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Controls: Real-World Savings
OTHER PARTS OF THIS ARTICLEPt. 1: BACnet Systems Offer Many Opportunities to Improve SustainabilityPt. 2: BACnet Connectivity and InteroperabilityPt. 3: Interoperability and Green BuildingPt. 4: This PagePt. 5: Why BACnet?
For the facility professionals who have turned to BACnet systems to manage energy usage and further contribute to sustainability initiatives, the payback, despite up-front costs, is real.
Consider this simple example: a small office building that operates from 7 a.m. to 7 p.m. on weekdays. If all the lights are left on over the weekend, the building could add 2 percent to its annual energy bill for lighting, says McMillan. "A weekend doesn't sound like much, but it turns out to be a lot," he says. "Even simple control applications can save a lot of money."
Clearly, effective controls offer a big opportunity for facility managers.
The Johnson Controls' world headquarters campus in Glendale, Wis., has four LEED Platinum-certified buildings that embody many green design strategies. These include hundreds of wireless controllers and sensors communicating throughout buildings on the campus' 33 acres. These controllers feed information to the building management system, which provides continuous monitoring of key performance indicators, such as energy consumed per square foot. When variances are detected, the systems can be adjusted automatically or with handheld devices from any location via the Internet. Numerous other energy efficiency technologies also are in use.
All that has paid off. While the square footage of the campus doubled, energy use fell by 21 percent. Water use has been reduced by 595,000 gallons per year, while greenhouse gas emissions have been cut by the equivalent of 857,200 million pounds of carbon dioxide per year.
Even seemingly small gains can add up, says McMillan.
Greg Turner, director of global offerings for Honeywell Building Solutions, cites a health care organization that used BACnet energy management to cut energy costs drastically. The facility's energy use was the biggest variable line item on the hospital's budget and varied drastically from month to month.
A study of usage patterns zeroed in on a medical office building attached to the hospital. Employees in this building enjoyed a flexible work schedule, and on Saturdays, the building was accessible to them between 8 a.m. and 2 p.m. During this time, a few patients would come for appointments and a small number of staffers would be there working in certain areas of the building, which was conditioned and lit throughout.
The access control system was used to see how many employees were coming in and how long they were staying, Turner says. Analysis revealed that so few people were coming in and using the facility during those hours that the net operating costs per employee were $600 per hour. "It wasn't a hard decision to adjust the HVAC and lighting controls based on this discovery," Turner says.
Turner says the building also had been fully lit and conditioned until 7 p.m. each night for the housekeeping crew.
"While it's a friendly strategy, when you look at the cost-per-hour multiplied by the number of housekeeping crew members in the building, it becomes an incredibly expensive proposition," he says. "With controls, you can factor in zone-controlled lighting and a temperature setback at the end of the workday and even program a second setback at the end of the cleaning period when the building is fully vacant."
As Tridium's Petock says, real-life examples such as this demonstrate how controls can help improve energy performance (and budgets) without sacrificing occupant comfort.
"Adjusting temperature, lighting and other features to actual occupant levels and building usage through control management can dramatically improve energy performance," he says.
BACnet management systems have true relevance in a world that is increasingly being driven by the LEED rating system and the desire to incorporate at least some LEED credits into a building's design, if not full LEED certification.
"It's no secret that a fully implemented and operational building management system is one of the best ways to ensure sustainability," says Terry Hoffmann, director of BAS marketing for Johnson Controls.
According to the "conservative estimates" of Ben H. Dorsey III, vice president of marketing and communications for KMC Controls, a properly designed and installed control system can lead to fulfilled credits worth 22 points in the LEED for New Construction (NC) rating system and 26 points for the LEED for Existing Buildings: Operations and Maintenance (EBOM) rating system.
"When the minimum level for building certification is 40 points, you can begin to understand the power of a control system," Dorsey says.
Building automation has the most impact on the Energy & Atmosphere (E&A) section of LEED. Points also are possible in the Indoor Environmental Quality and Water Efficiency sections, as well as the Sustainable Sites section.
Dorsey says that it is important to understand the difference between a contributory LEED credit and a compliance LEED credit.
"With rare exceptions, the use of a particular product or type of product cannot, in and of itself, lead to credit compliance," he says. "For the most part, products of whatever type contribute to the fulfillment of particular LEED credits."
For example, a building automation and control system complies with E&A Credit 3.1 in the LEED EB:O&M rating system. Elsewhere, for both rating systems, building automation and controls contribute to credit compliance. "Consider E&A Credit 1 in both rating systems," Dorsey says. "It calls for ‘optimized energy performance.' For LEED-NC it means performance simulation compared to the ASHRAE 90.1 standard. For LEED-EBOM, it means actual measurements against the Energy Star criteria. One to 19 points (one to 18 for EBOM) are available for this credit alone. And, simply put, for a commercially viable facility, achieving the requisite level of performance is not possible without a control system."
Additionally, as Shan Bates, education solutions manager at Schneider Electric Buildings, says, existing buildings already must have a BACnet system in place that is "not already interfaced or integrated in order to integrate third-party systems." Additionally, the third party systems, which include lighting, chillers, boilers, lab environmental and control systems, must be BACnet-compatible.
Also consider the commissioning requirements for LEED. The automation and control system is the commissioning agent's primary tool, so achievement of the credits would be nearly impossible without the contributory help of the control system, Dorsey says. While any control system can contribute to achieving these and any other LEED credits, a BACnet system offers an additional green advantage. That's because these systems are built for integration, a central notion of LEED-certified or other green buildings.
"For a building owner working to achieve LEED certification, a BACnet-based building management system adds value by streamlining building systems through integration," Bates says. "This produces savings in capital expenditure and operating expense, as well as improving energy efficiency."