As this can be done when the car is connected to the power supply, the car doesn’t use the battery pack’s energy.
Although many electric car drivers don’t use preconditioning in summer, it can still be a great help in extending range. On hot days, preconditioning while still connected to a charger can bring the cabin temperature down to a more comfortable temperature before setting off. This means that the climate control system doesn’t need to work as hard to reduce the temperature once you’ve set off. This, in turn, means that more of the battery’s energy can be used to drive the wheels - giving the driver more range.
Another clever trick is to choose the perfect parking space. A shady spot will prevent the cabin temperature from soaring when you’re away. A cooler car will require less energy to condition to the perfect temperature - saving battery energy.