Thermal stratiยฎcation is often established in heated buildings and ponds. In such cases, the temperature at the bottom is lower than that near the top, resulting in an inconvenient microclimate at the lower region. Thus, it is usually desired to further raise the temperature near the bottom. This can be done in two ways. The ยฎrst is by providing a surplus of heat without destroying the thermal stratiยฎcation, and the second is by mixing mechanically the medium (while heating) to establish a uniform temperature distribution and hence, to raise the bottom temperature. The objective of this study is to calculate the energy required by each method in an attempt to determine the one which is more economical. A theoretical one-dimensional (1D) model is developed to calculate the energy required by each method and the ratio between them. The model considers enclosures with inclined or vertical side walls. For typical conditions in buildings and ponds, the ratio between the energies of mixing and surplus heating is very small, indicating that mixing is much more economical in raising the temperature of the lower region of the heated enclosure. For the case of inclined side walls, it is shown that the ratio between the energies required for mixing and heating increases with the inclination angle.