Commercial
Three Ways to Beautify a Space with Grilles, Registers, and Diffusers
By Lukash Hoff-Pruss, PE
Design considerations typically focus on flooring, surface finishes, and lighting when creating an aesthetically pleasing room. A critical room design element that is often overlooked is the HVAC grilles, registers, and diffusers—or GRDs. Every room the building’s HVAC system serves will have some form and combination of GRDs. In fact, if done well and with careful selection, GRDs are so commonplace that they typically blend into the background.
However, if the style and shape of the GRDs are not properly thought out, they can stick out like a sore thumb and be a blemish in an otherwise perfect room. Here are three ways to hide or incorporate GRDs in your room design.
A return grille is designed into the soffits at Ravalli Electric Co-Op facility near Victor, Montana.
This image shows an example of a ceiling reveal for return air at the new Missoula Public Library.
In this image, a return grille has been designed to fit underneath a stairwell at the MSU Rendezvous Dining Hall.
This image shows an example of Light Troffer Diffusers. Photo courtesy of Price Industries.
Reveals
Hide return grilles by creating reveals within soffits for the return grille to recess into. Typically, these reveals are open to a plenum; however less common ducted configurations are also possible. The grille is hidden from view unless you’re standing beneath the reveal.
Another option is to create a reveal at the edge of a ceiling and leave the gap open to the ceiling plenum. This eliminates the need for a return grille and instead allows the return air to flow around the ceiling edge rather than through a traditional GRD.
It is important to properly size reveal openings to avoid issues with noise. If the opening is too small, a whistling noise may be created by the air as it flows through the reveal or it could reduce airflow that may cause downstream issues with the HVAC system. Size reveal openings like this such that the air velocity through the opening is 400 feet per minute.
Incorporate GRDs in Building Elements
Building elements that provide a natural dead space is another great way to blend GRDs seamlessly into a room’s design. For example, lobby spaces with exposed staircases often do not utilize the space beneath the staircase, which makes it a perfect spot for floor or wall return grilles. There are also an emerging number of products today that integrate GRDs into other building elements, such as ceiling fans or lighting. Light troffer diffusers, for example, are linear slot diffusers designed to attach to light fixtures to provide a seamless look. Notice in the image below how the supply diffusers appear to be just a normal border around the light.
These two images show the variety of diffuser designs.
Both options come in a variety of finishes.
A Word to the Wise
Taking an unconventional approach to airflow distribution requires special attention during the system’s design. Despite nice aesthetics, occupants will be unhappy in an uncomfortable room. A well-thought-out design ensures room air is thoroughly mixed, glazing is adequately air-washed, stratification is mitigated, and any noises associated with the system are acceptably quiet. With all these parameters to consider, it can be challenging to find the right solution. Collaboration between disciplines is key to finding a successful solution.
You don’t have to settle when selecting the right grille, register, or diffuser for a room, and your design doesn’t have to be boring! With some creative thinking and astute engineering, it’s possible to create new solutions for airflow distribution that enhance a room’s aesthetics while keeping its occupants comfortable.
About The Author
As the Missoula office’s Buildings Market Group Office Leader, Lukash Hoff-Pruss thrives on helping his team deliver high-quality projects for our clients.
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