by Alexis Kurtz LEEP AP, Project Consultant / Acoustical Consultant, The Sextant Group

If you design a LEED® Gold building — one that’s built on a restored brownfield site, finished with reclaimed wood, recycled materials, and low VOC paint, one that recycles gray water, offers sufficient daylight and views, and of course, has plenty of bike racks, but is too loud and distracting for people to work or study or sleep in — is it truly sustainable?

Sustainable design demands minimum land, energy and material use. This can easily conflict with common methods to reduce noise or increase the acoustic quality of buildings. However, fundamental to both sustainable design and acoustics is concern for the environmental impact, profitability, and health and safety in the built environment. Buildings are increasingly being required to meet legislative targets on energy use and other measures of sustainability. As a growing number of design and refurbishment projects strive to meet these sustainability goals, acoustics is often overlooked, or “value engineered” out due to cost constraints. This is because good acoustic design is not often understood to be a valuable component of sustainable design.

While the main goals of sustainable design (reducing greenhouse gasses and carbon emissions, decreased use of nonrenewable resources, decrease use of new materials, and decrease in electricity and gas consumption) must not be overlooked, it is important to remember that the main purpose of sustainable design goes beyond these goals.

True sustainable design is a holistic approach that looks to have positive improvements in three areas: Economy, Ecology, and Society.

The challenge for design teams is to provide practical acoustic design strategies for sustainable buildings that allow buildings to function sustainably without the acoustic quality of the building being compromised.

LEED Credits

Let’s examine the acoustical impact of the following sustainable design components from a LEED credit perspective:

Sustainable site location – To truly be a sustainable development, noise emissions must be controlled to ensure that ambient noise creep, or the gradual increase in ambient noise levels over time, does not occur. The location of the building in relation to existing noise sources will determine the feasibility of using natural ventilation strategies, and influence building orientation and planning to control noise ingress to satisfactory internal levels.

Energy use – The impact that sustainable energy systems have on the acoustic environment is not always benign. The use of passive cooling systems such as radiant flooring and chilled beams can conflict with the use of sound absorbing floor and ceiling finishes included to control reverberance and occupational noise levels in buildings. Alternative strategies to provide room acoustic control include the use of sound absorbing and sound diffusing surface finishes integrated into lighting fixtures and office furniture, or applying them to surfaces where exposed mass is not a requirement for energy use. It should also be noted that these passive cooling systems can also remove the masking noise benefits of traditional HVAC systems. Greater emphasis must therefore be given to alternative acoustic design strategies to maintain speech privacy.

Natural Ventilation – Just as we observe with the likes of radiant flooring and chilled beams, the use of natural ventilation in buildings, with operable windows, vents, and open floor plans can present difficulties with speech privacy and intrusive noise control.

Natural Daylighting – To facilitate the use of natural daylight in buildings, strategies such as lower partition heights, light shelves and interior glazing are often used. These can result in an increase in noise disturbance to workers seated at open plan workstations, and a reduction in acoustic privacy in meeting rooms using glazed walls.

Why is this Important?

Studies have shown that acoustics is the #1 complaint of respondents to post-occupancy surveys of LEED certified buildings. This bears repeating: Studies have shown time and again that acoustics is the #1 complaint of respondents to post-occupancy surveys of LEED certified buildings.

The perceived conflicts between acoustics and other sustainable design elements often cause design teams to ignore the acoustic environment in order to accomplish other, widely accepted sustainable goals. However, by looking closer at the effects of acoustics, it is easy to understand its place within sustainable design.

Healthcare – There is increasing evidence that patient health is influenced by the indoor acoustical quality of the space. Studies have shown that well-designed environments can reduce anxiety, lower blood pressure and lessen pain in patients. Other studies indicate that well-designed environments can help healthcare providers better cope with workplace stress, reduce absenteeism, and support their role in providing quality care. Additionally, research has also linked poor acoustic design to higher occurrences of delirium, elevated depression, greater need for pain medication, longer hospital stays, increasing sleeplessness, and elevated heart rate. And this doesn’t just affect patients — noise also has detrimental effects on workplace performance for the healthcare providers as well.

