Category: Articles

Motors are major consumers of energy in industrial and commercial facilities. Equipment such as pumps, chillers and compressors all have motors performing a mechanical function. Mark Farrell, program manager and energy coach, draws on his many years of experience to provide some insights into the best opportunities for reducing motor energy use.

1. Turn motors off when not in use

The biggest energy-saving opportunity for motors is to turn them off where they’re not being used. There’s a perception that it costs a lot of extra energy to turn a motor on, so they’re often left on during breaks. There’s a slight bump in energy use when you turn a motor on, but it’s a lot smaller than most people think.

Starting and stopping motors isn’t just an energy issue, it’s also a wear and tear issue. There are guidelines that tell you the number of starts and stops in a motor, which takes into consideration the wear and tear. For example, a 50 horsepower (hp) motor will have fewer starts and stops allowable over a one-minute period than a 3 or 5 hp unit. Those guidelines are spelled out in NEMA Standard MG 10 and they’re set up to cover wear and tear issues.

If a motor is going to potentially be off for five minutes or more, that’s an energy-saving opportunity. If it’s a smaller (two or three hp) motor, there’s an opportunity to shut it down that’s often overlooked.

For example, a single 10 hp motor operating 25% of the time at idle would consume roughly 1.0 kWh per day at idle. That would be around 200 kWh per year, which at an electric rate of 0.08/kWh would cost about $16 annually. If the motor operated at partial load, such as running an empty conveyor belt, that number could be ten times larger or $160 per year.

2. Right-size your motors

Make sure your motor is sized appropriately. Often, you’ll see motors that are oversized. That’s a good opportunity; the motors are wasting a lot of energy because they’re not operating in their most efficient zone.

For more information about determining if your motors are oversized and the potential savings from downsizing, see the U.S. Department of Energy fact sheet Replacing an Oversized or Underloaded Motor.

3. Add variable frequency drives

Another very common opportunity is to look at the motor load. If you have a varying load in the production process, such as a fan or a pump, that may be a good opportunity to add a variable frequency drive (VFD).

For more information about the energy-saving potential of VFDs in your facility, see Adjustable Speed Drive Part-Load Efficiency from the U.S. Department of Energy.

In the end, you want to be sure that the amount of energy being consumed fits with the application.

Good landscaping design adds beauty to your property and enhances curb appeal. While these are great benefits, did you know that properly placed trees and plants can also reduce heating and cooling costs and make your building more comfortable?

The shady side

Solar heat gain through windows and the roof reduces comfort on hot summer days and increases cooling costs. Leafy trees planted on the south, east and west sides of your building provides cooling shade in summer. In the autumn, the leaves fall, letting through warming sunshine all winter long.

Tree species are available in a variety of sizes and shapes for almost any shade application. Trees with high, spreading crowns (leaves and branches) on the south side provide maximum roof shading. Trees with lower crowns are more appropriate to the west, where shade from the lower afternoon sun is needed. Depending on the species and the building, a tree can provide a substantial amount of shade within five to 10 years of planting.

Shrubs and ground cover help shade the ground and pavement around the building. This reduces heat radiation and cools the air before it reaches the walls and windows.

Breaking the wind

Properly selected, placed and maintained landscaping provides good wind protection for multifamily buildings, reducing winter heating costs. A windbreak reduces heating costs by lowering the wind chill around the building.

Dense evergreen trees planted on the north and northwest sides are the most common types of windbreaks. Trees can be planted with bushes and shrubs to block wind from the ground level to the treetops. Location is important in providing an effective windbreak. Plant trees at a distance of two to five times their mature height.

Stay local

Native plants are those that have adapted over time to the local climate. They provide a naturally hardy, drought-resistant and low-maintenance landscape. Landscaping with native plants offers benefits like:

• Less watering. Native plants are accustomed to rainfall, humidity and weather of the region.
• No fertilizer. Again, these native plants are naturally capable of thriving in the local environment.
• No pesticides. Native plants attract native insects, helping to help keep away other insects posing a threat.

Work with local experts to determine which trees, shrubs and native plants will work best for your landscaping needs.

When planning your project, keep safety in mind. Call 811 to have all underground utility lines located and marked. It will help you avoid injury, service interruptions and costly repairs.

I get a lot of questions about load factor. What is it? How is it calculated? Is a high load factor good or bad?

Simply put, load factor is a ratio of your facility’s average load over your peak load. The formula is relatively simple.

First, divide your monthly electricity usage in kilowatt-hours (kWh) by the number of hours. That number is your average load.

Second, divide your average load by your peak demand, which is what your energy company charges you for every month. The result is your load factor, which is expressed as a percentage.

But what does that number mean? A high load factor — anything over 70% — is considered good. It means your peak demand curve is relatively level. It’s an indication you’re spreading out your demand, resulting in a lower peak demand charge.

A lower load factor means you have a higher peak demand compared to your average load. That sounds like an opportunity to flatten your load curve by spreading out usage more effectively throughout the day.

Simple strategies such as staggering scheduling, charging equipment during off hours and running processes at different times can all lead to higher load factors, lower peak demand charges and lower energy bills without reducing total production output.

Load factor is a good indicator of your opportunity to level peak demand, and that’s something you should factor into your planning. It can save you quite a load of money.