Georgia Taking Action to Address HVAC Supply Chain Challenges
The HVAC industry is dealing with challenges like every other industry. One particular challenge has resulted in a proposal to temporarily change the building code.
Insulated flexible ducts (the silver tubes) are suspended from the roof rafters in this attic. The flex duct carries supply air to the home or return air from the home. In this case, the insulation is along the ceiling below the flex ducts. The heating/cooling equipment is in a hot attic that can warm to 140 degrees in the summer.
What
It’s now difficult to find flex duct: a flexible, insulated duct that’s common in residential construction. There’s some available in the market though the supply chain is struggling to keep up with demand.
We’re hearing testimony at building code meetings that some houses are unable to be finished because they were designed for flex duct yet the right product or amount of product cannot not be found.
Where
The issue seems particularly acute with flex duct insulated to R-8. That’s the minimum level of insulation allowed on duct work in vented (unconditioned) attics. The energy code allows use of R-6 duct work elsewhere (such as crawlspaces) though hot attics have such a significant impact on the systems (air handler and duct work) in the attic that a higher level of insulation is necessary.
Alternatives
You don’t have to use any flex duct in your house. Flex duct is a common product because it’s relatively easy to install. It’s less expensive than sheet metal duct work and doesn’t require assembly like duct work made from duct board.
Also, choosing not to put heating/cooling systems in vented attics that get very hot in the summer means this isn’t an issue. You could choose to locate the heating/cooling equipment inside the thermal boundary of the house.
For most projects, that means one of two things: 1) the roof line is insulated rather than the ceiling and the heating/cooling equipment sits inside the insulation, or 2) the heating/cooling equipment is located in the house.
The first method can be achieved in a variety of ways. Though you might think of spray foam insulation on the underside of the roof deck as an insulated roof, you could use many other types of insulation along the roof line and any attic walls to accomplish this goal.
The second method typically involves an air handler in a closet with duct work distributed above the ceiling in a hallway. For example, think of a ranch house with an air handler in a closet. The supply duct work is installed in the center of the house with vents provided in each room (like sleeping rooms) that need conditioned air.
Sometimes the ceiling is high enough to install the duct work beneath the ceiling framing and frame a new ceiling below the duct work. Other times, the duct work is installed above the ceiling framing with new framing added over the duct work for air sealing and insulation.
Why?
So, if there are alternative designs and materials, why do we need a change in the building code to address flex duct installations? It can be a significant challenge to change the type of duct work system in the middle of a project.
For example, flex duct is typically round and sheet metal ducts are often rectangular. Changing from one to the other may mean that the new type of duct work won’t fit into a design or a house that’s already under construction with chases/openings framed for a certain type of duct work.
The proposed amendment is intended to help projects that find themselves in this situation. It’s intended to provide some relief for construction that’s been stopped due to a lack of duct work.
Owners pay carrying costs for these projects whether they’re stalled or making progress and lending rates are increasing. The goal is to help home owners with stalled projects.
Proposed Language
Here’s a copy of the proposed language that we expect to see presented before the States Codes Advisory Committee (SCAC):
Where required by Georgia State Minimum Standard Energy Code, R-6 Flexible Duct combined with an approved continuous Radiant Barrier as part of the roof assembly may be substituted for the required R8 Flexible Duct.
The use of this substitution will be valid until June 30th, 2023 at the discretion of the authority having jurisdiction.
(Effective September 1st, 2022)
Language that’s underlined is new language. In this case, this is all new language that would be positioned at the front of the energy code. That seemed easier than separately amending the four sections that address this issue.
The SCAC is a body of 21 members from various constituencies in the design and construction fields. The members are appointed by the Commissioner of Georgia’s Department of Community Affairs - the state’s housing agency. The SCAC will next meet on June 2nd to consider this language.
The Importance of a Radiant Barrier
Earlier in this blog post, we wrote about the challenge of locating heating/cooling equipment in a vented attic that gets hot in the summer. Solar radiation is typically what drives temperatures so high in vented attics during the summer months.
A radiant barrier is a reflective layer that rejects some of the solar radiation. There are different ways to install a radiant barrier: you can buy wood roof decking with a barrier laminated to the roof decking so simply building the roof results in a continuous radiant barrier. You can also purchase rolled products that can be fastened to the underside of roof rafters.
Radiant barriers are typically a layer of metal. Some, such as the rolled products, can be thin like foil. Others, like those laminated to roof decking, can be a bit thicker.
You might also consider using a vented metal roof to reject solar radiation before it reaches the roof decking. In that assembly, you get a durable roof material and a vented assembly that can thoroughly dry after it gets wet.
Southface Institute did some analysis of duct work with R-8 insulation in a vented (hot in the summer) attic compared to duct work with R-6 insulation combined with a continuous radiant barrier as part of the roof assembly. They were very close in performance: the duct work with R-6 insulation and a radiant barrier performed slightly better in the summer because the radiant barrier rejected solar radiation. The duct work with R-6 insulation and a continuous radiant barrier performed slightly worse in the winter when the vented attic was cold.
Window of Opportunity
The language in the proposed amendment gives building code officials some needed flexibility in dealing with projects that have become stalled for the reasons shared here. Even if a project was permitted under the energy code without this amendment in place, a building code official could (on a case-by-case basis) decide whether to re-permit the portion of the work that needs relief. That might be done for a small administrative fee.
The September 01, 2022 effective date is as fast as Georgia can move because of the requirements for open meetings. The end date in the proposed amendment does not mean the substitution cannot be done after the end date. We expect the end date will mean a project that intends to use the substitution would need to be permitted by the end date even if work has not yet started.
Be careful about using the substitution as the building officials asked for the language making the substitution at the building officials’ discretion. Some building officials were not seeing/hearing of any supply chain issues in their jurisdictions and didn't want a substitution if it’s not absolutely necessary. Be sure to work with your building official well in advance if you’re contemplating using this substitution.
In Conclusion
We have two items to share in conclusion. The first is don’t reduce the insulation on duct work in a hot attic even if it’s allowed unless you absolutely have to. Weakening passive systems means you pay more for active systems that operate every month.
We like that (properly) vented attics dry out after the roof has become wet from rain or snow. If you have a vented attic, don’t put your mechanical equipment in the attic. You can have your designer use an energy model to determine what assembly would be best for your project.
Second, we’re teaching a course on heating/cooling systems this Thursday 05|26. We’ll address this issue in the course and we welcome questions as we go. There are still seats available. Real estate agents/brokers can earn continuing education credit. All are welcome to attend.
What challenges have you found in your community? Leave a comment below to share your guidance and concerns.
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