate meters and sensors conveys benefits in three main categories: comfort, financial, and environmental.
Comfort Advantages
In terms of tenant comfort, the most obvious benefit from a BAS is temperature regulation. By automating HVAC systems, a BAS can help to avoid frigid and sweltering mornings in the winter and summer, respectively, by powering up temperature control systems before anyone arrives and turning them down after everyone leaves.
Building Automation Systems are also sometimes used to regulate the amount of fresh air that is allowed into a building or to maximize the ratio of natural-to-electric light.
While it’s difficult to measure directly, the impact from increased tenant comfort is an important appeal for modern building automation systems. Building engineers know that a correctly configured BAS can mean the difference between a quiet morning and a morning punctuated by calls about the temperature from your most difficult tenant.
The amount of fresh air is also important. Remember that drowsy feeling everyone gets during afternoon meetings? Chances are, the room is full of carbon dioxide.
Financial Advantages
A correctly used BAS will generally pay for itself over time in lower utility bills alone. According to one estimate, simply monitoring occupancy and allowing the BAS to adjust HVAC use accordingly results in savings between 10 and 30 percent. Reductions in peak load and other energy use benefits serve to further decrease utility costs.
A building automation system can also help to optimize the use of heavy pieces of equipment, increasing their lifespans and providing more indirect savings.
It is also important to factor in property value increases. Properly managed smart buildings are more comfortable and more environmentally friendly, making them more desirable for certain tenants. This may result in a bump in property value that exceeds the increase from reduced operating costs.
Environmental Advantages
While environmental advantages don’t generally accrue to the building owner directly, as noted above, they can serve to make a property more desirable. Many owners also have a personal interest in maintaining a portfolio of energy efficient buildings.
Buildings operating a BAS tend to have significantly smaller carbon footprints. A building that also includes smart metering for use with its BAS can also use that data to validate its energy usage for regulatory agencies. This opens to door to certifications like ENERGY STAR, Tenant Star, or LEED. Major tenants may also take an interest in these factors for use in their corporate sustainability reporting.
Building automation systems control various components within a building’s structure, such as heating, ventilation, air conditioning (HVAC). HVAC system performance and sustainability is key for today’s building operation.
The primary goal of this type of infrastructure is to improve system efficiency, reduce costs and increase safety. A centralized building management platform brings all of these parts together, but this description is a simplification of what’s really going on behind the scenes.
What is Building Automation
The Basics
Complete autonomous control of an entire facility is the goal that any modern automation system attempts to achieve. The distributed control system – the computer networking of electronic devices designed to monitor and control the mechanical, security, fire, lighting, HVAC and humidity control and ventilation systems in a building or across several campuses.
The Building Automation System (BAS) core functionality is to keep building climate within a specified range, light rooms based on an occupancy schedule, monitor performance and device failures in all systems and provide malfunction alarms. Automation systems reduce building energy and maintenance costs compared to a non-controlled building. Typically they are financed through energy and insurance savings and other savings associated with pre-emptive maintenance and quick detection of issues.
A building controlled by a BAS is often referred to as an intelligent building or “smart building”. Commercial and industrial buildings have historically relied on robust proven protocols like BACnet.
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, typically integrated with power over Ethernet wiring, so by definition always accessible to a BAS through the Ethernet connectivity. 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.
Communication of a BAS
Buses and protocols
Most building automation networks consist of a primary and secondary bus which connect high-level controllers with lower-level controllers, input/output devices and a user interface devices. ASHRAE’s open protocol BACnet or the open protocol LonTalk specify how most such devices interoperate. Modern systems use SNMP to track events, building on decades of history with SNMP-based protocols in the computer networking world.
Physical connectivity between devices was historically provided by dedicated optical fiber, ethernet, ARCNET, RS-232, RS-485 or a low-bandwidth special purpose wireless network. Modern systems rely on standards-based multi-protocol heterogeneous networking. These accommodate typically only IP-based networking but can make use of any existing wiring, and also integrate powerline networking over AC circuits, power over Ethernet low power DC circuits, high-bandwidth wireless networks such as LTE and IEEE 802.11n and IEEE 802.11ac and often integrate these using the building-specific wireless mesh open standards.
