Planning Acoustics in Commercial Construction
What Happens When You Get it Right, and the Risks of Getting it Wrong
We know more today than ever before about the importance of building structures that are energy-efficient, safe and comfortable for occupants. Creating these high-performance buildings begins at the planning stage with design professionals and technical experts who consider all the factors that go into making spaces perform as they are intended. When it comes to acoustics, getting it right means improving the Indoor Environmental Quality—or IEQ—of a space.
And yet, the acoustics of a building is often still overlooked in the planning stage, even though we know the risks of poor acoustic design can range from irritating to harmful. In fact, noise has been defined by the Center for Disease Control and Prevention (CDC) as a pollutant and a hazard to human health and hearing. It has the potential to seriously affect people, interfering with daily activities at school or work, at home and during leisure hours.
The Risks of Poor Acoustics
Depending on the type of structure, the potential complications from poor acoustic building design can vary greatly, but all are significant. Consider the following:
- Noisy neighbours can be irritating and may contribute to loss of sleep and related consequences including the inability to focus, along with cardiovascular and psycho-physiological symptoms.
- Office workers can be distracted and experience decreased productivity by a noisy environment, as well as increased stress levels.
- The same can be said of students and teachers in educational settings.
- In healthcare environments, noise can limit a patient’s recovery, as well as the ability of healthcare professionals to properly do their jobs.
- In all of these settings, poor acoustical design can significantly limit privacy.
People speaking or moving about, electronics, HVAC systems… they all contribute to noise problems. But it’s not just interior sources of noise that can be troublesome. Exterior noises—everything from road traffic to construction sites—are considered noise pollution when excessive. When they are limited, however, their impact on our daily environments will support a positive occupant experience.
Why should we be thinking about acoustics early on during the planning process? First, because mitigating noise problems post-construction are often complicated and costly. Second, the junction of construction and design elements (e.g. walls and partitions) have a huge impact on sound transmission. When ignored or done incorrectly these junctions can lead to flanking paths for sound. In fact, walls and closed-door offices often give the illusion of privacy because of this oversight.
How Should You Get Started with Acoustics Planning?
Consider the unique needs and possible architectural acoustic challenges of every renovation or new construction project. With the application-specific goals in hand, determine whether you’ll need to work with an acoustical consultant or engineer. If you do, get them involved at project conception using an integrated design process. As part of that process, the team is encouraged to articulate and understand the specific objectives of a space, including:
- How important is speech privacy?
- Does speech need to be clearly intelligible?
- Does sound propagation need to be prevented, particularly in large open rooms?
Next, consider what the “source-path-receiver” model reveals for potential risks:
- What are the various sources of sound in a space—both interior and exterior? Do they reach the criteria for “noise pollution”, i.e. are they causing harm or discomfort to occupants?
- Which paths will be available for sound to travel, and what adjustments need to be made to limit its impact, or in other cases, ensure it gets delivered?
- Where is the receiver, and what do they require? Speech privacy or speech intelligibility? Or both?
It’s important to remember that meeting building code requirements for acoustics is a minimum standard and often falls short of the ideal conditions required for occupants. Instead, consider the value of moving to high-performance building design and following the strict requirements of certifications programs such as LEED v4 and the WELL Building Standard to create the ideal acoustical environment.
Put the Acoustics Design Plan in Action
What’s next? With this information gathered, your team can ensure that the right acoustic design and construction principles are incorporated for occupant comfort. Consideration should be given to the following:
- Transmission can occur due to sound leakage. The most common leakage spots are cracks and poorly made layers between the wall, ceiling and floor, poorly sealed doors and windows, non-insulated pipelines and crawl space, and poor brickwork (too little mortar between the bricks). An inadequately designed ventilation system will also increase sound transmission. That’s why the best method to solve for indoor and outdoor noise is at the source.
- The environmental noise of the site and plan the appropriate building envelope assemblies using stone wool insulation to increase noise reduction. DNL, or day-night average sound level, is the sound level in a space averaged over 24 hours. Selecting quiet HVAC equipment and locating it away from spaces sensitive to sound can be effective, as can using interior partitions with stone wool insulation to boost the sound transmission class. Speech privacy can be improved between rooms by using full-height partitions with stone wool insulation; likewise, speech intelligibility inside rooms can be improved by incorporating sound-absorbing ceilings, islands and baffles.
- Material selection for assemblies is important in helping to achieve acoustics objectives both through sound absorption and sound blocking or isolation. Frequently we want to achieve both, and stone wool solutions offer the ability to better control sound at the source and can be used effectively to limit vibration and sound transmission along the sound pathway in a space.
Compiling this information and planning specific design and construction details from the beginning will contribute to a space that meets its acoustics goals and supports a positive IEQ.
Good acoustics design is based on a strong foundation of technical knowledge. Building design and construction professionals, as well as homeowners, can look to ROCKWOOL for the services and solutions to help meet the desired specifications and outcome of a project. ROCKWOOL also has a catalogue of OITC and STC-rated wall/roof assemblies that can meet a variety of architectural specifications.
Our technical support team is ready to work with you in evaluating whether an assembly would satisfy the noise level reduction you are trying to achieve. We’ll also provide you with a recommendation on the right acoustic solutions for your specified requirements. Consider us a partner in your next project. In the meantime, check out the ROCKWOOL acoustics blog series at https://www.rockwool.com/why-stone-wool/acoustic/; it’s full of information and practical advice for your next project.