Iingcango zomlilo zingahlelwa kwiKlasi A, iKlasi B kunye neKlasi C ngokwamanqanaba abo, ahluke ngokwe-thermal insulation. Amabakala okumelana nomlilo weminyango yomlilo yi-0.5h (iKlasi C), i-1.0h (iKlasi B), i-1.5h (iKlasi A) kunye ne-2.0h kunye ne-3.0h. Wamkelekile ukudibana nathi.