The energetics of the nightside ionosphere of Venus are still not well understood. Rather large ion temperatures have been observed on the nightside. We have constructed a two-dimensional theoretical model of the energetics of the nightside ionosphere which takes into account the effects of horizontal and vertical bulk transport of heat. We demonstrate that the observed maintenance of the ion temperature can be explained in terms of these transport terms for solar zenith angles less than 150¿. Simple heat transport cannot explain the observed high temperatures for angles greater than 150¿.