Keep these three sound principles in mind when designing open-plan spaces for your next green office project.

By Dave Barista, Managing Editor, May 1, 2009, Building Design and Construction

Green Acoustics

For all the attention green buildings get these days, many fall woefully short of expectations when it comes to acoustical performance. Why?

In many cases, acoustical performance is an afterthought on green projects because some green building rating systems, such as LEED, do not include specific acoustical credits, says green acoustics specialist Jeffrey Fullerton, director of architectural acoustics with Cambridge, Mass.-based consulting firm Acentech Inc.

“Without a specific credit for acoustical performance within the LEED system, I think a lot of designers don’t think about it,” says Fullerton. “They’re thinking about so many other things, and the acoustics are not really considered.”

Another factor is the open-plan designs used in many green buildings, which tend to have fewer interior walls, higher ceilings, minimal finishes, and hard surfaces.

Getting the acoustics right in open-plan green workspaces doesn’t have to be difficult for Building Teams, says Fullerton. It’s as easy as ABC.

Absorb. In open-plan environments, the biggest source of sound reflection is the ceiling. “If you have a hard, sound-reflective ceiling, you’re going to have privacy issues between open workspaces,” says Fullerton. “The key is to design a very effective sound-absorbing ceiling for these spaces.”

Building Teams can soften open-plan ceiling spaces using any number of green approaches, such as spray-applying recycled cellulose insulation to the underside of the roof deck or direct-applying acoustical tile to exposed ceiling surfaces. Suspended acoustic “clouds” may also do the trick, provided they meet the project’s sustainable objectives. Green acoustic banners and baffles are also widely available.

For architects looking to re-create the look of drywall, Fullerton recommends a variety of smooth monolithic products, such as stretched fabric panels that can be mechanically attached to most wall or ceiling surfaces. “Drywall looks great, but it reflects a majority of the sound that strikes it,” says Fullerton. “These new monolithic products are exciting because they look like drywall and have very good sound absorption. Architects can achieve both the visual and acoustical goals, while also meeting sustainable objectives.”

Block. Having a solid barrier between building occupants is also vital to good acoustical performance in open-plan spaces. Unfortunately, modern furniture systems do not follow this principle, says Fullerton.

“The trend in office workstations these days is for lightweight, open, and airy products, which promotes openness and collaboration, but is actually the opposite direction you want to go for a private or semi-private environment,” he says.

Ideally, workstations should incorporate fabric-wrapped panels that are five to six feet in height. Designers who are looking for more transparency and daylight may want to consider panels topped with glass or transparent acrylic partitions. “The glass still works for acoustics by extending that barrier higher,” says Fullerton.

Cover up. Absorbing and blocking sound will help improve acoustics in open-plan environments, but achieving superior acoustical performance that provides freedom from distraction requires what Fullerton calls “acoustic perfume,” namely a speech-privacy or sound-masking system.

“By introducing a comfortable level of broadband background noise into the space, people are not able to hear as clearly conversations nearby or the meeting a few tables away,” says Fullerton. He says sound-masking systems on the market today are much smaller than in the past—speakers are no larger than a typical sprinkler head—and their cost has come down considerably. Also, a majority of the newer systems can be installed by facility managers, rather than electrical contractors.

“Designing for high-performance acoustics requires some type of cover-up,” says Fullerton. “You may incorporate the first two principles and still have people who aren’t productive in the workspace because of lack of privacy.”

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There has been a lot of interest generated in better understanding the 42″ panel height requirement in LEED Commercial Interiors, Credit EQ 8.3. In August the United States Green Building Council (USGBC) issued a Credit Interpretation Request (CIR) that clarifies what is and is not required with regard to panel height for this credit. To help clarify the requirements attached below are two slides and the actual credit interpretation that can be used in discussions with designers and clients about why taller panels are acceptable.

42″ Panel Height and LEED Clarification Slides

8/1/2008 -  Credit Interpretation Request
There is much confusion in the design community regarding the number 42 inches and its relationship to the allowable height of movable systems office furniture. We seek clarification that a systems furniture panel could be more than 42 inches tall in this credit since that number is for the eye level of the seated person, not necessarily the maximum height of the panel.

