You’ve heard the claims: This product will save electrical energy! If you install this system, you’ll be the greenest person on the block and will never have to pay another electric bill! How do you sort through the claims and pick out what is really possible for residential or industrial/commercial customers? Electrical contractors can find the real savings beyond the hype, leading to significant service opportunities for both types of customers.
First, let’s dispel some myths:
1 “Putting in a smart meter saves on your electric bill”—Nope, like any device that provides data or information, it is up to the viewer or user of that information to do something about it. Having feedback from a smart meter in a residential home can indicate, to some degree, what is consuming the most electricity and when, but it doesn’t reduce the consumption any more than a speedometer keeps someone from speeding.
2 “Switch to room air conditioning (AC) units; central AC is wasteful because you have to cool the whole house, rather than just the parts of it you’re using”—Not necessarily. It depends on the age of the units and whether they are properly installed and insulated. Central heating, ventilating and air conditioning (HVAC) systems have vents or registers that can be adjusted based on occupancy. With room AC units, there is often plenty of air leakage around the unit and window. Additionally, doors to unoccupied rooms would have to remain closed, or the AC units will cool those spaces as well.
3 “Surge suppressors and filters save energy”—No again, unless one considers that it takes someone else’s energy to produce new products to replace units damaged by transients and harmonics. Suppressors and filters shunt away the bad stuff and leave a “clean” voltage waveform from which the equipment operates. The energy may not reach the end-use product, but it still comes in the building and gets diverted and dissipated in the protection devices.
So, how does the contractor really make money by saving money for the customer? The first step involves some form of measurement because, if one doesn’t know where and how efficiently the electrical energy is being used, the expenses incurred in making the savings may exceed the savings. A variation on the Paretto Principle also is a good starting point—80 percent of the costs usually come from 20 percent of the equipment. In a residential dwelling, most measurements can be made at the breaker panel—provided the circuit labeling is reasonably accurate. The breaker panel serves as a proxy for what equipment is being measured. The alternative is measuring the power at each piece of equipment, such as the refrigerator, microwave and window AC units, but it isn’t easy for hardwired equipment, such as electric ovens, dishwashers and central AC units.
Industrial and commercial facilities can use a similar approach. Use a power logger or power quality monitor so that you can record enough data to determine a typical usage profile for the larger wattage loads. Then check the data against the nameplate ratings and what typical newer appliances consume. In any type of facility, either ask the facility manager/homeowner/accounting department or search online for the kilowatt-hour costs in the area to estimate what the appliance costs to run versus a newer equivalent model, assuming a five-year payback. Even though the appliance may last 10 or more years, this short-term payback will determine if it is cost-effective to replace, as many people don’t want to wait 10 years. If it isn’t cost-effective to replace, determine what maintenance work could be done on the equipment to improve the efficiency, such as cleaning or changing filters, lubricating bearings, etc.
Go after the low-hanging fruit, remembering that the Paretto Principle points to the biggest payback in a few items. It isn’t difficult to find 10–20 percent savings in the electricity costs, especially in industrial and commercial facilities.
Remember that, in those facilities, there also is a demand charge, which says that the peak power usage in any demand interval (usually 15 minutes) becomes a ratcheted penalty that gets paid for many months. Getting the demand charge under control usually requires a longer monitoring period and is best accomplished by permanent power monitoring that has projected limit alarms to warn the facility manager to shut down unnecessary loads to prevent creating a new higher demand value.
Motors, in particular, are good candidates for a closer look in industrial facilities. With the exception of a few industries, such as electric arc furnaces, motors are likely to be the largest consumer of electricity. According to the Department of Energy (DOE), there are more than 12 million 1 horsepower (hp) or larger motors operating in U.S. applications, such as heating, cooling, ventilation, process control and transportation. Three million motors fail each year, according to the Consortium for Energy Efficiency (CEE). Both the DOE and CEE websites provide tools for determining if it is cost-effective to replace with a newer motor, especially a “premium” efficiency one with efficiencies above 95 percent for 100 hp and larger motors. In addition, adjustable speed drives typically provide a lower operating cost, but consider the potential for power quality pollution of harmonics and notching transients. The newer drives that use 12 or 24 pulse converters can minimize this impact and be more efficient.
In commercial and light manufacturing buildings, lighting is often the largest electrical energy load. In the figure above, the red box highlights the closing time at a facility, when all of the general-use (non-safety) lights are shut off each night. The load drops to roughly half at that time.
Lighting retrofit programs have been around for several decades as technologies have evolved. The most recent focus has been the replacement of incandescent lamps with compact fluorescents lamps (CFLs), driven by the Energy Independence and Security Act 2007 and its minimum efficiency requirement that eliminates the manufacture and sale of some incandescent lamps. More efficient lighting also lowers the heat dissipated, which means less air conditioning is needed in the warmer months. However, CFLs require adequate air circulation to maintain the projected life expectancy. Utilities in California have reported 30 percent lower life expectancy of CFLs, but they are still generally cost-effective replacements.
With claims of T5 lamps saving more than 75 percent of the electricity cost and burning 1.6 times brighter than the phased-out T12 or T8 lamps, replacing the estimated 1 billion T12 lamps seems like a no-brainer. However, an issue arises with T5s when replacing T8s and T12s. The ballasts also must be replaced, and discussions are circulating that the T5s are lasting well below their rated life and a fraction of the T12’s life.
Power transformers are a third area to investigate for electrical energy savings. Most industrial/commercial facilities have at least a distribution transformer outside the service entrance (more than 1 million sold annually in the United States), and often, many smaller units distribute throughout. As of January 2010, the U.S. Department of Energy (DOE) mandates minimum efficiency standards for liquid-immersed and medium-voltage, dry-type distribution transformers. Though this ruling affects only the sale of new transformers, the overall cost savings from more efficient transformers should be analyzed for payback in retrofit programs. This issue is important for facilities where the increasing consumption levels are nearing the maximum sustained rating of the transformer and especially where the harmonic current levels are high enough to cause significant losses that would require derating the transformer.
These three categories are in the top areas for electrical energy savings in most facilities. There are others with lower paybacks, but every electrical dollar saved also is a benefit for the environment, reducing the carbon footprint from the generating facility. Motion-sensor switches for infrequently occupied areas counter the habitual problem of many people who don’t turn out the lights when they leave a conference or storage room. For example, at one facility, it was difficult to get the cleaning crew to turn off all the necessary switches when they were done at night. Those circuits were rewired with a single disconnect button that shut them all off at once, resulting in a 10 percent savings.
Providing the right amount of heating or cooling for the time of day, season and occupancy/work load can be accomplished through programmable thermostats in multiple locations. However, they should be controlled so personnel in the area can’t adjust at will. Setting the cooling point higher than in the past but still comfortable (and vice versa in the winter months) can lead to 2–4 percent savings per degree in some areas of the country. Similar to the motion sensor mentioned above, installing motorized or automatic blinds that can keep the heat in or out depending on time of day, season and sunlight levels can also save on HVAC costs, since it is often difficult to get the occupants to adjust blinds manually each day.
Energy-savings programs have been around for years, and many utility companies still sponsor rebate programs for them. However, recent tours through a number of different facilities have shown that there are bushels of low-hanging-fruit opportunities for the facility to save money and the contractor to make money. Real green, green and green.
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680.