Title: The odd ergonomic inch and why it matters in the office
Pages: 38 - 44
Author: Dorothy Meade
Text: The odd ergonomic inch and why it matters in the office
by Dorothy Meade
If you are a business tycoon, I expect you chose your own desk. Or you could easily insist on doing so. OK, so you chose a tycoon-type desk, and a suitably impressive swivel chair to go with it. Why not ? If you chose sensibly, they'll be comfortable too. And if you forgot about comfort, and chose a desk too high (shoulders hunched to get your elbows over the top), or too wide (you can't reach papers on the far side), with a deep underframe (your knees get squashed), or a kneehole drawer (the stomach - pummel joke), or an elegant shiny black top (a dazzling contrast with white paper); if your chair is too high (presses the back of your upper leg), or too deep (ditto your calf) ...Well, the blame and discomfort are yours alone.
But most office staff have no choice in the matter. Though staff are hired and fired, the furniture stays put. Short people, tall ones, fat ones, thin ones must all make the best of the same sized desks and chairs. If cost were no object, people could be fitted for furniture as for a new suit, or at least they could get the best fit 'off the peg'. But when one size must do for everyone, then that size must suit for the widest possible range of people. This is not just a question of cosseting the staff: people work better, for longer, if they are comfortable.
The sad thing is that the best standard size has been found and clearly defined - but largely ignored. Years of scientific study on the range of sizes of the population, and on postural requirements for working, resulted in a clear brief for office comfort. It was as long ago as 1958 that the British Standards Institution published a booklet(1), in which two ergonomists explained exactly why and how the shape and size of chairs and desks affect the comfort of the people using them. Two more BSI pamphlets, published in 1959(2) and 1961(3), gave recommended dimensions for furniture, which, if followed, vvould provide the greatest comfort for the greatest number of users. (These were, however, only recommendations and did not carry the more official seal of a BS specification.) If the manufacturers had heeded them, the desks and chairs produced would have been suitable for 90 per cent of the office population. But the manufacturers took precious little notice - and anyway buyers didn't insist on conforming furniture.
So office workers kept their cramps and, what is worse, discomfort looks like being officially here to stay. Last year a BS specification(4) was produced which gives a slap in the face to the ergonomists. Discounting most of their reasoned pleading for those shapes and sizes that would give comfort to the many (the office workers), the new specification has lent its ear to the growls of the few (the manufacturers). The makers of large, impressive, nonconforming office furniture wanted official blessing, - after all, they said, it's selling well and no complaints. Why, they reasoned, should we put ourselves out for the odd ergonomic inch?Their voice was the loudest, and the new specification is a victory for vested interests. (In all fairness, it must be said that the specification prints the recommended dimensions as well as those it gives as permitted dimensions - but will manufacturers turn anything but Nelson's eye to the recommended figures ?)
So the vast majority of the four million and more office workers in this country are likely to continue working in some discomfort, unless those who order new furniture insist on the recommended sizes which most manufacturers have chosen to ignore.
We took what we felt to be a representative sample of 234 soundly constructed, carefully detailed desks and chairs: we personally checked the measurements and found most of the furniture ergonomically incorrect. After poring over a pile of catalogues and trailing round showrooms and exhibitions with a steel tape, it is clear that this is also true of the market as a whole. So if you design, supply or make office furniture, if you choose or use it, and don't actively prefer discomfort, PLEASE READ ON.
1. BS 3044:1953 Anatomical Physiological and Anthropometric Principles in the Design of Office Chairs and Tables 2. BS 3079:1959 Anthropometric Recommendations for Dimensions of Non - adjustable Office Chairs, Desks and Tables
3. BS 3404:1961 Anthropometric Recommendations for Dimensions of Office Machine Operators' Chairs and Desks 4. BS 3393:1965 Specification for Office Desks, Tables and Seating
Ergonomists v others
It is over seven years since the ergonomists put their case for comfort in the design of office desks and chairs in the three publications, BS 3044, BS 3079 and BS 3404. (For convenience, the two pamphlets BS 3079 and BS 3404, which contain the recommended dimensions for office furniture, will be referred to in this text as 'R'.)
But recommendations alone don't carry much weight - most manufacturers sit tight until a specification appears. In this case it was BS 3893, a retrograde compromise and a perfect example of the difficulties of gaining acceptance of ergonomic principles. (BS 3893, the specifictiion, will be referred to as 'S' from now on.)
Height - the vital statistics
Chair and desk must be considered as one unit, and all ergonomists are agreed that 11 inches between chair top and desk top is comfortable for the majority of people. This can be fixed exactly because it depends on the length of a person's spine, and that of his upper arm.
