We have already talked about how Dynamic Air Cleaners, with their low static pressure, save money on energy consumption and possibly even fan selection. And how the long filter life, measured in years, saves money on maintenance. But did you know that Dynamic Air Cleaners can also save money on the acoustical side? Not to mention the role that acoustics play in worker productivity.

 

The NC Rating

Commercial tenants are increasingly looking beyond the surface when evaluating Class A space. Good acoustics are an integral part of that evaluation. The Noise Criteria (NC) rating, the numerical value of background noise generated by building equipment and occupant activities, should be below 40 and be consistent across the range of audible frequencies. Tenant leases are often times requiring the space to meet lower NC targets. The space should be free of low, rumbling and high, hissing noises which makes HVAC system design a key component where sound power level from fans are determined by motor power, capacity, static pressure and discharged volume.

 

Reducing Noise at the Source

Effective acoustic planning and design is important for many reasons. The cost of quieting an installed unit always exceeds the cost of a design that makes acoustics an integrated part of the space and system layout. Good noise control starts with effective design of the fan system, including its location, orientation to duct systems, and optional equipment. The low static pressure inherent in Dynamic Air Cleaners can translate to significant sound reduction which can eliminate the need for sound-dampening duct-lining treatments, baffles, silencers, duct sound attenuators, and/or electronic sound masking systems.

 

Case in Point

In 2005, Dynamic V-Banks were installed in 41 air handling units on a project in Washington D.C. at the U.S. Securities & Exchange Commission. According to Mark Shell at Boland, "When you can reduce total static by 1" there is a significant sound reduction. Reducing sound generation at the air handler location is the best approach to quiet acoustics in a space. On the SEC project my recollection is that we went from close to NC 40 to the lease target of NC 35 using special fans, plenums, low duct velocities and Dynamic Air Cleaners."  

 

LEED v4

Until recently, acoustics in commercial buildings had not been a formal part of the LEEDŽ rating system except on a case-by-case basis with possible credits in the Innovation in Design or Pilot Credit 24 categories. New LEED v4 criteria, however, now takes into account the value of good acoustics in enhancing occupant satisfaction and productivity. Under LEED v4, it is now possible to qualify for two points toward the Acoustic Performance credit in the Indoor Environmental Quality (IEQ) section of the new Interior Design and Construction (Commercial Interiors) rating system, and one point in the new Building Design and Construction (New Construction) system.

 

This is good news for U.S. commercial building occupants. Of 22,000 occupants surveyed over several years by the Center for the Built Environment, they found acoustic quality to be the only IEQ factor that on average registered a negative for dissatisfaction.