A way to integrate thermal bridges in EnergyPlus

[chris]

Thanks, @edpmay .

Now that we’re moving away from the more general topic of “how to take the Fairyfly U-Values and plug them into EnergyPlus simulation” and talking philosophy of Psi-value vs. smeared U-Value, have you tried the TBD measure that @brig mentioned here?

Using OtherEquipment to Approximate Thermal Bridges?

@edpmay - Have you tried Thermal Bridging & Derating (or TBD), an OpenStudio Measure? It’s been used recently by other LBT users. It works off of an OpenStudio model (.osm), but will work with an .idf (although additional steps are required). It offers what you’ve expressed (“approximate the impact of linear construction thermal bridges on Zone energy consumption”), but it is limited to what @MichaelDonn identifies as the smearing approach (simply because that’s what most energy codes/standards …

I have used it before and it is the way that I would recommend inputting Psi values for a Honeybee EnergyPlus simulation. Basically, @brig 's measure takes your psi values and performs a geometry analysis similar to what the HB Envelope Edges does but on the OpenStudio model instead of the HB model. Then, it derates the U-values of the constructions before sending the model to EnergyPlus for simulation.

If you set up your Honeybee model and run your simulation using this measure, it essentially allows you to use EnergyPlus the way that you want. Your honeybee model can be set up with u-values that follow the repeating TBs like studs. Then, you plug in the psi values of the construction TBs as inputs to the measure.

I know that running a measure is not as elegant as having it implemented natively in E+ but I know a lot of features that eventually get implemented within E+ start as their own separate measures. So, if you find this measure essentially gives the type of simulation results and workflow you want, there may be opportunities in the future to push for porting the functionality of the measure natively to future E+ versions.