A fixed chair height of 17 inches ('R' end 'S' are in agreement on this) therefore demands a 28 inch desk.
A higher desk involves raising the elbows and working in a cramped position, and the sage of the desk presses against the forearms; a lower desk, or one with a thick top, doesn't leave enough leg room below for comfort.
'R' gives a single desk height of 28 inches, but - and this is where 'S' has come a cropper - 'S' allows 28 inches to 29 inches, and up to 30 inches for executive desks. So 'S' heights include nearly all desks on the market- most of them uncomfortably high with a 17 inch chair.
The squashed thigh problem
If a desk top is too thick, it obstructs the user's legs and hinders changes of leg position. 'R' gives a maximum of two inches on a 28 inch desk, leaving 26 inch clearance below - enough room for most people to cross their legs comfortably. But 'S' gives an under - desk clearance of 25 inches, allowing a desktop thickness from three to five inches, according to desk height. Fat - legged people will find the desk top chafing their legs when they change position, and few can cross legs easily at this height.
At least 'S' condemns the knee - hole drawer, though customers can still specify one if they want squashed thighs and inaccessible storage - and a drawer handle at navel - prodding level.
Leg stretching space
There must be room to stretch your legs and move them around under the desk. Both 'R' and 'S' allow for this with a minimum clearance of 18 inches from front to back under desk top, and 24 inches clearance at floor level.
And the kneehole must be wide enough to let you sit down and get up easily, and push your chair partially under the desk. 'R' gives 23 inches, 'S' is a bit skimpy at 21 inches, but most kneeholes are wider than this. No shelves must interrupt this space.
First chop your chair...
Both 'R' and 'S' agree that the best single seat height for a chair to fit the greatest range of users is 17 inches.
Those over 5 ft 9 inches will find an 18 inch high chair with a 29 inch desk, or - for the exceptionally tall - a 19 inch high chair with a 30 inch desk more comfortable.
Short people -those under 5 ft 3 inches are better seated at a 16 inch high chair with a 27 inch desk, or on a 15 inch high chair with a 26 inch desk - or they should use a footstool with a 17 inch chair.
Anyone with a desk above 28 inchesshould insist on an adjustable chair, and use a footstool if necessary - or chop a bit off the desk legs to fit their correct chair height.
It is easy to tell if a chair height is wrong. Too high, and it causes discomfort by pressure on the underpart of the thighs; too low, and the hips are bent up, with the lower part of the spine in a tiring convex position.
For comfortable sitting, the soft tissues of the underpart of the thigh should be well clear of the front edge of the seat when the upper leg is horizontal. This allows for changes of foot position without undue pressure on the underpart of the thigh.
The back of the calves should be clear of the seat front and the backrest should firmly support the lumbar region of the spine.
The main point of difference between 'R' and 'S' is the depth of chair seat. 'R' gives 15 inches maximum, 'S' allows 14 to 18 1/2 inches. Nearly everyone can sit on a 15 inch chair without pressure on the back of the calves, though the long - legged will find the seat too shallow. At 18 1/2 inches, over 25 per cent of men and over 50 per cent of women will feel some calf pressure.
Desks and chairs to make the typist happy
The usual method of typing, taught at most typing schools and used by the vast majority of typists, requires a lower desk than 28 inches, so that the typist's forearm is about parallel to the centre of the keyboard. The 'R' typing height is 25 to 25 1/2 inches. As well as making typing easier, typists find the lower height gives better access to other parts of the desk-to telephones, files, papers. But a secretary also needs a 28 inch surface for writing, so a desk at 28 inches with a typing extension at 25 to 25 1/2 inches is the ideal solution.
1 and 2 These diagrams show the relationship of the main dimensions for non - adjustable chairs and desks,1, and typists' chairs and desks, 2, contained in the BS recommendations. (The dimensions for the typists' chairs and desks are based on the traditional method of typing.) Any structural supports needed in the desks should be contained within the areas shown in black to allow free movement of the worker's legs.
3 In 95 per cent of men in this country 'A' measures less than 17 3/4 inches. In 95 per cent of women 'A' is less than 16 3/4 inches. It is hardly surprising that an 18 inch chair is too high for most people - even taking into account the effect of wearing shoes.
4 This diagram shows the range of the population that the recommended sizes for desks and chairs have been designed to accommodate. Five per cent of the women in this country are 4 ft 11 inches or less; 95 per cent of men are 5 ft 11 inches or less. Very short women will require a 1 inch footstool to compensate for the shortness of the lower part of their legs and very tall men would be more comfortable with a cushion.
