cSPACE letter to MLCA re: revised chiller design
The following is a letter sent on October 3, 2014, addressed to the Marda Loop Community Association President, Marc Doll. The letter contains information regarding the revised cSPACE chiller noise levels with respect to World Health Organization specifications. New data detailing noise comparisons and the chiller location is available for download at the bottom of this page.
October 3, 2014
Marc Doll, President
Marda Loop Communities Association
3130 – 16th Street SW
Calgary, AB T2T 4G7
RE: Revised specifications and design for chiller unit location at 1720 – 30th Avenue SW (cSPACE King Edward)
Dear Mr. Doll,
As a follow-up to our letter of September 15 2014, cSPACE’s team has worked diligently to address concerns from various 29th Avenue residents about the potential noise impact of our proposed chiller unit location at the King Edward site. I can assure you and the MLCA Board, we are taking this issue very seriously and are eager to resolve it with our neighbours in a timely manner.
Adhering to all municipal approvals processes, our previous chiller system design was never anticipated to be contentious. However, a thoughtful communication from a neighbour recently reminded me of an important point. As an aspirational community builder, cSPACE needs to constantly challenge ourselves to lead positive change. Our award-winning approach to sustainable design and community vitalization has showcased this intent from our inception.
With that intent, our team has completed an immense amount of work to improve the sound performance of our system to an international best practice.
In most cities, the lowest limit of urban ambient noise is approximately 40 dBa – this is also the threshold (outside a bedroom window) that the World Health Organization (W.H.O.) has identified where adverse effects on sleep begin to arise from sustained noise exposure at night. With our revised design, we are now achieving a maximum sound level at the property line of our nearest neighbour that surpasses that high international bar (see Attachments 1 and 2).
I would emphasize again to the Board that the 39.4 dBa on the north side of 29th Avenue SW is the worst-case scenario at peak cooling load – our new SMARDt chiller (see Attachment 3) includes variable speed motors on both the condenser and fans that slow during our normal operating levels. To achieve these performance levels, we have also invested in a solid acoustic enclosure around the unit that improves upon our original louvre design.
In addition to achieving W.H.O. levels, the City of Calgary has recently completed a substantial review of its Community Standards By-Law to address the low-frequency noise (‘hum’ and vibration) generated by residential air conditioners, fans, central vacuum systems and generators (see Attachment 4). Recently approved by Council in September, these new ‘C’ weighted levels are based on best practices from New Orleans. The new cSPACE chiller design also exceeds these performance levels substantially.
While cSPACE has 100% confidence in Nyhoff Ferrari Westwood Babits (architect), Hidi Rae (mechanical) and Threshold Acoustics (acoustician), we have recently offered the residents an option to have a 3rd party review of our team’s design and acoustic analysis should it be required to verify our approach.
I look forward to answering any questions that the Board and neighbours may have of our new design at the October 6 MLCA meeting.
President and CEO
cc Ward 8 Councilor Evan Woolley