The Good Guide To Office Seating
- Ergonomic Information
- Regulations
- The body at work
- Categories of seating and office work
- Features of well-designed office seating
- Other factors relevant to selection and use of office seating
- Special Needs
- The Working Environment
1. ERGONOMIC CHAIRS INFORMATION
The office environment is making increasing demands on employers and employees alike. Both have to contend with constant pressures for efficiency, and productivity; the complexity and choice of equipment and furniture available. The new British and International Standards to which these are expected to conform; and the greater emphasis being placed on health and safety requirements in European as well as UK legislation.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Comfortable office seating, correctly used, makes an essential contribution to a healthy and productive working life. The purpose of this Guide is to provide a comprehensive review of the role of office seating in the context of current legislation and standards which cover the working environment and places specific responsibilities on employers of office based staff..
The following information contains an explanation of the importance of correct sitting posture and the physical problems that incorrectly designed and used seating can cause; guidance on the selection of suitable seating; and the features that indicate the best seating for particular types of work.
BACK TO BASICS
Back pain is the single most important cause of occupational ill health and absence from work in the UK today. The Health and Safety Commission (HSC) estimates that more than half a million people - nearly two per cent of the employed workforce - suffer from work related back pain at nay one time, while as many as 60 per cent of all adults experience it at some time in their lives. Sitting is the most common position in the modern workplace and those most at risk are office workers, who constitute over 20 per cent of the employed population. They typically spend between 25 and 35 hours per week in a seated position - amounting to around 50,000 hours in full working lifetime.
Recent advances in office technology have increased the proportion of time in that office workers-particularly those performing dedicated functions-are liable to send seated at their desks or workstations in a static position. The multi-functional capability of the PC with its visual display terminals (VDT), and the availability of local and wide area networks, e-mail and the internet to transfer information, have all tended to reduce opportunities for moving-both in a seated posture and around the office during the typical working day.
Viewthe Chairs Direct range of Ergonomic Office Chairs
The consequence is that office workers are at risk of ceasing to benefit physically from the natural breaks and changes of posture that once formed integral elements of normal office life. Combined with the frequent occurrence of poor seated positions at work, these changes in routine have led to a rise in the incidence of health-related problems among office workers. Particularly vulnerable are those who spend a large proportion of their working day using keyboard to input into VDTs.
The resulting threats to their well being include body and visual fatigue, stress, and musculoskeletal problems leading to workstation-related disorders (WRDs). These range from soreness to chronic disorders such as repetitive strain injury (RSI) and are one of the commonest causes of absence from work.
Lower back pain (LBP) has long been recognised as the most common musculoskeletal disorder in developed countries and research shows that its incidence increases with the length of time that people are seated. The issue has been brought into focus by a number of recent decisions by courts which have awarded substantial damages to employees affected by keyboard and seating-related injuries sustained at their workstations. Legal judgements have held that employees should have known the importance of seating and posture for employees engaged in repetitive keyboard work.
According to official statistics, sickness absence and invalidity caused by back pain result in the loss of over 80 million working days a year, costing employers £5bn annually.
Correct specification and selection of office seating is therefore critical. The office chair is a key element within the modern office workstation unit and working environment.
Not only should we be concerned with the office workplace but know that our Homes are becoming a computer based environment and very little importance is being paid to how long we and our children spend sitting at VDUs. Correct seating in the home is as important as in the office environment, from a young age our children are developing therefore the correct seating is important and complying with the correct posture seating is imperative
Complying with these should not be the only area of concern. Recent studies of office workers indicate that provision of good ergonomic seating can increase productivity by at least 10 per cent, adding as many as 40 productive minutes to the working day of each employee.
Again, the well know Hawthorn Effect illustrates that employees experience increased job satisfaction and productivity when they become aware that their employer is acting positively to improve their working conditions. In one major sturdy of 70 companies employing telemarketers-one of the most intensely VDT and keyboard oriented groups of office employees-91 per cent reported that their immediate working environments significantly affected attitudes to their jobs.
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The changing office workplace environment and the consequent rise in health-related problems. Associated particularly with keyboard equipment; led to introduction by the European Commission of Directive no 90/70/EEC OF29 May 1990, on the minimum health and safety requirements for work with display screen equipment or video display terminals (VDTs)
Viewthe Chairs Direct range of Ergonomic Office Chairs
As an EC Directive, this was binding in terms of the results required by the left member States free to decide how to apply it nationally. It was implemented in the UK by the Health and Safety (Display Screen Equipment) Regulations 1992, which came into effect on 1 January 1993 and were incorporated in the Health & Safety at Work Act 1974. In the text which follows, these are referred to as the Display Screen Equipment Regulations
As important as these Regulations, is a new international standard, which deals with the design of office seating, footrest and both fixed and adjustable workstations. It covers issues including overall design, height, size and clearance, and places strong emphasis on providing workstation users with flexibility of movement and muscle exercise. It illustrates the correct (and comfortable) computer viewing position and recommends more legroom for users so that they can move around their workstations without meeting obstructions.
The new standard-BS EN ISO 9241-5: 1999, Ergonomics requirements for office work with visual display terminals (VDTs) - Part V, 'Workstation layout and postural requirements' - has been developed in Europe with the co-operation of national standards and supersedes BS 7179-5: 1990.
It specifies ergonomic guiding principles, which apply to the user requirement, design and procurement of workstation equipment for office tasks using VDTs. The general principles and requirements specified apply particularly to the technical design of the furniture including seating-and equipment, which together make up the office workstation.