Education – The most common instructional method used in U.S. education settings, at all levels, is the traditional lecture method, where communication from teacher to student is done via the spoken word. Younger students and those with a primary language other than English require better room acoustics to be able to understand speech as their cognitive and language skills are still developing. The classroom acoustic recommendations set out in ANSI S12.60-2010 (Acoustical Performance Criteria, Design Requirements and Guidelines for Schools, Part 1) are based on years of audiological research for providing students with a good signal to noise ratio, and a low reverberation time to be able to understand the concepts a teacher is presenting. A well designed acoustic environment has also been shown to reduce vocal cord fatigue in teachers, and reduce absenteeism.

Corporate Offices – In today’s world, open plan offices are standard. These layouts provide greater flexibility and encourage teamwork and communication. With shrinking workstation size, twice as many people inhabit the same square-footage as in years past. Although this saves companies costs on leases and energy use, this design style has vast implications on lighting and HVAC design. It also affects both speech privacy and ambient noise levels in offices. More tools have been introduced into the workplace to improve productivity and efficiency, such as mobile phones and speaker phones; however, they increase the noise level and distractions in an open plan space, and negatively affect the productivity of others.

Most jobs in the United States are service related and involve the creation and dissemination of knowledge, demanding high levels of concentration. Conversational distraction and uncontrollable noises are the primary causes of productivity loss within offices. Additionally, higher than recommended noise levels have also been shown to contribute to absenteeism, illness and staff turnover.

Neighborhoods – “Secondhand noise” is a phrase used to describe noise that is experienced by people who did not produce it. Causes for the increase in secondhand noise include the lack of adequate anti-noise regulations in many parts of the world; the noisy electronic gadgets which are common today; the rising number of vehicles on the world’s roads; and busier airports. In Japan, many inhabitants of Tokyo wear earplugs to combat the noise pollution caused by public address messages and other forms of city noise. According to the European Environment Agency, about 65% of the European population is exposed to ambient sound at levels above 55 dBA, while about 17% is exposed to levels above 65 dBA.

Human Health – Numerous scientific studies over the years have confirmed that exposure to certain levels of sound can damage hearing. Prolonged exposure can actually change the structure of the hair cells in the inner ear, resulting in hearing loss and tinnitus. Non-auditory effects of noise exposure were publicized in as far back as 1930, in a study published in the Journal of the Acoustical Society of America. The results showed that exposure to noise caused stomach contractions in healthy human beings. Other non-auditory effects include elevated blood pressure, loss of sleep, increased heart rate, cardiovascular constriction, labored breathing, and changes in brain chemistry.

According to the World Health Organization (WHO) Guidelines for Community Noise, “these health effects, in turn, can lead to social handicap, reduced productivity, decreased performance in learning, absenteeism in the workplace and school, increased drug use, and accidents.” Studies have shown that lower birth weights and greater numbers of birth defects are more common for infants born to mothers living near airports when compared to infants born to mothers living in quieter communities. Higher systolic and diastolic blood pressure among schoolchildren living near the Los Angeles airport was also found.

As research has clearly shown, freedom from excessive noise is an important element of sustainable design, with social, economic, and environmental impacts.

How does sustainable acoustics affect cost or finance on a project?
By holistically integrating acoustics early on in the design process, a project will have little to no additional costs associated with good acoustical design. However, if decisions are made early on without thought to acoustics, the resulting high noise levels, high reverberation times and lack of speech privacy can lead to a less functional facility, and fixing those problems can sometimes be very costly.

Good design up-front always trumps remediation.

 

About the Author
A LEED-accredited professional, Alexis Kurtz was appointed a Core Member of the LEED Indoor Environmental Quality Technical Advisory Group in 2007, and is still one of only three acousticians in the USGBC’s Acoustics Working Group. She is also a member of the 2010 Class of National Peers in the US Government Service Administration’s (GSA) Design Excellence and the Arts Program. National Peers are identified as distinguished private-sector design professionals who are selected to be critical voices in the formal review of all Federal government projects in the GSA’s Design Excellence and the Arts Program.

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