Wind speed

[PurpleDragon]

Right, having worked out what I was doing wrong (I think) on the DTI wind speed thing, I now have a list of windspeeds but dont know what the abbreviations mean ...

... anyone ? On a proper map, our house is situated on a contour line saying 130 - whatever the heck that means! Is that 130m above sea level?


Wind speed at 45m agl (in m/s)
7.3 7.5 8
7.9 8.3 8.7
8.7 8.8 8.8

Wind speed at 25m agl (in m/s)
6.5 6.7 7.2
7.1 7.5 8.1
8 8.2 8.2

Wind speed at 10m agl (in m/s)
5.5 5.8 6.3
6.3 6.7 7.3
7.2 7.5 7.5

Blank squares indicate areas outside the land area of the UK - i.e. areas at sea or of neighbouring countries.
agl = above ground level.
Squares surrounding the central square correspond to wind speeds for surrounding grid squares.

[Shirley]

I might be wrong, but I've just had a look at my area... and it looks like only the yellow figure (ie the one in the centre of each 9 figure reading) is the one to read... the others show the readings for the next grid square.

By the looks of it you get much more wind that we do!!

My readings were

Wind speed at 45m agl (in m/s)
5.8 6.2 8.2
5.6 5.9 7.8
5.9 6.2 7.8

Wind speed at 25m agl (in m/s)
5.1 5.4 7.5
4.8 5 7
5.1 5.4 7

Wind speed at 10m agl (in m/s)
4.2 4.5 6.6
3.9 4 6.2
4.1 4.4 6.2

[Martin]

blooming heck!
That is some SERIOUS wind!
Take one of the groups of nine - the centre square shows the average windspeed for your grid square - the others surrounding it are the surrounding grid squares - (the one below yours is to the south etc) - they are then repeated for different heights of mast. Most domestic turbines will be on something like 10m mast so that set of figures is probably most accurate
Do bear in mind that these are presuming that you have a "clear fetch", and are well away from turbulence causing obstructions - buildings, trees etc.!
(fancy putting in for planning for a mini-windfarm? - at those sort of windspeeds, proper turbines pay back really quickly! )

[Martin]

I was referring to pds wind, not Shirlz'!

[Martin]

I just happened to have a turbine power production curve on my desktop, and I've done some fast sums - in an 8m/s area, we could be looking at complete payback in as little as three years for a grid-tied turbine! (but you'd need a 45 metre mast) - at 6.7m/s on a 10 metre mast, payback would be well under 5 years! (still ludicrously good!)
It's the "cube" thing - 8m/s wind contains eight TIMES the power there is in 4m/s!

[Shirley]

I was referring to pds wind, not Shirlz'!

she's much windier than I am although we do get our fair share of wind here.

[PurpleDragon]

Martin, I have no idea what you are talking about.
It's windy here.
Sometimes it gets very windy!

What is a m/s ?

We have our house, then going down the hill, nothing. There are a couple of gorse hedges, and we have planted to hedging at the bottom (about 2 acres away from the house). The closest trees are about half a mile away. There is a lane beside the house, then a field (in fact several) and the same on the other side of the house. Still no trees, but plenty gorse.

The house has a fairly large footprint, but the other buildings are small.

So - what is the actual windspeed - does that tell you that?

[Stonehead]

What is a m/s ?

Metres per second. Your 6.7m/s at 10 metres above ground level equates to a wind speed of 14.9879mph. And don't forget that's the median over time, so you're going to have a lot of windy days!

You also have to remember that is the median for a 1000 square metre grid square and there can be quite a lot of variation in ground conditions and obsacles over that area.

I strongly suspect the 6.3m/s for one of our grid squares understates the case for the area of land running along the ridgeline, which is where you'd probably put your wind turbine.

[PurpleDragon]

Thanks Stoney :) Yes, we do have a lot of windy days. When it is gusty up here, it is often quite calm down in the village.

We don't have a lot of obstacles, as I say, we are nearly at the top of the hill at 130 on the contour line. The village is 90 and the top of the hill is 160. There are some trees at village level, and that is it - the wind comes up the valley and hits the front of our house.

I actually tink the wind turbine on the house thing quite funny - if we put something like that on our house, it would rip the walls off

[Martin]

Go for four!, in a good blow, you'd probably make it to Wales (well the roof would!)!
there's so many blessed measurements in common use for wind, it gets terribly confuddling - you've got metres a second, miles an hour (I can understand them!) - knots for sailors, and the Beaufort scale for sailors (force 8 and all that!)

[PurpleDragon]

You can keep Wales - I'm heading for Florida !

[Stonehead]

I actually tink the wind turbine on the house thing quite funny - if we put something like that on our house, it would rip the walls off

It's why I've not been able to take the boys out to fly a kite (well, aside from the power lines running through the field). It's either dead calm (20-30 days a year) or blowing so strongly I'd see the boys disappear into the distance, still hanging on to the kite.

[PurpleDragon]

Tie their ankles to the pigpens!

We sometimes get days that are fine for kite flying. The kids love it - when they can get their Dad to stop "showing them how"