• Kirkegaard Associates completes renovation of Bloomington’s Second Presbyterian Church — maintains “sense of community”

• March 1, 2007

In 1855, the Second Presbyterian Church in Bloomington, Illinois, was built to serve a population of approximately 2,500. One hundred and fifty years later it boasts a thriving congregation, a strong and varied music program, and, as a result of a recent $12 million renovation, a new home.

Chicago’s premier architectural acoustics consulting company, Kirkegaard Associates (KA), design architects BLDD, and theatre consultant, Bill Conner Associates, collaborated in the design of the new Sanctuary to maintain a strong physical reminder of the history and traditions of the Second Presbyterian Church. Design goals included the need to provide a “sense of community” within the sanctuary which led to the horseshoe, shaped plan with curved pews and raked seating.

In addition to the acoustic challenges inherent to the shape of the plan, the worship services at Second Presbyterian Church are diverse and include: amplified spoken word, amplified presentations related to video images, congregational singing, unamplified choral performance, and pipe organ. KA responded to this breadth of uses with the following:The flat gypsum board ceiling above the Chancel is slightly angled toward the audience to prevent flutter (imagine a repetitive echo) and project the sound to the congregation.

• The sidewalls in the chorus area are angled and shaped in a way to project sound and provide a medium for video projection.
• The rear wall of the Sanctuary is a multi-layer gypsum board construction with glass fiber paneling applied in locations to avoid problematic reflections from the audio systems.
• The shaping of the under-balcony allows the sound to be grounded to the audience, thus preventing focusing conditions at the Chancel and front seating areas.

The design also accommodates an audio/video and recording system — custom built passive line-array loudspeakers are concealed in the “cheek walls” of the Chancel and behind the choir on either side of the projection surface. There is also a front-fill loudspeaker system concealed in the mobile lectern and pulpit.

The video requirements are accomplished by projection on to walls, with fixed projectors located above the second floor vestibules. To respond to the recording needs of the Church, there is a complement of microphone inputs around the Chancel and the attic; fixed PTZ camera locations are at the underside of the balcony; video connections for portable cameras are located around the Chancel, at the rear of the choir loft and at the rear of the Sanctuary on the main floor. The recordings are mixed and edited in the TV Room located in the back of the second floor balcony.

The last elements of the design focus on the mechanical, electrical and plumbing (MEP) systems which are situated far from the Sanctuary, and noise and vibration control. An under floor displacement ventilation system delivers controlled air quantities to the congregation which is effective in controlling background noise levels attributed to the HVAC system. Working closely with the design team to eliminate traffic and environmental noise, criteria was established for the make-up of the exterior wall, doors and windows. The Sanctuary walls consist of a composite pre-cast concrete and rigid insulation panel to provide the necessary sound isolation. A multi-layer gypsum board ceiling at the underside of the attic roof trusses provides an interstitial space between the Sanctuary and the exterior.

KA’s project team members for the Second Presbyterian Church included Senior Consultant Louie Sunga for Architectural Integration; Scott Pfeiffer for Room Acoustics; Consultants Joanne Chang and Frans Swarte for Audio/Video system design; and Clete Davis for Noise and Vibration Control.