7 Construction Codes Support Tighter Air Ducts, More Rigorous Testing

Earlier this year, we published a blog post about various construction codes being updated with tighter duct leakage standards or more rigorous duct testing. We coined this phenomena, “2018: The Year of the Duct,” to encompass all the codes involved including ASHRAE, Uniform Mechanical Code (UMC), International Energy Conservation Code (IECC), and many regional authorities such as the California Title 24.

More recently, ACHR News echoed 2018 being the “Year of the Duct” highlighting the following codes with increased focus on air duct tightness.

2018 Year of the Duct Looming Code Changes
2018 Year of the Duct Looming Code Changes

Some of the codes relating to the “2018: Year of the Duct” phenomena are outlined below.

The most recent updates to the ASHRAE Handbook include expanded parameters for duct testing. According to this widely adopted manual, industry standard practice now dictates that the supply air, return air, and exhaust air systems be tested for leakage during construction and then again after the duct system is fully assembled and installed.

The new guidelines recommend that 25 percent of the system be tested during construction and another 25 percent if any of the initial sections fail. It then dictates that 100 percent of the system be tested if the system fails to meet acceptable leakage rates after the second testing. According to the handbook, leakage tests should be conducted by an independent contractor.

Additionally, the handbook is now recommending a maximum fractional leakage for fan systems of 5 percent. The “system” includes ductwork upstream and downstream of the fan as well as components mounted to that ductwork where leaks can occur (dampers, VAV boxes, etc.). Assuming an average air device leakage rate of 2 percent leaves contractors with very little room for duct leakage (2 or 3 percent), duct sealing becomes even more critical to meeting the requirement.

The latest version of ASHRAE 189.1, the Standard for the Design of High-Performance Green Buildings, is slated for official release later this year. Updates to this standard will expand duct testing requirements to include, for the first time, medium-pressure ducts as well as high-pressure ducts.

“I spearheaded this update to reflect the expanded use of lower-pressure ductwork and the industry’s growing understanding of the performance hit that duct leakage — even in low-pressure ducts — can have on energy usage, indoor air quality, and other building performance issues,” said Jeff Boldt, a voting member of the ASHRAE 189.1 committee and director of engineering at IMEG Corp.

“The industry has resisted testing because of the additional costs involved,” said Bob Reid, former chairman of ASHRAE technical committee 5.2 and currently with Spiral Pipe of Texas. “But new options now make sealing existing ductwork cost effective, so, in reality, building owners can either make a relatively small payment up front to ensure their ducts are operating properly, or they can continue to pay higher operating costs throughout the life of the building.”

Developed by the International Association of Plumbing and Mechanical Officials (IAPMO), the Uniform Mechanical Code (UMC) is an American National Standard used to govern the installation, inspection, and maintenance of HVAC systems. The recently updated code includes, for the first time, guidelines regarding the testing of ductwork that embraces a stepped approach, with an initial testing of 10 percent of the ductwork. If this sample fails to pass, it’s recommended that subsequent testing include an increasingly larger testing sample.

The latest version of this commonly used building guideline took effect Jan. 1. Among changes in the code is a provision that requires building owners to provide all HVAC equipment and testing data needed to determine proper installation. This is intended to increase post-installation testing and drive processes that ensure effective duct sealing has been accomplished.

In addition to these updates, the building industry is poised for other revisions affecting the performance and testing of duct systems.

The fourth version of the Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA) HVAC Duct Construction Standards manual reflects industry innovations that affect the construction, installation, and repair of HVAC ductwork — both metal and flexible ducts.

The new industry guideline, Method of Test to Determine Leakage of Operating HVAC Air Distribution Systems, is expected to recommend specific methods for duct testing.

Often used as the blueprint for other state building code standards, the latest version of California’s Title 24 building standards code is expected to include new emphasis on reducing duct leakage and the role that effective duct performance plays in the energy efficiency of today’s commercial buildings. With the latest updates to this standard currently in the review and comments stage, these changes are expected to go into effect in early 2020.

Why Construction Codes for Ductwork Matter

At surface level, codes might look like just politics between various government authorities. However, codes help us build better buildings. Whether you desire better energy efficiency, indoor air quality (IAQ), HVAC equipment performance, or compliance, codes can help.

More specifically, construction codes for ductwork offer overlooked opportunities for better energy efficiency, IAQ, HVAC equipment performance, and compliance. Basically, these codes ensure ductwork is sealed to an appropriate level of air tightness. If air ducts are not airtight, then they have duct leakage, which contributes to many problems.

4 Benefits of Tighter Ducts in Buildings

Energy Efficiency: Long story short, duct leakage makes ductwork less efficiency which makes your HVAC equipment less efficient too. Sealing ducts airtight improves energy efficiency (and saves you money too).

Indoor Air Quality (IAQ): When ductwork is not airtight, it leaves room for dust and airborne allergens from unconditioned spaces in a building to enter the ductwork and get distributed to the conditioned spaces where people can breathe that bad stuff in their lungs. Sealing ducts airtight minimizes the risk of bad air mixing with clean, conditioned air.

HVAC Equipment Performance: It’s often overlooked how duct leakage actually hurts HVAC equipment performance. When ducts leak, conditioned air from the AC unit or furnace leak out of the ductwork instead of getting distributed to the desired spaces. Sealing ducts airtight ensures conditioned air flows to where you intend it to flow.

Compliance: The fourth benefit of tighter ducts can vary by region. As code authorities update regulations with an increase focus on tighter ducts and more rigorous testing, compliance becomes more important. Non-compliance can have systemic effects for the life a building. Sealing ducts airtight ensures your building will remain compliant and achieve optimal performance.

Are you a building owner? Aeroseal can help you improve energy efficiency, IAQ, HVAC performance, and compliance by sealing the ductwork in your facilities. Find an Aeroseal commercial service provider near you to get started.

Are you a contractor? We’d love to chat with you how Aeroseal can help you help your customers with common building issues they face. Call us 877-349-3828, email us, or leave a comment below.

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