JB Heritier's profile - activity

• Yes, it is a result of a change of thermostat, as I explained. Every day at 17:00, there's the "same" peak difference with halved results. But I was still wondering how the real load (so the blue) could be predicted accurately.

• Yes, my HVAC system is only IdealAirLoads, as I didn't explain ;) . It's an IdealAirLoads with heat recovery ventilation (80%). And I guess the difference between blue and red is the remaining 20% of cold air blowed in by the ventilation. Which I was expecting to be included in the predictor.

• What do you mean by is it at 'detailed'?

Not on the second time step : yellow + green = way more ! Even green by itself is above both. But I agree for the other timesteps.

I am currently trying to simulate a on-off control, that would turn on only if the predicted load is higher than its nominal capacity.

I am using an EMS script for that, using the sensor Zone Predicted Sensible Load to Setpoint Heat Transfer Rate, with the Model Calling Point AfterPredictorAfterHVACManagers, as described in the example file EMSConstantVolumePurchasedAir

Until now, I am only sensing the value of the predictor, not actuating anything.

I am getting 3 different results for something I was hoping to be the same :

• The ems sensor Zone Predicted Sensible Load to Setpoint Heat Transfer Rate
• The report DistrictHeating:Facility
• The normal report Output:Variable, *, Zone Predicted Sensible Load to Setpoint Heat Transfer Rate, timestep;

I am pretty sure the difference between the two first is due to the mechanical ventilation loss (with HR) under normal conditions. But there is also a big difference when the thermostat setpoint is changed (+2°C)

How can someone get the real load during an EMS simulation?

And why is the last one (=sum of the two zones) that different from the two others?

Hi,

I'd like to model a system based on a heat pump system, using extracted air instead of outside air. The point is to recover the few degrees that are still rejected to the outside, even after going through the ERV.

Then, using a Heat pump water heater, I'd like to set my inlet air to the node after the ERV. Is there any way this is possible in openstudio, with or without a measure, or directly in the idf?

It looks like it could work using the "inlet air mixer fraction schedule" and putting (1-efficiency of heat recovery system), but then it isn't true when by-passing the ERV...

Thanks, JB