Energy information systems (EISs) and building automation systems (BASs) fall under the category of energy management and information systems (EMISs), though all three terms are used interchangeably. Typically, EISs show energy-usage information for processes within a facility, while BASs manage the controls that govern the processes. Each can function well on its own, though they naturally work well together. EISs monitor and display energy usage but can also have a BAS automatically work controls. Some systems offer both EIS and BAS functionality. EISs and BASs work together by monitoring energy use on a central computer or through cloud services.
You may benefit from an EMIS (particularly a BAS) if your facility is an energy-intensive commercial or industrial facility that runs complex processes. EMISs require large up-front costs, but the larger your facility, the more likely an EMIS will pay for itself within a few years through energy savings.
Facilities that benefit from EMISs include:
- Data centers
- Large breweries
- Chemical processing plants
- Pulp and paper plants
Retail facilities aren’t good candidates for EMISs since their largest energy uses are HVAC and lighting, which you can manage with simple, less-expensive controls.
BASs control HVAC and other systems in most new commercial and industrial buildings (figure 1). Although most BASs are designed for HVAC control, many incorporate additional functions, such as lighting control, computerized maintenance scheduling, safety functions, and security control.
Savings from an EMIS will depend on whether this is your first energy management system or if you’re replacing an older system; savings will also depend on how old your building equipment is. An EMIS will save at least 5% to 15% of a building’s overall energy consumption. EMISs are most cost-effective in large buildings in the commercial and industrial sectors; BASs are in more than half the buildings in the US that are larger than 100,000 square feet (ft2). If your building is older or requires heavy maintenance, a BAS retrofit may yield savings of more than 30%.
In addition to increasing energy savings, EMISs reduce overall maintenance costs by identifying operational problems early. They collect data from multiple zones around the building and display it on the system’s front-end computer. You can monitor and access the data to diagnose an operational problem rather than sending a maintenance crew to search for it.
Include commissioning in your installation process to maximize the benefits of your BAS. Commissioning is a comprehensive testing and review process that happens during the design and construction process. It’s complete when your building’s systems are working as planned and your operations team is trained to use all of the system’s features. Commissioning is required for some buildings, such as public institutions and buildings certified by the US Green Building Council’s LEED (Leadership in Energy and Environmental Design) program.
It’s important to keep your EMIS working properly. You can perform recommissioning—using trending and energy-consumption data to verify, document, and improve a building’s operation—throughout the life of your building.
What are the options?
Energy management and information system The two main configurations for an EMIS are:
- An EIS and a BAS working together
- One integrated system that provides both an EIS and automatic controls
There is more research on EISs and BASs individually than there is on how they work together, although more research is underway. EISs can work well with an existing BAS system, depending on the age of your facility or your BAS; the EIS can use the BAS’s sensors and data to perform more-sophisticated analysis to improve HVAC system performance and reduce the building’s energy consumption.
Energy information system EIS functionality varies, but the purpose of an EIS is to provide you with information such as, equipment usage, frequency, on-off and load cycles, and other forms of information that help you get a specific view of how your equipment is using energy.
There are different forms of EISs. Some systems let you enter your utility bill data so you can create year-over-year comparisons. Some build a baseline assumption of energy usage based on weather since weather changes make energy-consumption improvements harder to track. Others break out energy by end use, predict peak demand for the coming week, and suggest energy-conservation measures.
EISs can be part of a manufacturer’s BAS package, work with a different manufacturer’s BASs, or not integrate with a BAS at all. But no matter their functionality, EISs analyze all your end-use data to help you improve your building’s energy performance.
Cloud-based EISs are less expensive; they cost $0.01 to $0.77 per ft2 (not including installation costs). According to the 2017 ACEEE paper Smart Buildings: Using Smart Technology to Save Energy in Existing Buildings, EISs save between 5% to 10% in whole-building energy usage and pay for themselves in under two years.
Since the hardware for EISs is cheaper, vendors typically offer service contracts as their business model. In some cases, this means that once your service contract is over, you will lose access to your EIS until you renew your contract. As part of the contract, the vendor’s staff provides ongoing support and analysis based on your EIS’s data.
You may find that your vendor’s outside analysis of your building performance convenient and helpful, but if you already have knowledgeable facility management staff, these services may not be worth the expense. In this case, a BAS may be a better choice.
Building automation system Traditional BASs are more expensive than EISs, but they almost always save more energy. Systems cost $1.50 to $7.00 per ft2 but can achieve between 10% and 25% building energy savings with a payback of three to five years. Along with managing automated control functions, a BAS performs fault detection and diagnostics to find systems and equipment that aren’t performing properly.
