Snow melt insulation options

Mars_2

I have seen a lot of different options as for as insulation under a snow melt system. Ranging from the thin reflective bubble wrap, concrete insul tarp to closed cell extruded pollystyrine, any oppinions on these products from the real world would be great. thanks
Matt R

Steve Ebels_3

Only one good options

For best performance and vastly superior economy (less heat soaked away in the ground) 1 1/2" or 2" foam board. The others are what you say........options