ISO 10551:2019

Overview

ISO 10551:2019 - Ergonomics of the physical environment - Subjective judgement scales for assessing physical environments - provides principles and practical examples for constructing valid, reliable subjective scales used to assess how people perceive and evaluate physical environments. The standard does not mandate specific scales; instead it describes how to design and use scales that measure perception, comfort, preference, acceptability and tolerance across environmental components such as thermal, visual, air quality, acoustic and vibration.

Key topics

• Principles of scale construction: guidance on wording, structure (e.g., bipolar vs. unipolar formats), instructions, and bias reduction to improve validity and reliability of subjective responses.
• Types of judgement scales: perceptual (sensation), evaluative (comfort/discomfort), preferential (future choice), and personal acceptability/tolerance statements.
• Administration and format: recommendations for presenting scales, repeating enquiries over time, and ensuring consistent instructions to respondents.
• Data handling: summary guidance on data analysis and integration (e.g., repeat measures, overall means, changes and variability).
• Practical examples and annexes: commonly used scales for thermal, acoustic, visual, vibration and air quality environments plus worked examples and application notes.
• Scope limitations: excludes scales for effects on reading/display performance, manual performance, mood, pain or stimuli that cause injury; it does not standardize questionnaire design (see ISO 28802 for environmental surveys).

Applications

ISO 10551:2019 supports practical use cases where human judgement of environmental quality matters:

• Building design and post-occupancy evaluation (POE) - measure occupant satisfaction with indoor environmental quality (IEQ).
• HVAC and thermal comfort studies - design or evaluate heating, cooling and ventilation strategies using standardized subjective inputs.
• Lighting and acoustic assessments - evaluate perceived brightness, glare, noise annoyance or acceptability in workplaces and public spaces.
• Workplace ergonomics and occupational health - supplement physical and physiological measures with subjective assessments of comfort and tolerability.
• Research and comparative studies - create consistent scales to compare subjective data across studies, populations and countries.

Who should use this standard

• Ergonomists, human factors specialists and researchers
• Building engineers, HVAC designers and architects
• Occupational hygienists and facility managers
• IEQ consultants and environmental psychologists
• Standards developers and survey professionals (to incorporate compatible subjective scales)

Related standards

• ISO 28802 - environmental surveys (complementary scales and survey guidance)
• ISO 13731 - ergonomics of the thermal environment (vocabulary and symbols)

ISO 10551:2019 is a practical resource for anyone needing to construct or apply subjective judgement scales to evaluate indoor environmental quality, ensuring consistent, interpretable and comparable human-centred data.