It looks like eco friendly WiFi will soon become a reality - in Europe. Romanian free hotspot provider cfree wireless is proposing a certification standard that determines how eco friendly a hotspot provider is. It is currently free for anyone to join as long as several requirements are met:

1) All wireless equipment complies with RoHS (2002/95/EC) and WEEE (2002/96/EC) EU directives

2) There are no signal boosters over the default manufacturer settings

3) The hotspots will not interfere with the 2.4Ghz wave spectrum

Cert drafts and official requirements will soon be posted on their site.

Site [cfree.ro]