Understanding VAV Sound Standards - Trane
providing insights for today’s hvac system designerEngineers Newslettervolume 47–4Understanding VAVSound StandardsAcoustics are an important and oftenoverlooked topic in HVAC&R. Manypieces of equipment in these systemsgenerate sound, including chillers, airhandlers, rooftops, and variable airvolume (VAV) boxes. In this EngineersNewsletter, we are going to provide anoverview of acoustics related to VAVboxes.Fundamentals of AcousticsWhen discussing sound, you will see avariety of terms and phrases, includingsound pressure, sound power, Aweighted, noise criteria (NC), room criteria(RC) and many more. When discussingindoor acoustics, NC and A-weightedsound values are used.Sound pressure and power Soundpressure, sometimes written as Lp, refersto the pressure disturbances created assound waves pass through air. The humanear responds to these sound pressuredisturbances. Obstructions in the soundpath between the source and receiveraffect sound pressure.Sound power, Lw, is the magnitude ofacoustical energy created by the soundsource. Unlike sound pressure, distanceand obstructions do not affect soundpower.Noise Criteria (NC) NC values are likelythe most common single-numberdescriptor used to define indoor soundquality. Building owners may requirespecific NC levels for spaces. NC curvesslope downward from left to right toreflect the human ear’s increasingsensitivity at higher frequencies. LowerNC values indicate quieter spaces. The 2018 Trane. All rights reserved.following procedure determines NCgiven sound pressure levels in a rangefrom 63 to 8000 Hz:1. Plot the sound pressure levels foreach octave band on an NC chart.2. Identify the highest NC curveintersected by the plotted soundpressure level. This curve identifiesthe NC rating.Figure 1 shows sample sound pressurelevels on an NC chart. In this example,the 63 Hz octave band determines therating of NC 40 because this is thehighest NC curve intersection. Sound inthe higher frequency ranges drops offquickly.A-weighting Weighting curvesdeveloped by Fletcher and Munson andpublished in 1933 have been used tocompensate for the human ear’s varyingsensitivity at different frequencies. The“A” weighting curve, often written asdBA, is most often used because it bestapproximates human hearing at lowsound pressure levels where hearingprotection is not necessary.To calculate an A-weighted value:1. Subtract A-weighting curve values, indecibels, from the correspondingoctave band sound pressure level foreach octave band (63 to 8000 Hz).2 Use logarithmic addition to sum the1
adjusted sound pressure levels for alleight octave bands. The resultingvalue represents the A-weightedsound pressure level to be expressedwith “dBA” as the unit of measure,e.g. 41 dBA.Figure 1. Plotted sound pressure levels on an NC chartThe entire procedure is explained indetail and with an example in the“Acoustics in Air Conditioning”Applications Engineering Manualpublished by Trane.VAV box acousticsConditioned air is supplied from an airhandler or rooftop unit to spaces tomaintain space temperature in amultiple-zone VAV system. VAV boxesinstalled downstream of the supply fan,are used to vary the supply ofconditioned air to the spaces. The VAVbox contains an airflow-modulationdevice (air valve), controls, anddepending on system application,possibly a heating coil, filter, and smallterminal fan. The air passing through aVAV box generates sound.VAV box sound standardsThere are currently two major soundstandards for VAV acoustics in NorthAmerica: ANSI /AHRI Standard 880and ANSI/AHRI Standard 885.Representatives from AHRI-membercompanies participate in standarddevelopment, which results in industryagreed-upon standards. AHRI publishesits standards online and free to view. Goto www.ahrinet.org to view thesestandards.AHRI Standard 880 AHRI Standard880-2017 “Performance Rating of AirTerminals” establishes testrequirements, rating requirements, andminimum data requirements for airterminal devices.to determine VAV boxsound power. These devices mayinclude pressure-dependent air valves,pressure-independent air valves, fanswith on/off or speed control, heating2Trane Engineers Newsletter volume 47-4elements, and