Metrics for chemists are much argued, but the energy usage of a reaction has to be one of the most simple and effective methods of comparing technologies. In this concept paper, the energy consumed in preparing one mole of a chemical compound is compared for a variety of technologies. Data are gathered for traditional oil bath, supercritical CO2 (SC-CO2), and microwave reactors. Two different Suzuki couplings, a Knoevenagel condensation, and a Friedel-Crafts acylation are all compared in both the microwave and oil bath, as this is where the most noticeable differences were observed. The most notable result was an 85-fold reduction in energy demand on switching from oil bath to microwave reactor for a Suzuki reaction.