Fenestration Forum: April 2015
March 23, 2015 By Brian Burton
As urban noise levels have steadily increasing over the past two
decades, window, door and sealed glazing unit manufacturers have done a
remarkably good job in their efforts to improve the acoustic performance
of their products.
As urban noise levels have steadily increasing over the past two decades, window, door and sealed glazing unit manufacturers have done a remarkably good job in their efforts to improve the acoustic performance of their products. Acoustic performance is improved or enhanced by isolating individual components and incorporating air spares that limit the pathways for sound. The experts I spoke to agreed that these improvements have been at least equal to similar sound control improvements in other components that are part of the building envelope assemblies.
Excessive noise in cities, whether intermittent or continuous, can result from aircraft, increased traffic volume and construction as well as clustered buildings, public transportation and industrial activities. In response to increasing levels of nuisance noise, many municipalities are now passing new bylaws that attempt to restrict excessive noise levels. It’s probably too early to judge whether these preliminary efforts will produce meaningful results.
Sound levels are usually measured using a standardized unit termed a decibel (dB). Acoustic performance also involves determining “sound transmission class” or STC. A normal conversation creates a sound of approximately 55 dB, while urban traffic levels, even indoors, can range between 75 and 95 dB, depending on the time of day. Studies suggest that noise levels measured above 75 dB, especially when they are continuous, are considered intrusive and are deemed to be less than acceptable. Sound levels of this intensity can affect sleep patterns, concentration and general comfort.
Due to the adverse effects of urban noise pollution experts have suggested a number of possible noise reduction strategies including placement of acoustic barriers near heavily traveled highways and restrictions on heavy vehicle traffic near residential areas.
Acoustic improvements to fenestration components are significant because limiting unwanted noise to maintain acoustic comfort is considered an important factor in occupant wellbeing in residential settings. Resident surveys demonstrate that acoustic comfort is very important along with air quality, thermal comfort and adequate levels of daylighting. Excessive noise, between units at least, is a common complaint in condominiums according to the Ontario New Home Warranty Program (now referred to as Tarion)
I recently interviewed two building scientists who had completed a number of on-site investigations of excessive noise in condominiums and they reported that it was eventually determined that the noise was emanating primarily from the hallways and adjoining units. In addition, some of the condominium units were relatively close to raised expressways and at certain times of the day excessive traffic noise was recorded. Both professionals also mentioned that investigating reports of excessive noise can be problematic because residents may perceive noise differently even though the sound may actually be of the same intensity. In addition to excessive noise created by external sources sound may be also be created within the building itself by mechanical systems and elevators. Even when sounds may be created by other occupants, it can be extremely difficult to distinguish between internal and/or external sources of noise. In addition, noise can be transmitted through floors, wall partitions, core doors and hallways both through the air and materials as well. As a result occupants may not always be able to distinguish between internal and external sources. Ideally when designers consider the acoustic characteristics of fenestration products they need to consider building orientation, location and occupancy requirements. By necessity there may be trade-offs between the need to provide sufficient daylighting and, in some cases, natural ventilation with adequate sound control. In this regard, the manufacturer is probably the best source for educated guidance.
Brian is now involved with an innovative multidisciplinary firm that specializes in technical business writing: Award Bid Management Services http://award-bid-management-services.com/ . The firm assists companies interested in selling goods and services to governments and institutions. He can be reached at Burton@award-bid-management.com
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