Thermal wheel

Okay, so imagine you have a big round thing that looks like a merry-go-round at the park, but instead of kids sitting on it and spinning around, it's used to help control the temperature inside a building. We call it a thermal wheel.

Now, this thermal wheel has two sides, one side is warm and the other side is cool. When air from outside the building comes in, it passes over the thermal wheel, and the warm side gives some of its heat to the cold side, making the air a bit warmer.

When air from inside the building needs to be sent out, it goes over the thermal wheel too! But this time, the cold side gives some of its coolness to the warm side, making the air a bit cooler. The air is always moving in and out, and as it passes through the thermal wheel, it helps keep the temperature inside the building just right.

Think of the thermal wheel like a sandwich, with the warm inside stuff being separated from the cold inside stuff by two sides, kind of like two slices of bread. Except instead of eating it, we're using it to help control the temperature and save energy!