Question $1$

$($a$)$ A vertical fa$$ade with size of $\backslash (10\backslash$mathrm$\{$~m$\}\backslash$times $12\backslash$mathrm$\{$~m$\}\backslash )$ is to be illuminated by four floodlights, with each containing one metal halide lamp. Two of them are installed at the top of the wall and the other two are at the bottom. The dimensions of the fa$$ade and locations of the floodlights are shown in Figure Q$1\mathrm{.}1$ and Figure Q$1\mathrm{.}2.$ The isocandela$/$zonal flux diagram of the floodlight is shown in Figure Q$1\mathrm{.}3.$

Figure Q$1\mathrm{.}1$ Front view of the banner

Figure Q$1\mathrm{.}2$ Side view of the banner

Relevant data are given below:

The floodlights aim at $\backslash (2/3\backslash )$ of the vertical banner height.

Initial luminous output of lamp $\backslash (=50,000\backslash$mathrm$\{$~lm$\}\backslash )$

Maintenance factor $\backslash ((\backslash )$ Light Loss Factor $\backslash ()=0\mathrm{.}6\backslash )$

Calculate the average maintained illuminance on the vertical fa$$ade$.$

$(12$ marks$)$

$($b$)$ Calculate the illuminance at the aiming point of a luminaire due to itself.

$(7$ marks$)$

$($c$)$ What are the good and bad things about daylight factor? What is CBDM$?$