The overall objective for an innovative approach to determine DG is the identification of relevant cognitive structures activated in Discomfort Glare conditions. and find links between physical lighting parameters used today for the DGI and cognitive structures.

Cognitive structures are often described using dimensions. Schierz & Krueger found for various lighting conditions in work places the three dimensions which map the cognitive structure. As the objective the DGI is the assessment of the (dis-) satisfaction of the current lighting conditions the pure elaboration of cognitive structure dimensions are not satisfying but they have to incorporate the individual appraisal. On the cognitive level a distinction between spatial and light dimensions and emotional perception is unlikely, mental concepts typically include the emotional appraisal. So the most crucial step for a more user oriented assessment of discomfort glare is the identification of appraisal factors towards glare. As the results from Chauvel et al. (1982), Osterhaus and Bailey (1992) and Sivak and Flannagan (1991) indicate the so-called setting of the lighting environment, i. e. a work environment instead of leisure, the degree of concentration for the tasks, the duration of one task or the social situation of the setting might have a severe influence as they might be a part of the cognitive structure.

Conclusions

Future research on discomfort glare considering the cognitive dimension of users demand for a revised strategy: Though measures of reaction speed, time for task performance and number of mistakes are comfortable for the researcher they exclude cognitive factors. The relevant factors for appraisal have to be identified (first phase) and it has to be studied under which conditions the individual assessment of discomfort glare shows any temporal consistence (second phase).

The first phase implies in first instance an explorative methodology. Explorative interviews in the field (e. g. in buildings where discomfort glare is a frequent problem) as well as research studies in cognitive, environmental and industrial psychology lead to the elaboration of a heuristic model of cognitive schemata activated in glare environments. The heuristic model allows to deduct hypotheses about cognitive procedures and human reaction.

In the second phase the hypotheses are tested under real office conditions, at different sites and different lighting conditions, with large number of subjects and with different shading systems.

When the cognitive appraisal model is stable, in a third phase the allocation of physical glare data to human appraisal can start and might lead to a reliable index scheme which will permit planning of buildings in which user discomfort glare can be avoided.

In the research about discomfort glare the cognitive gap still exists. This explains that the results from DGI do not match with user assessment and the reported qualitative factors which seem to have an influence. Regarding the importance to provide a comfortable working environment the efforts to be spend into the outlined research seems to pay back without any doubt.