Prepopulate boundary conditions from passive house model

[maren@rodell.design]

I've found a problem in transferring data between Passive house verification and WUFI Plus. Assigning boundary conditions from the passive house model in WUFI plus is continually adding to the heat load/ demand on the verification side. After selecting the option to prepopulate boundary conditions from passive house model on the WUFI Plus side, when I return to the Verification side the heating demand and load have both increased. If I click ‘Assign’ to Populate Boundary Conditions multiple times, on the WUFI plus side, the model gains more heat demand/load on the verification side every time. I can't find which data fields are being changed on the Verification side, and can't go back to the original model.

Looking for any insight on what exactly is being changed, and why data seems to be updating in both directions, not just from the model to WUFI Plus.

Thank you!
Maren

[mpazold]

Hi Maren,

thank you for your post! actually this is a bug, which will be fixed in the next release version (past 3.1.1.0).

Within the monhtly balance calculation, the effective heat recovery efficiency is calculated, depending on the ventilation device HRV/ERV efficiency and e.g. the ducts.

by assign the boundary condtions from passive house model, the effective heat recovery efficiency is set for the HRV/ERV efficiency of the device, for the dynamic simulation (because there is no dynamic duct model so far).

unfortunately it replaces also the input for the verification side. So with each click on assign, the HRV/ERV efficiency for the mechanical ventilation device is reduced.

I will post the insight on what is being changed soon, and it will be added in the manual. The data update with the prepopulate boundary condition button should be one-way (from verification to the dynamic inputs) and only for dynamic WUFI Plus input, which is not used, or different on the verification side. global input, like the building geometry, is always coupled in both scopes.

Thank you!
Matthias

[maren@rodell.design]

Matthias,

Thank you so much for your quick response! We've spent a few stressful days trying to find the changes to the verification model to trace our steps backward and this is an easy fix. Looking forward to the next release.

Maren

[maren@rodell.design]

Another question on a related topic...The setpoints carried over from the passive house model include Internal loads: "A constant internal load is added depending on the internal heat gains of the passive house calculation." Does this load include people, appliances, and systems as a constant load? If so, then we would need to add profiles for occupants, etc on the dynamic side to be more accurate, right?

[mpazold]

Yes, the internal loads per square meter from the passive calculation are set constant each day, and only as convective internal heat load on the dynamic side.