Fanger PMV and KSU TSV show sudden spike in results specifically at 8:00 pm during one day simulation, why is this happening?

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I performed thermal comfort simulations using Fanger model, pierce two node model and KSU- TSV model. But the Fanger PMV and KSU TSV results show sudden spike during specifically at 8:00 pm during one day simulation. Can someone tell me why is this happening? Should I change the time step in simulation? Or there is any other parameter which needs to be changed? The pierce model results are consistent and Fanger PPD is also consistent...