In October 2004 the Department for Education and Skills, now the Department for Children, Schools and Families introduced software with the capability to power off computer devices remotely. Since the above date, this software has been configured (and runs nightly) to detect which computer devices are left on at a predetermined time in the evening and turn these devices off.
To answer part (a) of the PQ: the number of computer devices left on overnight in the Department when not in use is 0.
To answer part (b) of the PQ: the cost per year of leaving computer devices on overnight when not in use in the Department is 0.