aspects of the invention support simultaneous operation of a cooling side and a heating side of an apparatus to change the temperatures of a cooling serving surface and a heating serving surface , respectively . a cooling semiconductor device transfers heat from its top to its bottom while a heating semiconductor device transfers heat from its bottom to its top . a heat pipe transfers waste heat from the cooling semiconductor device &# 39 ; s bottom to the heating semiconductor device &# 39 ; s bottom and waste cold from the heating semiconductor device &# 39 ; s bottom to the cooling semiconductor device &# 39 ; s bottom .