Missing Weather File Data[LINK]

The weather description of data contains “missing” descriptors, a new concept not introduced previously in our IDD conventions. In this case, it will be processed as though those values are “missing” in the weather conversions and/or EnergyPlus weather processing. This may not always be desirable though EnergyPlus will fill in “missing” value with something “appropriate”. Eventually, these missing values will be available through the IDD and users will be able to supply their own values or EnergyPlus will calculate those values (such as radiation and illuminance) that are not a simple value replacement. Until then, the following are used:

Table 44. Missing weather replacement values

Data item	Supplied Value	Units
Dry-bulb Temperature	6	C
Dewpoint Temperature	3	C
Relative Humidity	50	%
Atmospheric Pressure	Standard** Barometric Pressure (altitude based)	Pa
Wind Speed	2.5	m/s
Wind Direction	180	Deg
Total Sky Cover	5	(tenths)
Opaque Sky Cover	5	(tenths)
Visibility	777.7	Km
Ceiling Height	77777	m
Precipitable Water	0	Mm
Aerosol Optical Depth	0	Broadband turbidity
Snow Depth	0	Cm
Days Since Last Snow	88	Days
Radiation Values (Direct/Diffuse)	0.0	Wh/m2
Illuminance Values	0.0	lux (or CD/m2)

**Standard Barometric pressure based on location elevation is taken from ASHRAE 2001 Handbook of Fundamentals, Page 6.1 & 2.