Intelligent control and monitoring systems allow facility owners to optimize energy use and achieve quick ROI.
More than ever, control of energy costs is a crucial factor in the profitable operation of institutional facilities. Although structural improvements to a building’s heating, ventilation, and air-conditioning (HVAC) system are often made—such as installing a more efficient chiller or air-handling system—many times there is any easier way to optimize energy use. Technology providers are offering intelligent HVAC monitoring, analysis, and control systems that keep facilities managers informed of overall system performance—and, often, these systems inform HVAC system components how to operate in dynamic environmental conditions.
Four case studies demonstrate how intelligent controls can provide owners of facilities, from museums to airports, and schools to hotels, with the maximum return on their HVAC system investment.
Seasonal Adjustments in a Historic Building
An upgrade of the HVAC system at the Maine Discovery Museum in Bangor, ME, demonstrates that it’s possible to greatly improve the heating and cooling efficiency of even old historic buildings through the use of advanced analysis and building automation systems.
The six-floor, 29,000–square foot museum, which opened in February 2001, is located in a former department store building in Bangor’s historic downtown district. When the museum moved into the building, the facility systems and equipment were modernized. However, the building’s energy use soon proved far from optimal. For example, the museum was using more than 1,000 gallons of heating oil—during the summer months—and 30% more in the winter. In 2007, the museum’s average monthly cost for heating oil and electricity was $8,000, meaning that energy accounted for the majority of operating costs.
The museum runs on a shoestring budget and relies solely on grants and admission fees for funding. Maximizing attendance is important for an organization that generates most of its revenue from ticket sales. So maintaining a high comfort level is important amid changes in occupancy. When the number of visitors approached a peak of 700 on some days, comfort issues became more prevalent, according to Don Flanders, the museum’s director of finance and operations. The museum staff also complained about warm and stuffy offices, Flanders says. “I was solving problems as best I could, sometimes manually closing individual heating valves while trying to open others.”
The museum hired Honeywell Building Solutions to conduct a facility audit, a boiler retrofit, repairs, and routine preventative maintenance, in February 2008. Results of the audit revealed that broken temperature sensors in the building were causing redundant heating and cooling between the facility’s HVAC systems. Having one HVAC system cooling while the other HVAC system heated the building had resulted in the use of more than 860 gallons of heating oil in June 2007. Heating oil expenses in the summer for a similar facility should have run around $50, but the museum was spending close to $2,700. The audit also uncovered that, among other neglected parts, HVAC filters and coils had gone years without being cleaned or changed, contributing to system inefficiencies. The museum had a maintenance contract for this type of work, but the repairs weren’t completed as agreed on.
Several changes to the HVAC system were recommended and implemented. The building’s automation system was restored, thermostats were calibrated to match occupancy rates, and a dual-fuel oil and natural gas burner were installed to replace an old oil-fired boiler. The new boiler gives the museum the flexibility to choose the cheaper of the two fuels for burning, which adds a layer of budgetary protection.
The next task was repairing the building automation system and controls. Honeywell tested and restored the system, including its hardware and software, to ensure accurate communication. This work also included checking HVAC schedules against occupancy schedules and changing temperature set points to reduce costs when museum traffic is light or parts of the facility are unoccupied. The museum’s thermostats and valves were also calibrated to ensure that they read temperatures accurately. Additional improvements included changing filters, cleaning fan coils, vacuuming motors, and replacing damaged sensors.
Additionally, Honeywell performs ongoing system maintenance. Flanders and other museum employees can access the status of current service activity and review several years of service history, and submit online service requests using Honeywell ServicePortal, a Web-based application.
In June 2008, after the project was completed, the heating bill dropped to $39 for the month. The museum also saw significant decreases in electricity use, cutting consumption by more than 40% in March 2008 versus March 2007, for example. Flanders reports that total energy costs have been reduced by about half.
In the first five months after the repair work, the museum also cut its oil use by 2,400 gallons, which reduced carbon dioxide (CO2) emissions by an estimated 54,000 pounds. In the same time span, the museum saved more than $11,000. The museum is on track to reach the three-year payback term for the burner conversion and maintenance work within one year. “I get a lot fewer calls and complaints for sure and the new system has very much stabilized our environment,” says Flanders.
What does this project demonstrate? “There’s always money to be saved if you take the time and spend the money to analyze your system,” he says.