diffusers. The standarddoes not apply to air registers or diffusersand grilles without an air valve.For rating purposes, all manufacturers arerequired to test with a differential staticpressure of 1.5 inches H2O and 100%airflow. This ensures that sound data fromone manufacturer can be comparedequally to another because the data wascollected at the same rating conditions, ifthe data was collected with the sameversion of Standard 880. If differentversions of the standard were used, twosets of data may not be directlycomparable due to the addition of duct endcorrections (see page 3).Discharge sound power refers to thesound that leaves a VAV box. In soundpredictions, the discharge sound power isused to help predict the sound levelsinside a space because of supply airpassing through the VAV box, flexible duct,and diffusers into the space.Radiated sound power escapes the VAVbox casing. This sound will affect indoorsound pressure levels unless attenuatedby acoustic ceiling tiles, for example. It isbecoming more common for commercialbuildings to be built without acousticceiling tiles. With HVAC equipment opento the occupied space, designers mustbe more aware of radiated sound toensure acceptable sound pressure levelsin the occupied spaces. A mitigatingoption would be to locate the VAV boxover a non-critical area.Standard 880 requires that sound powerlevels from octave band centerfrequencies 125 through 4000 Hz bepresented in documentation like catalogsand selection reports. Alternatively, thismay be written in octave bands from 2through 7 (125 to 4000 Hz). Octave band1 at 63 Hz is omitted from the standardbecause air terminals do not generatesignificant sound at this frequency.Manufacturers are allowed to publishdata beyond the required sound bands.Table 1 shows an example 700-cfm shutoff VAV box tested in accordance withAHRI Standard 880. Both discharge andradiated sound power are shown.providing insights for today’s HVAC system designer
In a parallel fan powered VAVinstallation, a small terminal fan in theVAV box recirculates air from theplenum when heat is needed. In aseries fan powered VAV installation, theterminal fan operates continuously.Additional tests with the fan on and offare required for fan-powered VAV boxesbecause the fan generates additionalsound and, depending upon theconfiguration, may not run the entireperiod of operation.Parallel fan-powered VAV box soundpower data is presented for terminalfan-only operation and standard coolingoperation (where the terminal fan is notoperating) as shown in Table 2. Seriesfan powered VAV box sound power ispresented for terminal-fan operationonly and terminal fan plus primaryairflow operation as shown in Table 3.Footnotes generally accompany thetable of data indicating which version ofStandard 880 was used for testing andrelevant commentary on the VAV boxand/or tests.Duct end corrections The Standard800 committee added “duct endcorrections” to the standard beginningin 2011 in an effort to account for openended duct terminations into largerooms. This can be referred as “endreflection loss.” This gives testers theability to account for the sound thatshould enter a test chamber to bemeasured but does not. Instead, somelow-frequency plane waves reboundback into the duct and are notmeasured. In an installation, thisphenomenon is usually desirable as itreduces the amount of soundtransmitted to the space through thesupply air path.Certified sound Manufacturers maychoose to participate in AHRI’s VAV boxCertification Program. Annualindependent verification of randomlysampled VAV boxes ensuresmanufacturer’s performance claims areaccurate within tolerance limits set byboth Standard 880 and the CertificationProgram. The VAV box operatingcharacteristics evaluated includedischarge and radiated sound power (forthe damper and, in the case of fanpowered boxes, the fan), wide-opendamper pressure drop, and fan motorpower consumption.Once approval is received,manufacturers are able to use the AHRIVAV Certification Mark to showcompliance.While certification applies to oneoperating point and cooling-only VAVboxes, manufacturers typically publishdata that covers the entire operatingrange of their products, including