HB Energy Boundary Conditions options!

Hello,

I am setting up an energy model in HB Energy. The default surfaces’ Boundary Conditions are “Outdoors”, “Adiabatic”, and “Ground”. However, in the EnergyPlus list of boundary conditions there are more options of which the “Zone” seems more realistic for some surfaces in my model. I don’t know really how this option, “Zone”, can affect the heat flow calculations. There is another option, Outside Boundary Condition Object, in BuildingSurface:Detailed of EP (not implemented in HB Energy) that is not required but seems feasible for some surfaces. Since I have used face model to build the rooms in order to have more freedom over the materials in my research, it is very tedious to manually edit all the boundary conditions in the IDF editor. Does anyone have any suggestion?

Thanks,
Habib

Hi @Habib ,

Honeybee is structured in a manner where rooms are always composed of closed volumes of faces, meaning that interior faces are duplicated between each room and the EnergyPlus “Zone” boundary condition cannot be used. However, Honeybee supports the “Surface” boundary condition for cases where you have heat flow from one room to another. You can set surface boundary conditions in your model by using the HB Solve Adjacency component to geometrically figure out which faces are adjacent to others.

Hi Chris,

Thanks! I already have used HB Solve Adjacency component. I may need to compare the results with the “Zone” boundary conditions if I can manually set that.

Best,
Habib

You’ll have to manually edit the honeybee-exported IDF to do this but the results should be exactly the same whether you use Surface or Zone boundary conditions. There Input/Output reference is pretty clear about this that everything under the hood is the same whether you use one or the other:

https://bigladdersoftware.com/epx/docs/9-5/input-output-reference/group-thermal-zone-description-geometry.html#field-outside-boundary-condition

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