Wind Speed Measurements
We have access to many meteorological sites around the country that give detailed data on wind measurement including access to NIWA wind maps. This information gives a good indication of the general wind conditions in your area. However, localised conditions can be very different.
Gaining a better idea of your wind conditions can be done in various ways to differing levels of accuracy:
Looking at relevant wind data and using local knowledge to assess if you are in a windy or sheltered spot compared to the local area. This is highly subjective and will only give a rough indication.
Using the Griggs Putnam Index of Deformity as shown below. This uses local conifer tree growth and gives a good indication of long term wind-speeds gathered over the lifetime of the trees. It is surprisingly accurate but is still somewhat subjective.
The most accurate method is to undertake a wind survey by installing an anemometer and taking readings. Ideally you would have a minimum of 1 year of data although longer would be more accurate. These would be compared to national figures to assess if the year was a standard one.
To reduce time (with a subsequent loss of accuracy) three months readings could be taken and then compared with a local site. This comparison can then be extrapolated to give an annual variation from the local site.
Griggs-Putnam Index of Deformity
Wind Speed |
I |
II |
III |
IV |
V |
VI |
VII |
km/hr |
11-14 |
14-18 |
18-22 |
22-25 |
25-29 |
29-32 |
36 |
Knots |
6-8 |
8-10 |
10-12 |
12-14 |
14-16 |
16-18 |
20 |
m/s |
3-4 |
4-5 |
5-6 |
6-7 |
7-8 |
8-9 |
10 |
Tecnico can help with all of these methods and are happy to advise you further.
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