Why Maintenance Falls Short on Energy Savings

Why Maintenance Falls Short on Energy Savings

Is the goal behind maintenance really to save energy, or to maintain the performance of the system and avoid its deterioration and increased energy consumption over time as the system ages?

News from utility company maintenance programs is disrupting the long-held assumption that HVAC maintenance delivers measurable energy savings. We all believe we save energy, so let's take a look at some reasons why energy savings are not being realized when typical residential and commercial maintenance programs are offered to our customers.

An effective maintenance program will ideally begin with measuring and scoring the installed performance of the system, followed by service and renovation upgrades to bring the system to an acceptable level of performance.

A Few Definitions
As you consider your role your company’s or utility’s maintenance programs let’s start with a few definitions.

Maintain - The word maintain can be defined as causing or enabling something to exist or continue without changing.

So, is the goal behind maintenance really to save energy, or to maintain the performance of the system and avoid its deterioration and increased energy consumption over time as the system ages?

Service – Service is often lumped in with maintenance, when actually it is a completely different set of tasks with completely different objectives. Service is where energy is saved because systems undergo a change.

It includes providing mechanical services far beyond maintaining the system. Service technicians  who use measurement, calculations, and vast experience coupled with advance troubleshooting and creativity to provide solutions. The outcome of their work is measurable energy efficiency increases.

When the difference between maintenance and service becomes clear, the source of confusion in the industry becomes apparent.

Utility maintenance programs have taken maintenance standards that are designed to not change an HVAC system and have tried to turn them into programs that do change systems in the name of energy efficiency.

There is no way to improve performance without changing a system. Maintenance does not change a system; service and renovation not only change a system, they also improve performance and save energy.

The Failed Assumption
Programs and standards currently make the assumption a system can be "brought to baseline," or brought to an acceptable level of performance. This is typically done by completing a maintenance-based checklist focusing primarily on the equipment and refrigeration circuit versus looking at the system and its efficiency as a whole.

Checklists alone cannot lead to satisfactory installed system performance. Field measurement, calculations, scoring system performance, effective diagnostics, and surgical repairs are required before maintenance repairs can produce intended savings.

System performance cannot be optimized through service tasks only.

Almost every system is in need of some degree of renovation for maintenance, refrigeration repairs or adjustments, and other technologies to realize their full impact on measurable system efficiency.

This renovation and optimization step takes the typical measured installed system performance from the 55% range to above 85%. Only after performance is optimized can the efficiency and comfort potential of the system and the improvements made deliver the intended energy savings.

A study of performance data taken before and after more than two dozen commercial systems were brought to a maintenance-checklist-only baseline shows an average improvement in the installed system performance score of less than 2%; which is barely measurable.

Is that juice worth the squeeze?

How Energy Savings are measured?
Actually, this is the root of the problem -- In utility maintenance programs, individual system savings aren't measured. Scary, isn't it? Savings are calculated based on research averages according to the maintenance tasks that were performed on well-functioning laboratory systems. Then a corresponding fraction of a kW-per-ton savings estimate is assigned to each maintenance task. The savings from the tasks are simply added up and assumed to have happened,

At the completion of the program this savings estimate is usually heavily discounted because the measurement and verification professionals can't find the savings. Why? Any potential energy savings are negated by a poorly performing system. But since few can measure performance, the cause of "no savings" remand hidden.

The same principle holds true for routine service customers. The potential savings of well-performed maintenance cannot be realized without first optimizing the system performance.

An effective maintenance program will ideally begin with measuring and scoring the installed performance of the system, followed by service and renovation upgrades to bring the system to an acceptable level of performance.

New Technologies and Maintenance
In a last ditch effort to keep maintenance programs alive, utility programs are being flooded with new technologies that promise substantial energy savings.

These technologies work great in the lab under ideal conditions, and do produce real savings. But when strapped onto a system operating at 45% of capacity due to low-installed system performance, laboratory savings evaporate.

Although this concept makes sense now, it is a hidden barrier masking potential savings and shutting down maintenance programs across the country. It is wrongfully bringing the value of some standards into question.

Maintenance programs with no requirement to collect measured performance data run great risk to customer satisfaction and achieving utility savings goals.

Adding technologies to maintenance programs has proven to produce fewer savings than anticipated because existing undetected system degradation prohibits the technology to function as designed, reducing savings throughout the life of the system.

Bottom line: Substantial energy savings are only realized when performance is measured before and improved after holistic system upgrades are made as a result of effective diagnostics and completion of an effective scope of work.

Benchmarking with Field Measured Data
Understanding that maintenance is to cause or enable something to exist or continue without changing, a measurement technique called benchmarking becomes essential in tracking performance of a system.

By documenting several key metrics at the time of renovating and commissioning a system, maintenance benchmarks are established. The benchmarks can then be used for a variety of purposes including comparing to manufacturer data, tracking performance degradation over time, and diagnostics.

You can then use benchmarked data to pinpoint causes of system airflow deterioration, refrigerant issues, control failures, as well as issues with economizer performance and duct system functionality. Benchmarking enables detection and surgical correction of uncovered and often invisible system defects. By relying on accurate airflow data, traditional refrigerant diagnostics becomes substantially more accurate as well.

HVAC contractors can and do save energy. Many are really good at it. Energy is saved by testing and calculating performance and then by using each system’s data to effectively diagnose and make surgical system upgrades customized for each individual system.

Rob “Doc” Falke serves the industry as president of National Comfort Institute -- an HVAC-based training company and membership organization. If you're an HVAC contractor or technician interested in a free procedure to benchmark a system, contact Doc at [email protected] or call him at 800-633-7058. Go to NCI’s website at nationalcomfortinstitute.com for free information, articles and downloads.

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