what will be the equivalent circuit if ambient temperature is steady inside and outside wall

Question

Solar energy is absorbed by the wall of a building as shown in the figure below. Assuming that the ambient temperature inside and outside are equal and considering steady- state, the equivalent circuit will be as shown in given figure                                                                                                                      1998

Symbols:

R_co= R_{convection outside}

R_ci= R_{convection inside,} R_w= R_wall