Abstract: A transportable PCM (phase change material) module comprises a number of PCM packs; a housing for thermally insulting said number of PCM packs from a module's surrounding medium; spaces separating said packs and forming one or more channels for the flow of a fluid; said housing incorporating a fluid inlet and a fluid outlet; whereby, in use, fluid flows through said channels from said inlet to said outlet. A PCM (phase change material) pack comprises a laminate of a first conducting panel and a second conducting panel enclosing a portion formed primarily of PCM; wherein said portion of PCM incorporates thermal conductors.