Untitled - Journal of Lighting Engineering

Heli NIKUNEN, Marjukka PUOLAKKA, A RANTAKALLIO, K KORPELA, Liisa HALONEN
the background luminances were much
higher (average pavement luminance
1.07 cd/m 2 ). Thus, the results of this study
suggest that in familiar environments,
perceived pathway brightness is a
significant factor only at very low
luminance levels. The result corroborates
the findings by Boyce et al. 16 , who suggest
a non-linear connection between brightness
and perceived safety. However, the results
indicate that already at fairly low luminance
levels, spectral distribution may be a more
important factor than perceived brightness
in predicting safety and pleasantness in
near-home environments.
The results may be affected by
familiarity. Lighting needs and expectations
may differ in near-home environments from
those in unfamiliar environments. In areas
that are only used occasionally, visual
performance may be more important
because people will want to observe the
environment thoroughly, whereas a pleasant
atmosphere may be more appreciated in
near-home areas. There were also no special
safety concerns in the study areas.
The relation between extensive lighting
and perceived safety was significant in areaaA,
which was a more remote area with very
little surrounding lighting and a rather high
spatial enclosure. Also, in the free
responses for area A participants mentioned
dark spots between the street luminaires,
the spatial enclosure and dark surroundings.
In area C perceived safety was
connected with evenness. This may be due
to the fairly uneven luminance distribution
(Ul=0.39). However, in Herttoniemi the Ul
values were even lower in both areas (0.34
and 0.27) but evenness was not a significant
factor. This may be due to that the Ul values
42
were fairly similar between the areas
whereas there were higher differences in the
colour quality (Ra and CCT values).
The results of this study indicate that at
very low luminance levels, pathway
brightness may be the strongest factor in
predicting perceived safety in near-home
environments. When the luminance level
becomes higher, it may lose its significance
and perceived colour quality may be the
strongest indicator of perceived safety.
Depending on the lighting expectations in
relation to the environment, the evenness
and extensiveness of the lighting
environment may also be significant
factors. In this study, glare was not related
to perceived safety. However, more
research in different environments is
needed to validate the results.
The relationship between a pleasant
lighting environment and lighting attributes
followed the same pattern as between
perceived safety and lighting attributes. The
results indicate that a pleasant lighting
environment substantially accounts for
perceptions that the colour of the light
makes the environment pleasant. It was the
dominant factor in four estimated areas out
of five. In addition, the Spearman
correlation coefficients were very high;
they varied between 0.51 and 0.93. At low
luminance levels (area D), the pleasantness
of the lighting environment may also be
connected to perceived brightness on the
pathway.
Glare had negative connection with a
pleasant lighting environment in area E.
Since glare did not form connections with
perceived safety, the results indicates that
the glare needs to be fairly strong in order
to have a strong effect on perceived safety,
Ingineria Iluminatului 2012; 14, 2: 33-46