This report has been used to lay the foundations for the development of a simple procedure to assess the visual comfort of daylit offices. Within the time constraints an actual document outlining the exact process required was not able to be produced. However, throughout this report suggestions have been made regarding what specific measurements and assessments are necessary in the procedure. The following section discusses the general needs of the procedure.

Format

The assessment procedure needs to be described in a short, readable document targeted at lay people without much experience in performing lighting measurements or analysis. Each of the measurements suggested above must be detailed step by step in a simple language to avoid confusion.

Glare - Solid angle and
Luminance or
Illuminance
Luminance Ratios - Luminance and/or
CCD photography
Illuminance and Uniformity - Illuminance,
Luminance,
Daylight Factor and
Reflectance
View - Window Area

Beyond that, an easily understood guide as to what each of the measurements mean so that the relevant analysis can be performed is critical. It is suggested that the basic layout should be based on a simple flow chart, which the assessors can refer back to at anytime to assist in the process of assessment. Furthermore, much of the analysis should use tables or graphs for quick interpretations of the results.

The exact result of the assessment procedure could be a pass or a fail, a score out of ten, a list of improvements needed, all of the above, or something completely different. How the final result is derived is also open for debate. Should the office have to ‘pass’ or ‘score well’ for every aspect of visual comfort for the office to be deemed visually comfortable? What if the office has a magnificent view and excellent illuminance and a good degree of uniformity but terrible glare problems? Should some of the considerations regarding visual comfort be of more importance than others and if so how should the weightings be calculated? Is the same format going to be applicable to every office?

Difficulties

The suggestions regarding how to assess the visual comfort of daylit offices made in this report are by no means the final word.

There will always be problems in trying to judge the subjective responses of occupants with objective measures. Fontoynont gives several examples of where the correlation may not be suitable. A stained glass window could be objectively assessed in terms of its luminous transmittance, spectral change in transmitted daylight, daylight factors and luminance; whereas, a subjective analysis would likely include the aesthetics of the stained glass window and its suitability to the function of the room. Thus the objective analysis does not truly reveal what the occupants would feel about the lighting conditions.

Even if the measurements taken fairly reflect the opinions of the occupants, the calibration of the objective measure will always be difficult because the inevitable wide range of responses from the occupants. The suggested assessment measures are all based on the average response of a large group of people. So even if the assessment reveals that the office is theoretically extremely comfortable, there could still be a few particularly sensitive occupants that are uncomfortable. It thus raises the question whether the level of visual comfort should be set so that everyone in the office is comfortable, or the majority of the people in the office are comfortable, or the theoretical ‘average’ person is comfortable.

Lastly, as already raised in the report, the existing assessment measures virtually all rely on the lit environment to be either exclusively artificially lit or exclusively daylit – a situation which is very rare nowadays. Therefore, for the most common lighting environment (a combination of artificial light and daylight) in offices there are no reliable and agreed-upon assessment methods.

Alternatives

The assessment method may not be applicable in all situations. The required equipment may not be available or the assessor may not feel comfortable about performing the procedure. An alternative assessment method should be provided.

A Post Occupancy Evaluation (POE) could potentially provide that alternative. It would mean that the series of measurements could be avoided; however it would also create a greater interruption for the staff members of the office. The accuracy of the results could be influenced by the interpretation and mood of the respondents. On the other hand, it would mean the results would be directly related to the occupants – for whom the space is meant to be comfortable.