Author Archives: CS Editor

Duct construction app

The Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA) has released an app for the third edition of its manual, HVAC Duct Construction Standard—Metal and Flexible. The app provides a simplified process for finding construction options for rectangular ducts with dimensions up to 3048 mm (120 in.) for applications discussed in the manual. It provides options for internal and external reinforcements. Internal options are limited to electrical metallic tubing (EMT) conduit tie rods, and external reinforcements are limited to angles. The app will provide users with a written description of the duct, as well as a visual image of it. It is intended to be used in conjunction with the manual, and is largely used for onsite work. It is available at the Apple App Store or the Google Play App Store.

Natural stone education online

A new online continuing education unit (CEU) course, “Organizations, Resources, and Standards Relevant to Natural Stone,” has been launched by the Marble Institute of America (MIA). The course will provide participants with information regarding the history of industry organizations and why each is relevant to design professionals. Learning objectives include creating an understanding of what resources need to be cited for specific needs and providing information to identify specific publications for stone industry requirements. The course has already been approved for Continuing Education Unit (CEU) credits by American Institute of Architects (AIA) and Landscape Architecture Continuing Education System (LACES). For more information, visit

A Sound Decision

Wood brings acoustic value to structures
by Michael Heeney

In the sea of concrete and granite that people have come to expect from buildings in Washington, D.C., one structure showcasing wood stands out from the crowd. When Arena Stage at the Mead Center for American Theater reopened in 2010, it was the capital’s first modern structure of its size to use heavy timber components. It was also the country’s first project to use a hybrid wood and glass enclosure to envelop two existing structures. Designed by Bing Thom Architects (with Fast+Epp Structural Engineers, Clark Construction, and StructureCraft Builders Inc.), the structure has a lobby large enough to hold up to 1400 patrons from all three theaters out at the same time. To warm that huge space and absorb sound, the design team again used stained poplar for the wood soffit on the lobby ceiling.
Photos © Nic Lehoux. Photos courtesy Bing Thom Architects

When designing a commercial structure, it is important to consider the situational aspects and parameters before selecting the most appropriate building products. While limitations such as budget and availability often sit at the forefront of these decisions, factors like aesthetic details and desired outcomes must be taken into account. One of the chief considerations for many projects should be the acoustics, encompassing everything from sound transmission to absorption and reverberation. Continue reading

Sounding Off on Acoustic Sealants

In the February issue of The Construction Specifier, we published the article, “Using Gypsum Wallboard for Acoustical Control,” by Ashwin L. Himat. The piece dealt with new drywall products designed to reduce noise. However, one reader was concerned there was a bigger picture to keep in mind. Steven Zalben, AIA, NCARB, LEED AP, wrote:

The use of acoustical sealant to reduce sound transmission was only cursorily mentioned. Using an appropriate sealant on both top and bottom plates, and sealing all perimeter joints of all layers, is as important—possibly, more important—than the mass. The mass primarily addresses the structure-borne sound, while sealing primarily addresses airborne sound.

We asked the article’s author to respond.

Mr. Zalben’s feedback on the use of acoustic sealants along wall and ceiling edges for dampening airborne sound transmission is quite valid. It is important to incorporate these sealants into all aspects of the gypsum-board-finishing process, and also to apply acoustical putty around all electrical boxes to prevent similar airborne sound transmission.
The function of gypsum board sealant is similar to that of the viscoelastic polymer used as the middle layer in laminated noise-reducing gypsum boards—both convert sound energy into thermal energy. The image below helps illustrate the sound transmission paths that could be present in most buildings.

SoundTransmissionI would further like to emphasize adding mass with layers of drywall to dampen airborne sound has its disadvantages. For instance, it is not as effective for improving the sound transmission class (STC) rating of the wall system, and it reduces the footprint of the usable space. Decoupling methods using resilient channels also have their limitations, as they are easy to short-circuit during installation. The newer concept of a laminated noise-reducing gypsum board achieves high STC ratings without any of the limitations that often result from adding extra layers of drywall or using resilient channels.

The Drive Toward Energy Efficiency

Energy-efficient light-emitting diodes (LED) luminaires provide consistent light levels for increased visibility and a secure environment.

Energy-efficient light-emitting diodes (LED) luminaires provide consistent light levels for increased visibility and a secure environment.
Photos © Kelly Lee Flora Photography

By Jeff Gatzow

The parking lot at the National Corvette Museum in Bowling Green, Kentucky has upgraded its illumination with light-emitting diodes (LEDs) to improve light quality and provide better lighting control.

Located across the street from General Motor’s Bowling Green Corvette assembly plant—the only place in the world Corvettes are made—it was constructed in 1994, and showcases more than 70 Corvettes.

Visitors can see mint-condition classics, one-of-a-kind prototypes that never went into production, racetrack champions, and modern-day wonders of engineering and design. Attendees also have the opportunity to interact with educational hands-on exhibits, enjoy a film in the theater, and see rare collectibles and memorabilia.

Lighting upgrade
The museum’s upgrade to its three parking lots with LED luminaires was a one-for-one replacement—17 1000W metal halide fixtures were replaced with the same number of 240W LED luminaires. Also, 27 400W metal halide fixtures were switched to 27 120W LED luminaires. At the time the decision to retrofit the parking lots’ lighting was made, the museum had two key priorities for the upgrade: improve the quality and color rendition of the lighting, and enhance control of lighting energy use while maintaining or improving the lot’s safety.

The LED luminaires provide consistent light levels for the entire parking lot, reduced hazardous waste disposal, and provide more efficient light distribution than the metal halide fixtures. Additionally, these luminaires are virtually maintenance-free, offering another opportunity to further reduce expenses.

“The exterior lighting allows us to dramatically reduce operating expenses,” said Bob Hellmann, the museum’s facilities and displays manager. “Additionally, the new lights help make the parking lot bright and secure.”

The retrofit of these 44 fixtures is expected to save the museum $9300 annually in energy expenses and virtually eliminate the $2000 spent in annual maintenance and repair for the incumbent metal halide fixtures. The National Corvette Museum will have a payback of only three years. Further, the utility company, Tennessee Valley Authority, provided $9350 in incentives for the upgrades.

Commitment to sustainability
The National Corvette Museum is committed to sustainability through several green initiatives with the goal of enhanced energy conservation and lessening its carbon footprint. Through these efforts, the museum not only realizes bottom line cost savings, but also works to strengthen business relationships and inspire environmental action by the facility’s patrons.

In addition to the recent retrofit of exterior LED luminaires of the parking lots, the museum has also upgraded other exterior and interior building fixtures to further reduce energy costs and improve the quality of lighting.

“The energy-efficient lighting allows us to drive down operating expenses, present our cars and exhibits in the best light, and contribute to the greening of our community,” said Hellmann. “We installed the LED luminaires and the more efficient fluorescent lights because they pay back in so many ways and it’s the right thing to do.”

Recently, the museum was the site of a 12-m (40-ft) wide 6-m (20-ft) deep sinkhole that swallowed eight vehicles and caused extensive damage.

Before the light-emitting diode (LED) upgrade, metal halide fixtures consumed a lot of energy and required ongoing maintenance at the National Corvette Museum in Bowling Green, Kentucky.

Before the light-emitting diode (LED) upgrade, metal halide fixtures consumed a lot of energy and required ongoing maintenance at the National Corvette Museum in Bowling Green, Kentucky.


Jeff Gatzow is national sales and marketing manager, lighting with Optec LED. The California-based supplier of high efficiency LED lighting fixtures feature a patented thermal management system for cool operation and extended life. Gatzow can be reached by e-mail at