Hi @chris and @kocat

The calculation of heat flow is very regulated in the OTTV calculation. This is true for all OTTV regulations from various countries that use the method. As such, we CANNOT used the energy flow calculated by simulation program. It is simply not allowed.

The regulation/standard will have a method to calculate the three heat flow components (wall conducation, glass conduction and glass radiation), and we need to stick to that method. Each country has a slightly different variation of the method (different constants, etc).

If we want to calculate the OTTV of the building we simulate, simply use the envelope summary report table where all the external walls and windows are reported. Combined with the material properties, the OTTV can be calculated with spreadsheet, or R, or python, or Honeybee object for that matter. But definitely it does not involve any other output from EnergyPlus.

Calculating OTTV using āactualā heat flow from simulation result will NOT be acceptable to OTTV regulation in respective countries. It is interesting to compare the number with the OTTV calculated with respective methods, but the difference in numbers is meaningless, there is no physical meaning to it.

I have been saying this to folks in Indonesia. But apparently, there is always somebody who wants a more āaccurateā OTTV calculation using āactualā heat flow from simulation result. Hopefully this answers the original question.