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NOISE ANALYSIS. Airports not close enough to have a significant impact. SITE ACCEPTABILITY STANDARDS. SITE ACCEPTABILITY STANDARDS. Normally Unacceptable Zone: 5 dB additional attenuation (above the expected 20 dB) for sites with up to 70 dB DNL

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Presentation Transcript
Noise analysis
NOISE ANALYSIS

  • Airports not close enough to have a significant impact



Site acceptability standards1
SITE ACCEPTABILITY STANDARDS

  • Normally Unacceptable Zone:

    • 5 dB additional attenuation (above the expected 20 dB) for sites with up to 70 dB DNL

    • 10 dB additional attenuation for sites with up to 75 dB DNL

    • Includes major rehabilitations and conversions


Site acceptability standards2
SITE ACCEPTABILITY STANDARDS

  • Unacceptable zone:

    • HUD actively encourages conversion to non-noise-sensitive uses in this zone. Funding requires specific approval by HUD and may require an Environmental Impact Statement

    • EIS Waiver for projects in unacceptable noise conditions

      • Noise is the only environmental issue

      • There are no outdoor noise-sensitive uses (patios, picnic areas, balconies, etc.)

      • Assurances of pre-occupancy mitigation of other issues



Noise mitigation attenuation
NOISE MITIGATION - ATTENUATION

  • Because building materials absorb sound, they can attenuate, or reduce, the level of sound coming into an area from outside, mitigating the effects of the noise level

    • Interior noise-sensitive uses (goal of 45 dB)

    • HUD assumes that “typical” construction methods and ratios of walls to doors and windows will result in a baseline attenuation of 20 dB


Noise mitigation attenuation1
NOISE MITIGATION - ATTENUATION

  • To increase the amount of attenuation of a wall system (walls plus windows plus doors), increase the thickness of the wall components and the density of the materials used and decrease the connections between layers of the wall

    • Supplement to Chapter 4 of Noise Guidebook provides STC ratings of example walls, windows and doors


Noise mitigation attenuation2

Walls:

From siding to brick or stucco

Add or increase insulation

From 4” studs to 6” studs

Add resilient channels to hang drywall

Add an air space between layers

Avoid penetrations in direction of noise source

Doors:

From hollow-core to solid-core

From wood to insulated steel

Decrease size of glass inserts

Add specialized seals

Windows:

Add storm windows

Add a layer of glass

Add specialized seals

NOISE MITIGATION - ATTENUATION


Noise mitigation attenuation3
NOISE MITIGATION - ATTENUATION

  • An architect should be able to provide an estimate of the sound transmission class (STC) of each part of the wall system – wall, windows and doors – and the percentage of wall area each occupies

  • HUD offers an online Sound Transmission Classification Assessment Tool (STraCAT), but at present windows and doors cannot be customized to match field conditions, so usefulness is limited.


Noise mitigation attenuation4
NOISE MITIGATION - ATTENUATION

  • Aside from STraCAT, options to calculate noise attenuation of selected building materials:

    • Figure 17, STC graph, of HUD Noise Guidebook

    • HUD Sound Transmission Class spreadsheet, available upon request


Noise mitigation attenuation5
NOISE MITIGATION - ATTENUATION

  • For sample site, architect reported the following:

    • STC of walls = 50 dB

    • STC of windows = 26 dB

    • STC of doors = 27 dB

    • Two walls analyzed:

      • Wall 1: 73% wall, 27% windows, no doors

      • Wall 2: 93% wall, 2% windows, 5% doors


Noise mitigation attenuation6
NOISE MITIGATION - ATTENUATION

  • To use Figure 17

    • Subtract STC of windows from STC of doors

    • Enter graph on vertical axis at resulting number

    • Cross to the line representing percentage of wall taken up by windows

    • Drop down to horizontal axis

    • Subtract resulting number from wall STC to get final STC


Noise mitigation attenuation7
NOISE MITIGATION - ATTENUATION

  • Alternative: spreadsheet



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