Demand-controlled ventilation issue

Hi,

I am quite new to HB and have an issue to model ventilation that is demand controlled.

In the HBSetSchedule component is written for the ventilation schedule :

"Note that this schedule overrides the typical ventilation that occurs based on the occupancy shcedule and the "ventilationPerPerson."

So I guessed if we didn't put a schedule there and specify a minimum airlow/m2 and minimum airflow/occupant, EP would calculate the volume flow rate at each timestep based on the schedule, but it doesn't seem to work.

Indeed, on the results, I only have a constant airflow that correspond to the maximum of vol/m2 and vol/occ. So I wonder how to use these components to have demand controlled ventilation.

What I really want is have a minimum airflow when the room is not occupied and a bigger one based on the number of occupants when the room is occupied.

I currently have :

outdoorAirRequirement input = 1 (maximum) in SetEPZoneThreshold

ventilation per area = 0.00035

ventilation per occ = 0.01 in set EPZoneLoads

No ventilation schedules input in SetEPZoneSchedules

Hope you can help,

Best regards,

Aurelien

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Replies to This Discussion

Permalink Reply by Julia T on January 20, 2017 at 9:23am

Hi Aurelien,

I would customize the occupancy schedule.

Create a new schedule with the values of the occupancy file with a function that substitute the values=0 (when there is no occupancy) for the amount that you need. You can always calculate this value by inputting a fraction of the ventilation per area or per person, as suits you.

Hope it helps

Julia

Edit: keep in mind that the simulation will calculate the ventilation per area/person multiplied by the number of the new schedule (approx to explain it in a simple way, hope Mostapha doesn't kill me for saying that), so be very careful with the numbers that you put there

Attachments:

customized schedule.gh, 20 KB

Permalink Reply by Aurelien Keller on January 20, 2017 at 10:44am

Hi Julia,

Thank you for your input !

This is approximately the way I am doing it right now but it requires quite a few unit conversions before having the right input and therefore higher risk of making a mistake..

In was therefore wondering if there was a nicer way to do it using the inputs already existing in the different components :)

PS : This workflow is quite useful to modify a schedule ! Thanks !

Aurelien

Permalink Reply by Julia T on January 23, 2017 at 2:48am

Hi Aurelien,

Unfortunately not that I know/ remember in this moment. Maybe someone else can help you better.

I know the possibilities of mistaking are high. What I do in these cases usually is I check thousands of times with other colleagues and run tests on small boxes to check its fine, and when I'm happy I cluster it, so I don't change it by accident.

But I'm afraid I cannot help you more, sorry.

Julia

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