flexiblefullpage - default
Currently Reading

Why Compact Duct Layouts for HVAC Make Sense

billboard - default
Quality Matters

Why Compact Duct Layouts for HVAC Make Sense

The approach shown here for HVAC duct layouts is a win-win: It saves money and reduces homeowner complaints about indoor comfort

By Tim Kampert March 3, 2020
HVAC duct plan review
It usually takes the average production builder about a year to redesign the ductwork in all of its floor plans and to work out any associated issues regarding installation quality. An alternative is to use compact layouts only on new plans going forward.
This article first appeared in the March 2020 issue of Pro Builder.

Conventional duct layouts place HVAC supply registers near exterior walls because those locations used to make sense: Homes of the past were poorly insulated and drafty, causing interior surfaces of perimeter walls to get cold in winter and hot in summer; blowing conditioned air across them evened out room temperatures and diluted those drafts.

With that, most conventional forced-air HVAC systems place the air handler in the attic—a location that requires long duct runs to reach the room registers at the edges of the floor plan. The result: lots of exposed ductwork in unconditioned attics, which increases thermal loss through pressure differences and duct leaks and forces the system to work harder to maintain setpoint temperatures.

But building is different today. Energy and building codes now require a high level of insulation, high-performance glazing, and better air sealing, so the temperature of perimeter walls doesn’t fluctuate nearly as much as it used to. 

The Case for Compact Layouts for HAVC Ductwork

That’s why some builders have switched to compact duct layouts. To deliver supply air more efficiently, such designs place the air handling unit (AHU) in conditioned space near the center of the home. Multiple plenums placed throughout the floor plan enable fewer, and shorter, duct runs from the AHU to diffusers in the ceiling or high on the wall of each room or area (see diagrams, below).

HVAC air handling unit placed at center of home, with compact duct layout radiating out



traditional HVAC duct layout vs compact duct layout
A centrally located traditional duct layout (left) requires long, less-efficient duct runs, while a compact duct layout (right) features shorter duct runs that reduce thermal loss and energy costs. | Diagrams: courtesy IBACOS


Reducing duct material and installation labor by not running ducts to the exterior walls means compact layouts save builders money on every house.

Some builders still worry that they must wash exterior walls with conditioned air, but today’s windows and code-mandated envelope details really do eliminate that need. In fact, the production builders we have helped to implement this approach report fewer indoor comfort complaints from homeowners

These Details Matter for HVAC Compact Duct Layouts

There are two caveats when it comes to compact duct layouts, but they’re neither complicated nor difficult. 

The first is that installers must be careful not to kink ducts during installation (which is something they shouldn’t do, regardless). Kinking is less of a concern with long, conventional runs that can be gently arched, but shorter runs tend to create tighter turns that may make them more likely to get pinched around framing members or when entering a boot connection.

Some builders still worry that they must wash exterior walls with conditioned air, but today’s windows and code-mandated envelope details really do eliminate that need.

The second is that, unlike conventional stamped registers in the ceiling or floor, you need to use ceiling- or wall-mounted diffusers, which have directional fins designed to serve larger areas. We recommend diffusers with curved blades, so that air is evenly spread across the ceiling and then gradually falls into the room. Once the system is on, the installer can adjust the diffusers for optimal comfort.

Note that diffusers cannot be placed on the floor. That’s not an issue with slab-on-grade homes, but if the plenum runs through a basement or crawlspace, then diffusers must be located high on interior walls.

Diffusing Resistance When Switching to HVAC Compact Duct Layouts

As for implementation, we find it takes the typical production builder about a year to redesign the ductwork in all of its floor plans and to work out any issues associated with installation quality. An alternative is to use compact layouts only on new plans going forward.

Also, while a compact layout takes less time to install, some builders are skeptical about getting HVAC subcontractors to embrace it. The builders we know that have experienced success started with just a few homes, and then, once their trades saw that it made their life easier and reduced callbacks, they readily jumped on board. 


Tim Kampert drives quality and performance in home building as a building performance specialist for the PERFORM Builder Solutions team at IBACOS.


Access a PDF of this article in Pro Builder's March 2020 digital edition


leaderboard2 - default

Related Stories


Sales and Texting? Know the Rules

Texting your sales prospects en masse can be an efficient way to get your message through if you follow these best practices

Business Management

How to Create a More Inclusive Workplace for Women in Construction

Consider these tips and techniques to attract and retain more women in your home building company and reap the benefits of a more diverse workforce

Women in Construction

Ways Women Are Overcoming Hurdles and Making Gains in Construction Careers

Actionable advice for women construction workers who encounter bias on the job

boombox1 -
native1 - default
halfpage2 -

More in Category

Delaware-based Schell Brothers, our 2023 Builder of the Year, brings a refreshing approach to delivering homes and measuring success with an overriding mission of happiness

NAHB Chairman's Message: In a challenging business environment for home builders, and with higher housing costs for families, the National Association of Home Builders is working to help home builders better meet the nation's housing needs

Sure there are challenges, but overall, Pro Builder's annual Housing Forecast Survey finds home builders are optimistic about the coming year

native2 - default
halfpage1 -

Create an account

By creating an account, you agree to Pro Builder's terms of service and privacy policy.

Daily Feed Newsletter

Get Pro Builder in your inbox

Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox.

Save the stories you care about

Lorem ipsum dolor sit amet lorem ipsum dolor sit amet lorem ipsum dolor sit amet.

The bookmark icon allows you to save any story to your account to read it later
Tap it once to save, and tap it again to unsave

It looks like you’re using an ad-blocker!

Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. There are two ways you can keep reading:

Disable your ad-blocker
Disable now
Subscribe to Pro Builder
Already a member? Sign in
Become a Member

Subscribe to Pro Builder for unlimited access

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.