We report on the energy usage required for one organic reaction in two small pilot plant scale reactors of different vessel designs (both 50 L) conducted in a kilogram scale facility. The background energy consumption of the building and all supporting services was determined beforehand, and this figure used to compensate for the energy usage required for each of six pilot scale batches performed under different conditions at the 20 and 40 L scale. The energy usage data was compared between these large scale batches and with the equivalent laboratory scale batches, including several earlier microwave-heated batches (Moseley, J. D.; Woodman, E. K. Energy Fuels 2009, 23, 5438−5447). The results showed little difference in energy usage between the two pilot plant scale reactors under the different reaction conditions, except on doubling the scale which halved the energy usage per mole. However, the energy efficiency of the laboratory scale reactors was higher than the pilot scale reactors under all reaction ...