Other relevant standards are the European standards EN 133
5, covering office chair dimensions, safety requirements and safety test methods, and EN 12528, Dealing with the dimensions, strength and durability of castors.
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In order to appreciate how the body behaves in the office working environment, it is helpful to know something about its anatomical features and natural posture, The spine has a natural 'S' shaped curve, with the lumbar region curving inwards, which it assumes when a person is standing.
Standing for long periods, however, results in the body's weight placing strains on the ankles, knees and hips. 'The lower body strain is relieved when the person sits down.
Viewthe Chairs Direct range of Ergonomic Office Chairs
The pelvis however, then tends to rotate slightly backwards. This in turn, makes the spinal column bend forward, crushing the protective intervertebral discs which separate the vertebrae and causing them over time to lose their characteristic wedge shape. At the same time, the forward bend can also dramatically increase strains on the ligaments of the spine.
To avoid the risk of both these conditions, the spine's natural 'S' curve needs to be maintained by being supported, particularly in the lumbar and pelvic regions, by a correctly-designed chair. (Proper lumbar support also take some of the body weight when a seated person leans back, reducing the load on the lumbar spine).
This is not, however, the case with the under-thigh area, where two major veins pump blood back to the heart against gravity. Unless the feet are resting firmly on the floor and supporting some of the weight of the leg pressure form the front edge of the seat can restrict blood circulation and cause discomfort. This condition can be alleviate by ensuring that the seat has a curved - or 'waterfall' front edge.
The angle between the trunk and the thighs should be at least 90 degrees, to avoid uncomfortable constriction of the abdomen. The legs are most comfortable and under least strain when the angle between the thighs and the lower legs is approximately 90 degrees.
The shoulders and arms are most comfortable and under least strain in a working position which allows the upper arms to be kept vertical, the forearms to be horizontal, and the hands to be at the level as the elbows
Armrests, which support the forearms, will relieve some of the strain on the shoulders and arms and can be beneficial, provided that they allow work to be carried out comfortably they will also relieve the buttocks and legs of some of the body weight.
The body is not designed to remain in any one position for lengthy periods, no matter how 'correct' that position may be in itself. 'The action of flexing the spine, for example, provides a necessary influx of nutrition to the intervertebral discs and encourages the circulation of blood to the muscles of the back.
Again, body movements shift the weight from one part of the buttocks and thigh to another, once more promoting better blood circulation. It is therefore essential that office workers change their position form time to time.
If, therefore, the demands of new technology inhibit movement, it must be encouraged in other ways-principally through well-designed seating. This allows employees-especially those using VDTs or performing repetitive work-comfortable degree of movement while continuing to support them in the right places.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Recent studies show that sitting in a chair which allows both adjustability and movement ensures that the back receives healthy exercise and contributes to the prevention of injury.
It is even more important that employees take regular breaks. The Display Screen Equipment Regulations specifically require employers to plan their employees' working lives so as to include breaks and changes of activity, stressing that frequent short breaks are more beneficial than less frequent but longer ones. Breaks, which include exercise programmes, can be particularly effective.
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This Guide is concerned with office seating used primarily at a desk or workstation for a significant part of the working day. The tasks being performed here generally fall into one of two categories: multi-functional and dedicated function.
Multi-functional tasks are typically those performed by managers, PAs, secretaries and other clerical staff who perform a variety of activities during the day-including using a PC AND VDT, but also telephoning, reading, writing, filing and taking part in office meetings. Many of these activities involve a degree of movement around the office.
Dedicated function tasks such as extended keyboard/VDT operation-for example by telemarketers and call centre personnel - can constrain staff to static oppositions for long periods.
A chair used for multifunctional work has to accommodate frequent or continuous movement by the user, while one used for dedicated-function work needs to support the user in a number of fixed positions. Modern, well-designed office seating is suitable for both categories of work. View our range of ergonomic office chairs
While there is a very wide variety of office seating products on the market, all should essentially:
Recent advances in office technology have increased the proportion of time in that office workers-particularly those performing dedicated functions-are liable to send seated at their desks or workstations in a static position. The multi-functional capability of the PC with its visual display terminals (VDT), and the availability of local and wide area networks, e-mail and the internet to transfer information, have all tended to reduce opportunities for moving-both in a seated posture and around the office during the typical working day.
Viewthe Chairs Direct range of Ergonomic Office Chairs
The consequence is that office workers are at risk of ceasing to benefit physically from the natural breaks and changes of posture that once formed integral elements of normal office life. Combined with the frequent occurrence of poor seated positions at work, these changes in routine have led to a rise in the incidence of health-related problems among office workers. Particularly vulnerable are those who spend a large proportion of their working day using keyboard to input into VDTs.
The resulting threats to their well being include body and visual fatigue, stress, and musculoskeletal problems leading to workstation-related disorders (WRDs). These range from soreness to chronic disorders such as repetitive strain injury (RSI) and are one of the commonest causes of absence from work.
Lower back pain (LBP) has long been recognised as the most common musculoskeletal disorder in developed countries and research shows that its incidence increases with the length of time that people are seated. The issue has been brought into focus by a number of recent decisions by courts which have awarded substantial damages to employees affected by keyboard and seating-related injuries sustained at their workstations. Legal judgements have held that employees should have known the importance of seating and posture for employees engaged in repetitive keyboard work.
According to official statistics, sickness absence and invalidity caused by back pain result in the loss of over 80 million working days a year, costing employers £5bn annually.