Web-based Airport System Monitoring
Norman Y. Mineta San José International Airport’s recent Terminal Modernization Program included upgrading of one terminal, construction of another new one, upgrades of two 450-ton chillers installation of variable-frequency drives (VFDs), and readjustment of air-handling units. To optimize the operation of the new HVAC system components, though, the airport is using enterprise software developed for commercial HVAC systems.
The city’s goals included more efficient and profitable operation, reduced carbon emissions, and Leadership in Energy and Environmental Design (LEED) Silver certification. To increase efficiency and service the new B terminal and its 380,000–square foot north concourse, the engineer, WSP Flack + Kurtz, added a 1,100-ton chiller, two cooling towers, two condenser water pumps, and two chilled water pumps, and had VFDs added on the airport’s two existing 450-ton chillers. Just as importantly, the engineer incorporated the use of a Web-based Optimum Energy LLC OptimumHVAC monitoring and control system.
The software resides in a microprocessor-based control appliance that hooks up via Ethernet to a Building’s Automation System (BAS) and can communicate with any BAS. According to Optimum Energy LLC, the system is scalable due to the modularity of the control appliance, which eliminates the need for time-consuming direct system programming. An OptimumLOOP system, used at the airport, is targeted at buildings over 100,000 square feet that have centrifugal chiller plants. The program adjusts the chillers, pumps, and tower fans to maintain occupancy comfort and optimizes equipment efficiency based on current load conditions. Another available system, OptimumTRAV, is designed for buildings with Variable Air Volume air-handling units.
The appliance utilizes the Tridium platform, which facilitates device-to-enterprise applications and real-time system control and monitoring over the Internet. The OptimumHVAC system receives operating performance information from the building automation system and adjusts the devices. For example, the number of chillers, chilled-water, and condensed water pumps that are running is adjusted based upon current load conditions. Performance Assurance software provides facility managers with views of consumption monitoring; trend lines of different colors indicate actual consumption versus what it would be without the system. Additional screens include kilowatt-hour savings by day, month, and year; CO2 emissions; dollar savings; operating costs per hour; dollars saved per hour; chiller performance; and chilled water temperature. Managers can generate monthly and annual reports showing the savings and possible further savings with more mechanical changes. According to Optimum Energy, the real-time monitoring can allow 18- to 36-month paybacks on HVAC upgrade investments.
The Optimum Energy portion of the airport project was awarded in mid-2006 as part of the overall construction project for the north concourse facility and the anticipated completion date is June 2010. Since site commissioning in September 2008, however, the OptimumHVAC system has been yielding significant savings. After six months, the system had reduced HVAC energy by more than 351,000 kWh (reducing the average kilowatts per ton to 0.64 from 1.27 kW per ton, a 49.7% reduction), utility costs by more than $52,000, and CO2 by more than 414,000 pounds. The payback on the upgrades was targeted at 1.2 years and possibly less. The facility was also on track to achieve the LEED Silver certification.
“Without optimization, energy consumption would have been higher as well as overall operating expenses,” says Patrick Tonna, the airport’s deputy director for facilities and engineering. “Optimization has provided a much improved decision-making process that can be applied to future expansion projects. Based on the results so far, we have included the OptimumLOOP as part of the installation of two new 650-ton chillers being installed later this year.”
A Self-Funding Schools Initiative
Earlier this decade, the Metropolitan Board of Public Education (MBPE) for the City of Nashville and Davidson County, TN, sought to improve the energy efficiency and sustainability of its 184 buildings, including 137 schools. The Nashville school district is the 64th largest in the country, with over 75,000 students.
Funding such improvements with a tax levy was not an option, and the improvements are being made gradually over a 15-year period starting in 2004. The initiative is being funded by more than $45 million in bonds that will be repaid by completion of the project. Kirk Whittington, business development manager–energy solutions for Siemens Building Technologies, points out that the initiative is self-funding, i.e., the bonds are being repaid with savings in electricity, natural gas, and water. To date, the upgrades are saving the MBPE the projected $3 million annually.
By the end of the initial five-year phase of the project, improvements to HVAC systems were made to more than 30 schools and lighting retrofits were completed at 110 schools. Water conservation measures had been instituted at more than 50 area schools, and water treatment systems were installed at 93 schools. More than 70 schools received building controls upgrades, and new building automation systems were installed at 15 schools. More than 14 million square feet and about 5,000 classrooms were involved in one of the largest energy-performance projects to date in the southeastern United States.
