Principles of ergonomic design
ISO 6385 establishes the general principles: design must be based on the needs, capabilities, and limitations of the user population, considering anthropometric, strength, and skill variability; it must involve the people who will use the workstation; it must be integrated into all phases of the project (conception, detailed design, implementation, and evaluation); and it must address the work system as a whole, including the space, equipment, physical environment, tasks, and organization. The preventive approach prioritizes eliminating unsuitable design requirements rather than compensating for them with organizational measures, training, or personal protective equipment.
On the physical level, the design considers the dimensions of the space and the furniture based on anthropometric data, with adjustments to accommodate a wide range of the population; working heights according to the type of task (precision, light or heavy); reach zones to place frequently used items; working postures, avoiding forced and prolonged postures, with the possibility of alternating between sitting and standing; the necessary forces and the use of mechanical aids; and the environmental environment (lighting, noise, temperature, vibrations).
From a cognitive and organizational perspective, the design addresses the presentation of information and controls, the compatibility between indicators and actions, mental workload, pace and autonomy, breaks, job rotation, and training. The emergence of new work models (remote work, shared workstations, intensive use of mobile devices) requires applying the same principles in less controlled environments.
Regulatory requirements applicable to job design
- Workplaces. Royal Decree 486/1997 sets the minimum dimensions of the premises (height, surface area and volume per person), the conditions of the floors, corridors and access, the environmental conditions and the lighting.
- Visual display units. Royal Decree 488/1997 and its INSST technical guide (updated in 2021) establish the requirements for screen, keyboard, table, chair, space, lighting, reflections, noise, heat, radiation and humidity, and the conditions for work organization and health surveillance.
- Manual handling of loads. Royal Decree 487/1997 requires that manual handling be avoided and, when this is not possible, that the risk be assessed and reduced through workstation design, mechanical aids and organization.
- Work equipment. Royal Decree 1215/1997 requires that equipment be adapted to the ergonomic characteristics of people and the conditions of use.
- Machines and products. Machine design incorporates ergonomic requirements from the manufacturing stage, in accordance with machine safety legislation and harmonized standards.
- Adaptation to sensitive people. Law 31/1995 requires adapting jobs to particularly sensitive people, including people with disabilities, pregnant workers and elderly people.
- Technical standards. ISO 6385 and the UNE-EN ISO 9241 (human-system interaction), UNE-EN 1005 (machine safety, human physical performance) and UNE-EN ISO 11228 (manual handling) series provide design and evaluation criteria.
Design and evaluation methodology
- Task analysis. Description of the operations, their frequency and duration, the physical and cognitive demands, and the environmental conditions.
- Definition of the user population. Reference anthropometric and functional data, with attention to diversity and sensitive individuals.
- Space and furniture design. Dimensions, heights, reach, adjustments, and arrangement of elements according to frequency of use.
- Selection of equipment and tools. Criteria for weight, grip, vibration, strength and compatibility with the task.
- Organization. Rhythm, breaks, rotation, alternation of postures and training in the use of the workstation.
- Evaluation in use. Verification with users through observation, ergonomic evaluation methods (e.g., RULA, REBA, OCRA, NIOSH equation) and comfort and discomfort surveys.
- Continuous improvement. Review following changes in task, incidents, or health surveillance results.
Organizational application: how to ergonomically design a workstation
- Integrate ergonomics from the project: include ergonomic criteria in the purchase of furniture and equipment, in the distribution of spaces and in the design of new lines or processes.
- Analyze the tasks and define the user population, with anthropometric data and attention to especially sensitive people.
- Design the space, furniture and arrangement of elements according to working heights, reaches, postures and frequency of use, with regulations that allow individual adjustment.
- Select equipment and tools with ergonomic criteria and provide mechanical aids for loading.
- Define the work organization: rhythm, breaks, rotation and alternation of postures, and train people in the adjustment and use of the workstation.
- Evaluate the workstation in use with the participation of users and with ergonomic evaluation methods, and correct any deviations.
- Record the design, assessment, and measures in the preventive documentation and review them in the event of changes or health damage.
Preventive management software allows you to link the design of each workstation to its ergonomic assessment, plan measures and reviews, record training, and relate the results to health surveillance and indicators of musculoskeletal disorders with traceability.
Limits and common mistakes
- Designing for a non-existent average person instead of for a broad range of the population, without regulations or adjustments.
- Incorporate ergonomics only after implementation, when modifications are costly and limited.
- Buying furniture or equipment with an ergonomic label without analyzing the actual task or providing training on its adjustment.
- Ignoring the cognitive and organizational dimension (rhythm, breaks, mental load) and limiting the design to the furniture.
- Not involving users in the design and evaluation.
- Do not review the design after changes in the task, incidents or discomforts detected in health surveillance.
The dimensional and evaluation criteria are detailed in the INSST technical guides and in the cited technical standards; this sheet is for informational purposes.
Practical example
Situation: An electronic component assembly company is going to implement a new work line with twelve precision manual operation stations and detects frequent discomfort in the neck, shoulders and wrists on the current line.
- Analysis. The prevention service analyzes the tasks of the current line, measures heights and reaches, applies an ergonomic evaluation method and consults with the operators; work surfaces that are too low, excessive reaches to the parts containers and lack of support for the forearms are identified.
- Design. The new line specifies height-adjustable tables, container placement within the optimal reach zone, forearm supports, localized lighting, adjustable chairs with the possibility of standing work, and lightweight tools with a suitable grip; the design is reviewed with a workstation model and with the users.
- Organization. Rotation between tasks of varying demands and short breaks is established, and staff are trained in adjusting their positions.
- Follow-up. After implementation, each station is evaluated using the same method and a discomfort survey; the results clearly improve and the design is adopted as a standard for future lines.
Regulatory and reference framework
- Law 31/1995, of November 8. Law on Prevention of Occupational Risks; principle of adapting work to the person (article 15) and protection of especially sensitive people (article 25).
- Royal Decree 486/1997, of April 14. Minimum health and safety requirements in the workplace.
- Royal Decree 488/1997, of April 14. Minimum health and safety provisions relating to work with equipment including display screens.
- Royal Decree 487/1997, of April 14. Minimum health and safety provisions relating to the manual handling of loads.
- INSST Technical Guide on Visual Display Units (2021) . Criteria for applying Royal Decree 488/1997 to the design and evaluation of workstations.
- ISO 6385:2016 . Ergonomic principles for the design of work systems.
- NTP 242. Ergonomics: Ergonomic analysis of office workspaces . Dimensional and distribution criteria of the workspace.
Royal Decree 1215/1997 on work equipment and the UNE-EN ISO 9241, UNE-EN 1005 and UNE-EN ISO 11228 series complete the technical design and evaluation criteria.