Correct specification and selection of office seating is therefore critical. The office chair is a key element within the modern office workstation unit and working environment.
Not only should we be concerned with the office workplace but know that our Homes are becoming a computer based environment and very little importance is being paid to how long we and our children spend sitting at VDUs. Correct seating in the home is as important as in the office environment, from a young age our children are developing therefore the correct seating is important and complying with the correct posture seating is imperative
Complying with these should not be the only area of concern. Recent studies of office workers indicate that provision of good ergonomic seating can increase productivity by at least 10 per cent, adding as many as 40 productive minutes to the working day of each employee.
Again, the well know Hawthorn Effect illustrates that employees experience increased job satisfaction and productivity when they become aware that their employer is acting positively to improve their working conditions. In one major sturdy of 70 companies employing telemarketers-one of the most intensely VDT and keyboard oriented groups of office employees-91 per cent reported that their immediate working environments significantly affected attitudes to their jobs.
Back to top
2. REGULATIONS
The changing office workplace environment and the consequent rise in health-related problems. Associated particularly with keyboard equipment; led to introduction by the European Commission of Directive no 90/70/EEC OF29 May 1990, on the minimum health and safety requirements for work with display screen equipment or video display terminals (VDTs)
Viewthe Chairs Direct range of Ergonomic Office Chairs
As an EC Directive, this was binding in terms of the results required by the left member States free to decide how to apply it nationally. It was implemented in the UK by the Health and Safety (Display Screen Equipment) Regulations 1992, which came into effect on 1 January 1993 and were incorporated in the Health & Safety at Work Act 1974. In the text which follows, these are referred to as the Display Screen Equipment Regulations
STANDARDS
As important as these Regulations, is a new international standard, which deals with the design of office seating, footrest and both fixed and adjustable workstations. It covers issues including overall design, height, size and clearance, and places strong emphasis on providing workstation users with flexibility of movement and muscle exercise. It illustrates the correct (and comfortable) computer viewing position and recommends more legroom for users so that they can move around their workstations without meeting obstructions.
The new standard-BS EN ISO 9241-5: 1999, Ergonomics requirements for office work with visual display terminals (VDTs) - Part V, 'Workstation layout and postural requirements' - has been developed in Europe with the co-operation of national standards and supersedes BS 7179-5: 1990.
It specifies ergonomic guiding principles, which apply to the user requirement, design and procurement of workstation equipment for office tasks using VDTs. The general principles and requirements specified apply particularly to the technical design of the furniture including seating-and equipment, which together make up the office workstation.
Other relevant standards are the European standards EN 133
5, covering office chair dimensions, safety requirements and safety test methods, and EN 12528, Dealing with the dimensions, strength and durability of castors.
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3. THE BODY AT WORK
3.1 SUPPORTING THE SITTER
In order to appreciate how the body behaves in the office working environment, it is helpful to know something about its anatomical features and natural posture, The spine has a natural 'S' shaped curve, with the lumbar region curving inwards, which it assumes when a person is standing.
Standing for long periods, however, results in the body's weight placing strains on the ankles, knees and hips. 'The lower body strain is relieved when the person sits down.
Viewthe Chairs Direct range of Ergonomic Office Chairs
The pelvis however, then tends to rotate slightly backwards. This in turn, makes the spinal column bend forward, crushing the protective intervertebral discs which separate the vertebrae and causing them over time to lose their characteristic wedge shape. At the same time, the forward bend can also dramatically increase strains on the ligaments of the spine.
To avoid the risk of both these conditions, the spine's natural 'S' curve needs to be maintained by being supported, particularly in the lumbar and pelvic regions, by a correctly-designed chair. (Proper lumbar support also take some of the body weight when a seated person leans back, reducing the load on the lumbar spine).
- Support to the pelvis reduces lower intervertebral disc crushing.
- Support to the lower spine reduces strain in the lumber region
- Support to the lumbar region is essential to maintain the spine in its natural 'S' shape.
- Support to the upper body reduces the strain on the middle section of the spinal column and the thoracic discs.
- High-level support will help to avoid the risk of neck and shoulder pain
- A waterfall front edge prevents pressure under the thighs increasing blood circulation in the legs
- Support to the arms can relieve the buttocks and legs of some body weight, and the upper back and shoulders of some of the weight of the arms and hands.
This is not, however, the case with the under-thigh area, where two major veins pump blood back to the heart against gravity. Unless the feet are resting firmly on the floor and supporting some of the weight of the leg pressure form the front edge of the seat can restrict blood circulation and cause discomfort. This condition can be alleviate by ensuring that the seat has a curved - or 'waterfall' front edge.
The angle between the trunk and the thighs should be at least 90 degrees, to avoid uncomfortable constriction of the abdomen. The legs are most comfortable and under least strain when the angle between the thighs and the lower legs is approximately 90 degrees.
The shoulders and arms are most comfortable and under least strain in a working position which allows the upper arms to be kept vertical, the forearms to be horizontal, and the hands to be at the level as the elbows
Armrests, which support the forearms, will relieve some of the strain on the shoulders and arms and can be beneficial, provided that they allow work to be carried out comfortably they will also relieve the buttocks and legs of some of the body weight.
3.2 CHANGING POSITION
The body is not designed to remain in any one position for lengthy periods, no matter how 'correct' that position may be in itself. 'The action of flexing the spine, for example, provides a necessary influx of nutrition to the intervertebral discs and encourages the circulation of blood to the muscles of the back.
