Hmm... yeah that is a hard one. There are really very few resources available at the movement, and the ones that do exist are almost all for a European audience, so if you are in North America and aren't comfortable working in degrees-C or Meters it can be hard to find good guidebooks or tutorials for sure.
I think that the main resources you'd want are the ISO documents governing thermal bridge calculations such as:
- ISO 10211: Thermal Bridges In Building Construction - Heat Flows And Surface Temperatures - Detailed Calculations53
- ISO 10077-2: Thermal performance of windows, doors and shutters — Calculation of thermal transmittance — Part 2: Numerical method for frames76
- ISO 14683: Thermal Bridges In Building Construction - Linear Thermal Transmittance - Simplified Methods And Default Values46
Beyond that, there are some other resources from various folks such as:
- BY Hydro Thermal Bridging Guide (follow the link at the bottom for the guide PDF)68
- Fen-BC Window Thermal Bridging Guide61
Those are all probably really useful to have, but won't help you much with the actual nuts and bolts of doing the calculations yourself though. You could try Peter Warms classes (http://www.passivhaustraining.co.uk/online/156) though again, its all in metric.
If you are in NYC or therabouts we do pretty regular after-work classes here through the AIA-COTE, New York Passive House and other groups - the best place to look for those is the Urban Green Calendar I think. Hopefully we'll be doing more of those in 2020.