Managing power through networked electrical systems
Engineers should consider the benefits of networking electrical systems—monitoring and controlling power, its usage, and how it affects system reliability.
- Understand the importance of measurement and verification.
- Know the available monitoring solutions.
- Identify the criteria for integrating electrical networking solutions into facility electrical distribution systems.
In the ever-changing world of technology, at times it seems that marketing a new technology requires either creating new words or stringing old words into new phrases to make it sound new and cutting-edge, or perhaps just confuse the consumer altogether. In fact, it’s hard to imagine a profession that uses more buzzwords and acronyms than the field of engineering and construction. When it comes to networking of electrical systems and power management, there is no shortage of this trendy lingo: “digital energy networks” that monitor “distributed energy resources” tied to the “virtual power plants,” or the “detailed energy survey (DES)” for the “energy conservation measure (ECM)” and its interface with the “building management system (BMS)”—shall I go on? But what does it all mean as it relates to the networking of systems and overall power management?
In recent years, billions of dollars have been spent by electrical utility companies on Smart Grid technologies. A Smart Grid consists of two-way digital communications between energy users (facilities) and the utility’s network operation center. Capturing this smart technology concept and filtering it much further in to the facility (down to the end-use device) opens up opportunities to better manage overall power, ranging anywhere from an individual facility to a large campus system. BMS have been around for decades, providing the ability to monitor and control HVAC components, and more recently, the BMS may integrate fire, security, and lighting control systems. However, programs such as demand response and other energy management curricula have created a strong motivation to fully integrate what traditional BMS systems have left out. Additional components, such as power generation equipment, UPS, power switching equipment, and other metered loads now want to be part of the same smart system. One of the latest buzz phrases to describe this facility trend is “networked electrical systems.” This concept of a networked electrical system not only includes the electrical system that delivers the electricity, but also encompasses the components that use the electricity.
The facility manager’s struggle
Energy is a major operating expense for most organizations and, according to EnergyStar.gov, can represent 30% of a typical commercial office building’s operational costs (see Figure 1). However, managing energy usage can be a daunting task. The facility manager is often fighting mounting pressure to lower costs while energy prices are on the rise. Additionally, the reliability of that energy supply is declining. The expectation that facility managers “do more with less” presents a challenge even for the seasoned and highly qualified facility managers. The paradigm is that the workforce responsible for overseeing these complex energy systems continues to age. According to the International Facility Management Association (IFMA), in 2011 the average age of a facility manager was 49. And according to the Sloan Center on Aging and Work, it is expected that more than 50% of facility management personnel will retire within the next 10 years. The good news is that in 2011, IFMA also reported that more young people are entering facility management with 9% age 34 or younger. This is up 2% from 4 years prior. However, at that rate, a one-for-one replacement will not be possible, which presents a challenge for the design engineer and end user alike. As codes continue to rapidly change and energy costs continue to rise, the engineer is charged with providing a workable design solution for managing a facility. At the same time, the facility manager is responsible for operating the systems as they were intended with less overall manpower. The need for a connected and monitored system where usage can be tracked and controlled from a central location exists in any facility where power is critical. Facilities such as health care, commercial, industrial manufacturing, governmental, data centers, and higher education are perfect candidates for this technology. Large campus-type facilities are particularly good candidates because they have multiple buildings to monitor. A migration to a centralized management system could be the solution.
Measurement and verification
There are several aspects of networking electrical systems that must be considered. Step No.1 is to correlate the popular management statement as it relates to energy: “You can’t manage what you don’t measure.” Understanding what drives energy usage is the first key to managing it. Interpreting the data and recognizing what to do with them is the next step in successfully implementing changes in the system to provide the desired end result.
The industry term “measurement and verification” (M&V) is a process for quantifying savings determined by an energy conservation measure. Although M&V continues to be an evolving art, various standards and protocols demonstrate best practices. One of the most popular is the U.S. Green Building Council LEED rating system. LEED specifically references the International Performance Measurement and Verification Protocol (IPMVP) Volume III: Concepts and Options for Determining Energy Savings in New Construction. Another popular reference is ASHRAE Guideline 14: Measurement of Energy and Demand Savings.
The IPMVP Volume III protocol states that it was developed to “provide a concise description of the best practice techniques for verifying the energy performance of new construction projects. The objective is to provide clear guidance to professionals seeking to verify energy and demand savings at either component- or whole-building level in new construction.”
ASHRAE Guideline 14 was developed to “provide guidelines for reliably measuring energy and demand savings of commercial equipment.”
Using the available guidelines is an appropriate starting point for the engineer to design a solution that provides the facility manager with the proper tools to manage energy in the facility. These guidelines suggest various starting points based on the level of M&V desired, including performing a DES and planning specific ECMs to include in the design. Prior to implementation, however, it is important to assess the end users’ needs and capabilities when selecting the appropriate monitoring approach.
Some monitoring solutions may be as simple as monitoring the main power service and a few of the high-level distribution feeders. This rather simple system allows the facility manager to monitor the overall power quality and correct it at a system level. This type of monitoring has been around for quite some time; however, this type of approach is not exactly a networked solution. A fully networked electrical system incorporates a much broader range of system components including those that generate energy as well as use it (see Figure 2). Tracking provides the ability not only to monitor a system, but also to implement a control strategy to manage the energy usage and quantify the results. For example, an office building facility manager may want to monitor the plug loads at individual workstations to understand and chart usage. Tracking these data may reveal that an excessive amount of power is being used when the building is normally unoccupied, perhaps due to tenants inadvertently leaving computers or miscellaneous equipment on overnight. With this information, the facility manager is armed with the appropriate data to implement a building policy or perhaps install automatic switching devices to minimize usage.
