To assess the effect of applying a high emissivity coating to the reactor coils in a steam cracking furnace, a complete energy balance was made for two cases based on simulations of the radiant section, reactors, convection section, and transfer line exchanger. A base case with a typical emissivity spectrum for a generic high-alloy steel was compared to a case with an artificially increased emissivity corresponding to a high emissivity coating. At the same cracking severity, coating the radiant coils increases the radiant section efficiency by 0.70% absolute, reduces the required furnace firing rate by 1.73%, and reduces the flue gas bridge wall temperature by 14 K. Minor changes to the convection section layout are required to compensate for the shift in duty to the radiant section: the reactor feed is still fully preheated to the targeted crossover temperature, but the production of high pressure steam is reduced.