Refrigeration

1. How do I know if it makes sense, financially, to bring three-phase power into the building?

2. Making existing refrigeration equipment energy-efficient.

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Q: I'm expanding my gas station into a convenience store, so I'll be bringing in beverage coolers and freezers. I've been hearing about three-phase power and how it's more efficient than single-phase, which my building has now. How do I know if it makes sense, financially, to bring three-phase into the building?

- WC, near Montpelier, VT

Dan: Great question. Before we answer it, here's some quick info for readers who've never heard of three-phase or single-phase power: All electricity leaves generation plants as three-phase power. If you look at power lines coming from a utility pole to a building and you see a single cable, you're looking at a part of the system that's branching off to deliver single-phase power, typically to homes as well as to a variety of types of commercial buildings. When you see the full three lines leading to a building, it's a facility that's using three-phase power, because it needs more power than single-phase provides. Such a facility might have high-demand motors and/or compressors that operate for a significant number of hours, or it might be an office building with a substantial amount of equipment in its computer-server room.

Paul: It's unlikely that your convenience store's electricity needs will be high enough to make your building's conversion to three-phase power a good financial move. It's true that equipment with a three-phase motor typically is more energy efficient than a unit with a single-phase motor. And if your building already had three-phase power, it would make financial sense to buy three-phase-compatible coolers and freezers, open your convenience store, and not give your kind of power another thought. But converting to three-phase is expensive; it could cost thousands of dollars to bring three-phase power into a building. Then there's the cost of converting existing equipment to three-phase or buying new, compatible equipment if possible (three-phase compatibility isn't an option for some equipment). Because of these costs, conversion typically isn't cost-effective unless done in a building with significantly large power needs.

Dan: For your convenience store expansion, a far better use for your energy-saving dollars would be to optimize the efficiency of the coolers and freezers you plan to buy. Start by looking for efficient models. Many cost-effective options exist; you can find equipment with efficient motors and compressors, improved insulation, low heat-generating lighting, efficient anti-sweat door technologies, door-heater controls, devices that bring cool outdoor air into coolers and more. After you've installed your new equipment, you can further reduce energy use by keeping units well-stocked and seeing that coils are regularly cleaned.

Paul: Efficiency Vermont can work with you and your equipment suppliers to identify the right equipment for your needs. You can find out about available rebates for coolers and freezers by downloading the Small Commercial Refrigeration Rebate Application from the Business Rebate Center. Other equipment may be eligible for rebates, so contact Efficiency Vermont before purchasing equipment to see if you can take advantage of these incentives.

Dan: Seeing as you're expanding, I should also point out that the most cost-effective time to invest in energy-saving approaches (equipment, lighting, low-energy windows, efficient construction techniques) is at the time of renovation or new construction. Efficiency Vermont works with architects, construction pros, and equipment suppliers throughout the planning and construction process, to identify ways to get businesses the buildings they want, within their budgets, while lowering energy expenses for years to come.

Paul: If you want to investigate three-phase power further, your electric company can give you a sense of whether or not three-phase power is appropriate for your store's expected energy demand. They also can estimate the cost of bringing three-phase to your location. Best of luck with your store expansion.

Q: In my convenience store, I have reach-in, closed refrigerated cases and a walk-in cooler. I've had some of this equipment for many years and, if it weren't for this economy, I'd think about buying some new equipment. Instead, I'd like to know what can be done to make what I've got as energy efficient as possible.

- JL, Waterbury

A: Dan: Glad to help. It's a great move to look at the energy efficiency of your refrigeration equipment. There are a number of actions you can take. The main considerations in both reach-in and walk-in coolers are air tightness, motors, compressors, and lighting. And, for walk-in coolers, a key element is motor controls.

Paul: True enough. Let's start with the air-tightness of your equipment. A cooler functions in many ways like a building being air-conditioned in the summer. If a building has gaps or cracks where warm air can enter and cool air can escape, the cooling system will have to work harder to keep up. A refrigeration contractor can check your cooler's door seals for air tightness.

Dan: Next: Motors, controls, and compressors. A brushless DC evaporator fan motor (also known as an ECM®) can save $30 to $45 annually in a closed case and between $100 and $130 per fan in a walk-in cooler. Overall savings are greatest when combining walk-in coolers' efficient motors with motor controls, which limit motor operation to when the compressor is on. And if you have a failed compressor (minimum one horsepower) in a walk-in or reach-in, you'll benefit from replacing it with a scroll compressor, which uses less energy and can last up to a third longer.

