Ground temperature warning in the simulation of EnergyPlus
How can I solve this problem in EnergyPlus when I do the simulation?
Program Version,EnergyPlus, Version 8.4.0-832e4bb9cb, YMD=2015.12.02 09:25,IDD_Version 8.4.0
** Warning ** GetHTSurfaceData: Surfaces with interface to Ground found but no "Ground Temperatures" were input.
** ~~~ ** Found first in surface=A84D86
** ~~~ ** Defaults, constant throughout the year of (18.0) will be used.