Animated Material - i.e. Diffuse blending into Wireframe

Hi everyone,

I have recently started a project with the new Unreal Engine, and I don’t have a vast amount of experience seeing as I am coming from a 3D art background - hopefully I can properly explain what I am hoping to do in engine!

I am tasked with creating an ‘interactive animation’ to educate school kids about energy use and security - for this particular section, teaching them that 50% of energy in Europe is imported. The concept is to have a ‘3D Hologram’ of a city that the player can view, which is textured appropriately. However, when a certain ‘valve’ is turned in the animation, and the imported energy stops reaching the city, I am looking to have a partial ‘Wireframe’ effect to appear on the model city - so that it is a blend between the Diffuse texture map, and a wireframe. The reason I want to do this is to try and give a visual representation that the city is at 50% of its power now that the imported energy isn’t there.

I suppose perhaps the best visual explanation I could give is this image here :

I’m not quite sure where to start with this , or what materials / blueprint information I need; but any help whatsoever would be fantastic.

Thanks so much,