We use information that has been collated by RDC Aviation www.rdcaviation.com.

RDC collects and collates information from airlines around the world. This information includes engine types, average seating capacity, proportion of fuel used for cargo rather than passengers, distances between cities, fuel usage for all aircraft types.

The methodology used by RDC to calculate your emissions has been reviewed by AEAT group for the UK Department for Energy and Climate Change (DECC), and their Letters of Approval for that methodology can be seen here - Approval Letter 1 and Approval Letter 2.

This information is to calculate an average fuel usage for flights between all cities where airlines fly now, and calculated an average amount of CO₂ emissions per seat. 

This is why if you fly first or business class, the Carbon Offset is higher, because those seats take up about twice the space (and therefore generate twice the emissions) of an economy class seat.

All this information is used to determine the cost of the carbon offset when you calculate your emissions on this website. 

The cost of the Carbon Offset is then calculated by multiplying that emissions figure by the cost of the Carbon Credits.

How we work out the average Carbon Credit price for you

We want you to know where your offset money goes – and we bet you do too!

So we have explained our pricing process below.

If you have any questions about this, please go to our Contact Us page and send us a request for more information.

How We Calculate the Price

We gather data from various Voluntary and CDM Markets such as www.carboncatalog.org and, based on our knowledge of the carbon markets, we calculate our best estimates for the price per tonne over the next 3 months.

Then we calculate an average for the various types of projects that you may wish us to purchase the credits from, and from this we establish an average price per tonne. This lets us set a firm figure for the next 3 months.

For more information on the Projects we support, you can read more here.

After that we include the costs of running the business (see below) and from this we work out the price you pay.

So, at the moment, our best estimate of the carbon credit price we will be paying projects (including associated costs) over the next 3 months is USD$11.20 – in the example as at September 2009, our current price is USD$13.55 per tonne, and this will change (up and down) as we gather more data for the following 3 months.

As you can see, it is very transparent - if you ever visit another offset website, please check and see if they tell you why you would pay the amounts they are asking you to pay.
 

We think you should be aware that Voluntary Carbon Credits are still primarily traded on an "over the counter" basis (as distinct to formal Exchange trading) with direct negotiations between the buyer (ourselves) and either project developers or brokers. As a result, the prices vary between projects and at various times, so it is difficult to give an accurate cost per tonne at any particular date.

The Greenflight CO₂ calculator produces a detailed estimation of CO₂ emissions from the airline/aircraft combinations that are most likely to fly your route.

Where the majority of calculators available follow generic formulae based on distances flown, our model takes account of a number of variable factors such as the actual time of the sector flown and the different fuel burn rates by mode of flight e.g. takeoff, cruise and landing. The methodology for estimating your emissions also accounts for the type and age of aircraft flown, providing a credible estimation of CO₂.

Please remember that CO₂ per passenger figures are not necessarily a measure of total CO₂ output or efficiency of a flight. 

If you're ready to offset your flights now, go to the Flight CO₂ Calculator page from here