An important model
The IMAGE model of the Planbureau voor de Leefomgeving (PBL) is an important tool for Dutch environmental policy making. It is used to study the global environmental changes that are taking place and to try and determine the future course of events.
PBL needed a number of new functionalities to ease the use and development of IMAGE. One particular improvement was the option to restart a computation at a certain point in (simulated) time. Before, the IMAGE model always ran from 1970, but the first decades were often the same as scenarios only start to deviate after 2000. The restart functionality that VORtech implemented allows to do the initial part of the simulation only once, and then run additional simulations for the various scenarios since 2000.
To accommodate the restart functionality, it was necessary to restructure (refactor) the code. The various partial models within IMAGE have been separated more strictly. The restart functionality was then implemented for each partial model. A restart of the complete IMAGE model is then nothing more than a restart of the various partial models.