Semi-analytical solution of roof-on-grade attached underground engineering envelope

Using a mathematical model of heat transfer of attached underground Engineering Envelope, the calculation area is divided into 13 rectangular blocks according to the Interzone Temperature Profile Estimation (ITPE) technology, and the solutions are obtained for all the parts using the technique of variable separation. During the solution, the Fourier coefficients are determined based on the continuity of the heat flux and boundary conditions. The influences of the temperature of earth surface and the heat transfer coefficient between air and wall on heat flow through the envelope has been quantitatively analyzed. The results show that the heat flux through the envelope is no longer monotonously increase or decrease with increase of the influencing factors. By analyzing the curve of r-value (the ratio of the flux through the roof to the overall flux through the engineering section including the floor and walls), it can be concluded that the heat flow between the first floor of the building and the engineering is the major reason and the shape of the engineering is another one.