To provide the structure of a building having excellent energy-saving ability while relieving violent heat and the cold of winter as a countermeasure for the prevention of global warming in view of violent heat in recent summer under the effect of global warming, wherein the countermeasure against heat is a serious problem, and air-conditioning in summer and heating in winter are unavoidable in houses of highly airtight and highly heat insulating structures, which results in the steady increase of power consumption.

A plurality of hollow panels are connected in a plane shape and mounted to the outside of an exterior wall or/and a roof, and water is stored in the panels.