seen from the front of the building 14 the details of the flexible discharge tubes 18 and their attachment to conduit 16 are shown in fig2 and 4 the discharge tubes 18 in this preferred embodiment are provided every 2 5 feet along the length of the supply conduit 16 water may be supplied to the conduit 16 in a number of ways in this preferred embodiment additional piping 22 is provided from the conduit 16 to a point on an outer wall of the structure 14 the permanent conduit 22 may be connected to a conventional water tap 24 by means of a flexible hose 26 to allow draining of the system during freezing weather as well as for other possible reasons in this preferred embodiment the flow of water into the sprinkler system is controlled by an electrically operated valve 28 which is in turn controlled by a clock mechanism 30 the electrical timing system 30 and valve 28 may be the same as those commonly employed on automatic yard sprinkler systems such systems can automatically open the valve 28 for preselected time periods and at desired intervals throughout the day the precise setting of the control 30 depends on the particular dimensions of the roof to be cooled the dimensions of the sprinkler system itself and the available water pressure in general the sprinkler time period should not be so long as to allow excess water to run off the eaves of the roof 12 if desired the roof 12 may be provided with guttering.