Engineering Report

May 3, 2019

John Shirley Anderson Shirley Architects 95 Commercial St SE #5 Salem, OR 97301 [email protected]

Re: South Salem High School Addition –Noise Control Guidelines

REPORT: This guideline document is meant to provide typical methods of achieving the acoustical design criteria for building services systems (HVAC, Electrical, and Plumbing) and provide allowances to be made to accommodate likely treatments. These guidelines contain the basis for acoustical design to accommodate all users under typical conditions; they do not provide solutions for every conceivable acoustical situation. Adherence to the guidelines identified herein will provide a realistic starting point for the detailed design of the systems. Generally, the guidelines are intended to flag potential acoustical problems without undue restriction on the project designers' creative freedom. Nothing in these documents should be construed as modifying the requirements of any applicable building code. Where conflicts exist, the most restrictive condition should be satisfied.

HVAC Systems Noise Control Criteria The HVAC systems should be designed to achieve the following background noise level targets are shown in Table 1, presented in terms of Noise Criterion (NC). NC ratings are single number representations of a background sound level spectrum. We utilized ANSI S12.60 Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools and the 2015 ASHRAE Handbook – HVAC Applications for guidance in determining the maximum Noise Criteria (NC) levels.

ABD Engineering & Design ◼ Architectural Acoustics ◼ AV Design ◼ Noise and Vibration 321 SW 4th Avenue, Suite 700, Portland, OR 97204 124 Fulton Street East, Second Floor, Grand Rapids, MI 49503 Phone (866) 272-9778 ◼ www.abdengineering.com

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Table 1: Noise criterion level targets

HVAC Sound Location Level Target

Auditorium NC 20 - 25

Band, Choir and Orchestra NC 25

Black Box NC 25

Practice/Ensemble Rooms NC 25

Corridors and Lobbies NC 40

HVAC System Noise Control Design Guidelines HVAC systems produce noise from rotating machinery and aerodynamically induced noise in ducts, terminal units, diffusers and associated piping. It is transmitted to occupied areas by airborne transmission through ductwork and piping, and by transmission of vibration through the structure both from the machines and from attached pipes, ducts and conduits. Structure-borne noise problems can occur at considerable distances from the source, especially in concrete structures. This section sets out basic design and installation strategy to ensure quiet HVAC systems and is generally organized by system component. Adherence to the guidelines will minimize noise problems and help to meet stipulated background noise criteria in occupied spaces. In many sections, the guidelines propose allowances which should be made subject to review and modification by ABD. Planning • Equipment rooms should be separated and remote from acoustically critical spaces with ratings of NC 30 or less. • The HVAC system should be designed to minimize turbulence and flow resistance. Both of these contribute to higher sound pressure levels generated by the HVAC system, particularly at low frequencies. • Keep airflow velocity in ducts serving sound-sensitive spaces as low as possible by increasing the duct size to minimize turbulence and flow-generated noise. Sound Ratings • The manufacturers' sound rating information, which is used in the design of acoustical treatment, must be specified as the maximum allowable sound rating for the appropriate equipment. ABD will assist in preparing these specifications.