Brent Ostermiller, design services manager for Metro Nashville Public Schools, reports that the existing HVAC, lighting and water systems had room for improvement. “The buildings are anywhere from 100 years old to built within the past few years, and many of the older buildings have just the old two-pipe hot water-and-steam systems without air conditioning,” says Ostermiller. “So many of the schools have—we call them ‘window-shaker’ window units in them, and that’s how they get their air conditioning. The window units were inefficient and very noisy.”
Siemens’ Apogee building automation system was installed in 15 of the schools. The system automatically adjusts to fluctuations in mechanical systems, loads, and seasonal changes using Cybosoft Model-Free Adaptive control software, which was developed to be an upgrade over traditional Proportional, Integral, Derivative control. The Apogee system is designed to reduce cycling-induced wear and tear on valves and actuators increases their lifespan and reduce hardware repair, replacement, and maintenance costs. The reduced cycling and offset from setpoint provided by the system are intended to reduce energy costs, and precise temperature control is designed to increase occupant comfort. The Windows-based open-architecture BACnet infrastructure is installed quickly, Ostermiller notes.
“In most cases, we’ve had about a two-and-a-half-month window to do the work during the summer when the schools are shut down,” he says. “A key to the system is the time element of getting into the building, modifying the systems, and still getting the building open for students in August. One of the advantages of the control system is that everything ties back into a central system in our maintenance department, and they have the ability to monitor and control what’s going on in the buildings from a central point.”
Ostermiller adds that the platform allows energy optimization using occupancy sensors. “The temperature is controlled within a range. In the previous systems, the teacher or user could crank the heat up as high as they wanted to or crank the air conditioning down as low as they wanted to in a particular space. But with the central control system, we’re able to set the temperature and control it within a 4- or 5-degree range. The user still has the ability to control the temperature within that range, but the user can’t turn the temperature way down or way up and just leave it like that once a space is unoccupied.” He also says that variable refrigerant volume (VRV) systems are being used in several schools; the VRV systems utilize several fan units within individual rooms that are connected to one variable-speed condenser, saving more energy.
An important upgrade has been in the lighting systems, Ostermiller adds. “Most of our schools, especially the older ones, had T12 fixtures and regular ballasts, and we’ve changed them out to the [reportedly 40%] more efficient T8 fixtures with the electronic ballasts. And, we’ve put motion sensors on all of the lighting, too, so when spaces are unoccupied, the lights go off. That’s where our biggest energy savings have come from, and it gives us the funding to do the HVAC upgrade.”
The increased energy efficiency is yielding environmental benefits, too: to date, emissions have been reduced by 6,231,885 pounds of CO2, 53,093 pounds of nitrogen oxide and 197,660 pounds of sulfur dioxide.
Yet another upgrade to the HVAC systems has been the use of a chemical-free Flozone system used to treat water used in the cooling towers in the chiller plants serving the HVAC systems. Whittington reports that the system reduces scaling in the cooling towers, can be remotely monitored, and is already saving more than 24 million gallons of potable water per year.
Hotel Room Occupancy Adjustments
The needs of reducing burdensome energy costs, getting new system infrastructure installed quickly, and achieving a rapid payback were paramount when the Chartres Lodging Group recently upgraded the HVAC systems at its Sheraton Dallas and Sheraton Denver properties. The new system optimizes energy use by adjusting for room occupancy. At each location, the payback will be about three years.
The group sought the HVAC upgrade because it wanted to make the hotels as sustainable as possible amid budgetary limitations and achieve a reasonable payback on the investment. The energy costs in operating the hotels were significant: For example, the cost was about $800,000 per month during the summer in Dallas, according to Troy Hartmann, president of San Diego-based Pacific Energy Service and Facilities Inc., which installed the Networked Telkonet SmartEnergy (NTSE) energy management system in both locations over about three months, starting in the first quarter of 2009.
The NTSE platform utilizes wireless ZigBee IEE802.15.4 mesh technology and links Telkonet’s Energy Management Occupancy Sensors and thermostats or packaged terminal air conditioner (PTAC) controllers, and existing Internet/intranet infrastructures for rapid, retrofit installation without the need for back-haul wiring. The link between the sensors and thermostats is critical to the system’s ability to optimize energy use.
