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Application Notes:
Case Study: Energy Savings Make the Case for an HVAC Upgrade |
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Tools: Fluke 1735 Three-Phase Power Logger and Fluke 975 AirMeter test tool
Profile: Mike Klingler, Service Mgr., Farber Corporation
Measurements: Energy consumption, air quality
Business Needs:An older six-story building requires cooling even in winter. To condition the air, a 200-ton refrigeration unit operates year round, consuming major amounts of energy. The client wants to reduce HVAC energy usage without increasing the temperature.
Solution:Service contractor Farber Corp. measures energy usage and air quality. Tests show that installing a heat exchanger and shutting down a 200-ton chiller during winter months will save the building owner $9,954 in annual energy costs.
Tools Used:The Fluke 1735 Power Logger measures energy consumed by the chiller. The Fluke 975 AirMeter tester measures indoor air quality before and after the installation to verify system performance.
Cool it: There Must be a Better WayIt was a familiar challenge for Mike Klingler, service manager for Farber Corporation, an HVAC/R contractor in Columbus, Ohio: Prove to a customer that investment in a major HVAC system upgrade would pay for itself in energy savings, without compromising occupant comfort or indoor air quality (IAQ).
"I work in all kinds of buildings," says Klingler, "and I am often asked to reduce the energy costs of the HVAC systems." The subject this time was an older six-story building that once housed an insurance company, but now serves students at a Columbus-area law school.
Working on a project to replace two outdoor cooling towers and install variable frequency drives in the building's HVAC system, Klingler noticed that one of the facility's two big 200-ton capacity chillers was kept running to supply cold water for the system, even in winter.
"A lot of buildings we can cool with outside air," Klingler says. "When we get down to 50-52 degrees and below, we can just draw that outside air in and use it for free cooling. But because of the setup of the law school building, they had to run one of the chillers even when it was 20-25 degrees outside. Because of the duct distribution system we couldn't rely on outside air in certain areas of the building."
As a result, one chiller kept running to supply water chilled to 45 degrees to the air handling units and keep the building's occupied spaces comfortable. The big motors powering the device were consuming a lot of energy and money - power and cost the school could save if Klingler could find a better way to cool. Of course the solution would have to deliver acceptable indoor air quality.
Klingler had a plan in mind, but didn't want to guess how much energy the big chiller was consuming. The return on investment (ROI) for his system optimization program would hinge on energy savings.
Taking the guesswork out "What if I figure another way to cool the system?" Klingler asked himself. There was plenty of cold air available outside during the Columbus winter, where temperatures average 33.5 F in December, 28.3 F in January, 32 F in February and 42 F in March. Klingler figured he could bypass the chiller entirely.
We can use the water from the cooling towers on the roof, he reasoned, to cool the chilled water. Instead of running the chiller, why not use the cooling towers to cool the condenser side water down to 45 degrees F, and simply pump it through a plate and frame heat exchanger to extract waste heat from the chilled water loop? Instead of the chiller's powerful compressor motors, the system would run with just a small pump. The cost of the upgrade would be significant, but Klingler felt he could prove it financially with accurate data on the potential energy savings. (see illustration).
Proving in the PaybackKlingler's measurements with the Fluke 1735 showed that the big chiller averaged 790 kWh of power consumption over a 12-hour period. He computed a total power consumption over the four cold-weather months of 189,600 kWh. At a cost of six cents per kWh, running that chiller was costing the law school $11,376 every winter. Klingler figured his alternate approach would cut that bill by 87.5 percent, for an annual energy saving of $9,954.
He estimated that installing the heat exchanger, piping, valves and controls would cost $46,000. That meant the payback period for the project would be just 4.62 years. And that estimate did not include possible savings due to reduced wear and tear on the chiller unit.
While he's waiting for a response on his proposal for a system upgrade, Klingler has found lots of other uses for the Fluke 1735 and the 975 AirMeter. Beyond simply measuring power consumption, the Fluke Power Logger collects all kinds of power quality information that Klingler figures will help him do his job. And the AirMeter makes it a snap to calculate percentage of outside air required to meet standards.
Working on a one-floor remodel in a ten-story office building, Klingler had to calculate the percentage of outside air delivered to a newly laid out conference room. "We go to ASHRAE 62 and the local building code, and they say 15 percent of the air delivered to the space needs to be outside air, he said. "How do you know that 15 percent is really outside air? You have to go back to the big air handler, take a reading and say, how's this air handler set up right now? What's the percentage of outside air we're providing to the entire building?
A More Savvy Contractor"The power logger makes it real easy for the contractor or engineering group to come in and measure power consumption on individual components in a building, a plant or an industrial facility," Klingler said. "When you start to look at the individual components, it allows you to think in terms of control strategies: how can I control this piece of equipment to reduce energy consumption? How much is it costing me and what can I do for savings?"
Beyond such applications, Klingler sees the Fluke 1735 as a tool that can help him move his business to a higher level.
"For a mechanical contractor such as myself, you're adding service offerings through the use of this product," he said. "It allows you to be a more savvy contractor. It allows you to be more advanced and offer the additional services that I think we should be providing to our customers. You can export the data to spreadsheets, which you can use for presentations to the building owners. That's a big feature when I sit down at the table."
In addition to measuring power consumption, as Klingler did at the law school, the Fluke 1735 measures and logs voltage, amps, frequencies, waveforms, harmonics and power anomalies. "For maintenance and servicing, it's a troubleshooting tool," Klingler said. "You can see if you're having a problem with power, or when you're not sure what's happening and you can't see it with a snapshot from your meter. You can measure it, record it and view it with this device."
"As a contractor, I would use it as a diagnostic tool, and it would be just as valuable to me in that regard as it is as a power consumption tool. I can use it both ways."
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