The subject and praxis concerning urban wind energy systems is of great importance and I am very pleased that this subject is once again on the board.

Just over a year ago - on 20 Sept 2004 - I submitted a posting "Link to Wind Energy in Urban Areas" - This information can be found on page 6 on a file that can be accessed by going to "JF" on the discussion board archive and then open the indicated file link. As this specific file-paper of mine has previously only been available on a "pay-per-view" basis from the publisher - it is now avaible for study purposes in this present form.

I remain convinced that the most interesting perspective for the future large-scale introduction of these systems lies in a lower-cost mass production and thereby greater dissemination of the helical-screw horizontal-rotor models from Finland as shown with the WINDSIDE and SHIELD-JASPIRA designs or possibly in the direction as shown by the elegant combined wind-PV systems from SOLAVENT in Germany.

The question of what type of roof-top mounting does indeed raise some difficulties. - however inspiration can possibly be found by consulting the very good book by T. Lindsay Baker - "A field Guide to American Windmills" - USA 1985.

I have a copy of the often-mentioned however still relevant and interesting paper concerning the Jacobs wind turbine in New York "Windmill Power for City People" - NYC USA 1977 - Likewise I enclose two illustrations of large workshop-size rooftop-mounted models from the 1920's-30's as further possible inspiration.

The first image taken from a Danish machinery textbook/handbook from 1924 - shows a Danish Agricco model with airfoil blades from the 1920's. This model was normally sold with a grid-connected induction generator of 20-40 kW - as an integrated farm machinery  main-power-unit either by mechanical or by electrical means
These and other larger-size "Venetian-blind - slat-type" wind turbines were very common as roof-top mounted power systems and I have seen many of those still existing today.

The second image shows a German Herkules model from the late 1920's in a standard factory configuration as a complete woodworking workshop - the size of the blades can of course be estimated from the size of the machinery. Please note the infulence from the American farm-type water-pumping windmill designs.
This picture is taken from the thick German book from 1995 "Die Geschichte der Windenergienutzung 1890-1990" by Matthias Heymann

As concerning the perhaps more usual three-bladed wind turbines - a good friend of mine in The Netherlands had reasonably satisfactory proformance with a 300 W.  - 2 meter diameter rotor model mounted on the side of a building - projecting up into the "air" by about 3½ meters or so. This was in the middle of a small town and even though the wind conditions were most certainly not at all optimal the very good furling system of this model was very suitable for these conditions.

Due to the increasing oil price etc - friends in my local small country village on a rough and windy sea coast are now starting to become very interested in these small 300-500 W. with 2-2½ meter rotor - under our wind conditions they would provide a very considerable addition to hot-water heating.

[for our space heating most heat with inside-the-house wood stoves - with of course the difficulty/[danger-factor] of hot-water heating using the excess heat from the stove]

Likewise I have seen in Scotland the extensive use of the small highly reliable AMPAIR models - some likewise rooftop or outside-wall mounted.

Further information concerning construction details for the absolutely necessary sucessful vibration damping with a roof-top mounting can be found in the previously very highly recommended series of three low-cost booklets for the home-made wind-turbine builder by Christian Kuhtz - available from http://www.oekobuch.de

With greetings and best wishes - JF