Standard EnergyPlus Units[LINK]

EnergyPlus expects information in a single unit system (SI). This requires interface developers to convert user inputs from those preferred by architects and engineers into the standard metric units of EnergyPlus. EnergyPlus will not perform any units conversions and will not have any unit conversion routines.

ASCII with no spaces is used for abbreviations. Note that exponents appear without any indication of exponentiation: i.e., kg/m3 not kg/m^3 or kg/m**3. Also note the use of dashes. We have W/m2-K not W/m2*K or W/(m2*K).

At the end we note the “problem” variables – the inputs that have non-standard units. Inputs using these units will have to be changed and the code checked to see how the quantities are used internally.

Table 1. Standard EnergyPlus Units

Quantity	unit	abbreviation
angular degrees	degree	deg
Length	meter	m
Area	square meter	m2
Volume	cubic meter	m3
Time	seconds	s
Frequency	Hertz	Hz
Temperature	Celsius	C
absolute temperature	Kelvin	K
temperature difference	Kelvin	delK
speed	meters per second	m/s
energy (or work)	Joules	J
power	Watts	W
mass	kilograms	kg
force	Newton	N
mass flow	kilograms per second	kg/s
volume flow	cubic meters per second	m3/s
pressure	Pascals	Pa
pressure difference	Pascals	delPa
specific enthalpy	Joules per kilogram	J/kg
density	kilograms per cubic meter	kg/m3
heat flux	watts per square meter	W/m2
specific heat		J/kg-K
conductivity		W/m-K
diffusivity		m2/s
heat transfer coefficient		W/m2-K
R-value		m2-K/W
heating or cooling capacity	Watts	W
electric potential	volts	V
electric current	Amperes	A
illuminace	lux	lx
luminous flux	lumen	lm
luminous intensity	candelas	cd
luminance	candelas per square meter	cd/m2
vapor diffusivity	m2/s
viscosity		kg/m-s
porosity		m3/m3
thermal gradient coeff for moisture capacity		kg/kg-K
isothermal moisture capacity		m3/kg