This article addresses part of a presentation Doc will deliver during the 2018 AHR Expo in Chicago on Monday, January 22nd. He will present with Ben Lipscomb about Easily Quantifying HVAC System Efficiency.
The way we look at the HVAC system efficiency has evolved over the last 50 years. If you are an HVAC professional, this history is part of your history. Let’s take a look at some of the events and thinking that have fueled these changes. We’ll end up gazing into the future, where no one has gone before . . .
Early man had a pretty good idea about efficiency basics. When he was cold, he dressed warm and made a fire. If he was still cold, he killed something really furry and made warmer clothes. This increased the efficiency of maintaining body heat. When the fire went out, he’d go out and gather more firewood. Eventually, the smart ones hunted for wood that would burn slower and hotter resulting in less effort gathering wood. Is that a measurement of efficiency?
The earliest step toward measuring airflow was made possible by the invention of the Pitot tube by French Engineer Henri Pitot in 1732. The device, and how it is used to measure air and fluid flow, was further developed by Henry Darcey in the mid-1850s. This technology is still the foundation of airflow measurement today.
Performance measurement, as we know it, has evolved much over the last 50 years. I know, because I was there for most of it (There are virtues to growing old, immersed in what doing what you love). Here is a look, over the decades, at the evolution of HVAC system performance testing.
1960s and 70s – Authority to Test and Verify
In those early days, the architectural and engineering community understood that the intent of their HVAC system designs was not materializing once systems were installed. The performance they created on paper just wasn’t showing up in the field.
In 1965, a fellow in Cleveland, Ohio named H. Taylor Kahoe, took his knowledge of how to field measure HVAC system performance and formed the first professional air balancing organization — The Associated Air Balance Council (AABC).
Over the years, other balancing organizations were formed including the National Environmental Balancing Bureau (NEBB), the National Comfort Institute (NCI), and the Testing, Adjusting and Balancing Bureau (TABB). Each of these groups published and advanced procedures and standards, further defining HVAC system performance measurement.
Then the US oil embargo by OPEC (The Organization of Petroleum Exporting Countries) in 1973 served as a wakeup call for this country as oil prices skyrocketed. Efficiency took on the spirit of panic and our industry hasn’t been the same since.
1980s – Equipment Efficiency Rules
During this decade the U.S. government jumped into the HVAC industry with a keen interest in saving energy through improving HVAC efficiency. HVAC systems accounted for the highest percentage of energy consumption in most homes and buildings and still do to this day.
Initially, energy efficiency efforts were focused on the contractors in the field. Soon it became evident that contractors were focused more on customer satisfaction and comfort than efficiency. The government shifted their focus to equipment manufacturers and utilities, empowering those two groups to help influence contractors through legislation, rulings, and incentive programs.
We’re still living with the results of that handoff. Until this day, HVAC efficiency is primarily defined by the yellow sticker on the side of the box. It depicts the laboratory-rated efficiency of the equipment. That makes sense for manufacturers because their entire business was and is focused on that box. But it didn’t make sense for the rest of the industry, even though the industry followed their lead.
During the 80s, utility companies controlled efficiency by paying rebates to contractors to sell and install equipment with high efficiency ratings. Finding they were able to have little influence on those in the field, utilities partnered with building scientists to devise a scientific approach to HVAC system performance.
1990s – Deemed Energy Savings
Because true HVAC system efficiency couldn’t really be measured in the field in the 1990s, the industry took the path toward verifying HVAC system performance scientifically.
Software was built to estimate and “deem” HVAC system energy performance and savings. In the energy efficiency world, because efficiency improvements could not be measured directly, methods were developed whereby HVAC savings were estimated, averaged, discounted, and calculated. Then an energy savings per ton was assigned or “deemed” to each specific system repair or upgrade.
Meanwhile, training and knowledge became available to the HVAC industry that was consistent with the daily testing and diagnostic practices used by contractors in their day-to-day work. This new testing was based on airflow and performance, which slowly began changing the industry perspective on performance.
2000s – Outsiders are Called In
An idea was conceived by the government to create a group to do the scientific testing and measurement that the HVAC industry would not do. This group was known as energy raters. To the HVAC industry, this was like calling in a plumber to verify the work of a gastro-intestinal surgeon.
The performance testing used by this community implies performance, but has never agreed with the testing used by HVAC industry itself that measures actual operating conditions of a system.
Meanwhile knowledgeable HVAC contractors adopted field testing methods to help their customers understand the performance of their HVAC systems. They placed test instruments in the hands of consumers where they were used as teaching tools. Customers began to learn why they should buy efficiency, and a new breed of field-measured system efficiency was born.
Test methods that quantifying levels of performance and efficiency were developed and then adapted by contractors and technicians. For the first time the real efficiency of an installed system could be measured and quantified in the field.
This field efficiency rating was used in combination with the efficiency rating of the equipment to provide a complete view of installed system performance.
Just as architects and engineers realized the buildings were not performing to design in the 1970’s, during the first decade of the 21st Century consumers, contractors, government, and utilities also began to rediscover the same truth.
During recent years we’ve seen equipment efficiency ratings being coupled with installed system efficiency ratings. Test procedures have been refined, training and certification have been developed, and test instruments have been created to improve the reliability of this testing and calculation method.
The principles that launched HVAC system performance testing introduced by the test and balance industry more than 50 years ago are the foundation of system performance testing. Many thousands are trained and certified to perform this testing and calculation method that produce a numerical score representing the percent of efficiency earned by the installation.
Unfortunately, the average US system operates at dangerously close to 50% of equipment rated efficiency. Even more shocking is that code-compliant systems perform only slightly better.
Into the Future
A committee currently writing an industry standard to measure and calculate performance of installed HVAC systems often uses an internal motto about this scoring method. In speaking of the future of this proposed standard they have been heard to mumble “The HVAC systems on the Starship Enterprise will be commissioned using this scoring method.”
We shall see where the future takes us.
Rob “Doc” Falke serves the industry as president of National Comfort Institute, Inc., an HVAC-based training company and membership organization. If you're an HVAC contractor or technician interested information from the AHR presentation, contact Doc at ro[email protected] or call him at 800-633-7058. Go to NCI’s website at nationalcomfortinstitute.com for free information, articles, and downloads