The design and use of heat sinks, which are compatible with sustainable development, involves a subtle balance between a superior thermal design, minimum material consumption, and minimum pumping power. Due to the rapid proliferation of electronic systems, substantial material streams, energy consumption, and entropy generation rates are associated with the cooling of computers, as well as other categories of electronic equipment. This presentation reviews the theory underpinning the least-energy optimization of natural and forced convection air cooled heat sinks, using the total coefficient of performance, relating the cooling capability to the energy invested in the operation and fabrication of the heat sink, as the sustainability 'metric'. Particular attentions is devoted to the determination of the most favorable fin and channel aspect ratios for plate and pin fin arrays, the allocation of available energy between fabrication and operation, and the selection of fin material, for both natural and forced convection air-cooled heat sinks. (c) 2005 Published by Elsevier Ltd.