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• When this information is requested of the suppliers, they should be informed that the sound generating characteristics of their equipment will be an important factor in the selection process. Failure to provide test data acceptable to ABD may result in exclusion from the selection process. • Suppliers bidding alternate arrangements for air handling units, etc. must ensure that the sound power transmitted to the rest of the system meets the sound power specification. If this involves supply and/or design of additional acoustical treatment, the total costs of such treatment must be included in the bid price. • It may be necessary for the project specification to require that the specific air-handling equipment serving acoustically critical spaces with a rating of NC 25 or less be tested for conformance with acoustical criteria, prior to delivery to site and in a certified acoustical laboratory. Vibration Isolation • Provide effective vibration isolation for circulation pumps, chillers, cooling towers, fans, and all other rotating machinery by means of neoprene, rubber or steel spring isolators as appropriate. • A Vibration Isolation Specification will be provided for review by the mechanical engineer. • Vibration-isolate ducts and pipes, using spring and/or neoprene hangers for at least the first 50 ft from vibration-isolated equipment. • Make all service connections to vibration isolated equipment with flexible connectors capable of withstanding the maximum displacement of the machine without strain or rupture. Pumps • Pumps should be mounted on concrete inertia bases with spring vibration isolators. • Neoprene flexible connectors should be used where pipe sections are attached to the pumps. • All piping at the pumps should be supported with vibration isolation in the form of either floor mounts or hangers. Fans and Air Handling Units • Allow for air handling equipment duct sound attenuators with a combined pressure drop of a maximum of 15% of the system pressure for each fan or air handling unit. • Selecting quiet air-handling units will result in shorter duct sound attenuators, less acoustical duct lining, and possibly lighter weight mechanical room walls and less acoustical duct lagging. Request that air-handling unit manufacturers submit their options for lower noise units and make it clear to their representative that noise is a

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significant concern for this project. Manufacturers can achieve lower noise levels by using different types of fans, using larger fans, using perforated supply and return air plenums in their air-handling units, and by other means. • To reduce fan noise and terminal unit regenerated noise during off peak periods, use variable frequency drives for volume control in variable volume systems. • Fan sound power level information must be requested of the specified fan supplier and included in tender specifications. A Sound Power Specification will be provided for review by the mechanical engineer. Fan-coil Units and Heat-pumps • In general, fan-coil units and heat-pumps should not be located within the ceiling void above NC 40 or quieter spaces. Fan-coil units and heat-pumps located above NC 40 or quieter spaces will likely require noise control enclosures. • Expect that fan-coil units and heat-pumps serving NC 40 and quieter spaces will require inlet and out duct sound attenuators. Ducts • In general, rectangular ductwork, with low airflow velocity, is preferred over round and oval ductwork. • Avoid routing main ducts through NC30 and quieter spaces. • Use balanced geometry for duct branches, duct tees, and transitions to minimize air turbulence and achieve low levels of regenerated noise. • Duct transitions should not exceed an included expansion angle of 15 degrees, or the resulting flow separation may produce rumble noise. • Ductwork at both the fan inlet and outlet should have a minimum of 5 duct diameters of straight ductwork to provide laminar airflow and minimize turbulence. • Locate elbows and duct branch takeoffs at least 4 or 5 duct diameters from each other to minimize flow generated noise. • Use turning vanes with mitered elbows or radiused elbows to achieve low regenerated noise levels. • Do not use flexible ductwork in spaces with a recommended noise level of NC 25 or lower. Duct Velocity • Duct air velocities should be designed to not exceed the values listed in the following tables. Be sure to allocate space early on for the large duct mains serving the Auditorium.

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Table 2: Maximum air velocity for rectangular duct

Maximum1 Air Velocity in Rectangular Duct, fpm Noise Criteria Main Duct Main Duct Branch Duct Final Main Duct (NC) (Above GWB (Above ACT & Duct after Run-out to (Exposed) Ceiling) Ceiling) VAV Box Diffuser NC20 800 800 800 625 400 NC25 1350 1000 875 750 450 NC30 1675 1175 1000 900 550 NC35 2000 1400 1150 1000 600 NC40 2400 1700 1375 1200 750 1. Assumes use of radiused elbows or turning vanes. Table 3: Maximum air velocity for circular duct

