Presentation on theme: "ASHRAE Chapter Meeting Acoustics in HVAC Design"— Presentation transcript:
1ASHRAE Chapter Meeting Acoustics in HVAC Design Presented ByCleve DoyenNoise & Vibration Control, IncThank you _________ for the intro and for the opportunity to speak with you all here this evening.Begin with brief background on BRD and then jump into the presentation.In business since 1975 providing noise and vibration control products, systems, and installation services…in addition to testing and analysis services…not only for purposes of noise control but also for purposes of machinery diagnostics and prognostics.Also provide services like precision alignment and dynamic balancing of rotating equipment because they reduce vibration.So we are involved in almost anything noise or vibration related.Our contact info is shown on the display and of course I have business cards, so if anybody would like one you’re welcome to see me after the meeting.The slide also shows the major markets we serve, not the least of which is HVAC, which is to be our focus here tonight so with no further delay let’s move on to the next slide and take a look at the topics of discussion for this evening.
3Power vs. PressurePWL vs. SPLCause vs. EffectWatts vs. Temperature
4“A” Weighting of Decibels Octave Band Center Frequency, Hz31.5631252505001000200040008000A-weighting-39-26-16-9-3+1-1Correction factors that turn dB into dBA
5Fundamentals of HVAC Acoustical Engineering ASHRAE - Detroit, MI 1-12HVAC Acoustics Tutorial5
6Best Practices Acoustical Design Answer the 4 questions Use 3 to 5 dBA safety factorCursory review on every project; in depth review when warrantedAssess site ambient noise levelsEvaluate airborne and structure-borne transmissionSystem problems require system solutions
7Just Right Acoustics Where are we now? Baseline data (standard) Where do we need to be? Acceptance Criteria (NC, RC, dB, dBA, etc…)What needs to be done to achieve compliance?How much will it cost?
9Construction Trends Less mass in building Less space between floors Drop ceilingsPremium for rentable/usable spaceValue EngineeringHeightened sensitivity of owners/occupantsANSI S12.60CURB MOUNTED RTUs
20RTU Case History #1 Downstream Fan Attenuation Internal RTU Isolation Factory Non-Isolation CurbDeck openings over cut by 4” to 6”Ductwork supports tied into wall studsNo In-curb acoustical treatmentNC-59/50.1 dBA
31RTU Specification Features Design specification with embedded acoustical performanceSingle source supply of Acoustical materialsSpecify procedure for the HVAC contractor to cut and seal deck openings for SA and RA inside the curbRequire acoustical material supplier to inspect & certifyEmbed acoustical specification with RTU equipmentPre-Assembled construction
44High Performance Design Features Plenumized CurbsAcoustical panel curb bottom with SA/RA openings offset from the unit openingSilencers closer to unit or recessed in the curbEliminates the elbow/transition/offset duct connection to the unit opening