Current systems provide interoperability at the application level, allowing users to mix-and-match devices from different manufacturers, and to provide integration with other compatible building control systems. These typically rely on SNMP, long used for this same purpose to integrate diverse computer networking devices into one coherent network.
Types of inputs and outputs
Analog inputs are used to read a variable measurement. Examples are temperature, humidity and pressure sensors. A digital input indicates if a device is turned on or not. Analog outputs control the speed or position of a device, such as a variable frequency drive or a valve or damper actuator. Digital outputs are used to open and close relays and switches. An example would be to turn on the parking lot lights when a photocell indicates it is dark outside.
Main Components of a BAS
Building Automation Systems can be implemented either during initial construction or through a retrofitting process for an existing structure. It uses five component categories to provide a smart building environment.
- Sensors:
These devices track temperature, humidity, the number of people in a room, the lighting level and other values. The sensors transmit this information to centralized controllers.
- Controller:
This component acts as the “brain” of the BAS. It collects data from the sensors and then sends commands to HVAC units, lighting systems, security alarms and other connected parts.
- Output devices:
Once the controller sends out a command, actuators and relays go into action to follow the requirements. For example, they can reduce or increase the heating in a particular part of the building, dim lights in unused offices, or turn on the air conditioning before people come to work.
- Communication protocols:
The BAS uses a specific language that’s understood by the system’s individual components. BACnet and Modbus are the most commonly used options.
- Terminal interface:
Users can interact with the BAS through this interface. It presents information so that users can monitor the condition of the building or choose to override settings manually.
Importance of User Interfaces
The terminal interface is an important part of an effective building automation system. Organizations need a way to access the data produced by the sensors, discover whether problems need troubleshooting, and look for areas of inefficiency they can address. A poorly designed user interface may not provide the necessary access or analysis that a business needs to understand its BAS performance levels.
Modern visual data overlays provide building managers with insights delivered in a user-friendly form. Managers can quickly react to changes because it’s easy to see what’s going on in the system on a day-to-day basis. Machine-to-machine communication guides decision-makers with objective information.
Functions of a BAS
The primary function of a BAS is to provide control over heating, cooling, ventilation, lighting and other critical building systems. However, building automation systems also monitor their individual components to alert building managers about detected problems. Depending on the issue, the system may attempt to automatically resolve a problem before getting a human involved. The system’s continually monitors and optimizes its own performance, although the building manager can make adjustments as needed.
Types of Data a BAS Collects and Its Applications
A BAS has access to a wide range of sensor data, depending on the smart systems installed in the building and the needs of the business. Temperature is one of the most common data points tracked, as this information is critical for proper climate control. The indoor air quality is monitored to ensure the correct mix of external and internal air, and this method is often used to control the humidity in the structure, as well.
Pressure and chemical sensors help the system troubleshoot problems with air quality or discover issues with mechanical aspects of the building. The security system relays data that can indicate potential intruders, such as motion in supposedly empty buildings.
Alarms can come from many parts of a building, such as power supplies, elevators or electronic doors. The data gets passed along to the UI when it meets certain requirements, such as when a data center’s power has gone out and it’s switched to an uninterruptible supply.
Main Challenges of Using a BAS
Many buildings are equipped with legacy building automation systems that provide limited information to the building manager. While low-level systems operate fine with this configuration, the business can’t get the most out of optimization efforts, since there’s no easy way to get to the data. A full upgrade can require a substantial amount of upfront investment, but many managers reduce this cost by using a retrofitted system.
Vendor lock-in is another challenge. When a single company provides the integrated system in a building, adding new features often requires sticking with the existing ecosystem. A retrofit or overlaid system can overcome this challenge. Otherwise, the proprietary upgrades may offer limited features and lack the flexibility that the manager wants from a modern BAS.
The final challenge of using a building automation system is obsolescence. A decade or two after installation, the technology in the building will likely be out of date. Building managers need a strategy in place to address this eventuality.
A BAS offers an excellent way to have centralized control over a building’s systems. Modern options provide significant insights into operations, from discovering problems well in advance to continually optimizing performance. Most processes are handled without any direct input, allowing building managers to focus on issues that require their full attention.