Maximum1 Air Velocity in Circular Duct, fpm Noise Criteria Main Duct Main Duct Branch Duct Final Main Duct (NC) (Above GWB (Above ACT & Duct after Run-out to (Exposed) Ceiling) Ceiling) VAV Box Diffuser NC20 1000 1000 1000 625 400 NC25 1875 1500 1275 850 450 NC30 2250 1875 1600 1075 550 NC35 2625 2250 1950 1300 600 NC40 3175 2800 2425 1625 750 1. Assumes use of radiused elbows. Sound Attenuators • It can be expected that all air handling units and fans serving the performance spaces, rehearsal spaces, and practice rooms will require 7 to 10 foot long primary duct sound attenuators located in the air handling unit supply and return air ducts. Depending upon the HVAC system design, secondary duct sound attenuators or acoustical duct lining may be required near the performance, rehearsal, and practice spaces. Air handling units and fans serving all other spaces will likely require 5 foot long primary duct sound attenuators in the supply and return air ducts. The exception may be smoke evacuation fans, unless they are positioned such that attenuators are necessary to reduce transmission of exterior noise into the Auditorium. • In order to contain noise in the mechanical room, sound attenuators should be located bridging the mechanical room partition with two-thirds of its length within the mechanical room, If smoke/fire dampers are required at the mechanical room partition,

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the attenuator should be located fully within the mechanical room and as close to the partition as possible. • Be sure to size mechanical rooms to allow for these sound attenuators and bear in mind that attenuators should be separated from elbows by a distance of at least 3 times the elbows depth (where depth is the duct dimension measured in the plane of the elbow. • ABD will provide a Sound Attenuator Schedule for reference by the Project Mechanical Engineer. Terminal Units • Manufacturers must provide sound rating information for both ductborne and radiated noise for terminal units over the full range of service conditions. • For spaces with NC ratings of 35 or higher, the first run out branch should be no closer than 5 feet downstream of the terminal unit. For spaces with NC ratings of 30 or less, the first run out branch should be no closer than 10 feet to the terminal unit. • Terminal units should not be located above spaces rated NC35 or less. • Fan powered terminal units should not be located over a space rated NC40 or less. • Allow for installation of attenuators and/or duct lining in downstream ductwork for spaces rated NC35 or less. Diffusers, Grilles and Registers (Air Devices) • Manufacturers must provide sound rating data for all diffuser, grille and register selections. The selection of high velocity air devices should be restricted to general use areas. • Long throw (high velocity diffusers and supply registers) should not be used in the performance, rehearsal, or practice spaces. • Ductwork connecting to a supply air device should be straight (i.e., no offsets or fittings) for at least three duct diameters and the same size as the inlet collar. • Balancing dampers should not be located within three equivalent duct diameters of the diffusers. An inherently balanced system via ductwork layout and sizing is the preferred method of air balance for noise sensitive spaces. Otherwise, ductwork downstream of dampers may need acoustical lining or be double wall fiberglass insulated duct with perforated lining. • Select diffusers, registers and grilles for an NC rating that is at least 7-10 points below the recommended NC of the room.

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PLUMBING AND PIPING SYSTEM NOISE & VIBRATION CONTROL GUIDELINES Plumbing and piping noise, particularly that attributable to the supply system, can be a major cause of annoyance in many modern buildings. Careful installation practice and attention to the points discussed in these guidelines will minimize disturbances due to plumbing and piping generated noise. It must be emphasized that a systematic approach to the piping installation is necessary to achieve maximum benefit from the recommendations contained herein. In particular, careful equipment selection and close attention to detail during the rough-in stage will help to assure success. The most carefully designed noise control measures can be rendered ineffective on the job site through poor workmanship or oversight. Supply Piping • For pipes attached to the inlet or discharge of prime movers and pressure reducing valves, use spring vibration isolation mounts within the mechanical room or to within 50 feet of the prime mover (whichever is greater). • All active water pipes 6 inches or larger in diameter shall be mounted with spring vibration isolators. • Plumbing should not be run in walls of critical rooms (NC30 or quieter). Where such locations are unavoidable, the pipe chases should be loosely filled with batt insulation and additional layers of gypsum board may needed for the chase wall and/or pipes may need to be wrapped with a mass-loaded vinyl noise control lagging material such as Kinetics KNM100ALQ. Table 4: Recommended Maximum Water Flow Velocities (in feet per second)

Pipe Inside Diameter (in) Maximum Flow Velocity (ft/s) 1 3 2 4 3 6 4 7 6 8 8 10

• Quiet models of faucets and diverter valves should be specified. • Water pressure should be limited to 40 PSI at any fixture. • Water hammer arresters are needed for all systems with fast acting shut-off valves.

