Standard for Procedure for Estimating Occupied Space Sound Levels in the Application of Air Terminals and Air Outlets

ARI Standard 885: Estimating Occupied Space Sound Levels from Air Terminals

For engineers and designers striving to achieve optimal acoustic environments in buildings, understanding and controlling noise generated by HVAC systems is paramount. ARI Standard 885 provides an essential framework for accurately estimating the sound levels introduced into occupied spaces by air terminals and air outlets, directly impacting occupant comfort and building performance.

What is ARI Standard 885?

ARI Standard 885, developed by the Air-Conditioning and Refrigeration Institute, establishes a comprehensive and uniform industry procedure for estimating the sound pressure levels within occupied spaces that are attributable to air terminals and air outlets. Its primary purpose is to offer designers and engineers a reliable methodology for calculating these sound levels, thereby facilitating informed design decisions and the achievement of desired acoustic goals.

Scope & Purpose

This authoritative standard governs the procedures for calculating sound pressure levels in occupied spaces that originate from air terminals and air outlets. It focuses on the sound transmitted through these devices and the subsequent attenuation within the occupied space. While it provides a robust method for estimating noise from these specific components, it explicitly notes that sound contributions from central fans, upstream ductwork, equipment rooms, and exterior ambient noise are outside its direct scope and must be considered separately by the designer.

Who Must Comply?

• • Primary audience: HVAC designers, mechanical engineers, acoustic engineers, building consultants, and architects.
• • Industries affected: Building construction, HVAC manufacturing, architectural design, and mechanical engineering consulting.
• • Compliance nature: Typically voluntary, but often adopted by reference in project specifications, making it a de facto requirement for many projects.
• • Enforcement: Primarily through project specifications and peer review by consultants and building owners.

Key Requirements Overview

• • The standard requires the use of a defined acoustic model that accounts for the sound source (air terminal/outlet), the transmission path, and the receiver within the occupied space.
• • Professionals must ensure they utilize sound power ratings provided by manufacturers, often referencing complementary standards like ARI Standard 880.
• • Key provisions include methodologies for calculating sound attenuation through ductwork and plenums, as well as adjustments for room acoustics and environmental factors.
• • The standard outlines procedures for integrating sound contributions from various components and for comparing estimated sound levels against established Noise Criteria (NC) and Room Criteria (RC) values.
• • It emphasizes the importance of understanding the limitations of the model and the need to consider other significant noise sources not directly covered by the standard.

Related Standards & References

ARI Standard 885 works in conjunction with ARI Standard 880, which provides industry-agreed methods for determining the sound power ratings of air terminals and distribution devices. This allows ARI Standard 885 to leverage these proven sound power data for its own estimation calculations. Additionally, the standard references research and data from organizations like ASHRAE, underscoring its foundation in industry-leading acoustical science.