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# How to Control LowtemperatureRadiant system and typical HVAC system through external algorithm?

Hello All,

I want to control LowTemperatureRadiant system by using an algorithm e.g. I want to use Model predictive control. I know EnergyPlus can control LowtemperatureRadiant based on different temperatures e.g. indoor air temperature, MRT, outdoor air temperature etc, We also have to define a throttling range, meaning if the set-point is 15 degrees and throttling range is 2 degrees C then there will be no water flow where the temperature is at or above 16 degree and maximum flow at 14 degrees and so on. My question is can we implement our own control algorithm so that we specify flow rate at a given time step meaning the control algorithm will pass values of Water flow rate to EnergyPlus? the same goes for a typical HVAC system? How can we specify Ts AND ms (Labelled in the figure) from outside EnergyPlus. I more interested in LowTemperatureRadiant systems (top figure). Please see the figure below, where I have tried to draw both systems.

Thanks

Kindest Regards

Waseem

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Look into using the Building Controls Virtual Test Bed for control capabilities outside of what's provided within EnergyPlus.

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Hi Eric, I have control algorithm, what I want to do is just to pass optimal values of flow rate/supply temperature to EnergyPlus and run energyplus simulation. Any idea?

( 2015-01-29 11:03:22 -0600 )edit

Sure, you could implement your algorithm in, e.g., MATLAB and link it to your simulation with the BCVTB. Or, it looks like you could do it by coding a routine using the EnergyPlus Energy Management System. See the EMS Application Guide (included with EnergyPlus Documentation) for how to do that. Looks like there is an actuator for Low Temperature Radiant Hydronic water mass flow rate.

( 2015-01-29 11:23:57 -0600 )edit

I will have a look at EMS, but I think there may be another way of doing it.

( 2015-01-29 12:06:55 -0600 )edit