in ‧ su ‧ la ‧ tion /ˌɪnsjəˈleɪʃ ə n, ˌɪnsjʊˈleɪʃ ə n $ ˌɪnsə-/ BrE AmE noun [uncountable]
1 . when something is insulated or someone insulates something:
Good insulation can save you money on heating bills.
2 . material used to insulate something, especially a building:
glass-fibre insulation