how can I apply airflow network with ideal air loads?
Hi all,
I activated the airflow network in EP and used a schedule for when windows should be open (at 25°C), and I also have an ideal air load with cooling and heating schedules. The purpose of that was to examine the benefits of natural ventilation (AFN) in minimizing the cooling loads. The cooling and heating loads that resulted from this were very unrealistic! I have been reading previous posts and EP documentation, but I couldn't understand how to activate mixed mode using AFN with ideal air load. I applied ideal air load, as I am not a mechanical engineer and am still not much familiar with how to apply HVAC in OpenStudio or EnergyPlus. I appreciate your help in this!
A few links on AFN vs IdealLoads: here, here, here. I suspect EMS will be required, e.g. overriding heating/cooling setpoints f(opening area).
Have you looked at the zone temperatures, supply air heating/cooling energy, and AFN ventilation rate outputs? They might help you understand what's going on. A common issue for example is that the ventilation could be running at the same time as the heating, causing the loads to blow out. Here's some detailed discussions on AFN ventilation controls if that causes you problems.
Thanks Denis and Jamie. You are right; the AFN is running while the IAL is being used. I've gone through Ep documentation again, and I found " HybridVentilaion" system manager, I think I need to use this one if I require the natural ventilation to be off once the operative temperature is not within the 80% adaptive model threshold upper and lower limits; otherwise, EP would not turn off AFN or wind and stack open area if ideal air load is on.
Mmm, that might work but I'm inclined to think it won't. In my experience the "clashes" happen because the ventilation from the open windows can be incredibly strong with the AFN. The result of this is something like:
So the heating and AFN are "technically" never on at the same time, but in practice clash
Here in Brazil we use the NBR15575 standard to determine the thermal performance of the building, naturally ventilated and with conditioned ventilation. I have a small .pdf file that can help you, but it is written in Portuguese. I made it as a guide when I use E+ (Version 9.6.0) I can only upload directly to an answer reply. Is it OK? even though it is not (perhaps) an answer to your question.