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Open-plan office designs - promoting organizational productivity Charles, K. E.; Pero, K.
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Open-plan office designs – promoting organizational productivity
N R C C - 4 5 6 2 0
C h a r l e s , K . ; P e r o , K .
A version of this document is published in / Une version de ce document se trouve dans: Construction Canada, v. 48, no. 4, July 2006, pp. 36-38, 40, 42-43
Designing Open-Plan Offices to Promote Organizational Productivity
By Kate Charles & Karen Pero
For many organizations, the physical office space is seen simply as a place to ‘house’ employees, and therefore a cost that should be minimized. However, inappropriate office design choices can compromise workers’ comfort, making it hard for them to work effectively, while also increasing the potential for staff turnover. As such, ill-chosen designs could cost organizations more in the end.
A recent guide created jointly by the National Research Council’s (NRC’s) Institute for Research in Construction (IRC) and Public Works and Government Services Canada
(PWGSC)—Workstation Design for Organizational Productivity—explains how the
indoor environment affects office employees and provides recommendations for
designing open-plan offices that promote organizational productivity.1
Many of the recommendations are based on research findings from IRC’s Cost-effective Open-plan Environments (COPE) project, a four-year multi-disciplinary investigation
examining the effects of the office environment on occupant satisfaction.2 The guide also
draws on studies investigating other occupant outcomes, such as: • task performance;
• health;
• physical comfort; • mood;
• absenteeism;
• job satisfaction; and • staff turnover.
These occupant responses are important because of the part they play in influencing organizational productivity.
The guide provides practical advice on the design and management of open-plan offices, including such parameters as:
• privacy and acoustics;
• indoor air quality (IAQ) and thermal comfort; • lighting and daylighting; and
• workstation design and layout.
It also provides a summary of recommendations organized by elements of the office, such as workstation panels, luminaires, and mechanical ventilation. This article summarizes the main recommendations from the guide.
Privacy and acoustics
Office employees typically identify distracting noise—particularly speech—as one of the leading factors limiting their ability to work effectively. Excess noise can lower
concentration, task performance, and comfort, while simultaneously increasing stress levels. As such, creating acceptable speech privacy is a key concern in open-plan offices.
Speech privacy can be determined using the Speech Intelligibility Index (SII), a ratio of the level of speech sounds relative to background noise. An SII rating of 0.2 is generally considered acceptable for open-plan office design. The three most effective means of creating acceptable speech privacy are:
1. Specifying panels that block the direct path of speech from one employee to another (i.e. 1.6 m [5.3 ft] or taller).
2. Specifying a highly absorbent ceiling with a sound absorption average of 0.90 or greater.
3. Increasing the size of workstations to widen the distance between neighbours (i.e. 6.3
m2 [67 sf] or larger)
A suitable level of neutral background noise helps cover distracting speech sounds. A dedicated sound masking system is the preferred technique, providing a consistent level
of neutral sound throughout the space.3 A background noise level in the range 45 to 48
dB(A) can effectively mask speech without becoming an annoying noise source itself. The layout of workstations should also be considered. Where possible, one should avoid placing workstation entrances along high-traffic corridors or adjacent to noisy office equipment. The provision of alternative spaces, such as enclosed meeting rooms and lunch/social rooms, can encourage employees to carry out noisier activities away from those trying to concentrate.
IAQ and thermal comfort
Complaints about thermal and air quality conditions in open-plan offices are common. Uncomfortable conditions can make it difficult to carry out tasks and may lead to symptoms such as headaches, drowsiness, and eye, nose, and throat irritation. Both the office itself and the mechanical ventilation system influence the perception and creation of comfortable, healthy, working conditions.
It is important to provide an adequate supply of outdoor air to dilute and remove
contaminants. Mechanical ventilation systems providing 8.5 L of outdoor air per second per person (L/s.p) is a minimum recommendation—10 L/s.p is better. If the space is being reconfigured, the volume of outdoor air should be adjusted, to reflect the number of people occupying the space. The mechanical system must have the capacity to provide the required volume of air for the number of people in the space.
