Styrofoam insulation panels are often referred to as ‘blue board’ as can be seen in this successful project carried out in San Carlos, California. Large electrical transformers need insulating in climates where temperatures drop sharply in the winter. In this case the transformer manufacturer ordered large 48” x 96” sheets of blue Styrofoam insulation panels and cut them to size to fit each section required. Spot the blue board in these images of the new facility. https://univfoam.com/insulation/styrofoam-used-to-insulate-electrical-transformers