Hi everyone,
I hope you can help me. When I use the HB Airflow Network Component my Infiltration rates are very wrong unfortunately.
Ninf = 0.09 ACH as supposed to reality Ninf = 0.3 ACH
I’m currently using the leakage Template VeryPoor. Anyone else encountering this problem as well and knows how to help.
My Issue:
I am simulating a Classroom in regard to natural ventilation and how it affects the adaptive comfort in Occupied Discomfort Degree Hours, there are no mechanical systems at all.
As a reference I have a research paper with specifically analysed the infiltration and ventilation rates of a exsisting classroom in south korea with the tracer gas method. So the results I have as an reference are measured in real life and not simulated. Link to paper: https://www.sciencedirect.com/science/article/pii/S0048969721028357?via%3Dihub
In Table 2 the following values where measured:
For Infiltration (Base Case) Ninf = 0.3 ACH
For Ventilation (30% single sided) Nvent= 2.9 ACH
Fig. 1 Screenshot from Paper Classroom
Fig.2 Rebuilt Classroom in Grasshopper
My Simulation:
I rebuilt the classroom in grasshopper and simulated it with a Epw file from the same location suwon, south korea.
The classroom Dim : 8.2 m Length x 7.9 m Width x 2.5 m Height. Volume 162 m3
Window Size: (30 % case) in total: 1.08 m2 (4 windows sized 0,27m2 each)
Height Window Sill: 1.5 meter (exactly as in the research paper)
Orientation Windows: South
Schedule Windows: Open during occupied school hours, closed at night.
AFN Leakage Template: VeryPoor
Without AFN I set the infiltration in HB Infiltration to 0.0006 m3/s per m2 facade.
My Simulation Results: for the day 10.07 at 8 am i have a temp difference inside (Top) outside (Drybulb) of about 3 degrees.
AFN:
When using the AFN component I get following results.
Ventilation: Nvent = 3.07 ACH very close to 2.9 (im impressed)
Infiltration: Ninf = 0.09 ACH wrong (real value Ninf= 0.3)
WITHOUT AFN:
When not using the AFN just HB Window Opening + Infiltration:
Ventilation: Nvent = 5.2 ACH wrong (real value Nvent = 2,9)
Infiltration: Ninf = 0.28 ACH (very close to 0.3)
So apparently when i use the AFN component my ventilation values are right but my infiltration is wrong. And without the component the opposite.
I would really like to continue with the AFN component as it gives proper results for the ventilation.
My Question: Does anyone know how i can fix this so I get more realistic infiltration Values while using the AFN component ?
Thank you so much your help is much appreciated, currently writing a thesis at TUM at the chair of climate responsive design.
All the best,
Nick
PS: Some more results from my simulation.
you can see ACH for the 10.07, the max values for the year, and the mean of the year.
