An Energy Audit Can Find Your Plant's Power Hogs

Performing an energy audit can help reduce your plant's 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.

Energy Hogs

Start your audit with a simple question: Which machines and systems consume the most power at your plant? Possible "energy hogs" include chillers, lighting, compressed air systems and water heaters. Estimating energy consumption rates helps you find immediate ways to save energy costs.

energy audit concept

You can get a rough estimate of each machine's consumption 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 2,000 hours a year, it costs $20,000 a year to operate (100kw × $0.10 × 2,000). If your paint booths have a total of 20 60-watt fluorescent lights, and they're on 2,000 hours a year, they cost $240 per year (.06kw × $0.10 × 20 × 2,000).

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 these estimates can tell you how to prioritize.

Walk through your plant to ferret out inefficiencies. 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.

Cost-Saving Measures

Once you figure out 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, however. 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. As a general rule of thumb, every degree you set your thermostat above 70 degrees in the winter or below 70 degrees in the summer generally increases your utility bill by 3%.

Outside Expertise

Rather than relying on in-house personnel to conduct an energy audit, consider asking your utility company or an energy consultant conduct a comprehensive assessment. An energy consultant has experience looking at your building, equipment and manufacturing processes for potential savings. He or she can also recommend possible deregulated energy choices, alternative energy sources, on-site generation and other options your utility company probably won't suggest.

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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