it makes metal to metal contact with the opposite sidewall 14 thus creating the desired thermal short to 34 turn off 34 the insulated effect of the panel 10 cooling of the metal of dimple 212 will of course result in contraction of the dimple 212 away from sidewall 14 thereby re enabling the insulative effect of panel 10 as in other thermal shorting switch embodiments described above this switch 210 can also be actuated actively by a heating element not shown that can be turned 34 on 34 and 34 off 34 when positioned adjacent the switch 210 another variation of thermal shorting switch 230 is shown in fig2 wherein a concave dimple or depression 232 is formed in a sidewall 12 of panel 10 however in this embodiment the dimple 232 comprises the same metal as sidewall 12 but it is confined at its edges by removeable anchors 234 236 that are welded or otherwise affixed to sidewall 12 as the metal of dimple 232 is heated by a heat source 100 it expands however since it is confined at its edges by removeable anchors 234 236 the dimple will expand in a direction perpendicular to the plane of sidewall 12 toward the opposite sidewall 14 with sufficient heat and expansion therefore the dimple 232 will expand to the position shown by broken line 232 where it contacts the opposite sidewall 14 and creates a thermal short across the panel 10 upon cooling the dimple 232 contracts away from sidewall 14 thus re.