Integrating BAS, electrical systems
Owners of high-performance buildings expect engineers, manufacturers, and building system installers to work together to increase the performance of the building’s systems. However, superior performance typically is associated with increased complexity and cost.
Modern microprocessor-based equipment is replacing electromechanical devices. Industrial networks connect equipment and systems. Sensors provide feedback to measure results and enable enhanced control and functionality. Enhancing, connecting, and integrating industrial systems with a building’s control platform allows engineers to exceed the high-performance building owners’ expectations.
BAS has become a ubiquitous feature of the modern commercial building, providing a window into the complex operation of building mechanical systems and therefore allowing operators to do their jobs more effectively. Modern BAS systems are also well equipped—out of the box or with very little extra cost—to speak the standards-based network protocols, such as Modbus, found in many electrical systems. The addition of network wiring or wireless communications can enable easy integration. By consolidating electrical and mechanical system monitoring into a single unified BAS platform, the full potential of electrical equipment and systems can be harnessed, unlocking new opportunities for high-performance strategies.
In addition to managing the building mechanical systems, the modern BAS can leverage many of its features, such as trending, alarming, and web-based graphics, to monitor the electrical systems as well (see Figure 1). Integration can also employ a building operator’s existing experience and training to enable more efficient building management.
Integrating a building’s electrical systems into its BAS can unlock new opportunities for high performance. BAS integration opportunities include expanding operational efficiencies, coordinating historical data, optimizing maintenance staff effectiveness, and leveraging fault diagnostics.
Expanding operational efficiencies: Having data from each system on a single platform allows building operators to draw conclusions to further implement energy efficient strategies that can’t easily be achieved with stand-alone systems. By simultaneously tracking and analyzing both mechanical and electrical systems through benchmarking (i.e., comparing initially installed amperage to current amperage), operational staff can take corrective action if and when equipment efficiency drops. Determining the best way to reduce peak demand energy charges becomes easier when these systems can be viewed from one platform. Reducing building loads in reaction to demand response requests becomes simpler when actions can be executed from a single location. Understanding these tasks in real time allows building operators to set and meet efficiency goals while reducing energy costs.
Many modern BAS implementations include a real-time interface to a CMMS or similar facility management software that manages equipment maintenance and triggers work tickets based on operating parameters such as equipment run time or equipment faults. Leveraging the software for electrical systems via a BAS interface can enhance operator attention to electrical equipment maintenance.
Coordinating historical data: To manage and improve any process, a data baseline is imperative. One cannot know of a potential issue if the real-time data cannot be compared to how equipment had been operating prior to the problem. The opportunity to review historical data from power meters and be able to pull charts and graphs from multiple systems over time will enhance an operator’s ability to investigate and solve problems.
Optimizing maintenance staff effectiveness: Moving electrical system control and monitoring to the BAS will instantaneously generate new ways to analyze building data, including the opportunity to meet and set more effective operation and maintenance goals. When the MEP systems are tied together, the chief engineer can spend more time doing preventive maintenance than reactive problem solving, which typically reduces maintenance costs. BAS integration for monitoring electrical systems also allows staff to be alerted immediately of potential power issues, such as providing a warning of a forthcoming overload on the power distribution system that could take out a critical life safety system or cause significant losses due to extended downtime.
Additionally, staff effectiveness will naturally improve when one piece of software does it all, as operators are likely to remember how to manage the system as part of their daily routine and will remain trained on it over time. Furthermore, when operators are familiar with the BAS, they are more likely to learn and use higher-level functions and analyses.
Leveraging fault diagnostics: By interfacing electrical systems into a BAS, fault diagnostics become possible. The more data that is acquired, stored, and analyzed, the easier it is to write meaningful fault algorithms. These algorithms teach the BAS to indicate when a piece of equipment is about to break or if it is not running at optimal condition by comparing values of different parameters based on historical data. For example, if one system is using more electricity than it did yesterday to operate under identical conditions, the BAS can alert the operator to investigate a possible equipment issue or point to problematic settings.
Electrical systems integration
Many types of modern electrical equipment are microprocessor-based, meaning they can easily collect and act on data in real time. Sending data to the BAS enables users to optimize each system it supports to provide effective maintenance protocols. Typical electrical equipment that can be integrated into the BAS includes:
Power meters: Because one cannot manage what is not measured, the smart power meter is a vital part of BAS-electrical system integration (see Figure 2). For example, sustainable design rating systems, such as U.S. Green Building Council’s LEED system and Abu Dhabi’s Estidama Pearl system, encourage separately metering power consumption by load type (i.e., lighting, HVAC, plug loads, and IT loads). The BAS becomes the central location for gathering and monitoring these data.
