Further development of the theory of Dynamic Thermal Networks for the application in building energy simulations

Paper in proceeding, 2009

This work considers the modeling of time-dependent heat transfer in buildings by using Dynamic Thermal Networks (DTN). The method, which is essentially a response function method, is based on the concept of thermal response of a wall on a unit step change in boundary temperature. DTN gives handy solutions to the transient heat flows through walls, independently on the length and the magnitude of a time step. In order to account for the radiant heat gains in a space, the original DTN method is extended here by the model for the thermal response of a wall on a step change in radiant heat flux. The actual heat gain or cooling load from the radiant heat flux is introduced as the regained flow. It is shown that the regained flux can be modeled with the basic set of weighting functions, which are called in DTN as the absorptive and the transmittive. The incorporation of the regained flux into the heat balance equation for a wall is presented in full extent.