The spell light, doesn't produce any energy.
The spell continual flame doesn't produce any energy.
The spell darkness does not say that fires go out, or energy gets dampened in its effect. At the end of the day, you just cant apply physics to this system of magic, because this is a poorly written magic system to deal with scientific function.

If anyone would like to make a scientifically accurate magic system, be my guest.


I think mass effect did a fairly decent job with its magic biotics.