Khazzoom-Brookes postulate is the name given to a theory that tries to explain what happens when we try to save more energy. It says that if we try to save more energy by using more energy-efficient technology, we will end up using more energy in the long run.
Think of it this way: Imagine you love playing with toys and you have a toy that uses batteries. You decide to save the batteries by using a more efficient toy that uses solar energy instead. But soon you realize that because you are saving on batteries, you can play with the toy more often, which means you end up using more solar energy than you would have used with the battery-powered toy.
Similarly, in real life, when we try to save energy by using more efficient light bulbs, cars, or appliances, we tend to use them more often or for longer periods of time. For example, if we install energy-efficient light bulbs that last longer, we may leave them on for longer than we would have with regular light bulbs.
So, the Khazzoom-Brookes postulate argues that we should not expect to reduce our energy consumption simply by adopting more energy-efficient technologies. Instead, we need to be mindful of how we use them and try to modify our behavior to use them less often.