Smart materials react to external changes in the environment using no electricity or computer controls. Thermobimetal is one that reacts to temperature changes. Because it is a lamination of two alloys of metal with different coefficients of expansion, it curls when heated.
As the temperature goes up, one side of the lamination expands more than the other causing the material to curl.
As the sun heats the material, the individual TBM petals reverse their curl, flip and become activated. This distribution of weight converts to the opposite position and blocks the solar radiation from entering the building.