The nominal vacancy rate is the marginal vacancy rate which prevails in a market over and above the structural (equilibrium) vacancy rate.
The following dynamics should occur in theory: if the nominal vacancy rate is higher than the structural (equilibrium) vacancy rate, the market is oversupplied and there is surplus vacant stock.
Decreased rents should be predicted in such situations. If the current vacancy rate in the market is lower than the equilibrium vacancy rate, it indicates that there is a shortage of assets and that the market is undersupplied. As a result, higher rents should be predicted.