8” UFAD: Bringing UFAD benefits to height restricted areas

3 August 2020 Tate
8inch Height Restriction

City height restriction laws, which limit the maximum height of building structures, are put in place for a variety of reasons. Some cities put a limit on the height of new buildings so as not to block the views of other historic buildings in the area, while others do it for practical reasons, like safety around airports. Washington, D.C., for example, does not allow buildings to be more than twenty feet taller than the width of the street that it faces in order to maintain a light and airy feeling in the city, per the 1910 Height of Buildings Act. These height restrictions can make certain aspects of the design and construction process more difficult. In the past, one of those difficulties was being able to take advantage of the many benefits of Underfloor Air Distribution (UFAD). Originally, UFAD required floor heights of 12-18” to accommodate the air distribution equipment, and architects weren’t always able to accommodate the vertical space required to incorporate UFAD in a building, no matter how beneficial it was. Now, with developments in UFAD technologies, UFAD is possible under 8” floors, enabling buildings in height restricted cities to take advantage of it. We’ve already talked about the technology behind 8” UFAD and the benefits of 8” UFAD in retrofit and multi-tenant offices, but now let’s talk about using 8” UFAD in height restricted cities.

Height Restricted

You can read more about the way UFAD has transitioned from 12-18” to 8” in our previous blogs, but here’s a brief recap. By utilizing multiple smaller air handling units, instead of one large unit at the core, we eliminate ductwork and decrease the amount of space needed under the floor. This might be an oversimplification, but it’ll help you see why this is revolutionary for height restricted buildings.  

Using the space between the raised floor and the slab of the building as a pressurized supply plenum eliminates overhead ductwork and reduces the space required to supply building services. Before 8” UFAD, a 12” raised floor was typically required, resulting in a slab-to-slab height well over 11’ to maintain a 9’ interior floor-to-ceiling height. Now, slab-to-slab heights below 11’ are suitable for the technology. In fact, a 7’6” ceiling would only need a 9’6” slab-to-slab height to utilize 8” UFAD. As the ceiling height decreases, so does the slab-to-slab height as shown in figure 1. This allows virtually any building to reap the benefits of UFAD, like reduced energy costs, improved air quality and an increase in employee comfort, as well as higher, more open ceilings. In cities like D.C., every inch of usable space can make a big difference in terms of the building’s design and rentable space. 
Energy use is particularly worth investigating in these building because traditional design methods do not apply. Ducts are often squished into inefficient, wide rectangular shapes to accommodate the minimal service distribution space. Even further, beyond the inefficiency of these ducts, aesthetics play a role. Current design trends tend to eliminate the drop ceiling used to hide these ducts. Eliminating the drop ceiling is even more important when trying to save a few inches of building height while maintaining an adequate floor to ceiling height. Unfortunately, when you have a 6’ or 8’ wide duct coming from the core you are not exposing the desirable aesthetics of a concrete or steel structure, you are exposing an 8’ wide piece of sheet metal.
This same situation can be realized in existing building and retrofit projects. 8” UFAD can reduce the need for ramping and steps, as well as the drop ceilings and overhead air equipment. With heightened focus on improving indoor air quality and the need to reconfigure office layouts in the wake of the most recent Coronavirus pandemic, the ability to include the flexibility of a raised floor and the benefits of underfloor air distribution during these changes can be extremely beneficial. Again, you can read more about this application in our previous blog.
D.C. has one of the most expensive commercial real estate markets in the U.S., so every inch saved in the building’s design can mean thousands of additional dollars or more in rent payments to the building’s owner. And 8” UFAD is a revolutionary system that can save space and money, as well as improve your indoor air quality and employee comfort. Achieving these benefits in a height restricted building used to be a challenge, but now with 8” UFAD it doesn’t have to be. Let our team help incorporate Underfloor Air Distribution into your new build or retrofit project. Call us at 1-800-231-7788 or email us at info@tateinc.com.

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