Engineered Systems - September 2008 - (Page 24)

CaseInPoint stations’ listeners would appreciate hearing HVAC noise along with their favorite tunes. REDUCING NOISE AND VIBRATION Entercom completed a $12 million renovation of the 60,000-sq-ft building in October 2006. Tenants are housed on the ﬁrst ﬂoor, studio personnel on the second, and broadcasting studios for its eight radio stations on the third. Located on the corner of a busy intersection, the all-steel, prefabricated building required signiﬁcant renovation to overcome outside noise from trafﬁc and inside noise from reverberation. “Our acoustical requirement was between NC 20 and NC 25,” said Dave Dawson, principal of W.L. Cassell, the mechanical and engineering ﬁrm in Kansas City that completed the mechanical renovation. “It was all about making sure any equipment we put in didn’t carry into the studio through ductwork or radiate through the walls. We needed a solid, rigid HVAC system as well as a quiet one to prevent vibration and radiated sound.” Meeting an NC (noise criteria) requirement of 20 to 25 is challenging. Rooms in this range are considered “very quiet” and include concert and recital halls and broadcast and recording studios. HVAC systems 11:25:28 AM can be a signiﬁcant contributor to background noise, so Dawson also had to factor in air velocities for supply and return air. Recommended airﬂow for a room this quiet is 250 to 300 fpm for supply air and 300 to 360 fpm for return air. ROOFTOP LOCATION ADDS TO LOW-NOISE CHALLENGE Isolating the broadcast studios on the third ﬂoor from noise was relatively straightforward. “The studios are essentially a room within a room,” said Dawson. “One room is built inside the other and separated by the sound insulation. Duct silencers in the insulation help kill any air noise generated by air moving through the ductwork or any noise generated by the control damper or VAV box.” The bigger challenge was ﬁnding a place for the new HVAC equipment. Dawson would have recommended a separate mechanical room, but Entercom needed as much space as possible for tenants, ofﬁces, and studios. That left the roof as the only choice for the new HVAC installation. Working with Thermal Components, an HVAC supplier in Kansas City, Dawson was able to design a system with the ﬂexibility to meet his low-noise requirements. Two McQuay rooftop units were selected Input 8 at www.esmagazine.com/instantproductinfo Input 23 at www.esmagazine.com/instantproductinfo ESM07081Lattner.indd 1 6/23/08 24 En gi neer ed S y stem s September 2008 http://www.lattner.com http://www.esmagazine.com/instantproductinfo http://www.lattner.com http://www.automatedbuildings.com http://www.esmagazine.com/instantproductinfo

Table of Contents Feed for the Digital Edition of Engineered Systems - September 2008

Engineered Systems - September 2008 Contents Editor's Note HVAC Challenge Back2Basics Case In Point Commissioning Building Automation HVACR Designer Tips Application Checklist LEED®, Or Get (It) Out Of The Way? BACnet Supplement Race To Market Steam Humidification In Pharmaceutical Facilities Outside Air, Inside Data Centers Forecast: Increasingly Cloudy And Under Control Products Computers & Software Literature Glossary Classifieds Advertiser Index Tomorrow's Environment

Engineered Systems - September 2008

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