The present disclosure relates to an apparatus that can maintain a required thermal condition[TC] of an object for a period of time. The apparatus comprises a thermal sheet[TS] having thickness[t] nearly same as a blanket and incorporates a pipe to circulate a fluid. The thermal sheet can be used in combination with a Thermal Energy Reservoir [TER] that can be configured with a thermally insulated chamber to hold a thermal reservoir substance kept in the thermally insulated chamber. A pump can circulate the fluid through a second pipe placed in the thermally insulated chamber and thereafter through the pipe in the thermal sheet. A hot reservoir substance [heat source] can provide heating effects and a cold reservoir substance [heat sink] can likewise be used to provide a cooling effect. Thus the thermal sheet[TS] has the capability to keep a body at a required thermal condition[TC] (high or low temperature) for a period of time.