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Waste Piping • All drain, waste and wet-vents should be made from cast iron pipe. • Waste piping should not be run in walls of critical rooms (NC30 or quieter). Where such locations are unavoidable, the pipe chases should be loosely filled with batt insulation and additional layers of gypsum board may needed for the chase wall and/or pipes may need to be wrapped with a mass-loaded vinyl noise control lagging material such as Kinetics KNM100ALQ. • Risers should be supported only from the floor slabs and should be attached to the floor slabs by vibration isolation mounts. Rain Conductors • Rain conductors within NC 30 or quieter areas shall be enclosed within a shaft or lagged with a mass loaded vinyl and insulation system. • Vibration isolation clamps shall be used on rain conductors within spaces with a rating of NC 30 or less. ELECTRICAL SYSTEM NOISE & VIBRATION CONTROL GUIDELINES Electrical system noise can be problematic due to its tonal quality. Individuals find tonal noise more annoying than broadband noise. This leads to a particularly challenging noise control scenario since these systems must be well below background levels to not be heard. We offer the following guidelines. Wiring • Where possible, do not locate electrical outlet boxes back to back in partitions where at least one space is rated NC 35 or less. Install with horizontal separation of at least one stud space and connect with separate conduit leads; otherwise provide a vertical septum between boxes that has the same surface weight as a partition leaf. • The above applies also to outlets for telephone, video, data and other communication and service penetrations. • Disconnects and motor starters should not be mounted on walls common with noise sensitive uses. Lighting • Gas discharge lighting systems are potential sources of noise. The acoustical performance of such fixtures and devices should conform to the acoustic criteria of the areas in which they are located. High intensity fluorescent and mercury vapor lights may generate relatively high acoustical noise levels. Allowance should be made for remote mounting of ballasts. Samples of potentially noisy fixtures may be required for evaluation.

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• Low voltage halogen fixtures can also be a source of undesirable hum, particularly when dimmed, as a result of magnetostrictive effects in the transformer cones. A mock up may be required. • Lighting fixtures should also be evaluated for emissions of electromagnetic interference or radio frequency interference which could adversely affect some assistive hearing systems and hearing aids. • Do not use fluorescent lighting with magnetic ballasts in any space rated NC 30 or less. Dimming • Theatrical dimmers must be mounted in a remote location, preferably in a separate room. Dimmer racks will likely require vibration mounts. • Wall mounted dimmers can sometimes be a source of buzzing. Do not install in rooms rated NC 30 or less. Transformers • External vibration isolation mounts may be needed for indoor substations and for secondary transformers if those transformers are located near occupied spaces. • Transformers should be specified to have resiliently mounted core and coils to reduce casing radiated noise. • Even small transformers should not be located in rooms with doorways connecting to adjacent NC35 or quieter spaces, nor should they be mounted to walls of adjacent NC35 or quieter spaces. Vibration Isolation • Theatrical lighting dimmers should be mounted on spring vibration isolators and electrical power transformers may need to be mounted with neoprene vibration isolation mounts. • Electrical connections to vibrating or vibration isolated equipment must be made using a flexible conduit, cable or connectors. • An Electrical Equipment Vibration Isolation Specification will be provided for review by the electrical engineer.

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Following these guidelines is only a part of designing for acoustical design. A review and analysis will be performed, and our findings will be documented in a separate report for the subsequent stages of the project. If you have any questions, please call. Sincerely, ABD ENGINEERING & DESIGN, INC. Per:

Melinda Miller, PE, LEED AP BD+C Principal Consultant cc: Marci Boks, Erik Geiger – ABD Engineering & Design Karl Anderson, James Robinson – Anderson Shirley Architects