The combination of automated control and fault detection and diagnostics allows you to create a predictive model that links energy consumption with causes. You can use the model to:
- Identify periods of best performance
- Quantify savings
- Set targets for reduced consumption
- Compare actual energy consumption to goal energy consumption
- Determine when energy consumption is higher than expected
- Initiate actions to correct variances
Vendors provide training on creating facility-based benchmarks and managing the alerts that your system provides.
Energy-saving control strategies
Scheduling Scheduling is the practice of turning equipment on or off depending on variables such as time of day, day of the week, day type, or even outside air conditions. Improving equipment schedules is one of the most common and effective measures for saving energy in commercial buildings. A feature called Optimum Start, offered by all BAS manufacturers, increases energy savings by automatically starting a system no earlier than needed based on daily variations in the weather.
Lockouts Lockouts ensure that equipment doesn’t come on unless it’s necessary. They protect against nuances in the control system’s programming that may inadvertently cause equipment to turn on. For example, a chiller and its associated pumps can be locked out on a specific date, when the outside air falls below a certain temperature or when building cooling requirements are below a minimum.
Temperature resets HVAC systems use less energy when you adjust your temperature controls to meet the energy requirements of your building. As the weather changes, your building’s energy requirements also change. A BAS helps your equipment operate at greater efficiency levels by automatically varying these temperature setpoints.
The simplest approach is to use a reset schedule based on the outdoor temperature. For example, when the weather gets cooler, the BAS will raise the temperature of the chilled-water cooling system since it doesn’t need to work as hard to keep the chilled water cold (figure 2).
Although proportional resets work reasonably well, a more effective method is to base resets directly on building loads. You can link building control parameters such as supply-air and discharge-air temperature for fan systems that use terminal reheat, hot-deck and cold-deck temperatures for multizone HVAC systems, and heating-water supply temperature. For example, when chilled water in a cooling loop becomes warmer than the desired temperature, chilled-water valves open to receive incoming air to stay cool (figure 3). If your supply-air fan system can bring in more air as the valves need it, your system can work more effectively.
DDC All modern BASs use direct digital control (DDC) technology—sensors and controllers that manage valves, dampers, and other system components based on physical characteristics such as pressure or temperature.
If you have a pre-1980s BAS, it may use pneumatic controls, which operate using compressed air. Pneumatic systems are more likely to fail; they also require more calibration and maintenance to ensure a clean, dry source of compressed air for controlling components such as actuators.
In general, BASs that provide full DDC offer more benefits over systems that use manufacturer-provided controls or depend on older, conventional controls (figure 4).
Demand limiting Because electrical demand charges can make up 40% or more of a utility bill, EMISs benefit from demand-limiting or load-shedding functions. For example, when the demand on a building meter or piece of equipment, such as a chiller, approaches a predetermined setpoint, the EMIS won’t let the equipment draw any energy beyond the limit.
In buildings with electric heat, you can reduce electrical demand charges if you set your system to stagger the heating over several hours in the morning, starting with the coldest spaces first. Some EMISs can limit demand based on time-of-use pricing. This means that during times of day or night that your electricity rates are lower, you can have your system automatically draw energy during those periods and draw less energy during higher-priced periods.
Diagnostics If you use an EMIS to monitor information such as temperatures, air pressures, and actuator positions, you can use that data to see if equipment is operating incorrectly or inefficiently and troubleshoot problems. You’ll need several data points to create a robust building diagnostic (more than you’d need to control the building), but a modern EMIS will give you a head start on a recommissioning or ongoing commissioning program.
Modern versus older building controls
New buildings HVAC equipment often comes with temperature controls provided by the equipment manufacturer. In many cases, these controls (such as boiler and chiller operating controls and safety limits) are necessary and can’t be removed. In this case, the BAS can still provide a certain amount of control that will improve the efficiency and comfort of the building. For example, a BAS usually provides chiller, pump, and cooling tower staging for plants with multiple chillers. The BAS can also reset the chiller’s operating parameters and monitor other chiller operating conditions.
Sometimes boiler and chiller manufacturers provide their own “central plant” control systems. We don’t recommend them because they diminish the BAS’s capability to perform energy-efficient control and provide diagnostics.
Manufacturer-provided controls for additional equipment (such as air-handling units [AHUs], rooftop units, and variable air-volume [VAV] boxes) are usually optional. The advantage of using manufacturer-provided controls is that it reduces project costs and can provide better control because the manufacturers designed the controls around the equipment.
