[Equest-users] Temperature in weather data

[Joe Huang]

Chris,

My attention on this issue was first raised about 15 years ago when I 
was working with non-US weather data , i.e., the rest of the world, that 
are all reported in 0.1 C. I've noticed since that US stations have also 
moved to the use of metric units, i.e., 0.1 C for temperature. The DOE-2 
weather format is still in integer F, which leads to three unfortunate 
effects: (a) hourly records can be off by as much as 0.5 F, (b) clumping 
of the temperature distribution, and (c) statistics such as degree-days 
will be off by a percent or two compared to the original data. Now, one 
can say that all this is immaterial in the bigger picture of things, 
which has been the default attitude so far, but since it's really quite 
simple to fix, why not get it right, i.e., doesn't it feel much better 
to see the same temperatures in the DOE-2 outputs as in the original 
weather data?

BTW, all the weather data that I've looked at are records of conditions 
on the hour, not the average over the hour, except for solar radiation.

Joe


On 7/25/2012 9:53 AM, Chris Jones wrote:
> Joe
> Given that the time steps are an hour, and the fact that weather data 
> is averaged over an hour, plus the fact that the building local will 
> have variations from the weather station local, would an extra decimal 
> point provide more useful information?
>
>
> At 07:43 AM 25/07/2012, Joe Huang wrote:
>> This is not possible at present without changing the DOE-2.2 source 
>> code to read a weather input file with decimal values. When DOE-2 was 
>> first designed in the early 1980's, memory was a big concern, so the 
>> weather data was reduced to integers and then packed, which is why 
>> the DOE-2 *.BIN file is so small (146K). I have actually developed a 
>> modified file format for *.BIN where I save an extra digit of 
>> precision, i.e., temperatures to 0.1F instead of 1 F, but the source 
>> code would also need to be changed slightly to read this extra 
>> information. I've mentioned this to the developer of eQUEST/DOE-2.2 
>> and will be experimenting with making this change to the source code. 
>> If and when it's proven to work and gets incorporated into DOE-2.2, 
>> I'll let everyone know. I welcome anyone who thinks this is a useful 
>> modification to send me an e-mail. It might spur me on to do 
>> something! Joe On 7/23/2012 2:44 AM, 蔡昀芝 wrote: > Hi, everyone: 
>> > > We know that eQUEST can edit personal weather data. > But the 
>> dry-bulb and wet-bulb temperature in weather data can only > enter 
>> integers. > Is it possible to have more precise temperature to 
>> decimal place? > Thank you very much. > > > 
>> _______________________________________________ > Equest-users 
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>> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG > -- Joe Huang White Box 
>> Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga, CA 94556 (o) 
>> (925)388-0265 (c) (510)928-2683 www.whiteboxtechnologies.com 
>> "Building energy simulations at your fingertips" 
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> >>
> Christopher Jones, P.Eng.
> Suite 1801, 1 Yonge Street
> Toronto, ON M5E1W7
> Tel. 416-203-7465
> Fax. 416-946-1005
> email cj at enersave.ca
>
>


-- 
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D 
Moraga, CA 94556 (o) (925)388-0265 (c) (510)928-2683 
www.whiteboxtechnologies.com "Building energy simulations at your 
fingertips"