The Reference Guide refers to the calculation of Direct Line of Sight to Perimeter Glazing and provides Table 1, which includes a column labeled “horizontal view at 42 inches,” which may be the source of confusion. The Guide advises that the designer use open plan offices and configure high panels perpendicular to windows to keep views open. It does not state that panels cannot be taller than 42 inches.

It is our understanding that what actually determines whether there is a view for 90% of regularly occupied spaces includes the size and location of perimeter glazing (windows) and what structural components might block views. A person who is seated with their eye level at 42 inches can easily see over a somewhat taller panel to the view if the windows are large enough and appropriately placed. As is illustrated in the horizontal view diagram of Figure 2 in the Reference Guide, a plane of vision isn’t restricted to a straight line, narrow field, it expands out to a wider vertical plane. There is likely to be a maximum height of panel, but that would have to be determined case by case.

For this CIR’s purpose, we request agreement that a panel up to 45″ tall could be acceptable in a situation where the perimeter glazing is of the appropriate size and placement and required submittals support that the view is available to 90% of the seated occupants.
 
9/5/2008 -  Ruling
The way in which this credit is determined is if there is a direct line of sight from a point 42 inches above the floor to perimeter glazing. The perspective in this credit is taken from the seated position, requiring that there be no obstructions above that height in the view. There is no prescriptive requirement for the height of the panels used. In order to support that the credit requirements have been met, please provide floor plans and representative sections highlighting the areas with direct line of sight and showing interior partitions and perimeter windows with respect to the view at 42 inches above the floor.

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7 breakthrough acoustical products for green building

March 1, 2009
Building Design and Construction

For all the praise green buildings receive these days, many of these projects fall woefully short of expectations when it comes to acoustical performance. Why?In many cases, acoustical performance is an afterthought on green projects because some green building rating systems, such as LEED, do not require acoustical credits, says green acoustics guru Jeffrey Fullerton, director of architectural acoustics with Cambridge, Mass.-based consultant Acentech.

Another reason is the minimalist design approach applied on many of these projects: Green buildings tend to have fewer interior walls, higher ceilings, minimal finishes, and hard surfaces.

Luckily, building product manufacturers have recently flooded the market with acoustical products geared toward the green buildings market. We’ve asked Fullerton to select his top seven breakthrough green acoustical products. Here they are, in no particular order:
           
           

            
Ecophon Focus C direct-applied ceiling tiles. “A high-density fiberglass tile that can be used in a glue-up application in existing spaces where lowering the ceiling height is not possible,” says Fullerton. CertainTeed, www.certainteed.com/products/ceilings 
           
              

                        
Fiber-free, micro-slotted acrylic sound absorbers. “These products are ideal for sound absorption in spaces that might be using radiant heating/cooling systems. Because they don’t use fiberglass or porous materials for sound absorption, they eliminate many of the concerns that those materials present. For use in ceiling or wall applications.” DeAmp, www.deamp.com 
          
               

                     
Tierra rapidly renewable ceiling tiles.“The industry’s first biobased, rapidly renewable ceiling tile. For use in open-plan offices where very good sound absorption is sought.” Armstrong, www.armstrong.com/commceilingsna 
           
          

             
Echo Eliminator sound absorbing panels. “For use on walls or ceilings. You can use the panel as is or cover it with a stretch fabric for a more finished look. Ideal for conference rooms or video conference rooms where teleconferencing, audio recording, or microphones are used.” Acoustical Surfaces, www.acousticalsurfaces.com 
       
      

             
K-13 Spray-on acoustical finish. “For use primarily on ceiling surfaces to provide direct-applied sound absorption to an exposed structural deck in an occupied space.” International Cellulose, www.internationalcellulose.com 
         
         

              
Ultra Touch Cotton acoustical batt insulation. “For use in stud walls to achieve improved sound isolation of demising constructions, for example, between adjacent offices.” Bonded Logic, www.bondedlogic.com 
               

Oasis speech privacy system. “A scalable speech privacy (masking or ‘white noise’ system), paging, and background music system that can provide improved speech privacy in open office plans and for closed offices constructed with demountable partitions.” Cambridge Sound Management, www.csmqt.com

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