On the basis of Konstantinou's research, it has been determined that there are three strategies for the retrofitting of external walls, the Add-in, Wrap-it and Add-on strategy. With the Add-in strategy, something is isolated from the inside, with the Wrap-it strategy from the outside and with the Add-on strategy something is added to the existing. With the Add-in strategy, it is important that the material is somewhat resistant to moisture because of possible moisture accumulation. To promote the use of biobased materials, a set of examples will be developed showing the application of these materials in these three different strategies. However, the choice of a material application depends on a number of factors. During this research, the CO2 sequestration through fast growing materials, CO2 footprint, cost, thickness, weight, lifespan and source location are investigated. The results of this research are shown in Appendix 1. From the research it can be concluded that fast growing materials have a great potential with regard to CO2 sequestration. For example, grass insulation appears to be able to store the most CO2 per year per hectare of land compared to other insulation materials. Other findings are that I-joist constructions create fewer cold bridges, which can have a positive effect on the Rc value, decreasing the total width of a panel. Research also shows that straw scores different areas, namely lowest CO2 emissions, longest lifespan and most affordable. All the knowledge gained from the research comes together in the set of examples (Appendix 3). Here the different materials are combined with each other, whereby elements of the three strategies for retrofitting external walls are sorted according to the various testing factors. The different material combinations give an idea of how these elements can be built up. However, these can still be varied and further developed, and are intended to help the user in the initiation phase of choosing a building method for a building.