Standard EnergyPlus Conditions[LINK]

Standard Temperature and Pressure[LINK]

Several objects specify inputs at “standard temperature and pressure”. Standard Temperature is dry air at 20${}^o$ C drybulb. The program uses local barometric pressure to account for altitude using the equation for “standard atmospheric” pressure on p 6.1 of the ASHRAE 1997 HOF (SI edition) to initialize the air systems being simulated.

$$Stdpressure=101325\cdot {\left(1.0-Z\cdot {2.25577}^{-5}\right)}^{5.2559}$$

where

StdPressure = pressure {Pa}

Z = altitude/elevation {m}