The master version of the calculator model is developed entirely in a single, stand-alone Excel workbook. The workbook therefore contains its own user interface and all of the assumptions and modelling methodologies required to calculate the implications of the user’s selected pathway for energy, emissions and all other implemented outputs.
Building the Excel model is a sizable task, which requires knowledge of a number of specific concepts that are unique to the calculator. These are perhaps best learned in turn, and to reflect this, the explanation of each concept is presented here within its own appendix. A list of these appendices is given below, with an outline of its content.
- Appendix 1: The Excel** model structure– a full description of the different components of the model and how they fit together. Firstly, we introduce the user interface, or ‘control’ worksheet. Thenwe explain the concept of ‘sector’ worksheets sheets, using the offshore wind sector as an example. Finally,we describe the process used to combine all the sector outputs to form concise results for the full energy system, with the use of ‘year’ sheets and then the ‘intermediate output’ worksheet.
- Appendix 2: Complex Excel** formulae – here we explain the more difficult Excel conventions used in the calculator, which experienced Excel users may not be familiar with, and show how they are used in the calculator.
- Appendix 3: Vectors** – this explains the system used in the calculator to categories quantities of energy or emissions by type.
- Appendix 4: Units** – detailing the calculator’s approach to handling units in a flexible way.
- Appendix 5: Balancing** mechanism – this explains the way in which the UK calculator ensures that supply and demand in the electricity sector are balanced.
- Appendix 6: Calculating** emissions – shows the simplified approach used in the model to estimate GHG emissions.
- Appendix 7: Stress test** – an explanation of the way in which the model accounts for intermittency in the electricity sector and calculates any backup generation requirements.
- Appendix 8: Bioenergy** – how the amount of bioenergy in the energy mix is calculated, how this is converted for different types of usage and how the impacts on emissions are calculated.
NB: these appendices are designed so that they can be read in order or can be dipped into to retrieve particular details.