Generators: Often required by code for life safety purposes or used to back up critical systems in mission critical facilities, the generator has its own control system that ensures it runs as intended. Because there are so many things that can go wrong with a generator—from high temperatures to low fuel supply—the systems are typically monitored remotely with a status panel located at the fire command center and/or building engineer’s office. If also tied into the BAS, an electronic message can be sent in a timely fashion to the building engineer, who may be located remotely—both when the generator is running smoothly and when it has a problem that needs immediate attention (see Figure 3). The BAS can also be used to document and alert personnel when the next maintenance testing is required.
Transfer switches: The transfer switch connects life safety and critical loads to the alternate power source upon loss of utility power. Via the BAS, the position of the transfer switch can be remotely monitored (see Figure 4). It can be also be remotely controlled for testing the emergency system, for sending a signal to load shed to avoid overloading a generator, or for switching loads to the generator for demand response.
UPS: Any downtime on a UPS makes the connected critical loads more susceptible to power quality issues and in danger of going offline due to a sudden power failure. By integrating a UPS with the BAS, quick action can be taken by immediately notifying personnel when adverse conditions, such as high temperature, are experienced in the room or when a sudden UPS failure occurs.
Surge protection devices (SPDs): In addition to reliability, power quality is important in critical facilities. Metal-oxide varistors (MOVs) are the most common element used in SPDs to divert electrical surges away from critical loads. However, MOVs do fail over time while performing their intended function. Because these devices are not normally checked after installation, connecting them to the BAS to remotely monitor the quantity of surges diverted allows preventive replacement toward the end of their life to prevent the next surge from causing severe electrical system damage.
Transformers: Fans can be integrated into transformer housings to allow more power capacity from its standard rating by cooling the transformer with forced air. A controller is able to start the fan when the value of the transformer winding temperature indicates a load approaching its standard rating. Using the BAS to monitor temperature and fan status, and comparing it to the measured transformer power consumption ensures the fans are working as designed so the transformer can be loaded to its extended capacity.
Lighting controls: A lighting control system can—and often should be—its own purposely built specialty subsystem. If complex lighting system strategies are required, the lighting control system may handle them more effectively than the BAS. For example, when daylight-dimming controls are specified, algorithms are set within the lighting control system to optimize this functionality. However, the BAS can monitor and make basic operational changes to the lighting control system for normal daily operations or coordinate with the mechanical system’s schedule during off-hour occupancies. The BAS can also enhance HVAC energy efficiency by allowing HVAC systems to change setpoints based on occupancy sensor data received from the lighting control system.
Shades: Motorized shades on the building’s interior or exterior can be programmed to function according to the BAS time clock or the computed position of the sun relative to the building, instead of occupants manually opening and closing each one. Keeping shades down in an empty building in the summer can significantly reduce solar heat gain, while outdoor views and daylight are not required by occupants. Automatically operating shades to balance reduced heat gain and increased daylighting can contribute to increased worker satisfaction and productivity gains.
Photovoltaics: Some building owners install photovoltaic panels to optimize power generation. BAS monitoring is crucial to verifying that these panels are working optimally (see Figure 5). Soiling and shading can determinately and exponentially reduce the amount of power generated from a string of photovoltaic modules. By monitoring the photovoltaic array output power and coordinating it with historical weather data of a similar date and time or current weather conditions (i.e., estimating cloud coverage based on exterior photocell data), it is possible to calculate approximately what the output should be on a given day and compare that with real-time activity. When proper maintenance or action isn’t taken to ensure the system is kept in absolutely optimal condition, the estimated payback may double from the initially calculated amount and may not make this sustainable investment economically feasible.
Fire alarm system: Fire alarm system requirements are dictated by codes and authorities having jurisdiction, which generally discourage low-level integration with the BAS in favor of a dedicated specialty fire alarm system. However, fire alarms can be interfaced easily with the BAS to share summary zone alarms to provide supplemental monitoring. This can allow the BAS to send alarms by e-mail or text message. A BAS can even push emergency information to digital signage to alert occupants and provide egress assistance.
Security system: As with fire alarm systems, security systems are often provided as dedicated specialty subsystems with unique features and functions. However, when integrated into the BAS, the security system has the capability to create additional efficiencies and enhance security as well. Card access systems can maintain a count of occupants in a space when configured to require users to card out when leaving. This occupant count can be used to optimize building ventilation rates. In case of emergency, when there is a fire at a specific building location, the security cameras in that vicinity could be programmed to pop up on the security officer’s screen. Also, if there is a chiller malfunction, the chiller alarm could cause the camera in the mechanical room to appear on the officer’s screen.
Integrating electrical systems into an existing BAS can promote operational efficiencies, optimize maintenance staff effectiveness, and leverage fault diagnostics, while using historical data to set a baseline for it all. Taking advantage of existing BAS features, such as trending, alarming, web-based graphics, and analytics, can present new opportunities for integrating electrical equipment and systems when moving to a single, unified BAS platform. The result will be truly integrated, high-performance buildings.
Mar is senior associate at Environmental Systems Design and a member of the Consulting-Specifying Engineer editorial advisory board. Knight is senior associate at Environmental Systems Design.