Again, body movements shift the weight from one part of the buttocks and thigh to another, once more promoting better blood circulation. It is therefore essential that office workers change their position form time to time.
If, therefore, the demands of new technology inhibit movement, it must be encouraged in other ways-principally through well-designed seating. This allows employees-especially those using VDTs or performing repetitive work-comfortable degree of movement while continuing to support them in the right places.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Recent studies show that sitting in a chair which allows both adjustability and movement ensures that the back receives healthy exercise and contributes to the prevention of injury.
It is even more important that employees take regular breaks. The Display Screen Equipment Regulations specifically require employers to plan their employees' working lives so as to include breaks and changes of activity, stressing that frequent short breaks are more beneficial than less frequent but longer ones. Breaks, which include exercise programmes, can be particularly effective.
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4 CATEGORIES OF SEATING AND OFFICE WORK
This Guide is concerned with office seating used primarily at a desk or workstation for a significant part of the working day. The tasks being performed here generally fall into one of two categories: multi-functional and dedicated function.
Multi-functional tasks are typically those performed by managers, PAs, secretaries and other clerical staff who perform a variety of activities during the day-including using a PC AND VDT, but also telephoning, reading, writing, filing and taking part in office meetings. Many of these activities involve a degree of movement around the office.
Dedicated function tasks such as extended keyboard/VDT operation-for example by telemarketers and call centre personnel - can constrain staff to static oppositions for long periods.
A chair used for multifunctional work has to accommodate frequent or continuous movement by the user, while one used for dedicated-function work needs to support the user in a number of fixed positions. Modern, well-designed office seating is suitable for both categories of work. View our range of ergonomic office chairs
4.1 FEATURES OF WELL-DESIGNED OFFICE SEATING
While there is a very wide variety of office seating products on the market, all should essentially:
- Support the spine
- Prevent any restriction of the circulation of blood in the legs
- Provide long-term comforts and support for a wide range of users (including pregnant women and people suffering form disabilities)
- Help users adopt safe and efficient working positions
- Allow users freedom of movement and easy changes in posture
- Be easily adjusted in both seat height and the height-and-tilt of seat back, to suit a range of different working positions.
- Be mobile, safe and durable
- Have a footrest provided, if requested.
The main features of office chairs needed to meet these requirements re described in the chapter and summarised by Figure 1
Click image for larger version
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THE BACKREST
- The backrest should be designed to support the user's back in all sitting positions.
- It should normally end below shoulder blade level, except for types of work which demand a reclining posture.
- Lumbar support is the most important requirement, and the backrest should always have forward convexity
- A backrest height adjustment facility makes it possible to change the location of lumbar support to suit personal preferences and provides support to the upper back in medium back-height chairs.
- A backrest tilt facility allows working positions to change between upright and reclined and also changes seat depth. It should support the lower back at any chosen angle. Our Ergo 5 as extra lumbar support and complete back rest height adjustment.
THE ARMREST
- Armrests can support the neck and shoulder muscular systems as well as relieving the buttocks and legs of some of the body weight.
- Armrests can alleviate some of the symptoms of occupational upper limb disorders (as can wrist supports)
- The height of armrest is important. They should support the forearms in a horizontal position, while allowing the VDT user to get close enough to the work surface to be comfortable without having to lean the body forward or hunching the shoulders.
- They can also be helpful in steadying the forearms for certain dedicated tasks.
- An adjustable armrest should cover the range from the fifth percentile female to the 95th percentile male within the anticipated user range.
- Armrests provide useful support to people who have difficulty getting into and out of chairs (e.g. pregnant women)
- Armrests should not restrict the users working posture or the chair's ability to slide under the work surface. Adjustable or detachable armrests overcome this problem.
- Armrests can often be retrofitted to existing office seating, and some types are available in height and width-adjustable form.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Armrests are not specifically required by the Display Screen Equipment Regulation, but employers should make them available to people who can work more comfortable by using them. Our Ergo 5 has padded adjustable arm rests
THE SEAT
- The ideal seat height for office workers sitting upright is their popliteal height added to the thickness of their footwear
- Seat height should be adjustable to suit people whose height range from the very short to the very tall, allowing their feet to rest firmly on the floor (or footrest) in all cases. Our Ergo 5 enraptures all the above features.
- The seat should be wide enough to fit maximum hip widths and deep enough to provide support for tall people, without being too deep for short people
- Contoured designs encourage better posture and even weight distribution
- Rounded 'waterfall' front edges need to be well padded, so that they do not dig into the thighs.
- Seat tilt encourages better spinal posture, allows changes of position during the day and alleviates under-knee pressure. Most users are likely to find this a comfortable feature.
THE FOOTREST
- The sole of the foot should make a 90-degree angle with the lower leg when placed flat on the floor
- A footrest is necessary for workers who cannot comfortable place their feet on the floor when seated at a workstation
- A footrest should be independent of the chair and designed to remain in place when positioned where it is needed
- a footrest should have a non-slip surface large enough to allow some freedom of movement and be capable of being inclined.
(Note: the Display Screen Equipment Regulations stress that footrests should not be used where they are unnecessary, as they can result in poor posture). See our range of footrests in the main menu.
