How A Little Black Box Can Save Energy

Whether it blows hot or cold outdoors, an energy management system can cut consumption. But before you buy, lease, or share one, consider the pros and cons.

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Karla Evert, vice-president of materials management and product development for St. Cloud, Minn.-based Stearns Manufacturing Co., knew there had to be a way to reduce the company's energy bills, which reached $68,500 in fiscal 1981. The 120,000-square-foot building, which houses the factory and offices of the $15.5 million-a-year life-jacket manufacturer, is only 10 years old, and an inspection showed that insulation was "quite adequate." So Evert figured she could cut costs by simply having employees turn heating and air-conditioning up before opening and down before closing. But there were too many thermostats to handle, and it "became a nightmare," says Evert. The answer was the installation of a Honeywell W7000 load-control system. The payoff was almost $16,000 in energy savings in fiscal 1982.

The W7000 is one of hundreds of energy management systems (EMS), sometimes referred to as "black boxes." These devices are microprocessor-based units, usually not much bigger than fuse boxes. Mounted on a wall, they are programmed to switch energy-consuming equipment on and off at prespecified times or, in more sophisticated units, according to variables such as outside temperature or humidity. An EMS is simply "a light switch with a brain," says Steven Bennett, executive editor of The Energy Cost Cutter, a newsletter for businesses and industry (P.O. Box 78, Cambridge, MA 02138; 12 issues/$59).

Energy management systems have been around for a long time, but until five or six years ago, says Bill Dillard, secretary of the Orlando, Fla.-based Energy Management Contractors Association (EMCA), they were like a "white sidewall tire, something you'd hang on there if you had the money." But the sharp increase in energy costs has made them more popular with smaller companies. And, as computer chips have become less expensive, capabilities have gone up while prices have come down.

Depending on their complexity and the number of systems they control, the devices generally cost from $2,000 to $250,000, including installation charges, which can vary widely. You can, however, install a system that handles just one thermostat for as little as $500. The most expensive microprocessor units control up to 256 points, or loads -- the individual pieces of equipment, such as air conditioners and light circuits, which a device monitors.

Also on the market are energy management systems that are more like traditional computers, with keyboards, mass storage, and cathode ray tubes (CRTs). These will handle anywhere from 100 to more than 6,000 points and can be linked to security and fire-protection systems. The black boxes contain fixed software; users can program them only for certain functions, such as changing the time of day for activating a system. The computers are far more flexible -- and expensive, from around $50,000 to $1 million.

Unless you have a very large facility with several buildings, or want to expand in the future, you probably don't need a computer, says Robert Tinsley, engineering supervisor for Robinet & Associates Consulting Engineers Inc. in El Paso. "For the average small business, say a facility anywhere from 10,000 square feet to around 100,000 square feet," says Tinsley,"the black boxes are all you need." If you have more equipment than one unit can handle, you can tie several together through a central console.

The W7000 unit has proven ample for Stearns's requirements. Linked to 19 rooftop air-conditioning and heating units, the device helps reduce the company's consumption of electricity, natural gas, and propane by automatically setting back the heating, ventilation, and cooling systems at night and on weekends and turning them up again for the workday. It also cuts energy use by "duty-cycling" -- turning electrical equipment, such as air conditioners, on and off for short intervals during the day.

Electric-utility companies base an entire year's billing on a user's peak demand -- the period of highest consumption. "If we could reduce our peak demand that one or two days when it hits 90 degrees," says Evert, "we could reduce our bills substantially." The EMS lowers this demand by shutting down three or four air conditioners at once on a rotating basis, an operation known as demand control. (Another method of demand control is to "shed" loads, that is, turn off pieces of equipment in an order determined by the user.) "We had maybe two days out of the summer when it was a little warmer than usual and a little warmer than we'd like it to be, but we decided we could tolerate that to keep our peak demand down for the rest of the year," says Evert.

The system was installed in March 1981, by Advanced Energy Systems Inc., of New Hope, Minn. If it had purchased the W7000, Stearns would have paid $29,000. Instead it leased the system for $787 a month for five years with an option to buy the equipment for $2,000 at the end of that period. By the time the fiscal year ended in june 1982, Stearns calculated it had saved $15,690 at 1981-82 energy prices, not including a $6,000 energy tax credit it earned for the year. The figure topped the savings estimate given by Advanced Energy by more than $3,000. "We are extremely pleased with the system," says Evert.

Not every company's experience with an EMS is as positive as Stearns's. Darrell Sanderson, division manager of ProGraphics, the 32-employee, Clearwater, Fla., color-separation division of Progressive Graphics Inc., paid $10,000 for a Pacific Technology Load Programmer Basic 8 system. "I'm an anti-gadget person," Sanderson says. But he warmed to the idea of an EMS when a salesperson told him of the savings possible. Now, he says, "I'm not as happy as I thought I would be when I authorized the purchase."

When Suncoast Energy Controls Inc., in Largo, Fla., installed the Basic 8 in ProGraphic's 12,000-square-foot building, Sanderson was told the system would pay for itself in less than three years. "We now feel it will be in the neighborhood of five years," he says. But, he adds, "I don't think they could have picked a more complicated building or existing setup and conditions than we have."

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