MT: What does measurement have to do with energy saving?
THOMPSON: It’s all about ROI and the bottom line. Facilities need to consume a certain amount of energy to produce work—product, data, whatever it is. But most facilities are consuming too much energy. They’re inefficient energy users. Until the last decade, facility management as an industry didn’t really care—energy was cheap. Once energy became more expensive, managers became interested in reducing their energy bill, but the prospect had to be put into business terms: Where is the ROI conversion point where the waste is great enough that it makes sense to address? To answer that question, you need to measure how much energy you are consuming on the different types of work (systems) in your building and compare to standards. That tells you how much waste is occurring. Further measurement can help you identify root cause of the waste. The quantity of waste combined with the cause and the cost to address are the three points of an ROI equation.
MT: When does it make sense, for what kind of facility, in what places?
THOMPSON: Energy reduction makes sense for facilities that want to reduce overhead in order to increase productivity. Facilities that are looking to do more with less, not just spend less. Energy inspection identifies opportunities to increase efficiency, and gives the facility manager the data to understand which energy-saving activity makes sense, given the facility’s primary objectives, and which ones either don’t offer enough ROI or fall too far outside the priorities. The biggest opportunities typically exist in facilities that have old, large, high-energy-consuming systems that have not been optimized. Other good candidates include production facilities that have not introduced much automation or controls, as well as facilities with large steam or compressed air systems.
MT: Just how much can be saved?
THOMPSON: I wish I could promise that every facility could lower their energy bill by 25% —that’s a pretty common average saving potential referenced by the Department of Energy. The actual savings depend on a couple things. First, what kind of systems and activities occur in the facility? Large loads that have never been mapped to the utility rate schedule to take advantage of the cheapest times of day have the promise to deliver significant savings. A facility running mostly smaller loads may not see the same opportunity. Second, how inefficient are the building systems? A newer, well-maintained facility isn’t going to offer as many savings opportunities as an older facility where systems and equipment have drifted from recommended settings and maintenance practices.
MT: When I think about energy waste, cold air leaking in through my windows and replacing old light bulbs with CFLs are what come to mind. What does energy waste mean for a manufacturing or mixed-use facility?
THOMPSON:Your analogies are good. Both represent using energy to power inefficient processes. Using energy to heat or cool air and force it through the ventilation system only to leak it out the window forces the system to over-produce and, therefore, over-consume. How many other systems in the facility are working harder than they should, due to clogged filters, oversized motors and so on? Using energy to power incandescent light bulbs is inefficient because of the high percentage of the energy consumed that winds up becoming waste-heat. Extrapolate that to think about all of the possible aging equipment in a facility that consumes more energy to operate than new, high-efficiency models. So, yes, a manufacturing or mixed-use facility may experience both lighting and building-envelope wastes. But are those the first wastes to address? You can’t answer that question until you log power consumption at all of the major loads, map it to both the rate schedule and the operational schedule, and do the ROI math. Quite often, a facility will uncover enough maintenance and operational savings on large equipment that within a few years they’ve saved enough money to then accelerate the equipment replacement with a leaner model.
MT: How do you get started? Budgets, time and resources are all limited.
THOMPSON: Baseline! The place to start is identifying where—and when—energy is being used and by what (Fig. 1). Once you understand exactly how much energy is required to run the business versus how much is being wasted, you can make decisions and build a plan. Start by getting copies of the last several utility bills and look for signs of penalties and peak-demand charges. While you're at it, download a copy of the rate schedule from the utility Website to see how much energy units cost at different times of day, compared to your operational schedule. If you need help with this, call the utility service department directly. They'll be happy to hear from you.
Then, direct your in-house electrical team or electrical contractor to log power at the main utility service entrances, as well as at the supply panels to the largest systems and loads. By recording kW, kWh and power factor over a representative period of time, you can get a very accurate picture of the actual power consumption on three-phase circuits and loads. The biggest savings often comes from shifting load operations to cheaper-energy times of day.
MT: Can you briefly talk us through some of the systems that are the most common “wasters?”
THOMPSON: Aside from mapping the electrical supply system, I always suggest that people evaluate their electro-mechanical, steam and compressed air systems. They’re usually ripe with wasted energy usage—and fairly easy fixes.
Voltage/current overload and phase imbalance are two big energy wasters with electro-mechanical systems. Both of these issues can be detected with power-quality analyzers and thermal imagers.
