External wall insulation is like wrapping your house in a cozy blanket to keep it warm in the winter and cool in the summer. The blanket, or insulation, goes on the outside of the house, just like when you wear a warm jacket to keep you toasty on a chilly day.
You know how some houses have bricks or siding on the outside? Well, the insulation goes on top of that. It can be made of different materials, like foam or mineral wool, which are really good at trapping air and keeping your house at a comfortable temperature.
It also helps to save energy and money by making it easier for your house to stay at the right temperature, so you don't have to waste a lot of energy heating or cooling it all the time. And that's good for the environment too!
So, just like putting on a jacket on a cold day, external wall insulation can help keep your house cozy and energy efficient.