[EnergyPlus_Support] Re: New Australia weather data available for 69 locations

["Paul Reeves" <paulreeves5@xxxxxxxxx>]

It appears that there is a calculational error in some of the new 
RMY data for Australia, at least with quite a few of the ones that I 
reviewed.  That, or Australia has some very odd cloud behavior. 

It seems likely that the field direct normal solar radiation was 
calculated based on a multi-pyronometer array.  If the array is 
symetric about the noon axis (which I guess in this case is north), 
the calculation procedure that I was aware of many years ago would 
break down around noon.  This happened because the angle between the 
sun and half of the pyronometers is equal to the angle between the 
sun and the other half of the pyronometers.  The end result is the 
noon-hour depression that can be scene in at least these files:

Direct Solar Noon Depression with these files:
 - AUS_NSW.Coffs.Harbour_RMY.epw
 - AUS_QLD.Gladstone.Airport_RMY.epw
 - AUS_QLD.Weipa.Aero_RMY
 - AUS_WA.Forrest_RMY

No problem with these files:
 - AUS_NSW.Wagga.Wagga_RMY
 - AUS_ACT.Canberra.Airport_RMY

The direct normal solar takes a 20-30% "dip" around noon, when in 
fact it should be peaking.  When the problem exists, it happens 
virtually every day (all except days that are completely overcast).

There are reliable algorithms that calculate direct normal solar 
based on global horizontal and moisture content (the Perez 
Corellation, as I recall).  I have tested this correlation against 
measured data and it appears quite robust.  It is almost certainly 
better than using weather data that underestimates mid-day direct 
solar radiation by so much.

Paul Reeves

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Drury.Crawley@... wrote:
>
> New weather data for 69 Australian locations are
> now available on the EnergyPlus web site. The RMY
> Australia Representative Meteorological Year
> Climate Files were developed for the Australia
> Greenhouse Office for use in complying with Building
> Code of Australia.
> 
> 
http://www.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm
/region=5_southwest_pacific_wmo_region_5/country=AUS/cname=Australia
> 
> This brings the total number of weather files available on the 
EnergyPlus
> web site to more than 1300 worldwide.
> 
> As always, if you know of typical weather data sets for your 
country
> or region, please let us know about them!
> 
> The EnergyPlus Team
>




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