[Bldg-sim] wind speed in TMY

[Chuck Khuen]

The data in the newly released NOAA/NCEP/CFSR dataset (which we have built an interface to) for wind speed is the 2 minute average of the wind in the previous hour for that 35-km grid at 10 meters.  This is not an average for the last hour, but is less noisy than the peak readings and it is available hourly for a full 32 years.  

Chuck

_____________________
Chuck Khuen
Principal
Weather Analytics Inc.
www.weatheranalytics.com
781-856-5383

From: Jeff Haberl 
Sent: Saturday, June 11, 2011 9:20 PM
To: Paul Carey ; leen peeters ; bldg-sim at lists.onebuilding.org 
Subject: Re: [Bldg-sim] wind speed in TMY

Hello,



Unfortunately, historical wind speeds on TMY files that come from NOAA data are from peak 5 minute gusts, which can have little correlation to average hourly wind speeds. At some stations integrating sensors have been added, but it will take time to push these data through the average year data base.



In addition, previous work in England using ultrasonic sensors has shown that NOAA data also suffers from severe drop out at speeds less than 5 to 10 MPH, which means that most sites show "0" wind speed, whereas there is actually some wind, but not enough to move the cups on the anemometer. This can be a problem for simulation of natural ventilation.



ASHRAE's TC 4.2 continues to discussed these and other issues, which can be viewed on ASHRAE web page in their meeting minutes.



Jeff



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Jeff S. Haberl, Ph.D.,P.E., FASHRAE..............jhaberl at 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, 77843..................URL:www.esl.tamu.edu

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From: bldg-sim-bounces at lists.onebuilding.org [bldg-sim-bounces at lists.onebuilding.org] on behalf of Paul Carey [paul at zed-uk.com]
Sent: Saturday, June 11, 2011 4:16 PM
To: leen peeters; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] wind speed in TMY


Dear Leen

Most weather data quotes the reference wind speed which is that at 10m above the ground as measured at certain weather stations. Adjustment factors are then made for levels of surface roughness, I.e. urban, rural environments. I think the TMY follows the same convention.

Paul


Sent from my HTC

Dr Paul Carey
Director

Zero Energy Design Ltd
10a Portland Place
2-22 Mottram Road
Stalybridge
Cheshire
UK
SK15 3AD

Tel - +44 161 3386200
Mob - +44 789 4098012
Email - paul at zed-uk.com



----- Reply message -----
From: "leen peeters" <l.f.r.peeters at gmail.com>
Date: Sat, Jun 11, 2011 20:34
Subject: [Bldg-sim] wind speed in TMY
To: <bldg-sim at lists.onebuilding.org>

Hi,

can anyone tell me what wind speed is exactly meant in the TMY. Is it the
free, undisturbed wind speed, the wind speed above the roof, the wind speed
at 10 metres above the ground ....

Thanks,

Leen





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