Office seating needs to be both durable and safe when in use. the new European Standard EN 1335 Part 3 contains test methods, of which some (eg for stability) are largely as in the British Standard BS 5459: Part 2, 1990: 'Strength and stability of office seating; other (for castors) introduce requirements new to the UK; and others again (eg for fatigue) are less rigorous than BS 5459: Part 2
Considerable ergonomic study and design experience have led to the development of dimensional criteria for well-designed seating and workstations which will accommodate some 90 per cent of the office population. These are summarised in figure 3
Well-designed office seating should therefore provide:
People of smaller stature, and those using VDU keyboards on a conventional 720mm-height work surface, may also need a footrest to achieve a comfortable working position. The Display Screen Equipment Regulations require a footrest to be made available to any employee who wants one.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Seat height adjustment is usually effected by means of a pressurised gas cylinder located between the chair base and seat and is activated by a readily accessible lever. the Health & Safety Executive advises that persons weighting more than 100kg (16 stone) should not use a chair fitted with a gas cylinder unless it as been specifically designed and tested to accommodate them.
Mechanical height adjusters are also readily available. While these can have the advantage of avoiding the weight restriction on the use of gas cylinders, provided they are appropriately tested, they can not normally be operated from a seated position,
BS EN ISO 9241-5: 1999 approaches the issue of seat height, as well as of seat depth and width, on the basis of the concept of 'fit'. Adjustments in seat depth can be achieved by adjusting the relationship between the seat and the backrest; and in width by the provision of arm rests.
Experience shows that chairs which have too many handles, knobs and levers for adjustment are not in practice very 'user friendly' and people don't make enough effort to change position to suit their needs because they tend not to think of how they are sitting when they are working. Adjustment controls should always be safe and easy to use, and there has been a welcome trend in the direction of simplifying controls and mechanisms and introducing dynamic seating to encourage people to sit properly.
Dynamic seating is achieved by co-ordinating design factors including seat angle and back adjustments, back angle rake adjustment, swivel and castors. Its importance is stressed by BS EN ISO 9241-5: 1999
Seat adjustment capability falls into three main types: seat angle (tilt) adjustment; back rake and angle adjustment and back height adjustment. We feel our Ergo 5 has all the features and mechanisms required to give you the maximum comfort and support
Reward-tilting seats have been popular on conventional office chairs for many years mainly because they allow for multi-functional and postural relaxation. Even when combined with height adjustment in a fixed seat-to-back configuration they are unlikely to provide satisfactory levels of comfort and support for intensive VDT users.
Viewthe Chairs Direct range of Ergonomic Office Chairs
A tilt with the pivot position towards the front of the seat ('under knee') is particularly comfortable, as the legs are not raised as the seat relines. But to ensure proper support it should be capable of being locked at least in the upright working positions.
Mechanisms that allow the seat to be tilted forward have become increasingly popular for all types of office work, because they provide a greater variation of working position, allowing the trunk/thigh angle to be increased when the back is upright. This enables the user to reach further forward over the work surface.
Tilting seats, which are commonly used for dedicated-function tasks, normally operate in conjunction with back adjustment mechanisms of the kind described below.
These combined mechanisms operate either independently of each other or in a synchronised movement. Independent operation offers the advantage of high degrees of adjustability and comfort, although it may require multiple controls.
Synchronised or permanent contact mechanisms, in which the seat and back angles adjust together approximately in the ratio 1:2, have become widely used and again can provide a high level of comfort.
Synchronised or permanent contract mechanisms are usually available with the facility of being locked in any position - an important consideration for dedicated tasks. Tension adjustable mechanisms in an unlocked or permanent contact mode enable adjustments to be made to balance the user's weight. Our Ergo 5 is fitted with synchronised movement.
BS EN ISO 9241-5 1999 accepts both types
It has for many years been fitted to conventional typist chairs without a tilting seat usually in conjunction with a small, height-adjustable backrest, and is normally lockable in the chosen position to provide firm back support.
When in 'permanent contact' or 'free float' form, it is suitable for multi-functional tasks. Unless the spring tension is adjustable to support different body weights as the user leans back, it will not necessarily ensure good support.
It meets the minimum requirement of the Display Screen Equipment Regulations when used on a seat-height adjustable chair, and exceeds them when used as it normally is, with a height-adjustable back rest. The regulations require the seat to be adjustable in height and the seat back to be adjustable in both height and tilt. Provided the design meets these requirements, they do not require seat back height and tilt to be adjustable independently of the seat.
The key requirement is that the lumbar region is well supported. Seating designers have found that this can be met for the majority of users by means of a properly designed back rest, without the need for height adjustment - it is more important that the back reach/angle is adjustable. Independent back height adjustment is not required by the display screen equipment regulations.
Office chairs are generally fitted with five-star swivel bases on twin-wheel castors. Traditionally, standard castors have been designed for use on the carpeted floors, typical of UK offices. With braked castors or glides fitted on seating used on hard or shiny surfaced where there is a risk of chair fitted with standard castors skidding away form users about to sit down on or get up (a particular concern for e.g. pregnant women). If this is a requirement we at Chairs Direct will always advise and fit if these are a requirement.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Glides are always recommended for high chairs, such as those used by draughts persons, and to counter stools, in order to prevent unexpected movements.
The new European Standard EN 1335 part 2 includes specifications for castors with different treads for different floor surfaces, together with rolling resistance requirements- the first time that such specific requirements have been laid down for the UK. Compliance with the new European Standard 12528, 'Castors for furniture, castors for office swivel chair requirements' is not required to satisfy EN 1335
BS EN ISO 9241-5: 1999 requires the chair's swivel to allow users to rotate their bodies as a whole in order to reach equipment, without twisting their torsos.
