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ergonomics

Ergonomics for designers

Two terms are used to describe the application of scientific information about human variability and adaptability to the design process. Ergonomics (also known as Human Factors) describes information about humans in "working" situations. Anthropometrics deals with information about human body size and shape.

As an item of furniture is rarely used by only one individual, most furniture must accommodate the variations of a wide range of end users. The "average" person is a mythical creature. When measurements are taken from a target population for a particular design, a mid-point (termed the 50th "percentile") divides users into two groups - one above and one below the "average."

It may be logical to use this mid-point/average number to determine the height of a chair seat but not the height for the top shelf in a storage cabinet. In the latter case, it is standard practice to use a dimension that accommodates 90 to 95 percent of users who can reach an object on the top shelf. The design ideal is to provide for adjustability and use anthropometric data to determine the upper and lower limits for the range of adjustments, e.g., for workstation chairs.

Furniture designers should have a library of texts (or software) on this data-intensive subject. furniturelink recommends the three titles shown in the sidebar; several good titles are out-of-print.

For copyright reasons, furniturelink cannot provide data from the above texts. Fortunately, there are a few on-line sources for anthopometric data.

The Beauty of Fit: Proportion and Anthropometry in Chair Design , 206 PDF format pages (courtesy Caroline Kelly, Georgia Institute of Technology)

Human Factors Design Guide, Section 14, Anthropometry and Biomechanics, 61 PDF format pages (courtesy University of Michigan)

1995 Matched Anthropometric Database of U.S. Marine Corps Personnel: Summary Statistics, 225 PDF format pages, (courtesy Humanics ErgoSystems Inc.).

Body Dimensions of the Belgian Population, easy to understand data grouped by age range and sex, (courtesy of Ergonomie RC).

Ergonomic Factors Involved In Optimum Computer Workstation Design, 14 PDF format pages, (courtesy Ergotron, Inc.).

Ergonomics and Design: A Reference Guide, 66 PDF format pages, (courtesy of Allsteel).

Ergonomic Factors Involved In Optimum Computer Workstation Design, 14 PDF format pages, (courtesy of Ergotron, Inc).

A few caveats apply to the data from the above sources and to some of the published texts.

  • On-line data often uses measurements from military personnel (a sample of "healthy" people).
  • The data may be dated (the population may be changing year over year).
  • Technology changes, e.g., computer keyboards have a lower profile than traditional typewriters.
  • Country of orgin may affect the data.
  • Measurements are taken with nude subjects (normally, people wear clothes and shoes at work).

The design of workstations requires the application of anthropometic and egonomic data. furniturelink has provided a sample of relevant data taken from the Marine Corps study (listed above) and other sources. furniturelink added the information for the angle of sight (Z) from various sources that recommended angles between 5 and 15 degrees. For simplicity furniturelink shows the popiteal height (F) measured to the same baseline as the compressed seat height. To adjust for shoe height, add 25 mm for men or 45 mm for women (1).

Disclaimer: use this data at your own risk.

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# Female Male

  5% 50% 95% 5% 50% 95%

A 690 743 795 739 795 850
B 181 226 266 188 235 274
C 406 439 479 447 482 520
D 438 478 525 458 499 544
E 540 585 637 569 616 665
F 352 388 428 395 434 476
G 474 513 558 515 559 605

All measurements in mm. (A) Eye height sitting (B) Elbow rest height (C) Forearm-hand length (D) Buttock-popiteal length (E) Buttock-knee length (F) Popiteal height - no shoes (G) Knee height sitting - no shoes

(1) Ergonomics by Stephen Pheasant

© furniturelink 2014 (text and images)