An Energy Audit Can Find Your Plant's Power Hogs

There are opportunity costs lurking in your electric bill. Performing an energy audit can find your plant's power hogs, which is the first step in slashing energy costs. If you haven't had an energy audit recently or haven't made energy reduction a plant-wide priority, chances are you're spending more for power than you need to.

It may be worthwhile to have your utility company or an energy consultant conduct a comprehensive assessment. One advantage of hiring a consultant is they will look at your building, equipment and manufacturing processes for potential savings, but can also recommend possible deregulated energy choices, alternative energy sources, on-site generation and other options your utility company probably won't suggest.

You can also conduct a do-it-yourself audit to reveal possible opportunities for immediate savings. What do you think consumes the most power? Chiller? Lighting? Compressed air system? Water heaters?

You can get a rough estimate by examining your electric bill to determine unit costs. Divide your bill amount by the number of kilowatt-hours (kwh) consumed to get your cost per kilowatt-hour. Say it's $0.10. Check the kilowatt ratings of equipment and light fixtures, and estimate the number of hours of operation per year. For example, if you have a 100 kw kiln that runs 2000 hours a year, it costs $20,000 a year to operate (100kw times $0.10 times 2000). If your paint booths have a total of 20 60-watt fluorescent lights, and they're on 2000 hours a year, it costs $240 a year (.06kw times $0.10 times 20 times 2000).

To calculate the cost of operating motors, figure a 1-horsepower motor operates at 0.7457 kw. The numbers you get are only an approximation -- machines don't always run at maximum load, for example -- but they can tell you how to prioritize.

Then send employee teams on a walk-through audit to ferret out inefficiencies. Have them concentrate on priority areas, but also consider everything else, including HVAC, refrigeration, lighting (indoor and out), compressed air systems, hydraulic systems, material handling, fans, pumps, dryers, kilns, injection molding or extrusion, motors (including belts and drives) and energy management.

Once you know what accounts for your biggest energy consumption, put teams of employees to work on cost-saving solutions. What you learn from your own staff may be enlightening. For example, one company's staff members came up with an innovative idea. They determined that changing the plant's hours of operation to a 4:30 a.m. to 1:00 p.m. shift from May to October would drastically reduce energy demands during peak periods.

Another company saved money on air conditioning by purchasing a computer monitoring system to regulate temperatures year-round. You may not need such a system though. There are automatic setback thermostats that will turn off the heat or air conditioning in the evening after everyone leaves the building and turns it back on in the morning before anyone arrives.

On average, every degree you set your thermostat above 70 degrees or below 70 degrees increases your utility bill by 3 percent.

A word of caution: Utility experts warn that it is possible for energy-conscious building operators to outsmart themselves. The cost of reheating or cooling some facilities is so high that it more than offsets any savings from turning the heat or air conditioning off at night. In these cases, the most efficient approach is to set the thermostat at one temperature and leave it there 24 hours a day.

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