(b)such a temperature as will secure to workers therein reasonable conditions of comfort and prevent injury to health; and in particular,—(i)walls and roofs shall be of such material and so designed that such temperature shall not be exceeded but kept as low as practicable;(ii)where the nature of the work carried on in the factory involves, or is likely to involve the production of excessively high temperatures, such adequate measures as are practicable shall be taken to protect the workers therefrom, by separating the process which produces such temperatures from the workroom, by insulating the hot parts or by other effective means.