Grafton Village Cheese Company

World Class Refrigeration for a World Class Product. They've been making some of the finest cheeses in the world in Grafton, Vermont for more than a century. Grafton Village Cheese Company's 20 employees are continually proving that the cheddar they make is as good as it gets anywhere. Don't just take their word for it, though. Their three first place gold trophies in the last decade from the International Fancy Food Show speak for them. These people are into quality. With an expected production this year of 1.5 million pounds, Grafton sells its cheeses through fine food stores and mail order, some for more than ten dollars a pound. With a product this valuable they've turned to the Freeaire Refrigeration System to provide the proper 45 degree refrigerated environment needed for the 1 to 3 year aging process.

"It just makes so much sense." These were the words that came to Stan Mack, Grafton's head of facilities and maintenance, when he first heard about the Freeaire Refrigeration System. Those are still the words he uses today, more than a year after Freeaire systems were installed in each of their two 34,000 cubic foot refrigerated warehouses. Peter Mohn, the company's vice president, admits to "bragging that we now use Mother Nature to cool our cheese. It makes perfect sense, given the number of days it's colder than 45 degrees here in Vermont." Not only does the Freeaire appeal to these men's sense of frugality, long a Vermont tradition, by saving money on energy bills and reduced equipment maintenance in the future, it also seems just plain "sensible" to them to store their 100% natural product in such a natural way.

Each of the refrigerated warehouses uses a Freeaire System with two outside air packages. Here you can see the two intake wallcaps mounted on the gable endwall for the "North" cooler. There are two other intakes for the "South" cooler on the other end of the building. That is all that is visible from the outside of this tastefully designed structure. The four exhaust units deliver their air to the attic spaces vented by the cupolas on top. The fan and filter housings for the North cooler are mounted in the floor of the attic near the two doors next to the wallcaps. The air is then introduced into the space through the ceiling, as shown below. The air inside the coolers is circulated around by two Circ fans and two Upflow Circulating fans in in each cooler. You can see one of each in the background (right). Their location was dictated by the fact that the forklifts that load the pallets of cheese into and out of the racks to within 6" of the 15' ceiling would damage anything that projected lower than that. The intake damper housings in the ceiling were several inches out of harm's way.

You can see the two intake damper housings on the end wall of the central aisle of the South cooler (left).They project the cold outside air well out into the space.

Their fan and filter housings are accessible from the loading dock area on the other side of the end wall, as shown here (below, right). The flexible ducts bring the air from near the ridge line on the opposite side of the building from any idling trucks.

None of the exhaust units are visible from the aisle, as they are located next to the outside walls behind great walls of cheese.

The South cooler's Cooler Controller is located near the firedoor that links the two spaces (below, left). Notice the two Upflow fans that pick up cool air near the floor and throw it back down the 57' aisle towards the intake units at the far end. This arrangement keeps the temperature very consistent throughout the space at all times.

It's Payback Time. The most obvious way to determine just what the Freeaire is doing for Grafton Village Cheese Co. is to look at their electric bills for 1998 and 1999. As the two Freeaire systems went on line on December 20, 1998, this is a good place to start comparing before and after the Freeaire. Although the money spent on electricity in 1999 was only $1,229 less than in 1998, we will explain why their actual savings may be more than $100,000! Skeptical? Read on.

First of all, an electricity rate increase of 4.7% for all their power company's customers went into effect in January, 1999. Adjusting for this makes the savings for 1999 at least $3022. Of course, now that the Freeaires are in place, every rate increase in the future will result in further savings. Since we don't know what those increases will be, we just can't count them at this time.

 

The two graphs above were made from Grafton's electrical bills for 1998 and 1999 and show the energy use (kilowatt-hours) and demand charges for the two years. The January '99 bill covers only about two weeks of Freeaire operation, so January is not a good comparison. During the first complete month of Freeaire operation, shown on the February '99 bill, the graphs show an immediate and dramatic drop in both energy use (kwh) and demand (kw). What's more, this trend continues for the next seven or eight months as the two years' figures parallel each other nicely, even right through the summer.

In about September, 1999, this trend begins to break down and disappear as both the kilowatt-hours and the kilowatts begin to return to their former levels. This points out the difficulty in using this kind of "whole building" approach to electrical use. Grafton's electrical bill covers all the electricity used throughout the entire plant. It includes everything used by everyone in all their operations, the cheesemaking, the showroom, hot wax sealing and packaging, mail order and offices, as well as the refrigeration of the warehouses. A change in any of this areas will show up on the electrical bill, especially for a growing company like Grafton Village Cheese. Their busy season begins in the early fall and it doesn't stop until Christmas, and 1999 was their best year yet. It's really only the period immediately after a change like the Freeaire installations that a comparison like this works. We have been told that no major changes were made in the factory during the first nine months of 1999, but after a few months there are just too many variables thrown in to know what is responsible for any change.

As the two graphs both show a consistent trend for eight consecutive months, we will treat just these months as valid, and disregard the rest. The electric bills from February through September show an obvious " Freeaire Effect", and we can then extrapolate to estimate for a full year. From the graph we can estimate an annual savings of $2831 in the cost of electricity (44,168 kwh) and $1,119 for demand charges (an average 6.4 kW reduction per month). A little more than half of the savings comes during the four months that the higher winter rates are in effect.

