@Stranga ,
You can use the “HB Apply Room Schedules” component to assign the infiltration schedule:
Infiltration schedules in EnergyPlus are always fractional (between 0 and 1) and these fractional values get multiplied by the ACH value that you have assigned to give you the hourly infiltration value.
Hi @chris ,
Opening the 'Absolute_load_test" Grasshopper definition that you had uploaded previously and checking the IDF, it appears that the ACH value input has not been applied. Is this because it automatically calculates the ACH into an equivalent Exterior Surface Area?
@Stranga ,
Yes. Honeybee has one and only one property for defining the infiltration and it’s always on a per-exterior-surface-area basis. So you can always rest assured that the one infiltration value that you visualize from the Grasshopper interface is the only infiltration that is assigned to a given Room (no need to dig further into the IDF to check the 3 other fields or check the different E+ “Flow Rate Calculation Methods”).
Hi Chris
I am also wanting to input an absolute air changes per hour value but in Dragonfly. I am wondering if there is any way to do this for Dragonfly stories for example?
Since as far as I know there isn’t an equivalent component in dragonfly I would need to perhaps serialize to honeybee set my absolute values for the honeybee room and then run my model in Honeybee. Another option would be to bring the honeybee model back into dragonfly? Any thoughts here would be of much help, I can also open a new topic for this if you like.
Thanks in advance for the help
Hey @DonaldOtterson1 ,
This is a good question.
Given the level of abstraction that Dragonfly is operating on, it’s not really designed for this. The workflow with translating to Honeybee is probably what I would recommend, though it might be different depending on your use case. Can I ask why you’re using Dragonfly and not just doing it all in Honeybee?
If you’re using Dragonfly in order to run URBANopt simulations, there is a workaround that you could implement using the dragonfly core SDK and the dragonfly energy extension SDK inside a GHPython component. You would essentially need to duplicate the properties.energy.program_type assigned to each Room2D, edit the program’s infiltration to align with your ACH value, and then assign the new program type to the Room2D. So each Room2D would end up with a different program type. It’s not necessarily the cleanest solution but it will work if you really need to stay in Dragondly world and not translate to honeybee world.
Hi Chris, thanks for the very informative reply, really appreciate it.
That’s good to know I can fall back on Honeybee if necessary. We can actually get away with being slightly less precise on our infiltration values, since like you say the energy model is very abstracted at this stage. We are using dragonfly for calculating the heating, cooling and electricity demand of a development that will be BREEAM communities certified. I should probably read more into URBANopt to get the most out of our model but the logic has so far been that there are around 20 buildings so dragonfly would be more appropriate than making individual Honeybee models.
But thanks for the SDK tip, I will look into that if we need to be more precise with out infiltration.
