Good acoustics in open-plan offices

The argument made for open-plan office concepts is that they are transparent working environments conducive to communication. However, the planning and design of such offices is complex, for a number of reasons. The acoustics in particular pose enormous challenges. Methods for measurement and assessment relevant to the subject can be found in state regulations and standards.

Open plan, open space, open concept, multi-space, shared desks and shared offices: the open-plan office concept has countless names, and in the modern world of work may take just as many different forms. The design of open-plan office concepts presents major challenges: factors associated with indoor spaces, such as climate and lighting, must be addressed, and aesthetic requirements must also be met. Complaints arising during the use phase often concern not only the lack of privacy (De Croon EM, Sluiter JK, Kuijer PP, Frings-Dresen MH. The effect of office concepts on worker health and performance: a systematic review of the literature. Ergonomics 48(2) 2005, pp. 119-34.), but also the increased disturbance caused by speech (Schlittmeier SJ, Liebl A. The effects of intelligible irrelevant background speech in offices – cognitive disturbance, annoyance, and solutions. Facilities 33(1/2) 2015, pp. 61-75). Acoustics is therefore an essential factor in effective office design.

Many advantages are claimed for open-plan office concepts. One is that they are conducive to communication. However, a study (Bernstein ES, Turban S. The impact of the ‘open’ workspace on human collaboration. Phil. Trans. R. Soc. B 373(1753) 2018) conducted in two companies during a restructuring process concluded that in reality, direct communication drops, being progressively replaced by communication by e-mail and instant messaging. In other words, a loss of direct communication is experienced.

A further study reveals that in open-plan and shared-desk offices, sick leave levels are double those in individual offices (Bodin Danielsson C, Chungkham HS, Wulff C, Westerlund H. Office design’s impact on sick leave rates. Ergonomics 57(2) 2014, pp. 139-147). Despite the rental savings usually cited as a benefit from the reduced space requirements, the question therefore remains whether the open-plan office does in fact deliver cost reductions over other office concepts. The motivation and performance of employees, both of which may be reduced, must also be taken into account.

State regulations and principles in standards

For the reasons listed above, the room acoustics of completed offices must be considered from the planning stage. The ASR technical rules for work premises, which support the German Ordinance on workplaces (ArbStättV), provide assistance in this respect. In particular, ASR A1.2 governing room dimensions and free movement areas and ASR A3.7 governing noise must be considered and observed as an important reference for the design of open-plan and shared offices.

These rules have been supplemented by standards for the detailed acoustic planning of an office. EN ISO 3382-3:2012 (Acoustics – Measurement of room acoustic parameters – Part 3: Open plan offices) describes parameters by which the acoustics of a large office can be designed, particularly with consideration for the dominant disturbance factor of speech. Based upon these parameters, the German VDI Standard 2569:2019-10 (Sound protection and acoustical design in offices) enables an office to be evaluated and assigned to a room acoustics class. It also contains a wealth of information on the spatial and building acoustics planning and design of offices.

For calculation of the various parameters following measurement and for assignment to a room acoustics class, the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) provides two practical tools for shared offices.

Good acoustics in offices

Numerous factors must be taken into account for the design of a good acoustic environment in offices:

• The basic requirement for all further steps is an adequate level of absorption (generally achieved by means of an acoustic ceiling).
• Zoning into discrete areas which are separated from each other acoustically by selective screening helps to reduce noise disturbance (e.g. conversations between other employees). Zoning is based upon an analysis of the activities carried out in the office and enables it to be divided into areas each of which is adapted acoustically. For example, it is not advantageous for communicative and interactive activities to be performed in the same area as activities that are “quiet” and require high levels of concentration.
• Of equal importance to the division by activity and an adequate number of conference and privacy rooms is a defined communication and behaviour policy.
• Acceptance of open-plan offices rises when the employees are involved in the design of the workspace from the planning phase.

Good acoustics is conducive to motivation, forms a basis for good work performance and promotes good employee health.

Jan Selzer