How to color single building in a glTF?

A gltf contains a number of buildings and all the building has the same materials.
I Can get the pickObject by mouseclick and i change the materials like this: pickedObject.mesh.materials[0].setValue('diffuse', highlightColor);
After this all buildings change color... But is there is a way for single one by selected nodes like this?
pickedObject.node._runtimeNode

This is not easily doable, you would be better off creating the glTF with one material per building.