JimJast. By your definition, that eliminates all parts of the observable universe. If the universe began with a Big Bang, then there ought to be a relic neutrino background from the expansion of the original high temperature fireball, since all of our nuclear test algorithms, and particularly our hydrogen bomb algorithms (similar to supernovae algorithms) show energy losses due to neutrinos carrying it away.
On the other hand, if Hoyle & Co. turn out to be correct, then the ageless formation of stars ought to leak sufficient energy as stellar neutrinos to also populate every cubic meter of space. So there is no region of space that can be considered..."energy free". Neutrinos are real particles, have real properties, and carry both energy and momenta....similar to photons, but due to their relatively low cross-sections, cannot be excluded from any region of space. Every time you walk down the street...trillions pass through you. Space is not empty. pete.

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A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov