Metal baths (enamel on steel or cast iron) retain more heat than their acrylic or fiberglass versions
white. they reflect lightwaves containing heat the best.
insulators although they take a long time to heat up, it takes a longer time to cool down. that's why if you heat water in a metallic container it takes more time for the water to cool down than the coontainer.
Super Refractory is a refractory material which retains its shape and chemical identity in extreme heat, so super refractories are used in Industries for heat resistance.
The best material is copper of alumninium.
Mirrors reflect heat
insolation keeps heat in best.
The best insulator of heat is probably polystyrene foam or fiber glass.
Wood. Is the best material to use to seperate heat from cold.
Soil both absorbs and retains heat. The length of time soil retains its heat is dependent upon the amount of moisture or water in the soil.
Metals.
Copper.
Electricity does not conduct heat. Your question is meaningless.