Above and Beyond

Hi Daniel,

This credit is a new addition to the Pilot Credit Library, and has not yet been undertaken by any project teams.

The credit was developed in response to the market's request for an acoustic credit for LEED NC which encompasses a wide range of project types. Because the acoustic needs of "New Construction" projects vary, you'll notice there aren't specific criteria ranges listed in the credit. We are essentially asking teams to document the acoustic requirements (reverberation time, background noise, sound isolation, speech privacy) for their specific project and prove how they achieved their stated criteria.

In comparison to LEED for Schools, this credit is on par with the requirements of the Enhanced Acoustical Performance Credit. Both credits require compliance with reverberation time, background noise, and sound isolation. LEED for Schools requires compliance with IIC (impact noise isolation), whereas the NC credit asks teams to comply with speech privacy.

We look forward to hearing how project teams addressed the acoustic issues of their projects, and what improvements to the credit they suggest.

I was part of the design team for a military base NC project, for which this credit was submitted and approved. As required, a narrative was submitted documenting our recommendations for room noise, sound isolation, speech privacy, and reverberation times. There was no sound reinforcement system or sound masking system for this project.

We worked with the mechanical engineer to ensure that the room noise met the design guidelines outlined in Chapter 48, Table 1 of the 2011 ASHRAE Handbook. An acoustical model was used to determine the amount of sound level reduction required to meet these guidelines. Silencers, sound boots, and lined ductwork were the recommended treatments.

For sound isolation, the STC rating table shown in the Pilot Credit guidelines was compared to the partition schedule in the architectural drawings. The rooms were grouped by type, and a table showing the STC rating of the enclosing partitions was included in the narrative.

The STC ratings in the previously described table were combined with our modeled background noise levels to provide the speech privacy ratings. These ratings all met Confidential Speech Privacy at loud voice levels.

Most of the rooms in this project were offices or classrooms, which have volumes less than 10,000 cubic feet. NRC 0.90 acoustical ceiling tile covering all ceiling area not occupied by lighting was recommended in these spaces. There was an auditorium with a volume of 78,000 cubic feet in this project. This room will be primarily used for presentations. For this space an acoustical model was created. We recommended treatment of a percentage of the vertical surface area with acoustical wall panels in addition to acoustical ceiling tile. These treatments reduced the mid-band reverberation time in this space to approximately 0.55 seconds.

In my opinion, the guidelines of this Pilot Credit are appropriate and they are in-line with guidelines we typically try to meet in NC projects. My one recommendation for improvement on the credit would be to incorporate the Speech Privacy Class (SPC) metric into the speech privacy section. This is our preferred metric for determining speech privacy.

Our experience was similar to Nicholas'. Our project involved improvements and refurbishment of an existing office space, so we conducted before and after airborne noise reduction testing to quantify the improvement in noise reduction with the upgraded and changed wall assemblies. Other than that, our calculations and analyses were consistent with a new construction project as opposed to a renovation project.

First comment on this credit - please minimize ambiguity in the credit language. We are just starting on this credit, and were just as mystified by whether or not actual measurements are required.

Ours is also a military installation with specifications that pretty closely align with the requirements of this credit. So thanks Nicholas and Ethan, for your comments.