The problem is complicated by the fact that an entirely new method of typing (the 'claw' method) is now taught at some schools (with elbows tucked in, using wrist and hand movements only). This appears to cause no extra strain at a 28 inch desk. If further tests confirm this, and the new method prevails, it will clearly simplify office planning to standardise at 28 inches throughout. But few typists use this method yet, an d those who have learnt the old way cannot easily change. The 'S' range of typing heights (25 1/2 to 28 inches) covers both methods.
Above all, a typist needs a chair that fits her exactly. (Try typing all day in a chair that is too high and without back support if you doubt it.) The height should be adjustable ('R' gives 15 1/2 to 19 1/2 inches, 'S' 16 to 20 inches, seat height), with a footstool available when needed. A clear brief for backrests is given in 'S' (pages 12 and 13): in its simplest form, the backpad should be four to five inches high, adjustable vertically and horizontally, and 12 to 14 inches wide.
The mystery of the discarded dimension
Out of our sample of 131 office desks, only 18 conformed fully to 'R', made by seven manufacturers. (Of the 18, six made by three manufacturers are now no longer in production.) Most of the remaining 113 were higher than 28 inches; 18 of the 28 inch desks have less than 26 inch clearance below the desk top. We found 16 desks with horizontal bars within the kneehole space, too high for use as a footrest yet too low to give enough leg clearance. Four had a kneehole width of less than 23 inches. Most of the desks conformed to 'S'.
Out of 35 non - adjustable office chairs, only three conformed exactly to 'R' (of these, two, made by the same manufacturer, are now out of production). Of the remaining 32, 23 were higher than 17 inches, and when optional castors are fitted, the seat height is raised by another 12 inches.
Six of the nine chairs which were 17 inches high, were deeper than 15 inches ('R'), and the three remaining fell by the wayside in being narrower than 16 inches ('R' and 'S').
Out of 36 adjustable office chairs, only one conformed to 'R' exactly, and that is now out of production. Hardly any of the chairs adjusted below 16 1/2 inches, and so do not conform to 'S'. Thirteen would not adjust as low as 17 inches. Twenty of them conformed to 'S' seat dimensions. Many of the chairs with fixed backrests gave support too high for comfort.
Out of 32 typing desks and typing extensions (considering a typing extension as one unit), only one desk and two extensions conformed exactly to 'R' - and the desk and one extension are no longer in production. (We have not illustrated the one conforming extension as it is attached to a desk which does not conform.) 27 were higher than 25 1/2 inches, though nearly all came within the 25 1/2 - 28 inch range. Several gave inadequate kneehole clearance.
Case for the nonconformists
Why is it that most manufacturers choose to ignore BS recommendations ? I asked designers, manufacturers and suppliers about four key factors for comfortable sitting (all of them referred to in 'S' as the recommended dimensions) - desk height, depth of desk top, seat height and seat depth. This is what they said.
High desks in demand
"Our desks were designed before 'R'. The cost of modifying them does not justify the small demand for lower desks."
"A market research survey showed that most customers prefer a 29 inch desk. And it is cheaper to shorten desk legs for the few customers who want a lower one than to lengthen them for the many who prefer one higher than 28 inches." "We have lowered our desk one inch to 29 inches. We rejected the 28 inch height because some customers still demand kneehole drawers which aren't possible at 28 inches." "We export a large proportion of our desks to foreign markets where 28 inches is unacceptably low." "We designed an adjustable height desk (27-31 1/2 inches). This increased production costs (16s 6d for each leg), and hardly anyone adjusted the height below 29 inches." "Customers never ask about desk heights. They may sit at a desk for a moment in the showroom but make their decision on appearance and storage capacity." "Some customers actively dislike a desk height which is unfamiliarly low." "Customers are only concerned about height when they want a new desk to match up with ones they have already."
The case for nonconformists was most clearly put by the designer of a large new range of office furniture. "I wanted our new furniture to be ergonomically correct, but an extensive market survey found no demand for a 28 inch desk. So we have produced what we know our customers want- a 29 inch desk. Manufacturers can't be expected to educate the public at their own expense." But several firms said their new desks would be at 28 inches, and those who already made them at this height had no difficulty in selling them.