The system maintains a default or guest-selected temperature when a room is occupied. The Energy Management Occupancy Sensor determines when a room is unoccupied and adjusts the temperature using Recovery Time (RT) technology. The RT continuously performs calculations that evaluate how far each room’s temperature can drift from the occupant’s preferred setting by taking into consideration various environmental factors, such as the preferred setting, the location of the room within the building, window placement relative to sun or shade, humidity, variations in weather throughout the day, and age and condition of HVAC equipment. The NTSE is designed to better optimize energy use compared with fixed systems, which establish a setback temperature at one fixed temperature or increase or decrease the temperature by a fixed deviation.
The Energy Management Occupancy Sensor, which is typically placed on the ceiling, uses digital signal processing and passive infrared technology to detect motion and body heat in a room, including sensing when an occupant is sleeping. Using a wireless radio link, the sensor sends signals to an Energy Management Thermostat, which maintains occupant’s preferred temperature setting when the room is occupied. When the room is vacant, the thermostat recalculates the temperature to change as determined by the calculated recovery time. In rooms with PTACs, an Energy Management Controller works with the sensor to maintain the occupant’s preferred temperature setting and setback.
Hartmann argues that the system was a better fit for the owner than the alternative—fixed-setback systems that are activated by a door switch, not a human presence in the room. He explains that, when two people are in the room and one goes out the door, the system switches off. The preset might be 78°F in the summer and 68°F in the winter. But the fixed-setback systems do not account for thermal loads on different sides of building. On the north side, the preset temperature might be reached again quickly, but on south side, it might take 30 minutes.
Aside from the energy optimization, the NTSE had the advantage of being wireless, Hartmann adds. “[The owner] wanted wireless; they didn’t want to be pulling wires through these historical old buildings. The SmartSystem allowed global system changes due to the wireless design.”
As of April 2009, installation of the system in the 1,224 rooms in Denver and 1,840 rooms in Dallas was nearly completed. Hartmann contends that a wired system would have taken about a year, compared with the roughly three months for wireless. Getting the system operational quickly will lead to a short payback period: Hartmann reports that the systems will pay for themselves at the Sheraton Dallas in 38.6 months and in 33 months at the Denver Sheraton, which hosted the 2008 Democratic National Convention and is Colorado’s largest hotel.
Each device in the NTSE system functions as a wireless repeater, allowing the thermostats to communicate with each other and aggregate communications up to a master Telkonet Gateway Server that is located onsite. The wireless “mesh” network allows central control without the need for back-haul wiring. Every 15 minutes, the server gathers information from each thermostat in the system and aggregates data on the Telkonet network operations center databases. The system can be monitored remotely via a Web-based Telkonet Central portal, and alerts are issued indicating unusual HVAC performance.
It is also possible to generate reports to monitor system performance, such as a System Efficiency Report (rooms with above-average runtime in heat or cool mode, possibly signifying the need for cleaning or replacement) and a Savings Report (runtime hours and kilowatt hours saved on a room-by-room basis). Energy management reports can be accessed by downloading data directly from a thermostat or controller to a laptop computer. The reports contain energy cost-savings and consumption information, HVAC and PTAC runtime savings, HVAC unit efficiency, occupancy statistics, and ROI calculations.
Hartmann recalls that central system control paid immediate dividends for the owner. “They were excited about the centralized system, because they could actually see the savings,” he says. “As soon as we put a thermostat and a sensor in a room, it was already saving energy, but there would be no way to show it to the owners, whereas with the central control, they can physically look it up and see which rooms are on and which ones are off. Also, with the central system, we can download the data on the Web without having to walk rooms and download the data manually.”
Hartmann argues that energy optimization in a hotel is a wise investment—now more than ever. “Utilities are the second-largest cost for a hotel these days,” he says. It’s between employees and utilities, and I think it’s [nearly] a tie at this point. When you figure that hotel rooms are unoccupied pretty much all day long—people get up at 9 o’clock, or whenever, to go to their meeting or go shopping all day and come back at five—there’s no reason to heat and cool it all that time. Even in these economic times, [the Chartres Lodging Group] still committed to this system when they could have been holding this extra money. I don’t care if occupancy is down in a hotel—that’s even more of a reason to be doing this in these times. The value of a property goes up if the costs go down. Sometimes smaller owners, people who are worried about spending money, don’t tend to look at that, but you’re giving the money to the utility every month. You’re just diverting some of that money you’re diverting to the utility to an investment in the property.”