Room acoustics in shared offices

Status:

completed 11/2018

Aims:

Workers in open plan offices increasingly complain of poor acoustic conditions. Problems often cited are an excessively high noise level and a high level of distraction owing to conversations and noise caused by colleagues. Typical consequences are elevated stress levels, a lack of privacy, and impairment of cognitive performance.

Two standards for measurement and assessment of the noise situation in open plan offices now exist in the form of DIN EN ISO 3382-3:2012 and VDI 2569:2016 (draft). Both are aimed specifically at the particular conditions in shared offices. As yet, the German Social Accident Insurance Institutions have gained little experience with either standard.

In this project, field measurements were conducted to examine the practical suitability of the above standards, and to identify frequent problems in the acoustic design of open space offices, and measurement and assessment of their acoustic conditions.

Activities/Methods:

Measurements were performed in accordance with DIN EN ISO 3382-3:2012 in thirteen open plan offices (with between 11 and 50 workstations), and the results were interpreted. The acoustic conditions were subsequently evaluated in accordance with VDI 2569:2016 (draft). Based upon the experience and measurement results gained, problems of a general nature were identified, recommendations formulated for the accident insurance institutions with regard to the performance of measurements, and suggestions made for how the companies could improve the room acoustics in their premises. The measurement results were compared with the results of sound propagation simulations. In cooperation with the German Social Accident Insurance Institution for the administrative sector (VBG), the observations were incorporated into the revision of the publication concerning office acoustics. The project's findings were also published by the IFA in specialist periodicals and presented at conferences.

Results:

The standards studied proved difficult to apply in the field. The DIN EN ISO 3382-3:2012 measurement standard remains unclear in many respects; in turn, observance of the more precise provisions in E VDI 2569:2016 is frequently not possible. Consequently, it proved impossible for measurement to be conducted and results interpreted in a form consistent with the provisions of the two standards in any of the thirteen offices studied. The results of measurement and assessment depend, in some cases substantially, upon the actual (permitted) measurement positions that are selected. As a result, evaluations of one and the same office may yield differing results.

DIN EN ISO 3382-3 defines new parameters that are placed in direct relation to the distraction effect of speech and its intelligibility. Not all of these parameters are being incorporated into the E VDI 2569:2016 assessment guideline, however. Grading of the characteristics used for assessment lies within the range of the analytically determined uncertainty, as a result of which deviations in classification of the offices cannot always be resolved.

Special measurement equipment and intensive training are required for performance of the measurements; it is complicated and time-consuming, as is subsequent determining of the relevant characteristics. In order to save time and simplify the process, two software tools were developed that determine the characteristics for the user based on the measurement data entered, and assess the room based upon these characteristics. The measurement uncertainty is also output, thereby permitting a more differentiated assessment.

The simulated sound propagation in open plan offices differs, in some cases substantially, from the results of the on-site measurements. Reasons for this include a lack of data from the material manufacturers on the scattering coefficient of their products, and general uncertainty concerning the absorption values stated. Only with relevant experience in the performance of simulations was it possible for results of on-site measurements to be reproduced. Acoustic planning based upon simulations alone should therefore initially be performed only by experienced experts.

Altogether, a substantial need exists for the standards studied to be revised and developed further. A simplified procedure should also be developed that permits at least a qualified estimation of the acoustic quality of open plan offices, in a shorter time, and with use of standard instruments (e.g. hand-held sound level meters).

The project enabled considerable expertise to be built up in the acoustics of open plan offices. This expertise is now to be shared with the accident insurance institutions in the course of business consulting and seminars. Concrete guides to acoustic design and the assessment of shared offices have been published in the form of software tools and articles in specialist journals. Further publications are in preparation.

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