Why use stacked bar charts?

David MacKay uses the stacked bar chart in his discussions for a number of reasons. This link discusses some of the general reasons why you might choose to use this tool to enhance the effectiveness of your communication. In our case it's partly because, in the end, we want to compare the total energy use by and average person (the total height of the stacked red chart) with the total available energy from sustainable sources ( the total height of the stacked green chart). At the same time the different parts of the stack allow us to get an effective sense of the big players in the discussion particularly in the energy supply side.