(3 points)
INTENT
Establish background noise level criteria for enclosed spaces in order to promote best-practice HVAC and façade design techniques and ultimately bolster acoustical comfort within.
SUMMARY
ISSUE
A space that is negatively shaped by HVAC system and exterior noise intrusion can be described as either too loud or distracting. Both instances are individually problematic: the level of background sound may affect speech communication, audio features and, in extreme conditions, the effectiveness of public address systems. Studies indicate that employees are unable to habituate to noise in office environments over time, and office noise, with or without speech, can create stress and disrupt performance on more complex cognitive tasks (e.g., memory of prose, mental arithmetic). Background noise also poses a problem from a universal design and accessibility standpoint when the signal-to-noise ratio favors background noise over speech intelligibility, thus making it hard to engage in critical listening for the purposes of learning or performing tasks. In Europe, external noise intrusion from sources like transportation or industry have been linked to occupant annoyance in buildings. In adults, exposure to traffic noise can lead to complications with the cardiovascular system, diabetes, hypertension, stroke, depression and high blood pressure. For children, chronic aircraft noise exposure impairs reading comprehension, mental arithmetic and proofreading. In both industrial and community studies, road traffic noise exposure is related to raised catecholamine secretion levels in urine, indicating an increased stress level in subjects exposed to such noise. Increase in the use of light-weight construction materials has the potential to result in poor sound transmission performance across building façade elements.
SOLUTIONS
IMPACT
Designing with background noise level criteria in mind is key to ensuring acoustical comfort across a range of project types. When exposure to noise is reduced, occupants are less susceptible to distraction, overall stress and potential health risk.
REQUIREMENTS
Limit Background Noise Levels (Max: 3 points)
The following is achieved:
-
Background noise levels do not exceed the thresholds below:
Sound Pressure Level (SPL)
Open Workspaces,
Dining Areas
Enclosed Offices,
Residential Living & Sleeping Areas (Daytime)
Conference Rooms,
Classrooms,
Residential Sleeping Areas (Nighttime)
Points
Average SPL (Leq)
dBA
45
40
35
3
dBC
70
65
60
Max SPL (LMax)
dBA
55
50
45
dBC
80
75
70
Average SPL (Leq)
dBA
50
45
40
2
dBC
75
70
65
Max SPL (LMax)
dBA
60
55
50
dBC
85
80
75
Average SPL (Leq)
dBA
55
50
45
1
dBC
80
75
70
Note:
- Leq measurements may exceed optimal levels by no more than a 4 dB tolerance.
- LMax measurements are slow-weighted and may exceed optimal levels by no more than a 9 dB tolerance.
© International WELL Building Institute
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