The disadvantage is that the BAS needs to be able to communicate with the additional external equipment—using a hardware communication connection—to perform supervisory control of energy efficiency and provide diagnostics. Even with a communication connection, the manufacturer controls sometimes don’t allow the BAS to adequately perform the necessary supervisory control. Because of this, many manufacturer-provided BAS control designs involve an additional installation step so that their controls will work and communicate with your HVAC system components.
Existing buildings Existing buildings with older, conventional controls (such as pneumatic or electronic controls) present a different design challenge for BASs. You can find opportunities for savings, but you should see if connecting a modern BAS to old equipment meets your needs or is even feasible, since you may opt to upgrade your older controls separately.
Replacing older controls—typically a pneumatic thermostat—with conventional controls on terminal HVAC equipment (typically VAV boxes or reheat coils) provides energy-savings paybacks ranging from 10 to 20 years. However, the improved comfort of building occupants and enhanced ability to monitor, understand, and diagnose malfunctions in the HVAC system often provide value beyond the simple energy savings that a BAS offers.
In general, you should use a BAS to replace older controls for central equipment (such as boilers, chillers, and AHUs), which results in a short energy-savings payback (under five years). Keep in mind that since your BAS may be only partially compatible with your existing hardware, your BAS might not reach its full potential. Weigh the costs and benefits if you’re still trying to get more mileage out of older equipment. You’ll have to consider the payback of upgrading to conventional controls versus the payback of the energy-savings benefit the BAS provides to the older controls. When it comes to existing buildings, it’s important to bring in outside expertise to evaluate which path makes the most sense.
How to make the best choice
Clearly define goals for the EMIS Talk to consultants and controls vendors. You’ll learn how to define your goals for your building and match them with a system that offers the functionality you need.
While standards and communication protocols dominate discussions about system selection, you should choose a protocol that suits your system goals. Facility managers often want an easy-to-use, single-operator interface (such as a personal computer) to access and share data among DDC systems in one or more buildings.
Another performance versus protocol issue is interoperability. You can’t guarantee controllers from different manufacturers will work as a unified system by simply choosing the standard communication protocol.
When thinking about your system’s goals, you can decide how important open communication protocols are and if you’ll need gateways or other networking technology. Take time to verify that all the networking and control equipment is compatible, interacts how you want, and provides the data you need to manage your facility.
Collaborate with the IT department Be sure to collaborate with your IT department; their support can make the project successful. They can be responsible for handling software upgrades, network connections, and any computers that manage the EMIS. Also, ask how they can keep the network secure; IT staff are often willing to host EMIS software on the corporate servers so that they can ensure security for the company’s network with appropriate firewalls and encrypted data transfer.
Include commissioning considerations in the selection process Commissioning will keep all building systems performing properly. It includes specifications in the design phase, inspections during the installation process, tests conducted after installation is complete, and operator training.
You and your designers can do three things to ensure a successful EMIS commissioning process:
- Select a capable commissioning provider. Hire an unbiased engineer with commissioning experience to review design documents, help write specifications, design tests, observe the testing phase, and assist with operator training.
- Incorporate commissioning and recommissioning requirements into the specifications. These specifications should be detailed and include the project team’s roles and responsibilities, installation and initial system-review procedures, functional test requirements, training procedures, and documentation requirements.
- Ensure that the EMIS is fully tested. Although many standard functional tests describe requirements and procedures for testing EMISs, commissioning providers often customize these tests to more exactly match the technical requirements of the specific project.
In particular, have open communication systems thoroughly commissioned, and compare the performance of all system components with the published and submitted manufacturer’s performance data.
Consider modern retrofit alternatives Although not a BAS component, variable-frequency drive retrofit devices for rooftop units (RTUs) have some advanced features such as:
- Conversion from constant air-volume to VAV operation
- Demand-controlled ventilation
- Fault detection and diagnostics
- Economizer optimization
- Mobile app or web-based control and monitoring
Variable-frequency drives work like a BAS system but for each RTU instead of a whole building; they also cost a fraction of what a traditional BAS does.
What’s on the horizon?
EMISs are leading the way, and other technologies have been mimicking their functionality by using sensors and real-time feedback to provide interactivity to users. Modern EMISs continue to keep buildings running efficiently by aligning building energy use with the needs of occupants, but researchers are already thinking about what’s coming next. As more technology becomes connected through the internet, concerns about system vulnerability and cybersecurity increase. Developers are continuing to improve security protocols to prevent unwanted individuals from accessing building controls. New fields like artificial intelligence might enhance the building optimization already provided by modern EMIS technology.
Who are the manufacturers?
- Acuity Brands
- Automated Logic
- Current Daintree Enterprise Wireless Controls
- Delta Controls
- Osram Encelium Extend
- Honeywell Building Solutions
- Johnson Controls
- Schneider Electric
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