2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
the human condition of interest (e.g., comfort in vehicles) and a method of interpretation is
required. Examples would include changes in posture, movement patterns (e.g., away from
uncomfortable environments), and popularity of sitting positions (e.g., if some seats were in a
cold draught they would be occupied ‘last’). Advantages of behavioural methods include
minimum interference with what is being measured, and a direct ‘active’ measure of
discomfort. Disadvantages include the difficulty in establishing validity and reliability of the
method and direct interpretation of the results in terms of comfort. Change in posture could be
due to chair discomfort or other ‘non’ reasons.
The Standard makes reference to existing standardised methods for the physical assessment of
individual aspects of the environment (e.g., ISO-EN-7730), and is not aiming to replace them,
but to bring all the techniques together for as a complete assessment tool.
Survey design: The design of any environmental survey will depend upon the specific aims of
that survey. It is necessary therefore to be specific about the aims of the survey. It will aim to
provide general principles that can be used for the assessment of an integrated environment:
thermal, lighting, noise, air Quality, and vibration.
Subject sampling: A valid method of evaluating environments would be to use a panel of
experts. This technique depends upon identifying unbiased acknowledged experts. This is not
possible in the area of environmental comfort and the environmental survey design should
specifically avoid bias. It is usual to survey all of the occupants of a space, or if that is
impractical, then to identify a random sample as representatives of the population of interest.
This is a question of statistical sampling and relevant factors such as age, gender, experience,
and anthropometry could be identified and influence subject selection.
Measurement of Subject Responses: The responses measured will be selected according to the
aims of the survey. Typically, subjective responses are taken to quantify comfort. Objective
measures are sometimes used, mainly mean skin temperature (and sometimes sweat loss) to
complement subjective measures. In a novel situation, subjective scales should be established
from first principles by establishing subjective continua using psychological techniques.
Subjective scales for assessing environmental comfort have, however, become established.
Examples are provided below. It is important to note that the way in which a scale is
presented and administered can influence the results. A single sheet questionnaire for example
may be preferable to a number of pages. The exact question asked should be established. The
frequency of completion of the questionnaire must be balanced with the overall aim of design.
Translation of scales, as well as cultural aspects of the subjects will be issues. Knowledge of
the previous ratings or of other subjects’ responses is not normally provided. Subject training
and pilot trials are necessary. Some scales are used for rating overall and local comfort.
Selection of Operating Conditions: It is important to evaluate the environment in the
operating conditions of interest. These need to be representative of the conditions that the
occupants regularly experience (time of day, correct working procedures, etc.).
Subjective scales are provided for the several environmental characteristics (thermal, lighting,
noise, air quality), as well as guidance on issues of vibration and social factors. It also utilises
expert checklists, to aid the ergonomist to ensure that all the appropriate factors have been
considered. The results are used with a scoring system that will enable the ergonomist to
determine if there is a specific environmental feature that needs further expert evaluation.
362