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NORDIC LIGHT & COLOUR
117
of cool hues, errors can be up to 20 percent. The second reason
is the fact that the blue paint used in the scale models has very
low NCS chromaticness – 10. The rest of the chromatic colours
used in the models, e.g. Red, Green, Yellow and Blue have
equal blackness (05), see Table 1. This means that the Blue co-
lour has low saturation and therefore the Blue model has been
perceived as quite a dark room. A Grey room has the lowest
luminance values according to the HDR image – 35.4/37.7 cd/
m
2
on the window wall, 51.5-54.9 cd/m
2
on the side walls. This
was also scored by subjects as the darkest room. We can con-
clude that, because of the low saturation of the colours, it was
difficult for respondents to place the models in order. Still, the
results were compatible with luminance maps that accurately
replicated obtained data.
The consistency between the answers to the question about
light level from Part 2 (Which room has the highest light level?)
and to the question from Part 1 (“Do you experience the room
to be dark or bright?”) helps to conclude that the results are
quite reliable. Moreover, the participants’ responses to the
questions about rooms with the most comfortable lighting and
about their personal preferences varied. This means that the
subjects were guided not by predilections, but by the subjective
perception that was very similar to their responses to their first
impression of the rooms.
CONCLUSION
A colour contrast and the Helmholtz-Kohlrausch phenomenon
have been investigated and described in literature previously
(Valberg 2005). In this experiment we transfer these pheno-
mena into the field of architectural design and the perception
of the visual environment. From an architectural perspective it
is important to note that even poorly saturated colours have an
impact on the human perception of light level in spaces. This
impact can be strong, as with color contrast, or weak, as with
one-coloured models. Nevertheless, this impact can be taken
into consideration when using the luminance-based method in
lighting design.