Observations of Measured Partitions

Transcription

1 Acentech Incorporated 33 Moulton Street Cambridge, MA Telephone: Facsimile: Click here for new form Stuart Hodas Spaceworks Architectural Interiors Fort Point Station PO Box Boston, MA By Subject: Airborne Sound Transmission Tests of Moveable Walls Pearson Education 501 Boylston St, 6 th Floor Boston, MA Acentech Project No / Dear Stuart: On Wednesday, 5 October 2011, we visited the sixth floor of 501 Boylston Street to perform airborne sound transmission tests of the recent Spaceworks Architectural Interiors (SAI) moveable wall installation. This report documents our observations and measurements of your Starwall Finesse product, and discusses its use for sound privacy in office settings. Observations of Measured Partitions We conducted sound isolation tests of Starwall Finesse, which is a moveable wall product. We tested an office-to-office partition and an office-to-corridor partition, which are constructed as follows. Office-to-Office Partition ½ thick markerboard paneling on both sides of the wall 2 thick insulation Continuous 3 wide track on top of the carpet and at the underside of a suspended acoustical tile ceiling Office-to-Corridor Partition Double-glazed window with two ¼ tempered glass lites and a 2-1/2 airspace. Continuous 3 wide track on top of the carpet (except at the door) and at the underside of a suspended acoustical tile ceiling Pocket door installed in the 2-1/2 airspace of the double-glazing. The locations of the office-to-office and office-to-corridor partitions are shown in Figure 1 on the following page. The construction in the adjacent office (Huddle 6019) is similar and is shown in Photo 1 on the following page. The floor area of Huddle 6021 is approximately 70 square feet, and the ceiling height is 8 feet, 6 inches. The lay-in acoustical ceiling is Armstrong Dune, which is a mineral fiber product with a ceiling attenuation class (CAC) rating of 35. Due to time constraints the configuration of the return air ductwork was not confirmed, but sound transfer via the ductwork appeared to be negligible. Architectural Acoustics Audiovisual and Sound System Design IT Infrastructure Noise and Vibration Control Environmental and Industrial Acoustics

2 Stuart Hodas Page 2 Office-to-Office Partition Office-t to-corridor Partition Figure 1 Photo 1 Measurement Results We measured the sound isolation of the office-to-office partition, of the office-to-corridor partition with the door as installed, and of the office-to-corridor partition with simulated door gaskets. The measured ASTC ratings ranged between ASTC 22 and ASTC 29, and are presented below in Table 1. The tests are presented in greater detail in the attached test reports. Table 1 Measured ASTC Ratings Moveable Wall Type Office-to-Office Partition Office-to-Corridor Partition Moveable Wall Location Room 6022 to Room 6021 Open Office 6018 to Room 6021 (doors as installed) Open Office 6018 to Room 6021 (doors gaps filled) ASTC performance ASTC 29 ASTC 22 ASTC 25 Discussion ASTC versus STC The results reported here are Apparent Sound Transmission Class (ASTC) ratings rather than Sound Transmission Class (STC) ratings. It is important to understand that these two ratings differ. This is because the STC measurements are performed in a laboratory under ideal conditions where the tested partitions are inserted in a hole in a concrete wall so that flanking noise transmission (noise passing through the constructions surrounding the panels) is not physically possible, whereas ASTC measurements are performed in the field and the tested partitions often cannot be installed with as much precision (due in part to irregularities in the surrounding construction) and therefore include the effects of flanking noise, such as through a common ceiling plenum.

3 Stuart Hodas Page 3 As a result, field ASTC ratings of well-built constructions are typically lower than laboratory STC ratings by at least 5 points. But more importantly, the field performance of a construction is controlled by the element of the assembly that provides the least sound attenuation (such as a door, ceiling tile, etc.); therefore, the discrepancy between ASTC and STC can be even greater, particularly in cases where flanking noise is significant. This significant differencee in laboratory and field results occurs often when moveable partitions terminate at the undersidee of a mineral fiber acoustical tile ceiling; it is not unusual for the partition to test 10 to 15 points lower than the STC rating. For example, if the office-to-office partition were tested in a laboratory, we expect that it would achieve an STC rating of approximately 40 to 42 based on available field test data. Potential Improvements We expect that Starwall Finesse partitions will perform at least several decibels better if the weakest paths are addressed, such as through upgrading the glass and perimeter gaskets at doors. The sound isolation between rooms may be further improved if composite lay-in ceilings with an acoustical rating of CAC 40 are selected, and lined boots are used to connect return air grilles to the plenum (where applicable), although we recognize that these design decisions are beyond your control. With partitions that stop at the underside of a lay-in ceiling and with doors containing only modest gaskets (e.g., non-adjustable, self adhesive type), we estimate from the field measurements that Starwall Finesse will provide a level of sound isolation that is comparable to a permanent (and equal height) gypsum board partition; this is due to the fact that the lay-in ceiling plenum will likely be the controlling factor between offices, and the doors will likely be the controlling factor between an office and an open office area. Conclusion Starwall Finesse is a high quality moveable wall product that was installed effectively and provides a level of sound isolation that is at the upper end of those that we have tested thus far. Of particular interest were the tight-fitting doors and partition heads, which already provide a better than average seal; we understand that further improvements to the door gaskets are coming soon, which may increase the door s ASTC rating to be consistent with or exceed our door gaps filled test results. In combination with an electronic sound masking system (when necessary), we would expect Starwall Finesse to provide sound privacy that is suitably free of distractions for typical use (i.e., presuming that the occupants are not unusually sensitive to intruding sounds and that the talkers speak at normal voice levels). * * * * *

