Link CF

CF=AF

AD=CE

∠FAD=∠FCE

Then △ fad △ FCE

S quadrilateral CDFE = S△FCE+S △FCD

= S△FAD + S△FCD

=S△ACF

=( 1/2)*S△ABC

=( 1/2)*( 1/2) * 8 * 8

= 16