Energy Audit Revelations
An energy audit should be thought of as an annual physical.
May 13, 2020 By Anatoli Naoumov
When it comes performing energy audits, a common objection I hear from facility owners and operators is, “Everything is fine.” But from my observations, this is rarely the case.
With all due respect to maintenance and operational staff, recommendations of an energy audit are based on a direct observation of operations and a lot of measurements. Routinely the results of direct measurements contradict existing beliefs about the current state of affairs within a building.
Here are several examples we’ve discovered where existing beliefs were proven to be wrong and painfully expensive.
Belief: “The second compressor of our refrigeration plant comes online only when the first one can’t meet the cooling demand.”
Fact: We found that second compressor would come online randomly due to wrong settings. This was uncovered through a direct power draw measurement. The estimated energy waste was about 110,000 kWh per year.
Belief: “All of our condenser fans work. I have climbed onto the roof to check.”
Fact: An audit uncovered that identical fans were drawing significantly different power. Turns out blades were broken on the inner propellers that were not visible while the outer propeller was spinning. Inner blades were broken on two out of three fans, and the loss of 50% of air movement caused the compressors to work harder.
Belief: “During defrosting the evaporator fan stops at our refrigeration plant.”
Fact: Actually, the fan was not stopping, and it was blowing hot air into the freezer. An error in settings was causing energy waste and was deteriorating storage conditions. The audit uncovered this by directly measuring the power draw on the fans.
Belief: “The temperature in this pot is maintained within a narrow range, if it exceeds the range an alarm will sound and a red light will flash.”
Fact: The temperature was elevated by 25F. The alarm wire was torn off. Apparently, a minor failure of the controls triggered the alarm, and a disgruntled worker did not like the sound. Overheating in the area caused a waste of natural gas for heating and carbon dioxide for cooling down the production process at a total estimated cost of $22,000.
These efficiency opportunities were all uncovered during audits through observation and measurement. All were believed to be non-existent by maintenance staff.
The following two examples, suggested by our partners at Enviro-Stewards, reveal savings opportunities that clients did not know existed because they believed everything was in a perfect state already. Remember, efficient equipment does not equate to an efficient operation.
Fume Hood Mystery
An industrial kitchen had a strict standard operating procedure (SOP) which included: turn off fume hoods at the end of cooking. Employees followed the procedure, and the energy-consuming hoods were off by the end of day and were still off in the morning.
This observation alone was insufficient for the auditing team, so the auditors installed a thermocouple at the exhaust on the roof for a week, and they discovered that the hoods were operating several hours every night.
It turned out the cleaning staff was routinely turning the hoods on along with the lights.
The annual energy wasted during nightly clean up added up to $15K on natural gas for heating and $3K on electricity for HVAC.
A number of simple low-cost solutions that could eliminate this waste: a timer, thermocouple-based block on the fume hoods, or interlocking the hoods with the ovens.
Following professional advice from a previous energy audit, an advanced meat packing plant redirected reject heat from its refrigeration plant to preheat hot water in the facility. A $200,000 heat exchanger was installed and was being run 24/7.
However, the installation was performed without any oversight from the prior auditor. Two years later a new energy audit submetered the newly-installed heat exchanger and found that the electrical cost of pumping exceeded the savings on natural gas being achieved in water heating.
Turns out a mistake in the installation caused a very low delta-T, thus rendering the whole heat exchanger highly inefficient. Correcting that mistake cost less than $2,000, but the wasted energy will never be recovered.
An energy audit should be thought of as an annual physical. It must be done regularly to ensure good money is not wasted.
Anatoli Naoumov is a managing director and ‘chief energy waste-buster’ at GreenQ Partners (greenq.ca), which helps identify, implement and report energy saving projects. He has been named a Certified Measurement and Verification Professional (CMVP) by the Association of Energy Engineers (AEE) and the Efficiency Valuation Organization (EVO). For more information, contact him at email@example.com.
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