The supplied air must reach all the occupied zones within the workspace. Accordingly, supply air diffusers and return grilles need to be located to suit the geometry of the space, and the system should be properly balanced, maintained, and operated. Contrary to popular belief, the height of panels or the presence of a gap at the bottom of panels has little effect on airflow or ventilation efficiency in open-plan offices. However, panel height does influence occupant satisfaction, probably because employees perceive tall panels impede airflow. For this reason, panels 1.7 m (5.5 ft) or taller should be avoided.
Another effective way to ensure good indoor air quality is to avoid bringing contaminants into the workspace. High-quality filters in the mechanical ventilation system can reduce the amount of dust and outdoor contaminants inevitably entering the space. Some office furnishings, materials, and equipment emit chemical contaminants (particularly volatile organic compounds [VOCs]); therefore, careful selection of low-emitting alternatives can reduce the presence of these contaminants in the office space. Office equipment that produces contaminants should be isolated from workstations as much as possible. Areas under construction or renovation should be sealed off from occupied areas. Both the office space and the mechanical ventilation system should be cleaned and maintained on a regular basis.
Depending on relative humidity (RH) and air velocity, operative temperatures between 20 and 28 C (70 and 86 F) should be acceptable to the majority of regularly dressed,
sedentary office workers. It is also advisable to maintain air movement below 0.2 m/s (40 cfm) to avoid draughts. Employees seated next to windows can experience thermal discomfort from temperature variations (heat gain during summer and cooling during winter). To offset these problems, one should choose windows with high insulation values and provide additional sources of heating and cooling for occupants next to windows. One set of thermal conditions will never be acceptable to everyone, so whenever possible it is advantageous to provide systems giving occupants personal control over temperature, air direction, and/or air velocity.
Lighting and daylighting
A good lighting design requires consideration of several elements, not only the light level. Illuminance levels should reflect the tasks being performed, whether those tasks are computer- or paper-based. For example, recommended illuminance for computer tasks range from 300 to 500 lux on the horizontal plane, and 50 to 300 lux on the vertical. Illuminance on the desktop increases as panels are lowered, because there are fewer barriers to restrict the distribution of light. It is recommended task lighting be provided as a supplement to ambient lighting.
Luminance (i.e. the amount of light coming off a surface, which affects perceptions of
brightness) is also important. Darkly shadowed areas, or dark ceilings and walls, can create a ‘cave-like’ atmosphere and should be avoided. Specifying wall, ceiling, and
panel materials with high surface reflectances (i.e. light in colour) has a positive effect on
employees’ satisfaction and visual comfort. Ceiling reflectances of 75 to 90 per cent and wall reflectances of 40 to 70 per cent are typically recommended.
Since it can cause visual discomfort and render tasks more difficult to perform, glare should be avoided or minimized. It is best to use luminaires with low brightness when viewed directly (direct glare) and spacings and lenses that do not create reflections on a computer screen. Liquid crystal display (LCD) screens or anti-glare filters can help mitigate unavoidable instances of glare.
Most employees prefer daylight to electric lighting, and believe it makes them healthier and more productive. To maximize the daylight reaching the space, it is worth using
lower panels closest to the window, or placing them perpendicular to the window. However, usable daylight does not reach further than two workstations deep into a space (unless there are no panels at all), so reducing the height of panels towards the centre of the space is unlikely to increase the daylight available at these locations. Blinds or shades should be installed so glare does not become a problem for the occupants adjacent to the windows.
As with thermal conditions, occupants differ considerably in their preferences for lighting levels. Providing individually controlled dimmers gives them a means to adjust the
lighting to meet their preferences and task needs.
Workstation design and layout
The most important consideration when designing open-plan office workstations is the job requirements of the employees. Often the tendency is to apply the same workstation plan across a whole floor plate, even when jobs and tasks vary considerably. The proper approach is to consider such elements as privacy requirements, and the horizontal surface and storage space needs for the different types of work. Providing some degree of
personal control and adjustability also helps.
