The short answer is yes, coil cleaning does save energy and it is worthwhile,
in both time and money.
We have included an article published in the November 2006 ASHRAE Journal:
Coil Cleaning Saves Energy
This study looked at air handling units (AHUs) before and after coil cleaning
to see what impacts coil cleaning had on energy savings.
Three key variables that added credibility to the study:
See the following results and conclusions:
- 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.
- 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. (This would equate to the huge savings
being achieved in Gateway Shopping Mall. See below).
- 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.
- Conclusion: Good maintenance practices, including coil cleaning, can significantly
improve energy efficiency (by as much as 10% to 15% as in this case).
GATEWAY SHOPPING MALL - UMHLANGA
We have an excellent example of a
similar programme closer to home.
- Ken Davidson, one of South Africa's outstanding Retail Facilities Managers,
and a pioneer of the Going Green campaign in shopping malls, is the Senior
Facilities Manager of Gateway - arguably the country's largest shopping
- Ken has developed a similar programme to the one above. His findings are
that the pristine condition of the AHUs, in addition to the latest in chiller
technology, which they have installed at the complex, is contributing to
a saving of 10% of their monthly energy bill of R6, 000, 000. That's a
massive R600,000 per month!!
- Robert Britz, a master craftsman in air con maintenance, is the SFI Group
Site Manager. He and his team drive the O3 Going Green programme at Gateway.
They use a 1:1 dilution of the chemicals once a year, and a1:15 dilution
whenever they find any dirt in a coil.
- Ken estimates that 30% of the R600,000 can be attributed to O3 chemicals
- a saving of R180,000 per month.
- And SFI Group spent just R55,000 on O3 chemicals for the entire year to
achieve these results!
- In addition, because the O3 Going Green programme eliminates the traditional
3 cleans a year with water, there was a huge reduction in consumption of
that precious commodity.
- Furthermore, downtime has almost been completely eliminated.
- The tenants are happy because their customers can shop in comfort in spite
of Umhlanga's sky-high humidity in summer.
- It's a no-brainer. It proves Going Green does'nt have to be expensive!