Now have a look at these three charts showing the same period of time from one school. The first chart shows how the cost of the electricity, the second shows how much electricity has been used in kWh and the third shows the carbon dioxide emitted by that use.
Which of these charts is not like the others?
You may have noticed that, whereas the cost and the kWh charts align quite closely, the carbon emissions of school electricity use can sometimes be wildly different. Before reading on, think why that might be.
Calculating the carbon emissions for gas use is straightforward. It's more complicated when calculating the carbon emissions from electricity because the electricity we use is generated from a variety of fuels and sources, and from day to day - minute to minute in fact this changes.