A Good Partnership
A Good Partnership
One could argue that truss and HVAC design do not have the best history. Many component manufacturers (CMs) have stories about truss webs damaged to accommodate an HVAC system, or the dreaded call from the jobsite saying that the HVAC system simply doesn’t fit with or within the trusses. Much of this discord is due to deferred submittals, and how the people who design trusses and HVAC systems rarely communicate, or if they do, it’s during the later stages of a project.
Apex Technology, a building design company based in Jacksonville, FL, along with CM parent company True House, looked at this problem and asked, “What if we did things differently?”
Apex Technology and True House set out to work with builders and mechanical engineers to integrate all HVAC design into master plan sets. Through this collaboration, Apex can provide both an HVAC plan and a truss plan with duct layout overlay (see Figure 1), where both systems fit together and complement each other.
“We knew it would be cool”
While communication between the building trades has traditionally been fragmented, True House and Apex had a hunch that the market would benefit from this added coordination. “We knew everything was leaning toward Energy Star,” said Mike Kozlowski, P.E., President, noting that working with the mechanical engineer was a good step toward increased energy efficiency because the building envelop design has great influence over the demands placed on the HVAC system.
To test the waters, Apex and True House tried the process with a customer who specifically asked that mechanical layouts be incorporated into the master plans. “They were running into problems in the field with not being able to get ducts the way they wanted them done. They wanted to limit or eliminate those issues,” explained Dan Morris, Truss Design Manager. The early collaboration between truss design and HVAC went well, and True House and Apex knew they were on to something. Much like the initial test case, when other builders saw plans that included both the truss and mechanical design, they responded positively. “It started to fall into place,” said Kozlowski. “It fits together really well. We knew it would be cool.”
The early collaboration between truss design and mechanical engineering worked especially well for a client who wanted to use rigid ducts. After seeing instances where the webs of installed trusses were knocked out and removed to make room for the ducts, Apex and True House devised a solution that didn’t require fitting the ducts in the trusses. “We designed the entire floor system around the mechanical chases. We designed it so the rigid duct fits next to the trusses, without having to feed it through the trusses,” said Morris. “That worked out extremely well.”
“We eliminated a lot of the back and forth”
That first project and subsequent projects gave everyone involved a chance to learn and make adjustments to the process. One notable lesson learned along the way was the order of who should work on the plans. On the initial project, the mechanical engineer worked on the plans first. When the truss designer got the plans, there were HVAC issues that didn’t work with the component design. The team wondered if the process might work better if the truss designer worked on the plans before the mechanical engineer.
“As the truss designers got used to working with the mechanical engineer, they got to know what the mechanical engineer was looking for,” said Morris. The team fine-turned the workflow based on what they learned. “The process evolved, and now plans go to the truss designer first, and the mechanical engineer can usually work with what the truss designer develops. We eliminated a lot of the back and forth,” said Morris.
While truss designers and mechanical engineers may not have a long history of working together, Morris said mechanical engineers have been very open to working with them. “Once you start to explain to them why you can’t do what they want to do or how there’s a more cost-effective way, they’re very open to it.”
Truss designers soon learned that, while component and HVAC design didn’t go hand in hand under the old process, the two trades actually have quite a bit in common. “Mechanical layouts are not much different than trusses,” said Morris. “There are about ten ways to do something. None of them are wrong, but it’s a matter of finding what’s best for a project. It makes for a good partnership.”
To help in the collaboration with HVAC engineers, Mike Berry, P.E., Mechanical Design and Building Science Lead, drafted a document showing the allowable openings in floor trusses of various depths with warren webbing and fan webbing (see Figure 2).
Incorporating the truss design and HVAC into the master plan didn’t just make the lives of the truss designers and mechanical engineers easier—it also helped builders. “When Mike [Berry] does the energy calculations and sizes the system, [the builders] can then bid that out to multiple contractors and make sure they’re getting the system they want,” said Bryan Tebbe, VP of Customer Development.
Simply put, more information gives builders more power to get the structure they truly want. “Builders gain more control of the system and its performance. Some find great value with that,” added Tebbe.
“You don’t have to sell at all”
For Tebbe, it isn’t so much a matter of selling this new process than finding where it meets customers’ already existing needs. “It’s really client specific. You don’t have to sell at all. If they realize the need, it falls in line,” he said. Depending on a customer’s preferences, True House and Apex can adapt to provide the services to meet their project requirements. “Some larger companies, they have all of these master plans and they really understand and see a value in getting the plans complete all the way through. Others prefer to work things out in the field. The trick is knowing which clients have which philosophy,” said Tebbe.
Figuring out what clients want and meeting that need has definitely paid off for Truss House and Apex, and it may also be a preview of what’s to come in terms of the working relationship between truss designers and mechanical engineers. “The drum that I keep beating in the industry is for the truss design group to be part of the building design team instead of deferred submittals,” said Kozlowski. “This is a good thing for the industry. Everybody we talk to is wishing this was going on in their market.”
The Process in Action
For this two-story, 2,642 sq. ft. single-family home, the truss and HVAC systems were optimized together on the front end. Collaborating with the HVAC engineer early on led to some changes in the truss design that helped make installation easier and provided greater cost control.
“The floor truss depth was increased to 20 in. versus the traditional 16 in. depth in our market to accommodate duct work,” Berry explained. “Also atypical, and sometimes more expensive, floor layouts were designed to ease installation and performance of the HVAC system.”
As it turned out, optimizing the truss and HVAC systems on the front end saved money on the project. “The builder was presented with design options ahead of time, and made decisions that met both the truss and HVAC performance goals, which led to the lowest cost of the truss and HVAC combined—not separately as is traditionally done,” said Berry.