[Equest-users] Temperature in weather data

[Joe Huang]

Chris, others,

Since as you've raised the question of how significant would be adding extra precision to 
the weather data in DOE-2, I was sent a copy of a recent paper by Annie-Claude Lachapelle 
of the Univ. of Calgary given at eSim Canada 2012 on this exact topic, "DOE2 Dry-Bulb 
Temperature Precision Level Impact on Sensible Economizer Performance".   With the 
author's permission, I've attached the paper with this post.

Joe

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


On 7/25/2012 10:45 AM, Joe Huang wrote:
> 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 mailing list > 
>>> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org > To 
>>> unsubscribe from this mailing list send a blank message to > 
>>> 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" 
>>> _______________________________________________ Equest-users mailing list 
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>>> from this mailing list send a blank message to 
>>> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG </x-flowed>
>>
>> >>
>> 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
>>
>>
>
>
>
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