Analysis of simplified lumped-capacitance models to simulate thermal behaviour of buildings

Lumped-capacitance models for the simulation of the dynamic thermal behaviour of buildings have received a growing attention recently due to their low computational cost and ease of implementation into city district simulation models. This work looks at two simplified dynamic models to evaluate the energy performance of buildings in both heating and cooling. In particular, the xRyC models proposed by the International Standard ISO 13790 and by the German Guideline VDI 6007 are analysed in detail and compared with TRNSYS, in both long-and short-term, under the same boundary conditions. The analysis has been carried out considering an apartment with different types of building structures (high-low thermal capacitance, high-low thermal insulation). Four European climates (Helsinki, Venice, Vienna and Palermo) have been taken into account. The comparison has been done in terms of energy need, peak load and hourly heating/cooling load profile during both seasons. The simulation results show that the simplified 7R2C model of the VDI 6007 is in good agreement with TRNSYS, in terms of both energy needs and transient behaviour. The improvement over the 5R1C model of the Standard EN 13790 increases when the cooling season is considered.