Paul: As for energy-efficient cooler lighting, it saves energy in two ways. First, it uses less electricity to provide light and, second, it gives off less heat than conventional lighting, which means that a compressor won't need to work as hard to maintain proper temperatures. Replacing T12 fluorescent lights with High Performance T8 fluorescent lights can reduce refrigeration-lighting energy demands by up to 40%. With efficient LED lighting, as much as 60% refrigeration-lighting energy savings can be achieved. LEDs provide brighter and more uniform illumination than T12s; literally putting products in a better light.

Dan: Now that you know the top elements to consider, we want to alert you to additional ways to optimize refrigeration energy use. For example, when humidity is low, such as on dry winter days, you can save energy by turning offdoor heaters. Better yet, install a humidistat, which will turn on and off door heaters automatically, in response to conditions. These can save between $40 and $100 per door per year.

Paul: A simple and effective energy-saving action is to keep a cooler well-stocked with products. This will keep the cooler cold longer and reduce the amount of time the refrigeration system is active. You also can reduce system run times by regularly cleaning the evaporator and condenser coils, to improve air flow.

Dan: For your walk-in cooler, a great money saver is an outdoor-air economizer if you're refrigerating products in closed containers, like beverages. This technology reduces energy use by automatically introducing outside air into the cooler when outdoor temperatures fall below the refrigerated-box temperature. With an economizer, compressors need to run far less often, and condensing units operate up to 20% less. If you install an evaporator fan motor control with the economizer, you can save even more in some walk-ins because a portion of the evaporator fans will automatically shut down when the compressor isn't running.

Paul: You can find out about available rebates for many energy-saving refrigeration improvements by downloading the Small Commercial Refrigeration Rebate (PDF) Application from Efficiency Vermont's Business Rebate Center. Other projects may be eligible for rebates, so contact Efficiency Vermont before purchasing equipment to see if you can take advantage of these incentives.

Q: Guests in my inn often ask if I have a vending machine for beverages on the premises, so I'm considering getting one and I'm doing some research. I've been hearing about a gadget that lowers the amount of energy a vending machine uses. What can you tell me about that?

- MN, Newport, VT

Dan:

The device you've heard about is a simple, plug-in controller that completely powers down a vending machine when the area around it has been vacant for 15 minutes. It does this by using a passive, infrared sensor, which then turns the vending machine's power on when it detects movement nearby. It also periodically turns on, to keep products cold. I highly recommend it.

Paul:

I agree. On average, a cold-beverage machine costs about $350 per year to operate in Vermont. With a vending controller, you can reduce that cost by about $133 per year in high-traffic areas and by about $200 annually in low-traffic locations. Vending machine controllers also reduce maintenance costs and extend the life of the vending machine by significantly reducing the number of times the compressor cycles on and off, to keep the unit cold.

Dan:

To ensure that products stay cold, the controller automatically re-powers the machine at one- to three-hour intervals, depending on the room's temperature. Independent testing by both the Coca-Cola^® and the Pepsi-Cola^® companies determined that one such control - the VendingMi$er - does not adversely affect product quality or the vending machine itself.

Paul:

The VendingMi$er retails for $179. Efficiency Vermont offers an incentive of $45toward the cost of each unit purchased and installed, bringing the net cost to $134. This makes it possible to recoup the purchase price through energy savings in about a year. You can download an incentive form from the Business Rebate Center at www.efficiencyvermont.com. You may also be able to get incentives for similar products.

Dan:

Another way to reduce vending energy use is with ENERGY STAR^® qualified beverage vending machines, which are 50% more energy-efficient than standard models. These units incorporate more efficient compressors, fan motors, and lighting systems and come with an option that operates the machine in low-energy lighting and/or low-energy refrigeration states during times of inactivity. An advantage of these machines over vending controllers is that they come in both indoor and outdoor models, while controllers are designed only for indoor use. Note: If you have refrigerating vending machines (whether ENERGY STAR or not) outdoors, place them on the north or east side of a building, to avoid direct summer sun. That sunlight makes it hard for the condenser to release heat from the unit. This problem also can occur in unconditioned foyers and indoor pool areas.

Paul:

An ENERGY STAR qualified vending machine can reduce yearly electricity costs by about $150, compared to a non-ENERGY STAR model. If you establish a contract with a vendor operator, ask about getting a new or rebuilt ENERGY STAR unit. Efficiency Vermont may be able to work with your vendor to help offset the additional cost of these machines.

Dan:

Whether you go with a vending controller or an ENERGY STAR machine, you?ll be doing your bottom line a favor while you provide your guests with the vending convenience they want.