This report is the final report from the research project RO5. The report summarises the results from the research project RO5. The report consists of summary from a literature study, from computer simulations and from model scale tests. This, together with results from full scale demonstrational test (documented only in this report) leads to the conceptional solutions and recommendations presented in this report. The project focused aim was to investigate the effects of ventilation on fire development in ro-ro spaces with different ventilation conditions. Important conclusion from the literature study is that ventilation is primary to prevent flammable and other harmful gases from accumulating in the spaces, and the mechanical ventilation is not designed to be functional in case of fire. It is a must for the crew to gain knowledge about the ventilation system (i.e. fans, inlets and outlets) and its capacity from tests and experiences. It is important that guidelines, rules and routines are established for using the ventilation system in typical conditions (loading/unloading etc.) and that it is documented and passed on to provide guidance for the ship's crew. One of the most important conclusions from the model scale tests and numerical simulation study is that distinct limitation is found for 4% opening of space sides (natural ventilation) for the fire self-extinction to occur. This is dependent on the height and shape of the opening. For the mechanical ventilation case, in case of fire, stopping the ventilation is the best way to reduce the fire intensity. The tests show that mechanical ventilation is vital for the fire to continue to burn. The recommendations aim at giving advise concerning ventilation in case of fire and how to deal with the ventilation at different ro-ro spaces.