Which 3 materials are the best insulators out of the rest?
You don’t say what you are trying to insulate and why. Are you trying to keep heat in or out; or are you trying to keep something cold? Many of the above materials are good for keeping warm air in a house from radiating out through the walls. Fiberglass works well inside walls as does expanded polystyrene, polyurethane foam. Rockwool, vermiculite and cellulose work well to insulate a ceiling when you blow in a 16″ to 18″ layer. They don’t work in walls because they are loose and tend to pile up at the bottom, leaving the top of the wall empty. Metals such as aluminum, silver foil and gum wrappers are conductors of heat. Conducting heat is the opposite of insulating. In general, house insulation works by trapping pockets of “dead” air. As long as the air cannot move easily, it cannot conduct heat; therefore it acts as an insulator. The best insulating product, therefore, is the one that best traps the most air. I would probably select expanded polystyrene foam, extruded polystyrene foam
