  It is assumed that Be star discs are driven by viscosity. Emission from disc
models is calculated and is confronted with continuum observations. It is found
that the outflowing viscous disc models can reproduce the observed IR continuum
emission. However, to exist as outflowing discs, either the discs are
significantly acted upon by the stellar radiation field and/or there is
significant cooling with radius in the disc. The energy generated via viscous
dissipation is calculated and shown to play only a minor role in the energy
balance of the disc.
  A scenario whereby a B star may change into a Be star (and vice versa) by
generating (reaccreting) the disc is suggested.
