By Alix Kroeger
BBC News, Strasbourg
The monthly move is often referred to as the "travelling circus"
The European Parliament's monthly move from Brussels to Strasbourg generates more than 20,000 tonnes of carbon dioxide a year, Green Party MEPs say.
The Green Party commissioned the study, which says the carbon cost is equal to 4,000 households in London.
The monthly trek is often referred to as the "travelling circus".
The report is published on the same day the parliament is expected to set up a temporary committee to propose new measures tackling climate change.
Used by MEPs once a month
Not in use 307 days per year
One chamber, 21 large and 13 small conference rooms with simultaneous translation facility
Total cost 203m euros per year
CO2 burden estimated at 20,268 tonnes per year "and probably much more"
Nearly 800 MEPs travel by air, road and rail to Strasbourg - along with hundreds of EU officials, journalists, lobbyists and 15 lorry-loads of official documents.
The study, by York University's Professor John Whitelegg, says if the parliament stopped meeting in Strasbourg, it could get rid of more than 2,000 offices, a debating chamber and 50 conference rooms.
15 lorries carry documents from Brussels to Strasbourg in 4,000 metal trunks
1,220 parliamentary staff travel from Brussels, and 525 from Luxembourg
785 MEPs travel from their constituencies
More than 100 journalists travel from Brussels, as do staff of the European Commission, diplomats and lobbyists
That would save nearly 4,000 tonnes of carbon dioxide a year in electricity and gas alone.
The study is published on the day that MEPs are expected to set up a committee with a mandate to look at new measures against climate change and co-ordinate the parliament's policies.
The Greens say the parliament's failure to put its own house in order undermines its own credibility, and Strasbourg has come to stand for all that is wrong with the EU.