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It is highly unusual for any one-chair type to be able to suit all possible applications. Most manufacturers generally provide a range of chairs, with similar overall style and finish, but with particular features designed to suit the varying needs of operators. management, visitors etc.
STRENGTH AND STABILITY
Office seating needs to be both durable and safe when in use. the new European Standard EN 1335 Part 3 contains test methods, of which some (eg for stability) are largely as in the British Standard BS 5459: Part 2, 1990: 'Strength and stability of office seating; other (for castors) introduce requirements new to the UK; and others again (eg for fatigue) are less rigorous than BS 5459: Part 2
DIMENSIONS
Considerable ergonomic study and design experience have led to the development of dimensional criteria for well-designed seating and workstations which will accommodate some 90 per cent of the office population. These are summarised in figure 3
SUPPORT AND COMFORT
The vital importance of office workers being able to maintain a correctly supported posture has already been emphasised. The office chair should be stable, give support, move with the body and encourage natural movement without needing undue effort to Adjust it.Well-designed office seating should therefore provide:
- Shaped seats and backrest, which are covered with, firm, rather than soft upholstery
- Backrest of sufficient size to support the user's lower and middle back, with forward convexity in the lumbar region
- A range of back heights to allow freedom of movement or support for the upper back and shoulders, as preferred by the user
- Contoured seats that provide pelvic support at the rear and rounded 'waterfall' front edge to minimise under-thigh pressure
- Freedom of movement for occupiers
- Easy adjustability of seat height, seat angle (tilt), back rake angle, and back height.
SEAT HEIGHT ADJUSTMENT
Seat height adjustment is required by the Display Screen Equipment Regulations. Office chairs are usually designed to allow for adjustment in the range between approximately 420mm and 530mmn, which allows the majority of users to maintain a comfortable 90 degree thigh/lower leg angle with their feet resting flat on the floor.People of smaller stature, and those using VDU keyboards on a conventional 720mm-height work surface, may also need a footrest to achieve a comfortable working position. The Display Screen Equipment Regulations require a footrest to be made available to any employee who wants one.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Seat height adjustment is usually effected by means of a pressurised gas cylinder located between the chair base and seat and is activated by a readily accessible lever. the Health & Safety Executive advises that persons weighting more than 100kg (16 stone) should not use a chair fitted with a gas cylinder unless it as been specifically designed and tested to accommodate them.
Mechanical height adjusters are also readily available. While these can have the advantage of avoiding the weight restriction on the use of gas cylinders, provided they are appropriately tested, they can not normally be operated from a seated position,
BS EN ISO 9241-5: 1999 approaches the issue of seat height, as well as of seat depth and width, on the basis of the concept of 'fit'. Adjustments in seat depth can be achieved by adjusting the relationship between the seat and the backrest; and in width by the provision of arm rests.
SEAT ANGLE AND BACK ADJUSTMENT: DYNAMIC SEATING
There is a wide range of available mechanisms for adjusting seat angle, back position and a combination of the two. The effects of these can vary quite markedly in comfort and; feel', depending on the particular design of chair. The most expensive or highly engineered chairs may not necessarily be the most comfortable in use!Experience shows that chairs which have too many handles, knobs and levers for adjustment are not in practice very 'user friendly' and people don't make enough effort to change position to suit their needs because they tend not to think of how they are sitting when they are working. Adjustment controls should always be safe and easy to use, and there has been a welcome trend in the direction of simplifying controls and mechanisms and introducing dynamic seating to encourage people to sit properly.
Dynamic seating is achieved by co-ordinating design factors including seat angle and back adjustments, back angle rake adjustment, swivel and castors. Its importance is stressed by BS EN ISO 9241-5: 1999
Seat adjustment capability falls into three main types: seat angle (tilt) adjustment; back rake and angle adjustment and back height adjustment. We feel our Ergo 5 has all the features and mechanisms required to give you the maximum comfort and support
SEAT ANGLE (TILT) ADJUSTMENT
Tilt combined with seat and seat back height adjustment meets the minimum requirements of the Display Screen Equipment Regulations.Reward-tilting seats have been popular on conventional office chairs for many years mainly because they allow for multi-functional and postural relaxation. Even when combined with height adjustment in a fixed seat-to-back configuration they are unlikely to provide satisfactory levels of comfort and support for intensive VDT users.
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A tilt with the pivot position towards the front of the seat ('under knee') is particularly comfortable, as the legs are not raised as the seat relines. But to ensure proper support it should be capable of being locked at least in the upright working positions.
Mechanisms that allow the seat to be tilted forward have become increasingly popular for all types of office work, because they provide a greater variation of working position, allowing the trunk/thigh angle to be increased when the back is upright. This enables the user to reach further forward over the work surface.
Tilting seats, which are commonly used for dedicated-function tasks, normally operate in conjunction with back adjustment mechanisms of the kind described below.
These combined mechanisms operate either independently of each other or in a synchronised movement. Independent operation offers the advantage of high degrees of adjustability and comfort, although it may require multiple controls.
Synchronised or permanent contact mechanisms, in which the seat and back angles adjust together approximately in the ratio 1:2, have become widely used and again can provide a high level of comfort.
Synchronised or permanent contract mechanisms are usually available with the facility of being locked in any position - an important consideration for dedicated tasks. Tension adjustable mechanisms in an unlocked or permanent contact mode enable adjustments to be made to balance the user's weight. Our Ergo 5 is fitted with synchronised movement.
