Discrete event heat transfer simulation of a room using a Quantized State System of order two, QSS2 integrator

•Improves the DEVS model already published by us in a previous paper.•Focus the attention on the use of new hold functions for heat transfer.•Stimulate the new research area about DEVS models within this field.•Recalls the potentiality of the successive state transition method for heat transfer.•Shows an increase of one order of magnitude in simulation speed to the previous QSS.

In a previous paper [1] it was shown a proposal for a discrete event simulation (DEVS) model of a thermal zone. A quantized state integrator of order one (QSS) was used to integrate the evolution of the room air temperature. In order to increase the computational speed, this paper presents how the multi-layered wall, 1D conduction heat flow dynamics could be modified to allow its use with a second order QSS2 quantized integrator. The almost forgotten successive transition state method (see U. Yoshimi et al. [2]) is modified with changes in the hold function. Finally to validate the results, a test room has been employed to compare the results with EnergyPlus v7.1. Three cases have been studied: fixed TzoneTzone, floating TzoneTzone and floating TzoneTzone plus a random convective heat gain.