Your topic seems vaguely related to this thread. I don’t suppose you are working on different aspects of the same problem, are you?
In any case, Radiance is not really designed for long IR simulation inasmuch as materials are either emitters or passive reflectors/transmitters of radiation, not both. You can mix the “glow” type with other types, such as “plastic” to get some combined behavior, but it is tricky to do so correctly. Also, Radiance has no internal mechanisms for tracking temperature, thermal mass, conduction, convection, radiative losses and gains, or even black body spectra. All of that would be your job as well.
Assuming you are up for that, it is possible to explicitly model longwave radiation using the latest spectral rendering additions in the HEAD release found here. You would need to specify a range that included visible light from at least 468nm, and the photon-mapping add-on is not yet functional in this prerelease, but it is possible.
Regarding lens effects such as flare and bloom, we don’t have any built-in simulation models for these effects, and I am also unsure if or how thermal wavelengths differ from visible.
Given all that, you are welcome to give it a try, but there may be better-suited software out there. It’s not really my area of expertise; I just didn’t want your query to go unaswered.
Cheers,
-Greg