The case (or not) for Roof Mounted Wind Turbines http://www.hockerton.demon.co.uk/news/jan06.html#1

January 2006
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SPECIAL NEWS FEATURES

(1) The case (or not) for Roof Mounted Wind turbines

(2) Comparing HHP 5kW rated Wind Turbines

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The case (or not) for Roof Mounted Wind Turbines
Can we harvest useful wind energy from the roofs of our buildings?

Are you one of the many people who have read or heard that the next generation of roof mounted wind turbines will provide all the electricity needs of the average semi in the UK?

Nick Martin from the Hockerton Housing Project is sceptical and believes that the predicted rush for domestic roof-mounted turbines will further damage the precarious reputation that wind power already has in the UK. The following is an extract from an article that Nick wrote on this subject for the current edition of ‘Building for a Future’ (Vol 15, No 3, Winter 2005/6) – “The independent journal for ‘green building’ professionals and enthusiasts.”

Don’t believe the hype. I can tell you now that for the average house in the UK a roof-mounted turbine will not provide anywhere near your electrical power requirements estimated to be an average of 4200kWhrs. Nor will they save you £400 per year in electricity bills. They might, however, on a typical roof installation generate 600-1000kWhrs a year if you are lucky with the site of your house. Less output is a more likely scenario. As such you might expect to get savings a long way short of the £400 advertised by some.

Predicted paybacks of 3 years are also fantasy unless you get a free one. Even a payback of 20 yrs is unlikely unless you get a substantial grant for the total package and the product remains maintenance free for that period (will the manufacturers supply a 20 year warranty? I don’t think so.)

Am I opposed to wind power? On the contrary, I am an ardent supporter.

That is why I raise issue with products that are likely to do a disservice to the wind industry. The products in question may well be engineered and good value (there appears to be no independent assessment on this issue) but to over-rate their energy production will leave a lot of disappointed owners and dissatisfaction with wind power generally.

I am not the only sceptic on this issue – many share my concerns for very valid reasons…

To read the full article and Nick’s in-depth analysis of this subject you will need to get hold of a copy of the above edition of Building for a Future – we have a number of spare copies which you can obtain from us by sending a cheque for £5 made payable to ‘HHP Trading Ltd’ – send to Hockerton Housing Project, The Watershed, Gables Drive, Hockerton, Southwell, Notts NG25 0QU. Alternatively you can subscribe to the magazine via www.newbuilder.co.uk.

This edition of the magazine also includes articles by John Shore on ‘Wind power needs more friends’ and by Derek Taylor on ‘Calculating potential output’. So if you are interested in wind power this magazine should be of great interest!

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(B) Comparing HHP 5kW rated Wind Turbines

HHP erected a 5kW Proven wind turbine in early 2002 and in early 2005 complimented this with the installation of a 5kW Iskra wind turbine.

Both turbines are situated in the same area of the site and are at the same height of 26m. It is therefore interesting to compare the performance of these two products under almost identical conditions. Comparative data has been collected from April to Nov 05.
Proven = 2'486 kWhrs

Iskra = 2'310 kWhrs

The two turbines are producing similar outputs. Although Iskra’s performance is about 7% lower, it was less expensive (by more than 10%) – Therefore the cost-effectiveness is very similar. It is also worth noting that Iskra hope to improve the performance of their turbine with an upgrade to their current specification in spring 06. Please also note that the data does not include the bulk of the windiest part of year – we should get 5 to 6,000kWhrs for the full year (both wind turbines were originally predicted to produce around 12,000kWh annually with the wind conditions on site). This year is tracking lower compared to 04/05 data – just not been as windy!

We plan to add regular performance updates to our website for all these energy systems from this spring. You can obtain more information about the Proven wind turbine and our photovoltaic system by purchasing ‘Technical Factsheet 9: Energy Generation’

Due to the very low energy requirements of the homes at HHP (about 10% of an average UK home) relatively small renewable energy systems are able to produce enough energy to offset the occupant’s energy use. This minimises the amount of greenhouse gases the homes are responsible for and the HHP development meets a number of the highest environmental housing standards in the UK, namely net zero CO2 and Autonomous.

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