The organisers of the COP21 climate conference starting in Paris in a month's time are faced with an unenviable task as they prepare for an event that it is hoped will produce a new roadmap to stop the Earth warming.

They must welcome tens of thousands of participants to a site near the French capital, house them, feed and transport them, and do so in the greenest conditions possible, with the world's media dissecting every aspect of the event's organisation.

With US President Barack Obama and his Chinese counterpart Xi Jinping among more than 80 world leaders attending the 21st United Nations Climate Change Conference -- the biggest international meet in France since the Universal Declaration of Human rights was drawn up in 1948 -- security will also be tight when proceedings open on November 30.

But above all else, as world leaders come together aiming to reach a single agreement on tackling climate change, with the goal of capping warming at two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels -- the conference has to be ecologically exemplary.

This conference is "exceptional in every way, because of its duration (two weeks), the seriousness of what is at stake which affects us all, and because it brings together a great number of participants," said the official in charge, Pierre-Henri Guignard.

A temporary town is being built at Le Bourget near Paris to host the event, with organisers claiming it has been planned according to the principles of sustainable development.

- 21,000 tonnes of greenhouses gases -

The 40-acre site includes 60 buildings that house meeting rooms, restaurants, shops, a bank, a post office, a 24-hour press centre for 3,000 journalists and medical facilities -- and through all of that runs a covered avenue.

The estimated 21,000 tonnes of greenhouse gases expected to be produced by the site will be offset after the conference by projects in the Southern Hemisphere, the French government says.

French company Engie is supplying a condensing boiler that recovers the lost energy generated in the traditional combustion process, a technique the firm says delivers greatly increased efficiency.

There will also be so-called "wind trees" -- effectively windmills -- while Ikea will supply furniture, Google the computer screens and the Renault-Nissan group are providing 200 electric cars.

The 900 trees sacrificed for the wood in the giant room that will host the plenary sessions for 2,000 delegates will be replanted.

"The materials we are using have already been used, we are using them again and they will be used once again after the COP," said Patrick Bazanan, of Decoral, the company building part of the site.

- Biodegradable and returnable -

The collection of restaurants, snack stands, cafes and food trucks that will serve the delegates have been ordered to cut down on wasteful packaging.

By using biodegradable and returnable glasses and cups, two million plastic cups will be saved from the waste containers.

All cutlery will also be made from biodegradable materials, said Jean-Francois Camarty from catering firm Elior.

As you would expect, recycling bins will be situated throughout the site and electric-powered vehicles will pick up the waste.

With the organisers acutely aware of coming under scrutiny for "food miles", "74 percent of the food products will be made in France" and where possible they will come from a 200-kilometre radius, Camarty said.

Ten thousand bread rolls will be baked on the site every day and any unsold meals will be donated to charity.

To reach the site, delegates are being urged to use public transport, and are being given free travel passes as an incentive.

The French national rail company SNCF has taken measures to transport an additional 70,000 people every day on the suburban rail line that links the centre of the capital with Le Bourget.

But at least one group is shunning the list of official hotels and opting for a truly "green" form of accommodation -- a 100-strong French group of Young Ecologists have opted to pitch tents and camp during the conference.

They have joined the umbrella organisation, Coalition Climat 21, to criticise the organisers for failing to provide enough accommodation for the thousands of activists expected to demonstrate during the conference.