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NOISE ANALYSIS

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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NOISE ANALYSIS

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  1. NOISE ANALYSIS • Airports not close enough to have a significant impact

  2. SITE ACCEPTABILITY STANDARDS

  3. 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

  4. 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

  5. Questions?

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. NOISE MITIGATION - ATTENUATION • Alternative: spreadsheet

  14. Questions?

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