As previously mentioned, BMS have the ability to monitor and control HVAC components and other systems encompassed by the electrical systems. Many systems and their associated controls communicate through a common protocol, such as Modbus, BACnet, or LonWorks. However, incorporating additional system components tends to consist of various manufacturers and models that provide a wide range of assets and communication protocols. This is one of the greatest challenges in integrating systems, but as the trend continues, a growing number of companies such as Blue Pillar in Indiana and Power Assure in California are emerging in an attempt to provide a truly networked electrical system. The network solutions developed by such companies are claiming they are easier than ever to both integrate into new construction as well as retrofit into existing facilities. The potential energy savings and anticipated return on investment (ROI) renders the claims worthy of exploration.
Fully networked electrical systems are migrating together all aspects of energy consumption and generation (see Figure 3). The monitored infrastructure may include anything from chillers, air handling equipment, fuel systems, pumps, switchgear, lighting, and plug loads, to engine generators, UPSs, thermal storage, cogeneration, and other equipment. The goal is that anything that uses energy can be monitored and controlled from a single location while anything that generates and stores energy can be monitored and controlled to properly support the energy usage as efficiently as possible. The system network collects the information and provides the facility manager with the appropriate data to make informed and timely decisions. Some specific examples of the benefits a facility may realize from a fully networked system are detailed in the following sections.
Ensure optimum operation: When a facility’s energy infrastructure is properly designed and commissioned, optimum operating ranges are established based on uncontrollable factors such as weather, occupant load, etc. Over time, the optimum setpoints tend to shift for any number of reasons. The networked system diagnostics may be set to alert the facility manager when equipment is not operating at its optimum setpoint or using more power than anticipated so that corrective action may be implemented. Examples include leaking valves, faulty economizer damper controls, and manual overrides.
Improve reliability and power quality: “Dirty power” is the buzz phrase given to electrical anomalies that exist in a facility. Anomalies such as surges, sags, spikes, and transients can wreak havoc on sensitive equipment if not properly managed. Dirty power originates both outside and within a facility. For example, lightning, utility switching, and faults on the utility distribution system can affect the quality of power before it reaches the facility. Daily fluctuations inside the facility, such as harmonics produced by nonlinear loads and cyclical equipment with frequent on/off switching, affect the power quality from within. Monitoring of incoming power as well as individual end users, such as computers and motors, assists in identifying sources of dirty power. This allows the operator to take corrective action to improve the power quality, therefore avoiding critical damage on sensitive equipment and improving the overall reliability.
Prevent premature equipment failure: Monitoring large motors and HVAC equipment creates a predictive maintenance program by identifying when the equipment performance begins to fall below preset levels or other unexpected anomalies occur. For example, if a pump with a constant load starts trending toward increased electrical usage over time, the networked system identifies this tendency. It can provide an alarm for the facility manager to investigate potential causes, such as increased bearing friction or restrictions in the piping. This early detection system is a predictive maintenance system that may be used to schedule preventive maintenance. Preventive maintenance leads to overall reduced downtime before major equipment damage occurs.
Reduce overall energy costs: Monitoring total energy usage to determine exact historical values will identify ways to turn the network into a cost savings program. The data assists the facility manager in determining the optimum time to operate the on-site generating equipment or other energy storage devices to reduce peak demand loads. This also yields improved reliability by providing the capability to operate on-site equipment with known load parameters to ride through both temporary and extended utility outages. Note that the use of on-site diesel-fired engine generators for nonemergency applications triggers additional requirements from a regulatory standpoint, such as the U.S. Environmental Protection Agency (EPA) regulations that the designer must consider.
Improved efficiencies between integrated systems: Integrating the HVAC and lighting control systems provides improved efficiencies gained from common scheduling and occupant control. For example, codes and standards such as the International Energy Conservation Code and ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings mandate the use of occupant sensing devices to reduce the lighting and automatically control receptacles in unoccupied spaces. This equipment can be networked with the HVAC system to reduce additional energy by altering the HVAC supplied to the unoccupied space via changing temperature setpoints or reducing air changes.
Reduce staff hours: As previously stated, there is a concern with the aging workforce in the facility management as it relates to the future personnel workforce. With a fully networked electrical system, what once required a full crew at multiple locations can be done from a single location by the push of a button, such as initiating a demand response program. In addition, the data that are collected into the networked system can be used to automatically generate reports required for compliance reporting, such as Joint Commission for hospitals or the EPA. This also reduces the previous manpower required to physically monitor and record the tests.
While the idea of fully networked digital electrical systems is still rather new and continuing to make leaps and bounds with new technologies, the overall concept demonstrates value to the owners. Collecting and analyzing data through a system network allows trends to be recorded and then programmed to automatically modify load behaviors based on that analysis. Benefits include prevention of premature equipment failure, improved reliability and power quality, optimum equipment operation, reduced overall energy costs, improved efficiencies between integrated systems, and reduced staff hours.
An overall networked electrical system provides around-the-clock monitoring of the system components with immediate notification of changes and events. Collecting real-time data enables the facility manager to make data-driven decisions and demonstrate verifiable results. The potential energy savings and anticipated ROI of applying such systems in design is worthy of exploration and implementation into any facility design.
Danna Jensen is associate principal at ccrd in Dallas. With 14 years of electrical engineering experience, most of her work consists of designing electrical distribution systems for hospitals; however, she also designs electrical systems for office and retail facilities. Jensen was a 2009 Consulting-Specifying Engineer 40 Under 40 winner and is a member of the Consulting-Specifying Engineer Editorial Advisory Board.