4 FM quick reads on energy efficiency
1. Focus on Energy Efficiency: Sub-Metering Strategies
This is Chris Matt, Managing Editor - Print & E-Media with Maintenance Solutions magazine. Today's tip is using sub-metering to manage energy use.
The first step in sifting through sub-metering technology is to identify the organization's essential energy-management needs and determine the way the facility can address these needs with a data-collection system.
The type of energy information many facilities require often is beyond the capability of one master utility meter. Sub-metering systems, combined with useable and comprehensive data-collection systems, can give managers much more detailed load profiling. Managers can use the collected data to:
• understand energy-use patterns and trends
• implement demand response and control to avoid costly ratchet and peak utility charges
• profile an entire facility for demand-management and load-shedding measures
• locate true spare capacity within the electrical system.
In its simplest form, sub-metering involves installing separate meters downstream of the primary billing meter. These meters monitor specific points in the system. In campus settings, for example, sub-meters might be set up on a building-by-building basis to allocate energy costs among departments. In single buildings, managers can group specific system circuits and monitor the distribution system to minimize the number of sub-meters.
Some sub-meters can transfer data, while others also can record and store interval data. Other intelligent-breaker technologies allow system operators to control individual circuits in a distribution system separately, as well as monitor the system's data separately.
At a minimum, managers should install sub-meters on lighting, HVAC, alternative-energy systems, and other key pieces of equipment, which will produce the most valuable trending data. Managers can reconfigure and display this data to the building occupants and visitors with a energy dashboard that presents the information in a way they understand.
2. Lighting Retrofits: Look Closely at Controls
This is Chris Matt, Managing Editor – Print & E-Media with Maintenance Solutions magazine. Today's tip is the energy-savings potential of lighting controls.
Most managers considering lighting retrofits consider only the lighting equipment when, in fact, some of the greatest potential for energy savings comes from controls. At the most basic level, occupancy sensors can save 15-30 percent of a space's lighting energy use if the space has intermittent use throughout the day.
Occupancy sensors can be simple replacements for wall switches, and wireless versions are available that eliminate the need for an electrician to rewire the space. In rooms with daylight, photocells that automatically dim the lights in conjunction with daylight can save an additional 30-50 percent of energy use. By making the leap from devices to systems, managers can tie lighting controls to room schedules, give users individual control of the fixtures in their immediate area, shed load to avoid peak-demand charges from the utility, and set a high-end trim if light levels are higher than needed.
To analyze the opportunities a retrofit presents to an organization, managers will need to plan in advance. A lighting designer can guide managers through the many available options and prioritize the highest-yield returns. A salesperson associated with a manufacturer or distributor primarily is interested in selling their products, so managers need to be aware they will slant their sales pitches to achieve that goal. By comparison, an independent lighting designer who is knowledgeable about current technologies is more likely to look at all potential options.
The designer will learn about the organization and its operations to understand the level of feasible change. They do not have a financial interest in the final equipment selected, so they can make recommendations with the organization's best interest in mind.
3. Chiller System Design Can Improve Data Center Energy Efficiency
Today's tip: Pay attention to chiller system design to improve data center energy efficiency.
The early data center design phase is the time to address chiller system configurations, pumping system topologies, chilled water loop supply temperatures and selection of energy efficient equipment.
Today's chillers can be selected for far lower kW/ton electrical use than in the past. Equipping the chiller with a VFD and condenser water reset is usually the most efficient option, because the VFD will adjust the chiller performance as the compressor load and condenser water supply temperature vary. Newer, highly efficient cooling towers with drift eliminators can be selected to reduce water use by as much as 40 to 50 percent.
Chiller systems for data centers have historically been oversized, resulting in less efficient operation until the data center is completely populated and full design loads are realized. Chillers are designed to operate at a specific difference between supply and return temperature or "delta-T." An efficient and properly-designed system will allow the chillers to operate closer to the design delta-T over the entire range of expected load conditions. A number of design strategies can contribute to achieving this goal, including pumping system configuration and reducing system bypasses.
Variable, primary-only pumping eliminates unnecessary chilled water bypass and allows the chiller to operate nearer to its optimized delta-T both during full- and part-load conditions. A traditional chiller design, in which a constant flow through the chiller is maintained, results in the delta-T staying proportional to the load. In a variable primary-only flow pumping system, the flow tends to stay proportional to the load while the delta-T stays closer to the optimized condition for the selected chiller. Also, a variable primary system requires fewer chilled water pumps (which lowers first cost), has fewer single points of failure (which makes it more reliable) and simplifies the chiller plant installation and controls.
4. Project Management: Successful Lighting Retrofits
I'm Dan Hounsell, editor of Maintenance Solutions magazine. Today's topic is, lighting system retrofits.
Commercial and institutional facilities measure the success of building retrofits in many ways, including cost savings, reduced energy use, and improved productivity of those responsible for maintaining the new technology. But one important indicator that is difficult to quantify is the level of interest from peers outside the organization. A prime example of this dynamic is taking place at the University of California, Davis, where lighting retrofits are garnering a great deal of attention.
"It's been an interesting ride so far," says Chris Cioni, the university's associate director of utilities. "We've had a lot of inquiries from folks in the field who have found out about the projects just by searching on the Internet."
The university's Smart Lighting Initiative has turned the campus into something of a lighting laboratory, thanks in large part to the university's relationship with the California Lighting Technology Center, or CLTC, a demonstration and education facility on campus that develops energy-efficient technologies. Cioni uses CLTC staff as a sounding board when considering cutting-edge lighting technology for retrofit projects.
Cioni, his team, and the CLTC joined forces in retrofitting fixtures in campus parking structures and surface lots. Their next set of projects will focus on pathways, roads, and fixtures on building exteriors. The opportunities for savings are great, considering the number of exterior fixtures on campus — 2,300 fixtures in parking structures and surface lots, as well as 700 fixtures on roads, 1,300 on pedestrian and bicycle paths, and 3,000 on building exteriors.
The Smart Lighting Initiative does include interior lighting, but Cioni concentrates solely on exterior fixtures. The university spent almost $1 million retrofitting fixtures in its surface lots and parking structures, which generated about $300,000 in utility rebates. The projects have resulted in additional benefits, including energy savings, reduced maintenance, and improved safety.
"The energy savings were the first target," Cioni says. "What drove me was having those very large and prominent parking lots right near a very visible part of campus. We have a big performing arts center, and it's kind of a focal point. Seeing these empty parking lots when I would drive in early in the morning when it was still dark, it just caught me as wasteful and a real opportunity to do something different."