22.214.171.124 Dimensional Requirements
Designing office space requires attention to the proper arrangement of individual and group workstations. Firstly, the availability of the workstation must be taken into account, i. e. the possibility of free access of workers to workstations. Office space is a social and group space; therefore, it needs to be remembered that the adaptation of workstations in an office was conducive to proper cooperation
between design teams and members of these teams (Janiga 2000). Depending on the purpose, office furniture is designed for individual office work, construction and designing works, the work of groups and problem teams, call centre, training tasks, conferences, individual and collective customer service. Examples of some of these types of furniture are shown in Figs. 3.19, 3.20, 3.21 and 3.22.
Due to different purposes, each of the given types of furniture is characterised by different design solutions which ensure mobility or stability, variability of geometry and dimensions, sufficient stiffness, stability and strength.
When designing office furniture, it is assumed that the workstation should be adjusted in terms of space to the dimensions of 90 % of the adult population of both women and men. The minimum dimensions assumed are those which are not achieved by 5 % of the population, while the maximum dimensions are those which 95 % of the population does not exceed. The key figures and anthropometric criteria used in designing were collected in many positions of the literature on the subject (Batogowska and Slowikowski 1989; Drozynska 1997; Gedliczka 2001; Janow and Bielow 1971; Jarosz 2003; Juergens et al. 2005; Kamienska-Zyla 1996; Konarska 2001; Niejmah and Smirnov 1984; Nowak 1993; Pakarinen and Asikainen 2001; Troussier et al. 1999; Tytyk 2001; Winkler 2005). Spatial parameters were also developed concerning the positions most commonly adopted by employees at computer stations (Corlett 1999; Drozynska 1997; Kamienska-Zyla 1996; Troussier et al. 1999).
Figure 3.23 shows the spatial structure of the workstation at a computer in relation to anthropometric data of the Polish population.
When working at a computer takes place in a standing position, separate regulation of the height of the worktop should be taken into account both under the keyboard and under the monitor. This will allow to use the furniture piece also for work in a seated and kneeling position. The ranges of regulations of parameters of a workstation in a standing, seated and seated-kneeling position are shown in Fig. 3.24.
It is worth mentioning that well designed and properly aligned furniture has a significant impact on the correct posture of employees. Office furniture should be dimensioned in accordance with the provisions of PN-EN 527-1:2004, PN-EN 1335-1:2004 (Fig. 3.25). Furthermore, furniture must also meet the basic constructional and functional requirements (Baranowski 2004).
In the design of seats, innovative solutions and mechanisms should be used, which are to ensure the dynamic position of the body. The key issue here is the ability to adjust the chair or armchair to the individual needs of users. Therefore, an office chair should be characterised by regulated seat height, inclination of both the seat and the backrest, height and spacing of armrests and rotation of armrests.
When designing seats, the constructional parameters of individual elements are specified more and more accurately in order to ensure a seated position, at which the spine can maintain its natural shape. It is also recommended that the height of
Fig. 3.23 Spatial parameters of workstations at a computer (own development on the basis of a collective work 1990): M monitor, CLW central line of vision, D document, K keyboard (cm)
Fig. 3.24 Spatial parameters of a workstation in the following position: a standing, b seated, c seated-kneeling (cm)
the backrest amount to 55-60 cm, and its profiling ensures the support of the spine in the lumbar region, and at this point it should be convex, while at the chest height slightly concave. It is also important that the depth of the seat amounts to 40-45 cm and its width allows the user to assume a comfortable seated and standing position and provides him freedom of movement in carrying out any activities. The construction of the chair must be above all static, stable and durable, which is also why the base of the seat should be fitted with at least a five-armed frame with swinging wheels, rollers or driving balls.
For tables, the recommended optimum surface of the worktop amounts to 0.96 m2. Most commonly, this requirement is met by using rectangles of the dimensions 120 x 80 cm or 160 x 90 cm. When the table is equipped with drawers, their runners must have stops which secure them from falling out, as well as preventing the simultaneous opening of several drawers. An important feature of tables is the possibility of regulating the height of the worktop. Along with a proper chair, this regulation helps to configure a comfortable workstation. Currently, it is expected to allow regulation of this height from 68 cm to 90 cm.
When designing an ergonomic workstation, free space for the legs must be considered. This space is located below the surface of the worktop and should meet the standards of PN-EN 527-1:2004 (Fig. 3.25).