theeffects of options like reheat, VAV boxlining, and alternate housinggeometries.AHRI Standard 885 ANSI/AHRIStandard 885-2008 “Procedure forEstimating Occupied Space SoundLevels in the Application of Air Terminalsand Air Outlets” uses sound powertaken in accordance with Standard 880to estimate sound pressure in theoccupied space. This industry-Table 1. Discharge and radiated sound power for a 700-cfm shut-off VAV box.Octave ated575453454236Table 2. Discharge and radiated sound power for a 700-cfm parallel fan powered VAV box.Octave (Hz)125250500100020004000Discharge - valve only666360575449Radiated - valve only645853474235Discharge - fan only665959555048Radiated - fan only696260565249Table 3. Discharge and radiated sound power for a 700-cfm series fan powered VAV box.Octave (Hz)125250500100020004000Discharge - fan and 100% primaryairflow686259555452Radiated - fan and 100% primaryairflow746966636163Discharge - fan only645658545251Radiated - fan only605756535049providing insights for today’s HVAC system designerTrane Engineers Newsletter volume 47–4 3
developed method gives the user aprocedure to compute space soundpressure using hand-calculations or aspreadsheet.In many presentations of VAV boxsound data, a space NC level is printed.The attenuation values printed in TableE1 of Normative Appendix E “TypicalSound Attenuation Values”, often calledtransfer functions, are used as deductsto compute the space sound pressure.Each deduct is subtracted from theVAV box sound power value in thesame octave band to determine soundpressure. Then, the NC-level iscomputed using the sound pressureand published for both discharge andradiated sound. The result is twounique and different NC values for asingle VAV box.This appendix and the attenuationvalues used within are not used toestimate sound pressure for actualinstallations. The attenuation valueswere developed with a number ofassumptions, such as the size of aroom being served by the VAV box, theplenum depth, and acoustical ceilingtype materials. It is for these reasonsthat the NC level printed in a catalogor selection report should not beexpected in the actual installation.Instead, the NC level gives designersanother tool to compare VAV boxesfrom a sound perspective becauseeach VAV box NC level is computedusing the same criteria. To predict anNC level in the actual space, anacoustic model would need to be4Trane Engineers Newsletter volume 47-4created using software like the TraneAcoustics Program (TAP ) or a systemmock up.Separate attenuation values areprovided for the discharge and radiatedsound paths. Over the course ofseveral publications, these attenuationvalues have changed, complicatingmatters. For example, the dischargesound pressure from a medium sizedVAV box serving 700 cfm would bereported as NC 35 when tested inaccordance with ARI Standard 8851998 and NC 31 when tested withStandard 885-2008. For the same box,the radiated sound pressure would bereported as NC 26, NC 27, or NC 22depending on the acoustical ceiling tilematerial being used, if tested withStandard 885-1998 version. If Standard885-2008 were used, only NC 27would be reported. See pages 5-7 for acomparison of the attenuation valuesand their results from the two mostrecent versions of Standard 885.providing insights for today’s HVAC system designer
The evolution of AHRI Standard 885 Sound Attenuation ValuesThe sound attenuation values (transfer functions) found in AHRI Standard 885 have been changed over the course ofseveral publications. Discharge attenuation values have been provided in the standard from 125 to 8000 Hz while radiatedattenuation values have been provided from 125 to 4000 Hz.In the 1998 publication, there were three options for discharge attenuation values based upon VAV box size and airflow:ARI Standard 885-1998 – Table E1 – Discharge Attenuation values1252505001000200040008000Small Box (8 x 8 in.) 300 cfm25283853583128Medium Box (12 x 12 in.) 300-700 cfm27263951533326Large Box (15 x 15 in/) 700 cfm29304051513529In the 2008 update, the discharge attenuation values were largely republished with changes highlighted:ARI Standard 885-2008 – Table E1 – Discharge Attenuation values1252505001000200040008000Small Box (8 x 