Civil Engineering Reference
In-Depth Information
brightness of a luminary located on the line of vision. This index was developed
as a function on the experiments performed with 50 subjects aged from 20 to 40.
The methodology used to determine this index is briefly explained in Kim and Kim
(
2010
).
3.4.2.2 Discomfort Glare Index
This index is employed to evaluate the daylight discomfort glare for light sources with
non-uniform levels of luminance (Bellia et al.
2008
). It can be estimated according
to Eq.
3.19
.
478
N
L
1
.
6
s
i
0
.
8
ˉ
i
DGI
=
10 log
10
0
.
(3.19)
0
.
5
L
b
+
(
0
.
07
ˉ
L
w
)
w
i
=
1
In the previous equation
N
is the number of luminaries inside the room,
L
s
i
is the
luminance provided by the
i
th luminary in (cd/m
2
),
ˉ
w
is the solid angle of the
window,
L
w
is the weighted average luminance of the window in (cd/m
2
) and
ˉ
i
is
the solid angle of the
i
th luminary.
3.4.3 Colour Rendering
Finally, another important factor for visual comfort conditions is related to the nat-
ural rendering of the objects and human skin colour inside an environment, that is, it
represents the ability of a light source to show the colours of the objects and human
skin naturally in comparison with a reference light source. In order to obtain a quan-
titative measure of the colour rendering associated with a light source, the general
colour-rendering index has been proposed.
The maximum value of this index is 100, and it decreases with decreasing colour-
rendering quality (CIBSE
2002
). Furthermore, light sources with a colour-rendering
index lower than 80 should not be used in indoor environments where people remain
for long periods of time (CIBSE
2002
).
3.5 Indoor Air Quality Indices
3.5.1 Indoor Air Quality Index
Most of the works which can be found in literature use direct CO
2
concentration
in order to reach indoor air quality. Within the scope of this topic a new index is
proposed: the Indoor Air Quality (IAQ) index. This index classifies indoor air for
