Assessing challenges due to HVAC design constraints and their effects on VAV terminal unit noise - lessons learned from recent projects

For most projects requiring HVAC noise analysis, designers can reliably account for projected noise contributions from VAV terminal units. However, the authors' recent experiences on projects with challenging constraints (e.g., renovations to existing HVAC systems, prohibition of duct liner and/or flex duct, and restriction to packless/no-media silencers), show that manufacturers' published data are not always sufficient. In the provided project examples, published noise levels for terminal units have required greater consideration because of complexities of the HVAC systems and building conditions. A variety of contributing factors are discussed, as well as the challenges of in-field testing, diagnostics, and troubleshooting. Key takeaways include the need for coordinating with mechanical engineers about the accuracy of system set points; improving assumptions made about system pressure drops and manufacturers' data; and identifying project types that require greater consideration when using manufacturers' data.