Finding the appropriate balance between privacy and social interaction can be
challenging. Most employees prefer some degree of visual and acoustical privacy, so they are able to concentrate on their tasks. Even those employees working on team projects need a quiet place to concentrate on their individual contributions. At the same time, most employees need to feel connected to the organization as a whole, to have a sense of identification with their work group, and to have ready access to equipment, resources, and colleagues. To achieve this, it is best to strive for workstations neither too small nor
too large (i.e. 5.9 to 13.4 m2 [64 to 144 sf]), and for panels providing visual privacy (at
least 1.4 m [4.5 ft]). It is advisable to avoid large, unbounded ‘cubicle-farm’ layouts, which can create a sense of crowding and anonymity. Instead, the design team should aim for smaller clusters of workstations.
Access to windows is important. In addition to providing natural lighting, windows permit a connection to the outside world. A nice view—especially of attractive surroundings or nature—can help reduce stress and improve well-being. While it is usually impossible to give every employee close access to a window, office designs providing access to distant windows for more employees can be helpful. Window access in publicly accessed areas, such as lunchrooms and corridors, can also be desirable. By providing well-designed workstations that are regularly cleaned and maintained, employers send a signal they value their employees. Involving employees in the design process is all the better, as it shows their input is important. It enables the incorporation of some good ideas into the design process and the collection of critical job task
information. Employees also feel more valued and satisfied with the organization if they are given the opportunity to personalize their workstations with pictures, plants, and other effects. From a design standpoint, this means providing sufficient surface area and
Design interactions
Overall, a well-designed open-plan office considers the needs of the occupants, and all key aspects of the physical environment as described in this article. Inevitably, this means some design goals will conflict with others. For example, lower panels are preferable for lighting, access to windows, and ventilation perception, but higher panels are better for privacy and acoustics. Similarly, maximizing window exposure is advantageous for lighting and view purposes, but can lead to complaints about glare and thermal conditions. Choices can become easier when the priorities and needs of the particular occupant group have been determined in advance.
Notes
1. This report is available for download at irc.nrc-cnrc.gc.ca/ie/productivity/index_e.html. 2. For more information on the results of the COPE project, see Construction Technology Updates Nos. 60-64 on the IRC website at irc.nrc-cnrc.gc.ca/pubs/ctus/index_e.html. 3. For more on the topic, see “Sound-masking Made Clear” by Niklas Moeller, MBA, in
the September 2005 issue of Construction Canada.
Kate Charles, PhD, is a researcher in the Indoor Environment Program of the National Research Council’s Institute for Research in Construction (NRC-IRC). She can be contacted via e-mail at kate.charles@nrc-cnrc.gc.ca. Karen Pero is the lighting and workplace performance specialist in the Innovations and Solutions Directorate of Public Works and Government Services Canada (PWGSC) Real Property Branch. She can be contacted via e-mail at karen.pero@pwgsc.gc.ca.
The authors wish to acknowledge the contributions of Jennifer Veitch, PhD, and Guy Newsham, PhD, both of NRC-IRC’s Indoor Environment Program and part of the COPE & productivity guide projects (Dr. Newsham was project manager of COPE), and Alison Danforth, also a member of these projects and currently working towards a Masters degree.
Practical Advice
Supporting Research
Links to further information Photos and charts to
illustrate research findings and design
advice
Workstation Design for Organizational Productivity provides a variety of information for design professionals
The National Research Council Canada and Public Works and Government Services Canada joined forces to develop this design guide for open-plan offices
This printer has been placed in a room of its own, with a door and a dedicated exhaust system. This prevents contaminants from circulating in the office, and also i the noise annoyanc the equipment.
solates e of
The PWGSC-developed controls on this computer interface allow occupants to select lighting and temperature levels for their workstation, and also to set on/off timers for their lights.
arge, unbounded workstation layouts can create a sense of crowding and anonymity. L
These workstations are very exposed to the corridor and neighbouring workstations. Occupants are likely to be distracted by traffic and neighbours’ conversation, and there is little sense of enclosure. There is no acoustic or visual privacy in this arrangement.
These workstations have been set at an angle to the façade, with low partitions perpendicular to the window, so that most people have access to daylight and views. Acoustic privacy is lower here, but the occupants have chosen daylight and view over speech privacy. There are also issues of reflected glare on computer monitors.