BS EN ISO 9241-5 1999 accepts both types
BACK RAKE AND ANGLE ADJUSTMENT
This is the simplest form of adjustment mechanism. It allows both forward and rearward movement of the back rest by means of spring-loaded pivoting of the back support below the back of the seat.It has for many years been fitted to conventional typist chairs without a tilting seat usually in conjunction with a small, height-adjustable backrest, and is normally lockable in the chosen position to provide firm back support.
When in 'permanent contact' or 'free float' form, it is suitable for multi-functional tasks. Unless the spring tension is adjustable to support different body weights as the user leans back, it will not necessarily ensure good support.
It meets the minimum requirement of the Display Screen Equipment Regulations when used on a seat-height adjustable chair, and exceeds them when used as it normally is, with a height-adjustable back rest. The regulations require the seat to be adjustable in height and the seat back to be adjustable in both height and tilt. Provided the design meets these requirements, they do not require seat back height and tilt to be adjustable independently of the seat.
BACK HEIGHT ADJUSTMENT
Back pad position-height adjustment has been common for many years as away of altering the lumbar support positional It is available on many chair types, both for operator and management use, which have larger backs.The key requirement is that the lumbar region is well supported. Seating designers have found that this can be met for the majority of users by means of a properly designed back rest, without the need for height adjustment - it is more important that the back reach/angle is adjustable. Independent back height adjustment is not required by the display screen equipment regulations.
CASTORS
Office chairs are generally fitted with five-star swivel bases on twin-wheel castors. Traditionally, standard castors have been designed for use on the carpeted floors, typical of UK offices. With braked castors or glides fitted on seating used on hard or shiny surfaced where there is a risk of chair fitted with standard castors skidding away form users about to sit down on or get up (a particular concern for e.g. pregnant women). If this is a requirement we at Chairs Direct will always advise and fit if these are a requirement.
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Glides are always recommended for high chairs, such as those used by draughts persons, and to counter stools, in order to prevent unexpected movements.
The new European Standard EN 1335 part 2 includes specifications for castors with different treads for different floor surfaces, together with rolling resistance requirements- the first time that such specific requirements have been laid down for the UK. Compliance with the new European Standard 12528, 'Castors for furniture, castors for office swivel chair requirements' is not required to satisfy EN 1335
SWIVEL
BS EN ISO 9241-5: 1999 requires the chair's swivel to allow users to rotate their bodies as a whole in order to reach equipment, without twisting their torsos.
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4.2 OTHER FACTORS RELEVANT TO THE SELECTION AND USE OF OFFICE SEATING.
RANGES OF CHAIRS
It is highly unusual for any one-chair type to be able to suit all possible applications. Most manufacturers generally provide a range of chairs, with similar overall style and finish, but with particular features designed to suit the varying needs of operators. management, visitors etc.
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Ergonomic Office Chairs
In selecting a range, it is important to remember that:
Office seating upholstery needs to be hard-wearing and durable to maintain comfort and support for many users without collapsing or wearing out. There is a wide choice available of contract-quality fabrics which will prove highly satisfactory in use- the majority o wool, or wool/viscose mixtures which have good colour fastness, wear resistance and 'breathing' characteristics.
The flammability of upholstered furniture is a major safety issue. Office seating fabrics can be fire-retardancy treated to meet the varying levels of ignitability required by BS 5852: 1990 (ISO 8191).
The UK Furniture & Furnishings (Fire Safety) Regulations 1988 require 'combustion-modified' foams to be used for domestic furniture, and this type of foam is also widely used in manufactured office and contract seating.
The Display Screen Equipment Regulations make it clear that employers are responsible for ensuring that their employees receive training in the proper use of the workstation. Employers should therefore provide employees with explanations of their chair controls and adjustment mechanisms during induction or training sessions, and ensure that instructions for safe and correct chair use are available at workstations and with human resources and/or health and safety personnel.
This information should be kept straight forward and to the point. Overly detailed instructions typically prove off-putting and are rarely used.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Furniture manufacturers and distributors can help with the training and familiarisation process.
The clarity and comprehensiveness of instructions and warning labels are important issues under product liability and consumer protection legislation, especially where there is a risk of misuse or abuse.
While office seating in normal use should be trouble-free and require no routine maintenance, it is important for employers to make regular checks for wear and damage. When servicing or repairs are necessary; these should be carried out by trained staff, provided by the manufacturer or distributor.
In no circumstances should untrained persons attempt to dismantle gas-cylinder adjustment mechanisms.
Fabric upholstery should be vacuumed at regular intervals. If cleaning is required, only reputable upholstery cleaning products should be used.
Quality of customer support and service is a very important consideration in the selection of a particular manufacturer or distributor of office seating.
In addition to supplying reliable quality products, a reputable and experienced company will:
In selecting a range, it is important to remember that:
- An employee of relatively low status in the organisation may require a chair of higher specification than a more senior colleague
- The cost of a good office chair is relatively modest in comparison with that of the other elements of the workstation; or of the employee working inefficiently or (worse) being absent through illness.
UPHOLSTERY
Office seating upholstery needs to be hard-wearing and durable to maintain comfort and support for many users without collapsing or wearing out. There is a wide choice available of contract-quality fabrics which will prove highly satisfactory in use- the majority o wool, or wool/viscose mixtures which have good colour fastness, wear resistance and 'breathing' characteristics.
The flammability of upholstered furniture is a major safety issue. Office seating fabrics can be fire-retardancy treated to meet the varying levels of ignitability required by BS 5852: 1990 (ISO 8191).
