Fastener pieces are supporting a load and vibration that it make ideal to use piezoelectric material for an energy harvester. The forces can be compression or tension, many times both in the same element. It can be use to maximize the electric output.
The simplest element is the washer. It is easy to make and cheap. We can play with it and make a flag blowing in the wind. The pole is support by many metallic strips near the end. And they are fastener to the base by nuts and bolts, whit a piezoelectric washer, one in top other in bottom.
As wind move the flag and pole, there are a force upon the washers, in top one there are tension and in the bottom there are compression. This force is transformer in electricity, by the piezoelectric material inside the washer and send to battery.
Instead of a flag we have an antenna. Even in isolated place in dark days could be energy to work.
But is it the antenna became a building? Living load can be a source of energy, it could be a small one but permanent. A lot of Piezoelectric Fastener can do a Energy Harvester from all the moving inside the building, also outside from wind.
But the most important and useful could be in order to reduce the heavy of the building because a proper designed can put it in order to take advantage seismic forces. It is a rare but dangerous matter that makes all the structure be more robust and heavy. Many fasteners can take the seismic forces and use then to produce electricity instead of broken the structural elements, and they became lighter and all the building less heavy.