Offices, factories, hotels, schools, transport systems and electrical power are designed to permit full utilization during normal working hours, and to cater for peak periods which may occur at certain times of the day or during certain seasons of the year. At other times such facilities are under-utilized or completely vacant. Despite this under-utilization, if the facilities are perceived to be inadequate during the normal hours, further facilities will be called for to take care of the load during those hours. It has not proved possible to stagger utilization to any great extent.