Key considerations: Acoustics
“Acoustics were a key consideration, because of the open concept and design,” says Franzen. “On the first floor, the conference and meeting rooms were an important focus. There are eight areas specifically designed as quite spaces and private areas for employees, two specifically designed collaboration lounges, as well as a courtyard with tables, lounge seating, and ping pong.”
He emphasized that acoustic optimization in open spaces “was a particular concern as we have hard surface floors on 85 percent of the first floor” with 4.8-m (16-ft) ceilings.
SLR Consulting’s project engineer, Nick Block, PE Acoustics, LEED AP, assisted PGAL with performance-based ceiling product selections. “Our involvement was to work with the project team to help secure the EQc9 Acoustic Performance credit under the LEED rating system,” Block explained. “Grundfos was very particular about their acoustic goals and have their own acoustic guidelines.
Our scope pertained to meeting LEED acoustic guidelines, namely reverberation time and mechanical noise.”
Intent on meeting the acoustics requirements in LEED, Block contacted an acoustic specialist in Chicago to learn more about the performance
of stone wool ceiling systems. “[They] assisted by providing us with the acoustical data we needed to analyze their product line to find the right fit for both our acoustical requirements and aesthetic requirements by Grundfos and PGAL,” says Block.
SLR shared that the acoustic requirements for the suspended ceilings included a high Noise Reduction Coefficient (NRC) of 0.90-0.95. NRC is the metric used to describe the sound absorbing capability of an architectural surface material or finish. Additional sound isolation beyond what a typical fiberglass ceiling panel could provide was also necessary due to potential noise generated that the HVAC system in the plenum above the ceiling generated.
Using laboratory test data, the acoustic specialist confirmed that the stone wool ceiling panels would adequately attenuate the mechanical equipment noise in the plenum. To produce an optimal acoustic experience which complied with the LEED acoustic requirements—the final design combined sound-absorbing stone wool ceiling systems with an NRC of 0.95, sound-insulating full-height walls with the correct sound transmission class (STC) rating and appropriate background noise levels.
After the ceiling was installed, SLR tested the system to confirm it performed as per the specifications.
