Pulsed time-resolved photoacoustic calorimetry in combination with quantum yield determinations afforded the relaxed triplet energy of 1-phenylcyclooctene and the energy of geometric isomerization of cis-1-phenylcyclooctene. These values are combined with previous values of the energies of isomerization of cis-1-phenylcycloheptene, cis-1-phenylcyclohexene, and cyclooctene to evaluate several computational approaches for modeling strained cycloalkenes.