  We construct a mass or energy function for the non-Nariai class
Schwarzschild-de Sitter black hole spacetime in the region between the black
hole and the cosmological event horizons. The mass function is local, positive
definite, continuous and increases monotonically with the radial distance from
the black hole event horizon. We derive the Smarr formula using this mass
function, and demonstrate that the mass function reproduces the two-temperature
Schwarzschild-de Sitter black hole thermodynamics, along with a term
corresponding to the negative pressure due to positive cosmological constant.
We further give a field theoretic derivation of the particle creation by both
the horizons and discuss its connection with the mass function.
