A shutdown procedure is a set of tasks that everyone in your company should follow at the end of the working day, each department may have different shutdown procedures depending on what they do and where they are working and they can nominate one person in the department to be in charge of the shutdown procedure every evening in order to ensure that it is followed properly.
The shutdown procedure is to ensure that all non-essential equipment has been turned off (shut down) at the end of the working day, this prevents energy being wasted on powering devices that aren't in use. It ranges from simple obvious things such as shutting down your PC before leaving the office or turning off the lights as you leave a room to more hidden things such as putting a time clock on a vending machine so that it is not powered on when no one is in the office.
Essential equipment would be things like security lights or refrigerators that cannot be powered down at any stage and these will contribute to the base load of your building.
Ideally the shutdown procedure should be automated as much as possible so as to take the human error out of the equation as much as possible, there are many devices nowadays that can be used to save energy in a building when it is not occupied such as PIR sensors for lights or time clocks for heaters. By having the procedure as automated as possible it will shorten the list of things to do for the nominated individual which will make it easier to follow each evening but there is an increased cost associated with setting up automated systems.