4 Stuart Hodas Page 4 This concludes our report. Please do not hesitate to call us (Alicia: ; Tom: ) with any questions. Sincerely, ACENTECH INCORPORATED Alicia J. Wagner Consultant in Acoustics Enclosed: Thomas J. McGraw Senior Consultant Room 6022 to Room 6021 (office-to-office partition) ASTC Measurement Report Open Office 6018 to Room 6021 (office-to-corridor partition) with door as installed ASTC Measurement Report Open Office 6018 to Room 6021 (office-to-corridor partition) with simulated door gaskets ASTC Measurement Report

5 Airborne Sound Insulation Measurement Report Pearson Modular Offices - Room 6022 to Room 6021 Date of measurement: 10/5/2011 Consultant: AJW/TJM Acentech Project: Description of construction: 1/2" markerboard panel, 2" insulation, 1/2" markerboard panel; 3" track at top of carpet and at underside of ACT ceiling. Third-Octave Band Center Frequency (Hz) Average Source Room Average Receiving Room Ambient Sound Level Reverberation Times Absorption Effects Apparent Transmission Loss Aparent Sound Transmission Class (ASTC) Description of Source Room: Modular office - two gypsum board walls, one markerboard wall, one glazed wall with door, Description of Receiver Room: Modular office - one gypsum board wall, two markerboard walls, one glazed wall with door, Aparent Transmission Loss (db) Apparent Transmission Loss ASTC 29 Contour Third-octave Band Center Frequency (Hz) The test procedure was based on ASTM Standard E This page alone is not a complete test report; please see the accompanying report for other details associated with these test results.

6 Airborne Sound Insulation Measurement Report Pearson Modular Offices - Open Office 6018 to Room 6021 Date of measurement: 10/5/2011 Consultant: AJW/TJM Acentech Project: Description of construction: 1/4" glass, 2-1/2" air space, 1/4" glass; 3" track at top of carpet and at underside of ACT ceiling - gypsum board soffit junction. Partition contains door. Third-Octave Band Center Frequency (Hz) Average Source Room Average Receiving Room Ambient Sound Level Reverberation Times Absorption Effects Apparent Transmission Loss Aparent Sound Transmission Class (ASTC) Description of Source Room: Open office area - hard walls, exposed deck ceiling, carpeted floor. Desks/cubicles throughout. Description of Receiver Room: Modular office - one gypsum board wall, two markerboard walls, one glazed wall with door, Aparent Transmission Loss (db) Apparent Transmission Loss ASTC 22 Contour Third-octave Band Center Frequency (Hz) The test procedure was based on ASTM Standard E This page alone is not a complete test report; please see the accompanying report for other details associated with these test results.

7 Airborne Sound Insulation Measurement Report Pearson Modular Offices - Open Office 6018 to Room 6021 (filled-in gaps at door) Date of measurement: 10/5/2011 Consultant: AJW/TJM Acentech Project: Description of construction: 1/4" glass, 2-1/2" air space, 1/4" glass; 3" track at top of carpet and at underside of ACT ceiling - gypsum board soffit junction. Partition contains door - coats used to fill-in gaps between door and surrounding partition. Third-Octave Band Center Frequency (Hz) Average Source Room Average Receiving Room Ambient Sound Level Reverberation Times Absorption Effects Apparent Transmission Loss Aparent Sound Transmission Class (ASTC) Description of Source Room: Open office area - hard walls, exposed deck ceiling, carpeted floor. Desks/cubicles throughout. Description of Receiver Room: Modular office - one gypsum board wall, two markerboard walls, one glazed wall with door, Aparent Transmission Loss (db) Apparent Transmission Loss ASTC 25 Contour Third-octave Band Center Frequency (Hz) The test procedure was based on ASTM Standard E This page alone is not a complete test report; please see the accompanying report for other details associated with these test results.