8 in.) 300 cfm24283953594028Medium Box (12 x 12 in.) 300-700 cfm27294051533930Large Box (15 x 15 in/) 700 cfm29304151523932In the 1998 publication, there were three options for radiated sound:ARI Standard 885-1998 - Table E1 - Radiated Attenuation Values125250500100020004000Type 1 - Glass Fiber191921252935Type 1 - Mineral Fiber181920263136Type 1 - Solid Gypsum Board232625272728In the 2008 update, only the mineral fiber option was left with no changes to the individual octave band attenuation values.Because the octave band attenuation values were not changed for mineral fiber, a strict 1998-to-2008 comparison withmineral fiber should yield no changes.ARI Standard 885-2008 - Table E1 - Radiated Attenuation ValuesType - Mineral Fiberproviding insights for today’s HVAC system designer125250500100020004000181920263136Trane Engineers Newsletter volume 47–4 5
The evolution of AHRI Standard 885 Sound Attenuation Values, continuedAs a result, system designers must be very careful to ensure like-for-like comparisons when using Standard 885 and theresulting NC level derived from Appendix E. Three different VAV boxes were compared using 1998 and 2008 attenuationvalues. The resulting sound pressure and NC values are below.First, a small, 150-cfm VAV box with a 4-inch inlet was evaluated with both versions:125250500100020004000NCDischarge sound power757461585553.if ARI 885-1998: Small Box (8 x 8 in.) 300 cfm were used:5046235-322NC 36.if ARI 885-2008: Small Box (8 x 8 in.) 300 cfm were used:5146225-413NC 36125250500100020004000NCRadiated sound power:525250433933.if ARI 885-1998: Type 1 - Glass Fiberwere used:3333291810-2NC 23.if ARI 885-1998: Type 2- Mineral Fiberwere used:243330178-3NC24.if ARI 885-1998: Type 3- SolidGypsum Board were used:29262516125NC 18.if ARI 885-2008: Type - Mineral Fiberwere used:343330178-3NC 24NCNext, a medium sized VAV box with an 8-inch inlet serving 700 cfm is considered:6125250500100020004000Discharge sound power:717163595860.if ARI 885-1998: Medium Box (12 x 12in.) 300-700 cfm were used:4445248527NC 35.if ARI 885-2008: Medium Box (12 x 12in.) 300-700 cfm were used:4442238521NC 31125250500100020004000NCRadiated sound power:575453454236.if ARI 885-1998: Type 1 - Glass Fiberwere used:38353220121NC 26.if ARI 885-1998: Type 2- Mineral Fiberwere used:39353319110NC 27.if ARI 885-1998: Type 3- SolidGypsum Board were used:34282818158NC 22.if ARI 885-2008: Type - Mineral Fiberwere used:39353319110NC 27Trane Engineers Newsletter volume 47-4providing insights for today’s HVAC system designer
The evolution of AHRI Standard 885 Sound Attenuation Values, continuedFinally, a large VAV box with a 10-inch inlet serving 1100 cfm is considered:125250500100020004000NCDischarge sound power757067666157.if ARI 885-1998: Large Box (15 x 15in.) 700cfm were used:464027151022NC 28.if ARI 885-2008: Large Box (15 x15in.) 700cfm were used:46402615918NC 28125250500100020004000NCRadiated sound power:635954473932.if ARI 885-1998: Type 1 - Glass Fiberwere used:4440332210-3NC 28.if ARI 885-1998: Type 2- Mineral Fiberwere used:454034218-4NC 28.if ARI 885-1998: Type 3- SolidGypsum Board were used:40332920124NC 23.if ARI 885-2008: Type - Mineral Fiberwere used:454034218-4NC 28In the medium-sized VAV box, the reported discharge sound pressure is different when using the dissimilar attenuationvalues.Using NC does present somechallenges. Due to the nature of theprocedure, different sound spectrumscan result in the same NC level. Forexample, a sound spectrumdominated by low frequency soundcould resultin NC 40 shown as the,blue sound spectrum in Figure 2 (nextpage). Middle frequency sounddominates the second soundspectrum, in red, which results in adifferent human response but thesame NC level.Final ThoughtsVAV boxes serve as both soundattenuators and regenerators in HVACsystems. The industry has providedtwo separate sound standards thatpertain to VAV boxes: AHRI Standard880 to determine and present soundpower and AHRI Standard 885 tocompute space sound pressure andshow space NC level with a specificVAV box and representative spaceparameters.In general, radiated and dischargesound power is provided for VAVboxes without terminal fans. Boxeswith terminal fans will