Equipartition energy, Noether energy and boundary term in gravitational   action
  In the study of horizon thermodynamics and emergent gravity two natural expressions for energy, E= 2 TS (equipartition energy) and E=TS (Noether energy) arise which differ by a factor 2. I clarify the role of these two expressions in different contexts and show how E=TS is also closely related to the Noether charge arising from the boundary term of the Einstein-Hilbert action. 
T. Padmanabhan
gr-qc hep-th