The UK Furniture & Furnishings (Fire Safety) Regulations 1988 require 'combustion-modified' foams to be used for domestic furniture, and this type of foam is also widely used in manufactured office and contract seating.
INSTRUCTIONS FOR USE
The Display Screen Equipment Regulations make it clear that employers are responsible for ensuring that their employees receive training in the proper use of the workstation. Employers should therefore provide employees with explanations of their chair controls and adjustment mechanisms during induction or training sessions, and ensure that instructions for safe and correct chair use are available at workstations and with human resources and/or health and safety personnel.
This information should be kept straight forward and to the point. Overly detailed instructions typically prove off-putting and are rarely used.
Viewthe Chairs Direct range of Ergonomic Office Chairs
Furniture manufacturers and distributors can help with the training and familiarisation process.
The clarity and comprehensiveness of instructions and warning labels are important issues under product liability and consumer protection legislation, especially where there is a risk of misuse or abuse.
MAINTENANCE
While office seating in normal use should be trouble-free and require no routine maintenance, it is important for employers to make regular checks for wear and damage. When servicing or repairs are necessary; these should be carried out by trained staff, provided by the manufacturer or distributor.
In no circumstances should untrained persons attempt to dismantle gas-cylinder adjustment mechanisms.
Fabric upholstery should be vacuumed at regular intervals. If cleaning is required, only reputable upholstery cleaning products should be used.
CUSTOMER SERVICE
Quality of customer support and service is a very important consideration in the selection of a particular manufacturer or distributor of office seating.
In addition to supplying reliable quality products, a reputable and experienced company will:
- employ properly trained staff and professionally qualified distributor network to provide advice on the application, selection, layout and installation of particular seating appropriate for a specific working environment
- provide samples for user trials, so that all purchasing decisions are based on task suitability and user experience and preference
- provide employers with training assistance, to ensure that their employees use office seating safely and correctly
- offer responsible guarantees against manufacturing defects and of continuity of supply
- offer a comprehensive after-sales service for maintenance and repair
- offer and efficient sales support organisation ensuring reliability and accuracy of delivery.
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4.3 SPECIAL NEEDS
While generally-available office seating will meet the needs of the great majority of employees in the normal office environment, there will always be people with special needs resulting from physical stature or infirmity, or from the need to perform special tasks which form part of their employment. Most of these needs can ve met in one or more of the following ways.
FOOTREST
In addition to the points made, footrests are important for the comfort of people of restricted stature who may not be able to work comfortably at a normal height desk with their feet flat on the floor.
ARMRESTS
In addition to providing postural support, as described above, armrests can be useful aids to infirm or pregnant employees in sitting down and standing up. (In this application, armrests need to be particularly robust).
Consideration also needs to be given to fitting the chair with braked castors or glides so that it does not move away from an employee who is using the armrests for support.
HEAVY-DUTY APPLICATIONS
Most office chairs are used for up to eight hours a day. However, in applications involving use by heavily-built people, or in environments such as control rooms where there is continuons manning, employers should give consideration to providing seating that has been designed and tested to meet these special requirements.
The office chair is a key element in the workstation assembly and working environment and its design is critical for the health and well being of employees using VDTs. The principles of good design and working principles for the office-working environment are defined in the Display Screen Equipment Regulations and BS EN ISO 9241-5: 1999 View our range of ergonomic office chairs
5. THE WORKING ENVIRONMENT
The office chair is a key element in the workstation assembly and working environment and its design is critical for the health and well being of employees using VDTs. The principles of good design and working principles for the office-working environment are defined in the Display Screen Equipment Regulations and BS EN ISO 9241-5: 1999 View our range of ergonomic office chairs
WORKSTATION ENVIRONMENT
- use of equipment must not be a source of risk for the user.
- the workstation must provide sufficient space for the user to change position and vary movements
- it must have a sufficiently large low-reflectance area to allow flexible arrangements of VDT equipment and documents.
- the document holder must be stable, adjustable and positioned to minimise the risk of uncomfortable head and eye movements. It should position working documents at a height and viewing distance, ad in a visual plane, similar to those of the screen. A document holder is useful particularly for workers who experience difficulty in refocusing when switching their gaze between the screen ad documents they are working on.
THE SCREEN
- The screen must swivel and tilt easily and have a base that is either adjustable or separate from the computer
- It must be glare and reflection-free and produce a stable image
- Brightness, contrast and background must be easily adjustable.
- A facility for adjusting the height of the screen may also be useful
- The keyboard must be detachable and tiltable, with sufficient space available on the work surface in front of it to provide support for the hands or arms of users.
THE WORK CHAIR
- The work chair must be stable and allow the user both to sit comfortably and to move freely.
- It should allow users to keep their forearms approximately horizontal, with minimal extension, flexion or deviation of the wrists.
- The chair must be height-adjustable in height and tilt relative to the ground.
- The backrest must be adjustable, in height and tilt relative to the ground.
- A footrest must be available to any employee who requires one.
THE OPERATOR/COMPUTER INTERFACE
- There must be adequate illumination, with an appropriate level of contrast between the screen and the background.
- Workstations must be designed and positioned so as to avoid glare and reflection.
- Windows must be fitted with adjustable coverings (e.g. Blinds)
- Equipment noise must not distract attention or disturb speech.
THE OFFICE ENVIRONMENT
- Excess heat produced by equipment must not cause discomfort to employees.
- Radiation must be reduced to negligible levels.
- An adequate level of humidity must be established and maintained.