Eddy-viscosity turbulence models are sensitized to the effects of buoyancy, in order to improve the prediction in natural convection flows. The approach extends in a linear way the constitutive relations for the Reynolds stress and the turbulent heat flux, in order to account for the anisotropic influence of buoyancy. The buoyancy extension applied to two very different eddy-viscosity models lead to encouraging results for the highly challenging case of the differentially heated vertical channel.