Designing with stone wool ceiling panels for education facilities

The new Environmental Science & Chemistry Building (ESCB) at University of Toronto Scarborough Campus (UTSC) is designed and built to achieve Gold through the Canada Green Building Council (CaGBC) Leadership in Energy and Environmental Design (LEED) program. Once certified, it will be the second building at the University of Toronto Scarborough to attain this international rating.

Sound and sustainable
The stone wool ceiling panels installed on the ESCB are UL/ULC-certified for flame spread and smoke development—this is the standard CAN/ULC S102, Standard Method of Test for Surface Burning Characteristics of building Materials and Assemblies.In addition to these attributes and the high light reflectance, Tai highlights several other performance benefits:

  • suitability as return air plenum ceiling;
  • easy access to plenum;
  • easy-to-clean surface;
  • recycled content; and
  • a high noise reduction co-efficient (NRC).

Due to its inherently open porous structure, stone wool is a high-performing, sound-absorptive material. Most stone wool ceiling panels have an NRC of 0.85 or higher; those used in ESCB’s atrium have an NRC of 0.90 as standard.

NRC is important in areas where people converse in groups and high levels of noise are present. High sound absorption helps control the ambient noise levels and prevents excessive reverberance. This increases speech intelligibility, improves concentration, and mitigates the ‘Lombard effect,’ where people speak progressively louder to be heard when trying to talk in noisy environments.

Making speech intelligible requires a loud sound source, such as the professor speaking, and strong, early-arriving, acoustic reflections off the room’s surfaces that are close to either the speaker or the listener. It also requires attenuation of all noise. In other words, speech intelligibility requires a high signal-to-noise ratio.

Noise can come from many different sources, including from:

  • the exterior;
  • other interior spaces;
  • building systems; and
  • late-arriving, reverberant sound that persists inside the room itself.

The appropriate reverberation time for speech—which is typically between 0.5 and 1.0 second (mid-frequencies)—usually enables listeners to hear and understand each word without the sound of the preceding words interfering.

North American classrooms typically have speech intelligibility ratings of 75 per cent or less, meaning every fourth spoken word is not understood. Further, loud or reverberant educational spaces may cause professors to raise their voices, leading to increased vocal stress and fatigue. Considered in the context of academic performance and occupant health, acoustic comfort also can be a factor in LEED certification.

Recycled content is a more obvious consideration with LEED and sustainable design. Stone wool ceiling products are made from basalt rock and contain up to 43 per cent recycled material. (Metal products may contain up to 100 per cent.) In addition to the ceiling systems’ contributions to environmentally sound design, ESCB’s other sustainable features include:

  • an ‘earth tube’ system to supply 100 per cent fresh air to the administrative wing;
  • geothermal heating and cooling;
  • custom-fritted glazing to minimize solar heat gain;
  • rainwater collection for irrigation;
  • 100 per cent LED lighting along with daylight harvesting; and
  • a high-performance curtain wall.
No special tools are needed to remove one or several panels in the ceiling suspension system, gaining access to the plenum to make repairs or upgrades, and returning the panels without damage.

Clean and controlled
Another natural advantage of water-repellent stone wool is that it not only repels damaging micro-organisms, mould, and bacteria, but it also meets stringent requirements for restricting volatile organic compounds (VOCs). Helping improve ESCB’s indoor air quality (IAQ), the stone wool acoustic ceiling solutions have UL Environment’s GREENGUARD Gold Certification for low-emitting products.

Due to their low particle emission, the ceiling systems installed in the laboratories also meet stringent requirements for air cleanliness in healthcare and clean room environments.

“Where high moisture content is expected, such as the glass-wash facilities, and where the clean room standard is required for sensitive equipment or contamination control, [acoustic stone wool] ceiling tile together with the barrier grid suspension system is used,” described Tai.

These ceiling systems were specified and manufactured to meet Bacteriological Class B1 and Clean Room Classifications under International Organization for Standardization (ISO) Class 4, and are resistant to methicillin-resistant staphylococcus aureus (MRSA). Along with helping stop the spread of infection, selected product finishes are designed to withstand rigorous cleaning.

All of ESCB’s acoustic stone wool ceiling systems are durable and need only minimal maintenance. When upkeep is required, it is easy to remove one or several ceiling panels to gain access to the plenum and return them without damage. There is no need to use special tools or to start at the wall, removing panels until reaching the desired area.

UTSC’s Stepanian agreed having a ceiling that was easy to remove and replace was one of the most critical aspects in selecting the ceiling system. Additionally, he reiterated the importance of acoustic performance and light reflectance, as well as being durable, cost-effective, and esthetically pleasing.

Tai cited the “clean, simple, and crisp” esthetics and “smooth drywall look is definitely something we have in mind when reviewing acoustic ceiling tile options.”

In the Environmental Science & Chemistry Building’s laboratories, exposed 24-mm (15/16-in.)
suspension systems support about 1315 m2 (14,154 sf) of acoustic stone wool ceiling panels.

“The primary aspects of the lab design were its functionality and flexibility. Limiting noise from equipment was a significant consideration, given that the research labs are open-concept,” emphasized Stepanian.

“The most notable room where [acoustic stone wool ceiling panels were] used is the central sterilization room. This room contains two autoclaves and numerous dishwashers; it is considered to be a higher humidity/wet environment requiring a ceiling system that can be wiped clean,” described Stepanian. “So far, we are very pleased with the performance and durability.”

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