No I'm not talking of rockstar style fans, but of ways to keep one cool in warm climates.
There is remarkably little trace of the early history of fans. What types were available? Folding fans? fixed fans? how were they decorated? Were they even used?
The only image of a fan I've seen is from the work 'Liber ad honorem Augusti sive de rebus Siculis' (MS. 120 II Bern Burgerbibliothek) composed in Palermo (Sicily) by Petrus de Ebulo in 1196. In fact there are two images of fans in the manuscript both fanning people in bed - the latter is a dying William II, and I think the other image is probably also of a sick person. (Click on the links below to view the full picture)
The fan shown resembles a Renaissance flag fan. There are extant examples of a flag fan from c1600 which might provide clues as to possible construction methods for a proposed 12th C version. The second example in this image (from Katerina's page) is woven of plant material, which reminds me of the basketweave pattern shown on the manuscipt image (the manuscript image is even a neutral type of colour which would be consistent with dried plant matter).
Other than the above manuscript example of a flag fan, there are a few extant flabella (liturgical fans) which have been kept because of their exceptional decoration. Many extant examples I have seen are only the central portion of the fan, the metal portion would have been surrounded by parchment, feathers or cloth or something light I assume.
The 9th Century Flabellum of Tornus has accordion folded parchment (painted) held on a central ivory rod. This page has a few very good views of that flabellum as well as examples of flabella being used in modern liturgical practice. A similar 12th-early13th C piece of accordion folded parchment (British Library Add Ms 42497, unfortunately not yet digitised) has also been found, without a handle, but identified as the parchment portion of a flabellum. Part of a carved ivory handle, which might have belonged to a different 12th C german flabellum can be found in the British museum.
There are a number of other extant medieval examples of flabella I have heard rumors of too (note not the 19th C neo-gothic one in the cloisters though), for example a 13th C one of which I have no details. Some of these metal ones may not be central holders, but purely ornamental pieces, waved about in a ceremonial way rather than expected to actually move the air. I also expect there will probably be some written evidence for such liturgical fans, but haven't checked for it.
Perhaps secular examples of flagella existed the the 12th Century such as this 15th C example (courtesy of Karen Larsdatter)? This author claims sources for roman folding fans of the flabellum style, with a simple guide to construction.
Other types of fans?
Finally, what of modern folding fans? Most websites claim the folding fan didn't reach Europe until the 15th Century. The modern folding fan differs from the flabellum only in being a partial rather than full circle, and not having a long handle because of this. It wouldn't take much adaption to create this change, but why bother when something is working? The presence of accordion folded flabellum makes the modern folded paper fan more plausible, and by extension the modern panels of wood fan is only a step further away, but was it a step that was made? We may never know.
When searching for examples of fans in manuscripts images, I find it useful to consider what other forms of fans existed in later (or earlier) time periods. If I did not know of flag fans, I might have missed the example given above. Karen Larsdatters page on fans gives many renaissance examples of fans, including flag fans, folding fans, feather fans, and straw fans. Knowing of the existence of items such as the straw fan helps as such biodegradable items would not be expected to survive in the extant record, and would not be expensive enough to be deliberately well kept, and once aware of the possibility, we can search more easily for references. Islamic art and extant artifacts might also provide a number of examples of shapes of early fans, as I believe more examples of fans exist in artwork from the east of the era.
But were fans used?
There is very very little evidence for personal fans in the 12th Century Europe, but this could be just a case of them being not worth mentioning, rather than explicitly not used. Everyday objects are really hard to find in 12th C artwork, and literature can often be far too focused on other matters to describe the practical. There are certainly plenty of Renaissance era personal fans in Europe.
I obviously expect fans to be more used in places with warmer climates, and that holds true with the sparse evidence I've gathered for secular use is from Sicily. Perhaps most of Europe was too cool to bother with fans most of the time in the 12th Century? Liturgical fans are partially to keep insects out of the communion wine and part tradition, which would account for their being used even in cool weather.
Another hypothesis is that perhaps personal fans simply weren't used because they hadn't really been introduced in Europe. Both Spain and Sicily both had strong Islamic populations (and not as a repressed subclass) in the 12th Century, and I believe fans are clearly shown in Islamic art, so perhaps personal fans spread slowly from east to west? The presence of liturgical fans suggests this didn't need to occur, as the fans were present as inspiration to anyone in the west who was too hot.
I think it most likely fans were simply the sort of common object that we have such trouble finding in the historical record because they were largely beneath notice, rather than any of the above elaborate hypotheses. But any construction of personal 12th C fans must involve a moderate amount of interpretation unless more evidence comes to light.