Small change leads to huge difference in simulation duration

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Ha_Aria
Posts: 6

Small change leads to huge difference in simulation duration

Postby Ha_Aria » Mon Jun 11, 2018 6:25 pm

I am working on a big size building model that usually takes about 3 hr of simulation to get annual results. recently I added extra water heater (radiator) to some of the group zones to solve my setpoint not met hours. These extra heaters changed my simulation duration to 14 hr !!!!
I reviewed big size building modeling recommandations article however, I still can not understand why this small change leads to huge simulation duration difference and is there anyway I can fix this problem?
I appreciate any helpful comments :)
Luis Sousa
Posts: 337
Location: Stroud

Re: Small change leads to huge difference in simulation duration

Postby Luis Sousa » Fri Jun 29, 2018 11:55 am

Hi,

This increase in simulation time is expected when the Radiator component ( ZoneHVAC:Baseboard:RadiantConvective ) is used.

Basically, the calculation will partially distribute the heat to the zone air by convection and also by radiation on people and all surfaces within the zone. Then, it will be calculated an additional convective heat transfer from the surfaces to the zone air after these have been heated, and the radiant heat transferred to people is assumed to be added to the zone air heat balance by convection from people to the zone air.

All these calculations are done for each simulation timestep and therefore increases the simulation time when compared with a heating component that only models the convective heat transfer.

For more information on this, please see the E+ Engineering Reference.

BR,
Luis

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