Molecular antibonding orbitals energy When we heat hydrogen the energy of the molecular orbital of H2(1s) is increased .What happens to the energy of the antibonding molecular energy of hydrogen(1s*)?
Energy is not stored in the energy levels themselves but in the states which occupy them. 
At normal room temperature the bonding orbitals are occupied according to Maxwell-Boltzmann's statistics $P_i =e^{\epsilon_i /kT}/Z$, and store that chemical energy. At higher temperatures the antibonding orbital will become occupied releasing the chemical energy.