Interesting, thanks for sharing Wolfgang!
It's nice to think the PI System system is being used by both Microsoft and eBay (as far as Data Centers on this list) to monitor and improve their energy usage and efficiency.
It's a very interesting topic. The carbon footprint of an online search is has been discussed a lot. The estimates are all over the map though:
"A Harvard University physicist says a typical search on a desktop computer generates about 7 grams of carbon dioxide. Thus, performing two searches is comparable to bringing a kettle to boil, according to a report Sunday in The Times of London. While that may not sound like a lot, the report notes that Google handles about 200 million searches daily.", source.
In this article the estimate is 0.2 grams of CO2 per search.