have radiatedand discharge sound with and withoutthe fan operating. Sound power is aproperty of the VAV box and soundpressure is the result of installationproviding insights for today’s HVAC system designerand the various paths sound takes to reachthe space or receiver.Published NC levels are based uponexample installations where room sizesand materials are assumed and notspecific to the actual project. Two catalogNC values—one for discharge sound andanother for radiated—are provided. Thesevalues, when printed in a catalog orselection software, should be used only forcomparison. When comparison doesoccur, it is important to ensure like-for-likecomparison in the radiated and dischargematerial and parameters.By Eric Sturm, Trane. To subscribe or view previousissues of the Engineers Newsletter visit trane.com/EN.Send comments to ENL@trane.com.Trane Engineers Newsletter volume 47–4 7
Figure 2. NC chart with two different sound spectrums resulting in the same NC levelResourcesTrane ResourcesGuckelberger, D. and B.Bradley. Acoustics in AirConditioningapplication manual. ISS-APM001-EN. April 2006.Trane. “Fundamentals of HVAC Acoustics” AirConditioning Clinic.TRG-TRC007-EN. February 2018.Trane. “Achieving Acoustical Standards in theClassroom.” Classroom Acoustics White Paper.EDU-SLB026-EN. December 1, choolacoustics/EDU-SLB026-EN 072414.pdfIndustry ResourcesAir-Conditioning, Heating, and RefrigerationInstitute. Variable Air Volume TerminalsCertification Program Operations Manual. AHRI.ASHRAE . 2017. ASHRAE Handbook—Fundamentals, Chapter 8 (Sound and Vibration).Atlanta, GA: ASHRAE.ASHRAE. 2015. ASHRAE Handbook—Fundamentals, Chapter 48 (Noise and VibrationControl). Atlanta, GA: ASHRAE.ArticlesFletcher, H. and W.A. Munson. “Loudness, ItsDefinition, Measurement and Calculation.” TheJournal of the Acoustical Society of America 5, 82;October 1933.Analysis SoftwareTrane Acoustics Program (TAP ). Program detailsand trial software available at www.trane.com/TAPAir-Conditioning, Heating, and RefrigerationInstitute. 2011. AHRI Standard 880-2011:Performance Rating of Air Terminals (I-P).Arlington, VA: AHRI.Air-Conditioning, Heating, and RefrigerationInstitute. 2017. AHRI Standard 880-2017:Performance Rating of Air Terminals (I-P).Arlington, VA: AHRI.Air-Conditioning, Heating, and RefrigerationInstitute. 1998. AHRI Standard 885-1998:Procedure for Estimating Occupied Space SoundLevels in the Application of Air Terminals and AIrOutlets. Arlington, VA: AHRI.Air-Conditioning, Heating, and RefrigerationInstitute. 2008. AHRI Standard 885-2008:Procedure for Estimating Occupied Space SoundLevels in the Application of Air Terminals and AIrOutlets. Arlington, VA: AHRI.8Trane Engineers Newsletter volume 47-4providing insights for today’s HVAC system designer
Join your local Trane office for the 2019 Engineers Newsletter LIVE!Mark your calendar!Small Building System Control. Recent innovations provide more options toconsider for controls in smaller buildings. This program will compare differentconfigurations of packaged rooftop systems, describe the technologies available tocontrol each system type, and demonstrate how to specify the controls to meet theneeds of your customer.Chilled-Water Coil Design for ASHRAE 90.1-2016. The 2016 version of ASHRAEStandard 90.1 requires chilled-water cooling coils be selected for at least a 15 F ΔT.This ENL demonstrates the process for selecting coils and control valves to meetthis new requirement. illustrates coil configuration impact on part-load coilperformance, and discusses the impact on chiller plant design operation.Air and Waterside Economizing Reviews air- and waterside economizingadvantages, drawbacks and considerations when using one versus the other.ASHRAE Standard 90.1 requirements and exceptions will also be discussed.Design Considerations for Hydronic Heating Systems. Investigates variousmethods of providing efficient hydronic heating, including the use of heat-recoverychillers, heat pumps, and boiler systems.Contact your local Trane office for dates and details.Earn PDH credit - no charge and on-demand!NEW Online Courses Available!View all courses at www.trane.com/ContinuingEducationHigh-Performance Air Systems examines