Selection and evaluation of a thermal simulation method for a building simulator.

A network approach is chosen for a new building simulation program BUS, and a lumped capacitance method (LCM) is selected for the assessment of temperature levels and energy consumption of a building. An implicit solution algorithm is chosen to solve the energy balance equations and temperatures of network nodes. Both the simulation method and simulation parameters (number of thermal nodes and time-step) needed to simulate thermal behaviour of a single building structure reliably are tested by comparing the results of LCM with an analytical solution of a test case. LCM was found to be a reliable and effective sub-program for simulating building heat transfer processes when a material layer exposed to rapid changes is described with at least nine thermal nodes, and time-steps not longer than 5 min are used.