A Study Proving that Coil Cleaning Does Save Energy
This study, which was published in the November 2006 ASHRAE Journal, looked
at air handling units (AHUs) before and after coil cleaning to see what
impacts coil cleaning had on energy savings. We believe it is even more
relevant today, what with Eskom’s sky- rocketing energy costs.
The AHUs were large enough to provide substantial data (both units over
The AHUs were constant volume (not easy to find these days). It would
have been difficult to quantify energy savings on Variable Air Volume (VAV)
The weather data was constant during reporting periods. The study looked
at a huge building [34 stories] in downtown New York. See the following
results and conclusions:
Cleaning the AHU SF9 coil resulted in a decrease in the pressure drop
across the coil, of approximately 14%. This resulted in a corresponding
increase in airflow.
Cleaning the cooling coil in AHU SF9 resulted in an increase of 25.3%
tons of cooling (on prior 81 tons of cooling). They estimated that 100
tons (352 kW) of cooling capacity would be added to the building once all
four AHUs coils were cleaned. (Building had a total of 1,800 [6330 kW]
tons available capacity.)
Cleaning the cooling coil increased the thermal efficiency of the cooling
coil 25% with respect to its ability to transfer its energy to its sensible
loads (10% with respect to latent loads).
Cleaning the cooling coil would continue to save energy by decreasing
the load on the chiller plant, and making the heat transfer of this loading
more efficient. It reduced the time of multiple chiller operation and its
associated pumps, cooling towers, chemical costs, wear and tear, etc.
Restoration of the one air handler resulted in improvements that will
lead to energy savings of up to $40,000 this year, in accordance with the
results and assumptions of this study.
After coil cleaning and regular maintenance, the HVAC systems are cleaner,
and do not provide an environment for fungal, bacterial and microbial growth
in their coils, ducts, and pipes.
Overall tenant satisfaction with the building environment has been improved
as evidenced by the property manager's communications and positive feedback.
Three key variables that added credibility to the study:
Conclusion: Good maintenance practices, including coil cleaning,
can significantly improve energy efficiency (by as much as 10% to 15% as
in this case).