Forecasting of carbon intensity by the app is provided for the next 7 days and requires us to look forward at both the weather and at any incoming feed from the national grid. Our National Grid data is taken from the BMRS data feed, a service provided by Elexon. BMRS stands for Balancing Mechanism Reporting Service and provides the industry with information on the composition of nationally sourced electricity, and this service takes its own position with respect to forecasting. We also use the weather forecast from Darkskies to determine the expected level of generation for Wind and Solar power that is locally attached to the Western Power Distribution network. Historical and current data is all broken down into hours, but within the forecast, the BMRS is only supplying data per day, and as a result the closer we are to the current date, the more granular is the forecast. In the forecast therefore, there will be less variation in what is seen, especially at locations where there is relatively little local generation and the National Grid infeed dominates.
The historical display is taken from data that is retained in our records of what actually happened at each supply location. The overall result is therefore that there is more variation seen in the carbon intensity displays on the historical and now/today screens.