KCF Technologies Blog

Up on the Roof, There's Room for Big Improvement

Founded in 1980, the non-profit American Council for an Energy Efficient Economy (ACEEE) "acts as a catalyst to advance energy efficiency policies, programs, technologies investments, and behaviors" in the belief "...that the United States can harness the full potential of energy efficiency to achieve greater economic prosperity, energy security, and environmental protection for all its people."Since 1993, ACEEE has organized Summer Study sessions to examine key issues with important ramifications for our nation's energy use and policies, sharing papers on the their findings.

In 2004, one of the papers published was "Wireless Condition Monitoring and Maintenance for Rooftop Packaged Heating, Ventilation and Air-Conditioning" by Srinivas Katipamula and Michael R. Brambley of the Pacific Northwest National Laboratory.  By looking not at the largest HVAC systems in the land, but instead on the sorts of small-scale single-enterprise units that serve most sops and stores in the U.S., they focused attention where it was desperately needed.

Although the co-authors note that packaged cooling systems are used in 4.7 million U.S. businesses including 36.5 billion square feet of commercial space in more than half the businesses in the nation, they are not above dishing the dirt on these overworked, under-serviced, indifferently maintained systems:

"During commissioning and re-tuning, they are often found with inoperable dampers, dirty/clogged filters and coils, incorrect refrigerant charges, failing compressors, failed fans missing enclosure panels, incorrectly implemented controls, and other problems.  Frequently, actual operating hours deviate considerably from intended (and assumed) schedules."

"...These units are often run until a catastrophic failure occurs...Complete failure though is often preventable.  Avoiding failures by properly maintaining the equipment would reduce repair costs, increase operating efficiency, extend equipment life, and ensure comfortable conditions, but this would require awareness of equipment condition and when the equipment needs servicing."

After briefly examining the prohibitively high costs of many maintenance approaches, what do they recommend as delivering the best bang for the buck?  After a detailed examination of refrigerant-side and air-side problems, and major surveys of air conditioning breakdowns, causes, frequency and expense, they conclude that a low-cost wireless monitoring system would represent the best value and the greatest likelihood of achieving the desired protection.  (They figure the average cost at $78 per wireless sensor point, as opposed to $193 for a wired sensor point.)

But, would the achievable savings be worth such an investment, even at one-third the cost of wired sensors?  You be the judge:

"Although there is no reliable data on the number of package units in U.S. commercial buildings operating under degraded conditions and the energy waste associated with such operations, a range of savings from 10% to 30% is generally believed to be achievable by correcting operating problems of these units...Assuming the range of savings is between 10% and 30%, the potential national energy savings  ranges from 23 to 70 trillion BTUs annually."

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