In this video we describe the steps needed to work through our carbon emissions from first principles. This was more detailed than the on-line calculators. The calculation included factors such as cloud storage and water use, which were not itemised in the Business Carbon Calculator. Using this method, we arrived at a value significantly lower than the result from the Business Calculator. The discrepancies between different methods of calculation are interesting and give us something to talk about. However, they are not helpful for a small business wanting an accurate calculation of their greenhouse gas emissions.