Cooler Controller Confirmation: Fortunately, there is a way to verify some of these calculations using a data source that looks exclusively at the energy use of the refrigeration systems. That source is the Freeaire's Cooler Controller itself. Its "Energy Info" feature allows you to download the % runtimes (duty cycles) of all the refrigeration equipment connected to it for any period of time up to the previous year. The duty cycles that were recorded for Grafton's systems in 1999 were: compressors: 20% (using a total of 27.19 kilowatts for 1,753 hours for a total of 47,664 kilowatt-hours), evaporator fans: 22% (using 3.54 kW for 1929 hours and 6,829 kwh), Circ fans: 78% (.28 kW for 6,837 hours and 1,914 kwh), and Outside Air fans: 16% (.74 kW for 1,403 hours and 1,038 kwh).

What can we learn from these numbers?

The 20% duty cycle for the compressor sounds like quite an improvement over the 40-50% annual duty cycle that one might have assumed was the situation before the Freeaire systems were installed, but that assumption might not have been warranted. We have hard data only since the Freeaire systems have been installed, and this isn't enough to reach a definitive conclusion. If we make the very conservative estimate of 30% for the pre-Freeaire condensing units' duty cycle, their reduced runtimes would save 23,835 kilowatt-hours per year.

The evaporator fans' 22% duty cycle, on the other hand, tells us quite a lot. Before the Freeaires were installed the evaporator fans never switched off, so their duty cycle had to be 100%. We know that they have experienced a 78% reduction in runtime, and after subtracting the small amount of power consumed by the Circ fans, there would have been about 22,289 fewer kilowatt-hours used by fans inside the warehouses in 1999. Since we also know that all electricity used in the warehouses becomes heat that needs to be removed by the compressors (with a probable expenditure of energy of about 40% of the energy being removed) we can calculate that about 8,916 kwh of our undetermined compressor savings in 1999 was due to reduced evaporator fan operation alone.

The 16% annual runtime for the outside air fans is all new energy use and must be subtracted from whatever savings results from reduced compressor system operation. However, the 1,038 kwh used by the outside air systems would hardly change the savings from the other equipment.

This brings our total energy savings to 45,086 kilowatt-hours , which is only 1% more than the estimate derived from looking at the overall electric bills. Getting basically the same answer using very different methods indicate that the calculations are correct.

More Fun with Energy Info. The Refrigeration Use graph (right) was derived from the Energy Info feature of the Cooler Controller. Right away, we can see that some serious demand savings must be taking place. The compressor systems are taking the winters off, and they don't work very hard in the spring or fall either. The Cool Breeze outside air fans do all the cooling in the winter, and much of the work in the spring and fall. They are even able to find usable cold air during some early and late summer nights. We know there's a reduction of about 30 kilowatts every time the outside air fans and Circ fans operate instead of the four 5-horsepower condensing units and their evaporator fans. When you combine that with the hefty $22.63/kW that the power company charges for wintertime demand peaks, the cost of having the condensing units operate for even 15 minutes could be $672 in a single month. It's not guaranteed, but the warehouses' compressor systems are such large loads when compared to others throughout the plant that it is very likely that they will be involved in the peak demand period in any month in which they operate. A month in which they never operate is a month when they can't be part of the demand charge. The Cooler Controller can't tell if any of its loads have been part of any demand charges by the utility, but seems that the $1,119 savings estimate derived from the electric bills could be an underestimation.

Another thing that you can see in the graph is that extra evaporator fan operation is needed for defrosting purposes only during the summer. That is a dramatic difference from their constant operation before the Freeaire systems were installed. Now, the Circ fans can be seen to be operating whenever the evaporator fans aren't, ensuring adequate air movement, but using 94% less energy.

Live Long. Don't Exercise. Unlike human beings, machines can extend their useful lives by reducing the amount of "exercise" they do. The total estimated replacement cost for the four 5-hp compressors at Grafton is about $20,000 and $8,000 for the four evaporator units. If we estimated their useful life at 10 years before the Freeaire systems were installed, Grafton would have had to set aside about $2800 per year in its equipment replacement fund. However, since the Freeaire systems were installed, the condensing units are operating about 33% less and the evaporator fans 78% less. It should be reasonable to assume that the useful lives of the condensing units and the evaporator fans would be extended accordingly, thus saving about $1289 per year. Of course, the Freeaire's components would also eventually need replacing, but with the intake, exhaust and Circ fans rated for 50,000 hours of operation, their yearly replacement cost should run only about $240 on average for the first 20 years of Freeaire operation. The result is $1049 in estimated yearly savings on equipment replacement costs with their Freeaire systems.

The Bottom Line: When you add the estimates of $2,831 for annual electrical energy savings, $1,119 for annual demand charge savings and $1049 savings each year on equipment replacement the total comes to $4999 per year for the life of the system. (May we round that off to $5,000/year?) The installed cost of the two systems was $16,292, but with the power company (Central Vermont Public Service Corp) generously rebating half the cost, they invested only $8,146. This gives them a payback period of 1.63 years, allowing a 23% profit from their investment even before their 2-year warranty is up. That's very good, but this is only part of the story. You should also consider what the return is over the life of the investment. The phrase "for the life of the system" becomes all-important to the question "Is this just a very good investment, or is this an ABSOLUTELY AWESOME investment?" We would argue for the latter, since we expect the Freeaire systems to still be doing their jobs 20 years from now. We have already assumed $4800 for fan replacements over those 20 years, so there's no reason why the Freeaire's won't be working into 2020, and beyond. This brings us back to the $100,000 in savings spoken of earlier. $5,000 x 20 years = $100,000. That's a return on investment (R.O.I.) of more than 12 times the original $8,146 investment. It's an annual return of 61% for 20 years!

Only time will tell just how good an investment the Freeaire really is, but so far, the evidence points to Grafton Village Cheese having made a wise investment indeed.