Energy-wasting mechanical situations manifest as both overheating and excess vibration, detectable with thermal imaging and vibration meters. Possible causes vary, from cooling and airflow to bearing alignment and other causes of friction. Thermally scan couplings, shafts, belts, bearings, fans, electrical components, termination/junction box and windings—all things that can signal inefficient operations and, thus, energy waste.
As mentioned earlier, one of the easiest energy-saving solutions is to log power consumption at large electro-mechanical loads over a full operational schedule. Determine when the machinery uses the most energy (often at startup) and check whether usage times can be adjusted to points of the day when utility rates are the cheapest.
Using that same power log, compare the operational schedule to how often the machine uses energy. How much power is it using when not in active use? Without the use of controls, most machinery must be manually turned off to stop consuming energy, and manual actions don’t always occur. Not all machinery can be feasibly turned off, but most can be idled. Controls vary from simplistic to fully automated, and from using sensors and timers to flexibly idle machinery to hard-coding operations into a PLC.
Sizing and efficiency ratings are crucial when it comes to electro-mechanical equipment. In older facilities, especially, operational requirements change, but the loads stay as is, meaning that sometimes a large, expensive, hard-start motor is left driving a less horsepower-intensive system. The natural inclination of any facility manager is to get the maximum lifetime out of a large piece of equipment. However, it’s worth logging how much power the motor uses, compared with actual load requirements, as well as with a new, high-efficiency, right-sized unit. Calculate how much excess energy is being consumed and multiply by the rate schedule. Determine how long a new motor would take to pay for itself: Sometimes it makes financial sense to replace equipment before it fails. If not, consider whether controls could be used to modulate output.
Process heating accounts for a sizeable portion of controllable operating costs and must be regularly inspected to avoid several different energy-wasting scenarios. To begin, log energy consumption at the boiler, to get a baseline for energy consumption. Then inspect the distribution system, including: steam traps, pressure gauges, insulation, pumps and valves. Use a thermal imager to detect failed steam traps, leaks, blockages, value issues and condensate failures. The goal is to return as much pre-heated condensate to the boiler as possible.
An ultrasonic leak detector can also be used to check for steam leaks. Be sure to check for loose or missing insulation and proper operation of all steam traps; clean inside boilers, and check steam transmission lines for blockages. These combined efforts identify energy wastes and help the team plan energy-saving solutions—many of which can be implemented via maintenance rather than capital expense.
Compressed air systems…
A 100 hp air compressor can consume around $50,000 in electricity annually—as much as 30% of which goes to pressuring air that’s never used , due to distribution leaks and wasteful usage practices. Yet many facilities have never assessed the efficiency of their compressed air operation. In fact, when more air pressure is needed, many facilities will purchase and operate an additional compressor without ever realizing they could get more pressure out of their existing system.
Studies by the Compressed Air Challenge  have found that only 17% of compressed air users value efficiency as a system management goal: 71% simply want to deliver a consistent, reliable air supply. That philosophy transfers down to the point of use: pneumatic equipment installations frequently lack even simple solenoid shut-off valves, driving continuous compressor operation, and shop-floor personnel often treat compressed air as a free resource, using it to clean the work area and even to cool off. In reality, compressed air is a fairly expensive commodity to produce.
To identify and quantify the level of waste, start by logging power over a full business cycle at all air compressors. This will establish how much energy it takes to produce current air-pressure levels. Also log psi at the compressor output compared to the point of use, determine the amount of pressure drop, and verify manufacturer psi required to operate pneumatic equipment; don’t over-pressurize “just because.” A pressure module plugged into a logging multimeter is one way to conduct these tests without investing in specialized equipment. Finally, use an ultrasound leak detector to scan as much of the air-line footprint as possible, to determine the location and scope of air leaks.
Steps to improve energy efficiency include fixing identified leaks; setting compressors to generate only the necessary amount of pressure; installing air-shutoff solenoids at point of use; and using receive tanks for high-volume applications, rather than increasing overall system pressure.
We’ve just touched the surface here
1. Improving Compressed Air System Performance: A Sourcebook for Industry: Section 12, “Compressed Air System Economics and Selling Projects to Management,” p. 69.
2. See “Appendix D,” online Improving Compressed Air System Performance: a Sourcebook for Industry (http://www.compressedairchallenge.org/library/index.html#Sourcebook.). Study commissioned by U.S. Department of Energy, with technical support from the Compressed Air Challenge (CAC).