[bldg-sim] wind speed data in TMY2 files

[Jeff Haberl]

FYI

This point was well described by Geoff Levermore in his recent ASHRAE Seminar presentation, where he showed side-by-side measurements of  contact anemometers vs more accurate ultrasound sensors. This will cause under-predictions of buildings being analyzed for natural ventilation. 

So, until TMY2 files are recompiled with new data, or corrected somehow, we are all at least using the same bad data. Oh and don't forget the suspicious ground temperatures,  and as yet to be compiled service water temperatures, both potential fodder for future ASHRAE RPs.

Jeff
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Jeff S. Haberl, Ph.D., P.E.............................jhaberl at esl.tamu.edu

Professor......................................................Office Ph: 979-845-6507

Department of Architecture.......................Lab Ph: 979-845-6065 

Energy Systems Laboratory.......................FAX: 979-862-2457 

Texas A&M University..............................77843-3581

College Station, Texas, USA.......................URL: www-esl.tamu.edu

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-----Original Message-----
From: Andy Lau <asl1 at psu.edu>
To: Jeff Haberl <jeffhaberl at tees.tamus.edu>
Sent: Sun Sep 18 18:37:54 2005
Subject: Re: [bldg-sim] wind speed data in TMY2 files

Jeff,

Thanks.  Do you know of any investigations that have tried to better 
quantify the error?   Cutting out below 3-5 mph is not a big problem if 
using the data to predict turbine performance because they typically do not 
operate below 5-8 mph.

Andy
At 03:20 PM 9/18/2005, you wrote:
>I believe these are derived from NWS measurements, which tend to be 10 
>meter towers. However, the problem with NWS wind data is that it 
>represents an average of a 3-5 minute snapshot taken 15 minutes before the 
>hour, and thus seriously overstates the integrated average wind speed 
>taken over the whole hour.
>
>Also, until quite recently,  these were taken with contact anemometers 
>that cut-out below 3-5 MPH, which understates the amount of wind at low 
>wind speeds.
>
>Jeff
>BB 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  :=')  8=)  8=)  8=? BB
>
>Jeff S. Haberl, Ph.D., P.E.............................jhaberl at esl.tamu.edu
>
>Professor......................................................Office Ph: 
>979-845-6507
>
>Department of Architecture.......................Lab Ph: 979-845-6065
>
>Energy Systems Laboratory.......................FAX: 979-862-2457
>
>Texas A&M University..............................77843-3581
>
>College Station, Texas, USA.......................URL: www-esl.tamu.edu
>
>BB 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=) 8=?  8=)  8=)  8= BB
>
>
>-----Original Message-----
>From: bldg-sim at gard.com <bldg-sim at gard.com>
>To: bldg-sim at gard.com <bldg-sim at gard.com>
>Sent: Sat Sep 17 07:45:10 2005
>Subject: [bldg-sim] wind speed data in TMY2 files
>
>Does anybody know at what height the TMY2 wind speed data was measured?
>
>
>
>Andy Lau, Associate Director, Center for Sustainability, Penn State
>213-F Hammond Building, University Park, PA 16802
>814-863-9075, 814-863-7229 (FAX), andylau at psu.edu, www.engr.psu.edu/cfs
>
>
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