the properties of high-performance airsystems and provides guidance on their design. Topics include right-sizing andproper component selection, duct design guidelines, system control strategies,selection for part-load efficiency and much more.Demand Response in Commercial Buildings discusses the relevantimprovements that load shifting and demand response can provide, with examplesof the types of utility and funding programs that are available.Trane, the Circle Logo, and TAP are trademarks of Trane in the United States and other countries. ANSI is a registeredtrademark of American National Standards Institute, Inc. ASHRAE is a registered trademark of the American Society ofHeating, Refrigerating, and Air-Conditioning Engineers, Inc. AHRI is a registered trademark of Air-Conditioning, Heating &Refrigeration Institute, Inc. All trademarks referenced are the trademarks of their respective owners.Trane,A business of Ingersoll RandFor more information, contact your local Traneoffice or e-mail us at comfort@trane.com9Trane Engineers Newsletter volume 47–4This newsletter is for informational purposes only and does not constitute legal advice.Trane believes the facts and suggestions presented here to be accurate. However, final design andapplication decisions are your responsibility. Trane disclaims any responsibility for actions taken onthe material presented.ADM-APN068-EN (December 2018)
"Acoustics in Air Conditioning" Applications Engineering Manual published by Trane. VAV box acoustics Conditioned air is supplied from an air handler or rooftop unit to spaces to maintain space temperature in a multiple-zone VAV system. VAV boxes installed downstream of the supply fan, are used to vary the supply of conditioned air to the .
Variable-Air-Volume (VAV) Box Controller VAV-SVX07*-EN — Tracer UC400 Programmable BACnet Controller for VAV Units VAV-SVP01*-EN — VAV VV550 LonTalk Controller VAV-SVX01*-EN — VAV-UCM 4.2 IOM VAV-SVX02*-EN — VariTrane Pneumatic Controls ReceivingandHandl
Tracer UC210 Trane VAV Controller Tracer UC400 Trane- and field-applied terminal equipment (VAV, WSHP, fan coil, blower coil, generic) BCI-I (IPAK) Trane IntelliPak Rooftop equipment BCI-R (Reliatel) Trane Voyager and Precedent Rooftops Tracer UC600
VAV air-conditioning system is composed of AHU, fresh air/exhaust air/supply air/back air duct, VAV BOX, room temperature controller, VAV BOX is the most important part of this system. VAV AIR-CONDITIONING SYSTEM PLATFORM TASK . The introduction of the system platform . This task’s VAV syst
efficient HVAC solutions is the VAV system. This has led to a steady increase in VAV systems over the past several years. VAV systems save significant energy, comply with ventilation requirements, and provide reliable and personalized occupant comfort. Energy saving features of the Trane VAV
VAV System Overview 4 System Control Introduction The VariTrane VAV box can be connected to Trane’s Building Automation System through two types of control systems. Tracer System In Tracer, the work station using Tracer Summit software monitors the whole system and has many functions such as operating parameter setting, data
VAV systems are the most modern, energy efficient all air systems available for comfort air conditioning. VAV sys-tems require less fan capacity than a comparable constant volume system because with VAV only the required air is used. Typically a VAV system fan volume is 60% of a CAV system. Control of air flow in a VAV system is accomplished
2 BACnet MS/TP and IP VAV Controller I&O Manual 026-1221 Rev 3 1.1.2.BACnet MS/TP VAV Controller (810-8006) The VAV controller is designed to control and monitor various types of HVAC equipment such as baseboards, single and multi-stage duct heaters, fans, valves, and lights. The VAV controller features 4 universal hardware
This asset management policy provides the framework for the care and control of IT assets through their life cycle. The 5 life cycle phases cover acquisition, deployment, operation and maintenance through to decommissioning (retirement) and disposal of assets. The primary purposes of asset management are to: Support delivery of IT services in line with customers’ business plans .
