“…θ i, nε temperature of the internal air (1,2) θ si, nε temperature of the internal wall surface (1,2,4,6,7,8,9) θ se, nε temperature of the external wall surface (1,3,5,6,7,8,9,10,11) Let us note that the numbers of factors can be arbitrary. In the provided example the first 11 factors were used to ensure better clarity of notation.…”