Articles tagged “hvac noise”
15 articles covering hvac noise in acoustic engineering and building design.
ASHRAE Noise Criteria for HVAC Systems: NC, RC, and Design Limits
Master ASHRAE HVAC noise criteria — NC curves, RC Mark II method, design limits by room type, duct noise calculation, and common specification errors.
Background Noise Curves: NR, NC and RC Compared
Compare NR, NC, and RC background noise rating methods with worked examples showing which curve to specify for HVAC noise control in offices, studios, and hospitals.
What is a Background Noise Survey?
A background noise survey measures ambient noise levels in octave bands to assess compliance with NC, NR, or RC criteria. Learn methodology, equipment, standards, and how results affect acoustic design.
What is HVAC Noise? Controlling Mechanical System Sound in Buildings
HVAC noise is unwanted sound from heating, ventilation, and air conditioning systems. Learn noise generation mechanisms, NC/NR criteria, duct attenuation, and practical control strategies.
What is an NC Rating?
NC (Noise Criteria) is an octave-band rating system for background noise in buildings. Learn how NC curves work, how to read them, target values by room type, and how NC relates to NR and RC.
What is an NR Rating?
NR (Noise Rating) is the European octave-band system for specifying acceptable background noise in buildings. Learn how NR curves work, how they compare to NC, and NR targets by room type.
What is an RC Rating?
RC (Room Criteria) is an enhanced noise rating system that evaluates both level and spectral quality of background noise. Learn how RC curves, spectral balance, and quality descriptors work per ASHRAE.
HVAC Noise Control — The Ductwork Mistake Ruining Your NC 30 Spec | AcousPlan
HVAC duct velocity above 5 m/s generates noise proportional to V⁵. NC curve calculation chain with ASHRAE method. 5 noise sources, 1 worked example.
NC Curve Calculation from Octave-Band Measurements — Step-by-Step
Determine the NC rating from a set of octave-band background noise measurements. Step-by-step tangent curve method, controlling frequency identification, and RC Mark II comparison.
NC vs RC vs NCY — Which Noise Criterion? Most Engineers Pick Wrong | AcousPlan
NC misses rumble below 63 Hz. RC Mark II identifies spectral quality. NCY adds 5 dB penalty. Full comparison with decision matrix and worked example.
What Is Noise Criteria (NC)? — Background Noise Rating for Buildings
NC curves rate background noise across octave bands to reflect how human hearing perceives HVAC and mechanical noise. Learn what NC numbers mean, how they are measured, and what targets apply to your building type.
ASHRAE HVAC Noise Control: Handbook Chapter Summary for Acoustic Designers
ASHRAE HVAC Applications Chapter 49 is the authoritative guide for mechanical noise control in buildings. This summary covers RC/NC curve criteria, duct noise calculation, equipment selection, and silencer design for acoustic designers.
The 15 Acoustic Design Mistakes Architects Make — And the Standard Clauses That Prevent Them
15 specific acoustic design errors that architects commonly make, each matched with the exact standard clause that would have prevented it. Covers NRC misuse, low-frequency neglect, parallel wall flutter echo, soundproofing vs treatment confusion, HVAC noise, glass overuse, ceiling-only treatment, room modes, Sabine misapplication, occupancy effects, and flanking transmission. Includes worked examples and remediation costs.
NC Curves Explained: Understanding NC-25, NC-35, NC-45 Background Noise Ratings
A comprehensive guide to Noise Criteria (NC) curves: how they work, how to determine an NC rating, target values for every room type, and the differences between NC, NR, and RC rating methods. Includes ASHRAE recommended levels and step-by-step calculation examples.
Noise Criteria Explained: NR, NC, and RC Curves — Which One Does Your Project Need?
NR (Noise Rating), NC (Noise Criteria), and RC (Room Criteria) all rate background noise levels in buildings — but they use different curves, different frequency ranges, and are required by different standards. Here is how each system works, when to use which, and the specific values your HVAC engineer needs to hit.