ASHRAE Study: HVAC Coil Cleaning = $40,000 Savings from Just One Unit

It’s from an ASHRAE study whose results were published in November 2006, so it’s not exactly brand new news. But a March 5 article at Trans World News calls new attention to the radical savings that ASHRAE demonstrated can be obtained from coil cleaning, and we agree that this study is well worth revisiting — or noting for the first time, if you’ve never heard of it.

The study is titled “Study Verifies Coil Cleaning Saves Energy” (.pdf)  and is still available as a pdf in various places on the Web, such as the link just given. It reports the results of a coil cleaning study performed at 1500 Broadway in New York City, a 34-story skyscraper that is home to, among other things, ABC Studios (and is where Good Morning America is shot; see the Wikipedia article “1500 Broadway”). The study was published in the November 2006 issue of ASHRAE Journal and was authored by Ross D. Baker, P.E. and Robert Baker.

Here’s the short version of what it says:

• “Although it’s known theoretically that cleaning a coil can result in energy savings, little actual testing data and research exist to prove this point. As a result, building managers often ignore or reduce resources devoted to air-handler maintenance when faced with budget constraints. If proper maintenance is a consideration in overall energy costs, conserving in that budget area can be self-defeating.”
• 1500 Broadway has four air handlers. The study was conducted in July through September 2005 by restoring two of the handlers and comparing their performance to the other two.
• “Restoration of [one of the] air handler[s] resulted in improvements that will lead to energy savings of up to $40,000 this year. . . . The coil is 30 years old, and its last cleaning was one year ago, so the coil was in a dirty state.”

And there were other results besides just the $40,000 headline one, including decrease in pressure drop and increase in airflow, increase in thermal efficiency of the cooling coil, decrease of the load on the chiller plant, and increase in efficiency of heat transfer.

The authors concluded:

In addition to the hard results presented in this article, many other “soft” positive results come out of cleaning and normal maintenance operations and its resultant energy savings and airflow increases. The HVAC system performance is increased and can more closely perform to its original intended specified operation. . . . After coil cleaning and regular maintenance, the HVAC systems are cleaner, and do not provide the environment for fungal, bacterial and microbial growth in their coils, ducts, and pipes. IAQ and the awareness of good IAQ are increased in the building, and the overall comfort and work effectiveness can be greatly enhanced. Overall tenant satisfaction with the building environment has been improved as evidenced by the property manager’s communications and positive feedback.

Furthermore, not only will the owner benefit from the obvious energy savings and comfort increase, we also were able to help optimize some other building maintenance and processes and help enhance energy and maintenance effectiveness for years to come.

. . . . Good maintenance and operation practices including coil cleaning can significantly improve energy efficiency and IAQ performance of the HVAC&R systems in a building, such as reported here of 10% to 15%.