Kevin Clinger 2017-03-02 10:42:18
The good news in energy management is that many of the challenges in effectively monitoring and controlling HVAC systems have been overcome. Many buildings—both new construction and retrofits—use efficient heating and cooling systems that are optimized with building automation systems (BAS). Plus, under the latest building codes, building envelopes are much more energy efficient. Collectively, this means that the primary opportunities for further savings are with lighting and plug loads. In fact, the US Department of Energy (DOE) estimates that plug loads now account for up to 50% of energy use in commercial buildings. With today’s advanced BAS, energy managers can simply integrate control of HVAC, lighting, and plug loads within one front-end platform to maximize savings while meeting other building operating goals. Lighting Better lighting management holds huge potential for energy savings. The DOE estimates that occupancy and vacancy sensors can reduce electricity waste by upwards of 30%, and in some cases, even more. Although automated lighting controls are being added to more buildings, and codes are requiring motion sensors and passive infrared (PIR) sensors to turn lights off automatically, there’s still room to grow. In many buildings, lights are still left on when they’re not needed. It’s relatively easy and affordable to retrofit a building to include sensors to turn lights off when spaces are unoccupied. This is particularly true in K–12 schools, universities, and office spaces, which typically are not used as much in the late evening, overnight, or in the early mornings. By contrast, in critical environments such as hospitals, the need for brightly lit spaces usually occurs around-the-clock so they can fulfill their emergency services role any time. Another area for potential energy savings is daylight harvesting. This can be seen firsthand during fall in the Pacific Northwest, where it can be light outside one minute, and cloudy and dark the next. In conjunction with well-placed windows and skylights, automated lighting controls can help building owners take advantage of no-cost natural light, dimming electric lights when sufficient sunlight enters a space. In addition to the substantial energy savings from lighting controls, studies show that daylight harvesting helps enhance human productivity and wellbeing. For example, in a report prepared for the Pacific Gas & Electric Company, the Heschong Mahone Group found that, “Controlling for all other influences . . . students with the most daylighting in their classrooms progressed 20% faster on math tests and 26% on reading tests in one year than those with the least.” Similar positive effects have been found in offices, hospitals, and even retail sales. Plug Loads Plug loads are the “Alaska” of energy management—they’re the final frontier for efficient buildings. In virtually every building there is equipment with power draws that building owners and operators are unclear about. Without that knowledge, it’s difficult, if not impossible, to identify the biggest opportunities for saving energy. With plug load monitors integrated with a well-appointed BAS, facility managers can evaluate the biggest power drains and automatically turn off equipment when it’s not needed. Prime culprits for electricity waste include air conditioning units and photocopiers. Air conditioners may be left running when no one is in a room. And photocopiers still draw substantial power, even when they’re in sleep mode. There’s also the story of school district energy manager in the Sunbelt: A grade school teacher was cold when the building’s HVAC was running, so operated a space heater under their desk to keep warm. Energy management strategies work best when occupants are bought into the implementation process and do their part not to counteract these strategies. All of these examples underscore the point that it’s important for facility managers to remember that just because a piece of equipment has an Energy Star or similar efficiency rating, doesn’t mean that it still can’t waste electricity. Many building professionals default to thinking of energy savings when it comes to plug loads. While effective plug load monitoring and control can help reduce plug load costs up to 40%, the benefits of more reliable building operations are just as substantial. Although it is important to turn off equipment when it’s not needed (such as computers after business hours), it is also critical to ensure that some equipment stays on. For example, in a hospital or lab storing temperature-sensitive vaccines in a refrigerator, inadvertently unplugging that unit or a mechanical failure could have devastating consequences. With monitored outlets, the BAS would sound an alarm if the refrigerator stopped running, enabling building operators to take quick action to fix the problem. The same principal applies in matters that aren’t life or death. For example, school districts benefit from using BAS to monitor the walk-in freezers in their central kitchens, to avoid expensive and disruptive food spoilage if the power supply is interrupted. Features and Benefits of Advanced BAS Effective control of HVAC, lighting, and plug loads requires coordination of these systems. In many building operations centers, there are multiple PCs, each controlling a different building system. This makes it very hard for a facility professional to optimize the systems, as they have to enter scheduling data into different platforms. But with an advanced BAS, you enter scheduling information once, and can jointly monitor and control multiple systems. Picture a facility operator in a K–12 school planning for winter break. With an integrated BAS they can schedule the HVAC, lights, and plugged-in equipment all to be turned down or off while the students are on vacation. To further simplify the coordination, some BAS offer graphic interfaces that allow an operator to see, at a glance, what is happening with any building system. For example, Alerton Compass software uses “OmniGraphics” which transform background images into interactive building controls. Visual controls such as this enable even novice users to quickly get up to speed on controlling multiple building systems. Conclusion At one time, HVAC, lighting, and plug loads each accounted for about one-third of energy costs in uncontrolled buildings. As HVAC and building envelopes have become much more efficient, lighting and plugs loads have grown in prominence. With today’s advanced BAS, building professionals can integrate these systems for optimal energy savings, while providing comfortable interior environments and helping ensure reliable building operations. DE Kevin Clinger is a senior manager of customer marketing for Alerton, a Honeywell business.
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