2002 Addendum to ARI Standard 885-98: Typical Sound Attenuation Values - Normative

ARI Standard 885-98: 2002 Addendum - Understanding Typical Sound Attenuation Values

For engineers and designers working with HVAC systems, controlling noise is as critical as ensuring optimal airflow and thermal comfort. The 2002 Addendum to ARI Standard 885-98: Typical Sound Attenuation Values - Normative provides an essential framework for estimating and comparing the acoustic performance of HVAC components, making it an indispensable resource for achieving quieter, more comfortable indoor environments. This addendum offers proven methods for predicting sound levels, aiding in the design of effective noise control strategies.

What is ARI Standard 885-98?

ARI Standard 885-98, and its 2002 Addendum, is an authoritative document developed by the Air-Conditioning and Refrigeration Institute (ARI). Its primary purpose is to provide a standardized approach for calculating and reporting typical sound attenuation values for various HVAC system components, such as diffusers and Variable Air Volume (VAV) terminals. This ensures consistency in performance data and facilitates accurate noise prediction for a wide range of applications.

Scope & Purpose

This addendum specifically governs the estimation of sound attenuation for HVAC air terminal devices and diffuser noise. It outlines methods for manufacturers to present typical sound attenuation data in product catalogs, enabling end-users to compare products and estimate the acoustic impact on occupied spaces. The scope includes typical values for discharge sound, radiated sound within ceiling plenums, and diffuser noise. While it provides a valuable estimation tool, it does not replace detailed acoustical analysis for complex or critical applications.

Who Must Comply?

• • Primary Audience: HVAC Engineers, Acoustical Consultants, Mechanical Designers, and Product Engineers involved in HVAC equipment design and application.
• • Industries Affected: Building Construction, HVAC Manufacturing, Acoustics Consulting, and Building Services.
• • Compliance Nature: While the standard itself is often a voluntary industry consensus document, compliance with its reporting methods is frequently a de facto requirement for product competitiveness and specification acceptance.
• • Enforcement: Compliance is typically self-policed by manufacturers and verified by specifiers, engineers, and acoustical consultants during project design and review.

Key Requirements Overview

The 2002 Addendum provides engineers with methods to estimate sound attenuation in octave bands. Key provisions include:

• • Typical Attenuation Values: It offers normative tables presenting sound attenuation values for diffusers and VAV terminals.
• • Discharge Sound Estimation: Professionals must ensure they use the correct factors for VAV terminals based on airflow rates and duct sizes to predict noise entering occupied spaces.
• • Radiated Sound in Plenums: The standard details how to account for sound radiated into ceiling plenums, considering factors like plenum depth and construction.
• • Diffuser NC Calculation: It specifies a direct deduction from sound power to estimate the Noise Criteria (NC) level for diffusers.
• • Manufacturer Data Consistency: Manufacturers are guided to use these values to present comparable acoustic performance data in their product literature.

Related Standards & References

This addendum works in conjunction with broader acoustical standards. It complements ARI Standard 260 (Sound Performance of Air-Terminal Units) by providing specific attenuation values for component-level analysis. Furthermore, it aligns with general noise control principles found in standards like