Question about the quality of wind data within DOE epw files

A bit off topic.

I'm in the midst of a pedestrian comfort study and I'm currently analyzing wind velocities on 12 orientations. To do that I need an average velocity over the year for each of the orientations (0, 30, 60, ..).

I use a simple definition with native components to extract this information from the epw file. However, I run into some 'trouble'.

There seem to be a lot of 0 values in the wind velocities. Most of these 0 values seem to be associated with the 0 direction (north direction is common in this weather file, i.e. Singapore, but I doubt it is so many 0s).

I then proceeded to cull all the hours with 0 wind velocity and did the averaging over all the remaining hours (around 7100 for this weather file). However, I still get a bit of odd results that don't coincide with other data I have for the area. For example, average wind velocity in the north seems to be 1.12m/s while officially Singapore reports 2.1m/s. More discrepancies arise in the frequencies of the wind directions (the hours of each direction per year divided by total hours) from publically available data.

Anyways, I don't want to tire you with so many specifics. The question to the forum is if anyone has used .epw files to collect wind data before and if we believe they are dependable for such calculations? If not, do you have any idea on where I could find open wind data of good quality?

Thank you very much in advance.

Kind regards,

Theodore.

P.S.: Will be adding the definition once I'm in the office, even though it is quite straightforward.

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Replies to This Discussion

Permalink Reply by amedeo scofone on April 29, 2016 at 8:45am

Hi Mostapha Sorry for the delay,

You need to input Speed, Direction and Month in this wayi don't really plot Comfort on the wind map but I use ranges that relates to the Lawson criteria which is the most used comfort criteria for pedestrian in UK.

It isbe resumed in this graph

here you can fine some information http://www.slideshare.net/meteodyn2/pedestrian-wind-comfort-in-urba...

I hope this helps!

Best,

Amedeo

Permalink Reply by Abraham Yezioro on April 29, 2016 at 2:44pm

Hi Amadeus,

I also use the Beaufort scale for analyzing wind conditions and usability of open spaces.

I think it should be clarified that the percentage of time related to annual data and not user defined period. This is specially important to notice for B7-8 where the mechanical influence of the wind can put people in danger.

In your example above you basically took the wind data for one month (or any desired period for that matter)? Can be the whole year?

Another point for reflection is that the epw gives only data for the more frequent wind at any specific hour, but there are other winds at the same hour that unfortunately are not taken into account. For this there is nothing to do, but good to have in mind.

Thanks,

-A.

Permalink Reply by amedeo scofone on May 3, 2016 at 4:04am

Hi Abrahm,

Thanks for you comment.

I usually use 10 y weather data, calculating comfort based on a seasonal analysis (for example sitting is not really required for winter) and safety on all the weather data collected.

Best,