Trombe walls consist of a concrete bulk, with a layer of glass or reflective coating on the outside.
|Simplified from Wikipedia|
It isn't all about the glass though: The concrete provides a large mass to store the heat when it comes in, and acts as a buffer between the inside and outside. I had hoped to make a simulation of this, but my concept of what happens is that as the weather outside heats up in the day, and cools down at night, those changes are transmitted inside with a delay, as the concrete absorbs and re-emits the heat. That results in the inside being cooler during the day, and warmer at night.
Air conditioning will still cool things better than this method, but this has the advantage of being more eco-friendly. I didn't expect international living to inspire blog posts, but thanks to Marika's observational skills, I've learned something new!