You can read more about UCLEM here, but in short it responds to local weather and calculates energy consumed inside buildings (from heating and cooling and other energy use) and then emits that energy as waste heat back into the environment. In dense urban areas that waste heat can raise air temperature and cause convection, changing local weather in a feedback loop. Apart from that, it’s useful to know how much energy is being used in different weather conditions.
This first animation shows the air temperature over Eastern Australia, along with the energy used within buildings. The second is nested within the first for a higher resolution simulation over Melbourne.