Counterpoint: ACCA Standard More than a 'Checklist'

Nov. 11, 2014
In 2005, ACCA took on the challenge of answering that very question: what constitutes a quality HVAC installation? The resultant document — the ACCA 5 QI Standard — is, in essence, a commissioning standard that covers the initial HVAC system design, equipment installation aspects, distribution aspects, and system documentation.

Editor's note: In this commentary, Luis Romeo Escobar, manager of standards and codes for the Air Conditioning Contractors of America (ACCA), responds to a recent article we ran online by Rob Falke of the National Comfort Institute, on how to define a "quality installation." We invite our readers to provide comments to both articles.

I had high hopes, when I began reading the article, “Defining a ‘Quality’ HVAC Installation,” by Mr. Rob Falke, President of the National Comfort Institute. In it, Mr. Falke exhorts the contracting community to include performance measurements in the definition of a “quality installation.” I could not agree more. However, I’d like to take some time to discuss what the ANSI/ACCA 5 QI (HVAC Quality Installation Specification) Standard actually contains.


What is a 'Quality Installation'?
In 2005, ACCA took on the challenge of answering that very question: what constitutes a quality HVAC installation? ACCA led an industry coalition that sought to define minimum steps required to properly design, install, and commission residential and light commercial HVAC equipment. Thanks to the expertise of over 50 industry experts who participated in the draft development and public review process, the ACCA 5 QI Standard received American National Standards Institute (ANSI) recognition in 2007; the Standard was subsequently revised in 2010 with additional expert input.

The document is, in essence, a commissioning standard that covers the initial system design, equipment installation aspects, distribution aspects, and system documentation. Its specific requirements are applicable for both residential and commercial systems. It should be noted that ACCA 5 QI addresses comfort, indoor air quality, equipment robustness, and, as a byproduct, energy efficiency. The ACCA 5 QI is agnostic when it comes to equipment efficiency metrics (EERs, SEERs, HSPFs, etc.); the standard states that all HVAC equipment is to be installed in a manner that satisfies OEM instructions, federal regulations, local codes, and industry norms.

Without Performance There Is No Quality
Mr. Falke hit the nail on the head: the industry’s dirty little secret is that the typical system experiences substantial performance degradation due to improper installation practices.  He reiterates what ACCA has said for over a decade: the typical system loses 30%+ out of the box at time of installation due to a failure to observe standard practices.

Recently, this degradation impact has been quantified as a result of an international coalition (HPC Annex 36. Participating countries were Sweden, France, U.K. and U.S.) working under the auspices of the International Energy Agency (itself under the umbrella of the United Nations Environment Program). That effort undertook a systematic evaluation of the impact of failing to comply with the requirements in the QI Standard. The results were not surprising.

In September 2014, the U.S. National Institute of Standards and Technology (NIST) published, “Sensitivity Analysis of Installation Faults on Heat Pump Performance.” This report presents incontrovertible evidence that non-compliance with the ACCA 5 QI Standard results in quantifiable increases in energy usage and operating costs. In fact, the NIST report demonstrated that the increased energy consumption can be as high as 80% when multiple deficiencies (e.g., duct leakage, low refrigerant charge, equipment oversizing, airflow, etc.) are encountered.

ACCA 5 QI = Quality
We applaud Mr. Falke for recognizing that even when an HVAC system is designed correctly, it does not mean that the actual installation was subsequently done correctly. However, he incorrectly concludes that the QI Standard is nothing more than a “checklist” that ignores the need for testing, balancing and commissioning. We cannot state it emphatically enough: just because someone calls an installation a “quality installation” does not make it so — only those that fully comply with ACCA 5 QI can truly be considered a quality installation.

Even a cursory examination of the standard’s sections §4.0 (Equipment Installation Aspects) and §5.0 (Distribution Aspects) reveals that the installer’s measurements must meet industry-developed tolerances for:

  • Airflow or water flow through the indoor heat exchanger;
  • Proper refrigerant charge;
  • Correct Btuh input for fuel-fired equipment (“on-rate”);
  • Duct leakage;
  • Airflow or hydronic balancing.

The industry-developed tolerances are framed with respect to the initial system design and the manufacturer’s specifications. For example, measured airflow through an indoor blower unit must be within 15% of the initial design and be within the CFM range listed in the OEM product data; with a corollary requirement that the measured external static pressure satisfy similar constraints. Compliance with the standard is based on measurement and verification of specific aspects of the system’s performance.

To bolster the installer’s verification at start-up, the ACCA 9 QIVP (HVAC Quality Installation Verification Protocols) Standard sets the requirements for a third-party verification that a Quality Installation was in fact performed.

In-Field System Capacity Difficult to Measure
Establishing the in-field capacity of the equipment contains an inherent difficulty. Any physical measurement is limited in its accuracy by the sensitivity of the instruments used and the specific procedures and practices followed by the measurer (e.g., technique used with the varied measurement instruments, the precise equipment locations used to undertake the measurements, value recording/rounding, etc.). The individual error of each measurement will propagate with the use of equations that model the physical system. So the individual outcomes become dubious at best because of the likelihood for erroneous and unrepeatable results.

For that reason, comparing the in-field system capacity to the OEM’s rated capacity is not considered a standard requirement by the industry. However, ensuring that the key system measurements detailed in the QI Standard are within the stipulated acceptable ranges allows the installer to gauge the performance of the system as a whole.

More Than Equipment Installation
Mr. Falke is correct in stating that the simple replacement of equipment does not constitute a quality installation. As noted, a QI-based installation requires significant system testing.

Further, he will be pleased to learn that the standard also requires that the owner/operator be provided with the commissioning documentation as well as provided education on how their new system operates and should be maintained.

Efficiency Rating Are Not Guaranteed In The Field
Mr. Falke stated that efficiency ratings are not guaranteed in the field, to which I say, "Amen."

The best contractors adhere to the ACCA 5 QI Standard’s design, installation, and testing aspects. By ensuring that the in-field measurements are within the stipulated tolerances, contractors can be assured that the customer will be comfortable, safe, and more likely to realize promised savings on their utility bills. I am confident that if Mr. Falke were to take the time to review the contents of the ACCA 5 QI – 2010 Standard, he would concur with manufacturers, distributors, contractors, utilities, allied industry organizations (such as ACCA, AHRI, CEE, HARDI, NATE, RESNET), State and Federal entities, and advocacy groups, that it serves as the definition of a Quality Installation.

For those wishing to learn more, please be advised that the QI Standard, the QIVP Standard, and the NIST study are all made available as free downloads at

Luis Romeo Escobar, a graduate of The Johns Hopkins University, is a mechanical engineer and manager of codes and standards for Air Conditioning Contractors of America. He is an active participant and committee member at ASHRAE, National Fire Protection Association, International Association of Plumbing & Mechanical Officials and the International Code Council. He may be reached at [email protected].