Energy Efficiency Auditing in Commercial & Industrial Facilities

In this article we discuss Bridgestone Associates’ approach to energy efficiency auditing, and how this is part of development of an overall energy optimization and carbon footprint reduction strategy.

Facility energy efficiency is fundamental to reducing energy use, improving energy efficiency, and a key component in developing an energy optimization strategy (please see Energy Optimization in Commercial & Industrial Facilities) to minimize facility carbon footprint and reduce greenhouse gas (GHG) emissions.  Commercial and industrial facilities require energy in their day-to-day operations but how they use that energy, how their equipment and systems are designed, and how they are managed and operated all have a direct bearing on energy efficiency, costs and how that facility impacts the global environment.  Many facilities, especially those that are older, were not designed with energy efficiency in mind.  Equipment and systems were typically selected based on their first cost with long-term operating costs and energy use usually a distant second and third.  With higher energy costs and more awareness of GHG emissions, designers of newer facilities and the equipment and systems employed within have been more energy conscious but there is almost always more room for optimization and improvement, including re-calibrating and retro-commissioning of systems.  This is especially the case with the older facilities and their less efficient legacy systems and equipment.

Facility energy efficiency doesn’t mean just replacing old equipment with new, lower energy consuming and more efficient equipment.  While that is a major part of energy use reduction, understanding the equipment, the systems and processes and how they work is the key to determining how to optimize energy use, to determine if there are alternative processes or equipment that are more efficient, and to identify potential ways in which to lower other costs such as operations and maintenance (O&M).  A simple example can illustrate this.  In a recent energy study we examined a commonly used pneumatic conveying system design that transferred powdered milk within a milk processing plant by using a pressurized dilute phase pneumatic air system to blow the powder through a stainless steel pipe.  In our discussions about the system facility staff reported occasional pipe blockages, the wasted time required to clear them, and the lost product.  We advised them that converting to a vacuum system where the powder is sucked through the pipe rather than blown would improve energy efficiency because less energy is required to entrain the milk powder in the air flow before it can be blown down the pipe.  We also advised that a vacuum system would reduce O&M costs. In a vacuum system, when there is a blockage, milk powder will stop flowing immediately because no more can be sucked up from the source, whereas in a pressure system, when there is a blockage, milk powder will continue to pack the pipe until it is full.  This means clearing the blockage in a vacuum system can be much quicker and less expensive with minimal wasted product.  A vacuum system also minimizes any possible powder losses from leaks in the pneumatic pipe, and so helps maintain a dust free environment.  This example illustrates that by really understanding the process and the system and not just focusing on the energy use, we were able to recommend ways by which the system could be optimized to improve energy efficiency, lower energy use and associated costs, improve system performance, and reduce O&M costs.

ASHRAE (the American Society of Heating, Refrigeration, and Air-conditioning Engineers) provides excellent guidance on commercial and industrial facility energy auditing.  They have identified and defined three levels of energy audit:

• Level I – Preliminary Energy Use Evaluation and Walkthrough Assessment
  • Gather existing utility use and cost data
  • Facility Management interviews
  • Analyze use and cost. Compare to similar facilities.
  • Walk Through Analysis.
  • Some facility personnel interviews.
  • Identify low cost/no cost measures.
  • Identify and prioritize possible capital improvements for future study.
  • Establish baseline and expectations for savings.
• Level II – Energy Survey and Analysis
  • Detailed energy calculations and financial analysis of proposed efficiency measures.
  • Break out energy consumption by end-use.
  • Identify areas which present the greatest efficiency opportunities.
  • Analyze utility rate change opportunities.
  • Key personnel interviews – insights into facility operational characteristics and problem areas. Define financial/non-financial goals of the audit.
  • Develop detail and costs adequate to justify project implementation.
• Level III – Detailed Analysis of Capital Intensive Modifications and Investment Grade Audit
  • Engineering analysis of potential capital intensive projects identified in Level II
  • More detailed data gathering including sub-metering
  • Provides baseline for future measurements.

While these three levels help define the depth to which an energy audit is conducted and act as a good starting point for industrial and commercial facility energy efficiency scope discussions, they don’t necessarily cover all aspects of energy efficiency and process optimization that in total may provide considerable additional benefit to the facility owner.  As the example above illustrates, understanding systems and processes can result in more than just energy efficiency improvements.  In that case a simple energy audit might highlight the existing efficiency of the pneumatic blower motor and recommend a high efficiency motor. It might also recommend a control system to turn off the motor when no milk powder is being conveyed and a variable frequency drive (VFD) to manage energy use of the motor.  Those possible energy efficiency savings are, as noted above, only part of the cost and efficiency optimization opportunities for this system.  By understanding the objective of the process (i.e., to convey milk powder), and by having experience with similar process requirements, Bridgestone was able to present additional ideas that would not only optimize energy use and improve efficiency, but also lower O&M costs, reduce product losses resulting from clearing a blockage, and improve the work environment (i.e., minimize fugitive milk powder).  In this case, the estimated O&M and other non-energy savings almost equaled the estimated energy savings, something that may have been missed in a simple energy audit.

This example is typical of the way in which Bridgestone approaches industrial and commercial facility energy auditing and efficiency projects.  As we work with our clients to optimize their industrial and commercial facility’s energy use and efficiency and lower their carbon footprint, we look to understand their systems and processes, why they are designed and work the way they do, and the details of the equipment that is employed.  As our core team of energy and process engineers and consultants has decades of worldwide experience in industrial and commercial facilities design and the processes, equipment and systems that they contain, gaining this broad understanding can be accomplished quickly.  With that understanding we can then develop ways in which to not only lower energy use and improve energy efficiency, but also optimize process efficiency, lower carbon footprint, and lower O&M and other costs.  Sometimes it is as simple as changing or updating equipment, adding controls, or changing operating parameters.  But sometimes this may mean recommending a modification or change in the overall process used and the equipment employed.  We have heard many times “why should we change, that’s the way we’ve done it for 25 years.”  Yes, agreed it works, but that doesn’t mean there isn’t a better way that is more efficient, uses less energy, and has a lower carbon footprint, something not considered when it was originally designed.  Simply, in Bridgestone’s approach to commercial and industrial facility energy efficiency auditing, unless requested otherwise, nothing is off the table.  Lots of questions get asked and answered so we examine anything that could help improve energy and operational efficiency, lower energy costs, lower O&M costs, and reduce the impact on the environment.

For more information on commercial and industrial facility energy efficiency auditing and process optimization, or to discuss your project needs, please contact us.