Desk top difficulty
The arguments for a greater thickness than two inches for the desk top were mainly structural. Several designers of wooden desks put this point: 'You can't make a wooden desk stable enough for heavy office use with a two inch top unless it is strengthened elsewhere. This is easy enough to do, but it puts up the cost. It is cheaper to thicken the top - and very few people find the extra thickness uncomfortable." (But one expert commented acidly, "There need be no technical difficulties if the manufacturers make full use of up to date materials. Of course, if they hew desk tops out of oak trees with stone axes, they find it difficult to get a two inch thickness!")
There is no problem in making a metal desk with a two inch thick top - if the top surface is a structural member. But it was argued that knock-down metal desks with interchangeable tops needed added thickness for rigidity.
Height sells, they say
Both 'R' and 'S' agree on a fixed seat height of 17 inches, and 'S' stipulates a 17-20 inch range on adjustable chairs. Yet most of the chairs in our survey were too high. "An 18 inch chair is much more comfortable for everyone with desks at 29 inches or higher." "People find 17 inches strangely low when they have been used to a higher chair. Eighteen inches is easier to sell." "Our chairs sell well. Why should we spend money changing them when no - one asks - or complains - about the height ?"
Apparent comfort preferred On the question of seat depth, they said: "Fifteen inches is unnecessarily shallow. People prefer a more ample chair seat." "A chair which conforms to 'R' looks dull and skimpy."
Apparent chair comfort sells better than actual comfort. Look at all those deep, low, softly cushioned easy chairs and settees on the market - they look the last word in luxurious comfort but they are actively painful to sit on for long.
5 - 9 We have illustrated here one desk from each of the five manufacturers who together produce the 12 available conforming desks. 5 is model number C1602, designed by Keith Cleminson and made by Carson Brothers (Productions) Ltd; price, from £155 8s 10d. 6 is model number Dl/350, designed by Clive Hunt and made by Heals Contracts Ltd; price, from £117 3s. 7 is model number UDP/60, designed by E. R. Green of Rubery Owen and Co Ltd and made by Leabank Office Equipment Ltd. price £36 6s 9d. 8 is model number 43L designed by Ronald Harford and made by lan Audsley Workshops Ltd; price £47 8s 3d. 9 is model number EF8A, made by Evertaut Ltd and designed by the firm's development department, price £70 13s 8d.
ice £70 13s 8d.
The seven remaining desks which conform are: models Cl600 and Cl601 made by Carson Brothers (Productions) Ltd; models Dl/351, Dl/352, Dl/354, and Dl/356 made by Heals Contracts Ltd; and model 53 LlR made by lan Audsley Workshops Ltd. (In all cases, the designers are the same as those given previously.) 10 The solitary conforming chair is model number PL 49, designed by N. S. Allanson and made by Esavian Ltd. The price is £9 6s 1d.
Where have all the footstools gone ?
Anyone with short legs can sit more comfortably at a 17 inch chair by using a one inch footstool. (A stool adjustable both in height and slope is a still better answer.) Since about 25 per cent of women - even with a 1 12 inch heel would be more comfortably seated with a one inch footstool, and since both 'R' and 'S' advise their use for the shortlegged, one might at least expect to find the simple ones on sale. But they are almost impossible to buy, either as a separate stool or as a footrest attached to the chair. Why ? Once again, comfort doesn't sell. One leading office chair manufacturer told me, "We have prototypes ready for production as soon as there is a demand. But nobody wants them." Another manufacturer said, "They're just an expensive nuisance. Fixed to the chair, people bark their legs on them, and most people don't need them anyway. Loose ones get tricked all over the place, and are the curse of office cleaners."
The deadlock has been broken by the large organisations with a constructive purchasing policy, who order in large enough quantities to set their own standards.
Among the pacesetters are the Ministry of Works, whose typists use 25 inch desks, with chairs adjustable from 16 22 inches; London Transport, with 28 inch desks (and 26 1/2 inch kneehole clearance), using fixed seat heights of 17 inches and adjustable chairs for typists (footstools available when needed); Unilever Ltd. with 28 inch desks, (26 inch kneehole height) and 17 inch chair, 29 inch desks for senior management only, and 26 inch typing desks (the company makes a point of instructing all new staff on correct posture, and provides footstools when necessary); and British Rail, with 28 inch desks, 26 inch typing desks, and 17 inch chairs with a seat depth of 15 1/2 inches.
Ergonomics is a new science, and only recently has sitting comfort been accurately assessed.
People have become so used to approximate comfort, and come to hardly notice discomfort, that the ergonomist's insistence on precise measurements seems a quibble - an inch here or there - does it really matter ?
But when you consider that office furniture is made to fit people, and that the comfort and well-being of the people who use it are key factors in office efficiency, then the odd inch here or there matters very much indeed.