(JBED) - Summer 2006 - The Whole Building Design Guide

esidents. Another concern from the developer’s
perspective was the cost of
meeting this requirement.
In order to understand the noise impacts
on the proposed site, an analysis of
over 1,500 aircraft operations was performed.
These data provided a means to
relate the aircraft type, departure time,
departure height, and frequency of the
departures to determine a representative
sound spectrum at the exterior of the
building. This sound spectrum was applied
to the various windows that were
being considered. Sound transmission
level data from various window manufacturers
were used to determine the interior
sound levels for selecting acceptable
windows for the project. This was compared
to the sound isolation performance
of the pre-cast concrete façade,
which provided relatively good sound
isolation performance for the non-glazed
portions of the façade.
The noise study and the discussions
with the window manufacturers provided
several useful results. First, it was
possible to achieve the interior sound
level goal with typical commercial grade
glazing by limiting the size of some windows
(the smaller window sizes reduced
the exposure of the interior space to the
aircraft noise). Second, the upgrades
were installed in standard window framing
systems to minimize the cost of the
upgrades, as non-standard framing is
often considerably more expensive.
Third, the upgrades typically included
laminations or deeper airspaces to
achieve the interior sound level goal.
Post-construction testing has demonstrated
that the window performance is
consistent with the program goals for
noise reduction. Subjectively, aircraft departures
were perceived as relatively
quiet and unobtrusive to the residents.
There is an interest in surveying the occupants
to understand their day-to-day
experience and perception of the aircraft
noise impacts.
CONCLUSIONS
Architectural glazing can be selected
to provide improved sound isolation for
interior occupants of buildings. There are
several existing standards for performing
laboratory and field-testing, which includes
the derivation of single number
ratings (STC, OITC) for the test specimens.
Various upgrades for improving
the acoustical performance of glazing
systems can be considered. There are
several concerns to keep in mind and
avoid when considering upgrades to window
systems. These include glass thickness
and type, and the depth of the airspace.
Several case studies demonstrate
that the use of architectural glazing can
successfully improve the sound isolation
for building occupants.
REFERENCES
1. Monsanto/Saflex, Acoustical Glazing
Design Guide, 3.3-3.6, 1989.
2. Fullerton, J. and Najolia, D. “Aircraft
Noise Exposure along South Boston’s
Waterfront Development.” Proceedings
of Internoise 2002, The 2002 International
Congress and Exposition on
Noise Control Engineering, N400.
3. Whole Building Design Guide website:
www.wbdg.org
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30 Journal of Building Enclosure Design