[acsinuk (OP)]

We know that space has an above zero temperature so we can assume that a volume of empty space has a massless energy which could be magnetic energy E= 1/2*L*I^2 per m^3.  We also know free space has permeability, so what magnoflux units should be quote this energy in?

[PmbPhy]

We know that space has an above zero temperature so we can assume that a volume of empty space has a massless energy which could be magnetic energy E= 1/2*L*I^2 per m^3.  We also know free space has permeability, so what magnoflux units should be quote this energy in?

Energy is always stated in units of energy. The SI unit for energy is the Joule [J] which is 1 kg*m^2/s^2