A cooling element for cooling a body, comprising a heat conduction layer coterminous with a proximal side of the cooling element, a heat retardant layer coterminous with a distal side of the cooling element, and a heat sink volume disposed between the heat conduction and heat retardant layers, extending from a proximal boundary with the heat conduction layer to a distal boundary with the heat retardant layer. The heat sink volume comprises a porous material including a first substance; and the heat conduction layer comprises a porous material including a second substance. The first and second substances have thermal properties such that the first substance will solidify at a first temperature, the second substance being in the liquid state at the first temperature. The heat retardant layer has a lower mean thermal conductivity than the heat conduction layer.