For OBU degree project the numerical average of ACCA F4 through F9 papers is calculated and is considered in OBU degree assessment and then you are awarded the class of degree accordingly.
Please note that being eligible for OBU degree contain different criteria and assessment of your degree has some other.
Another important point regarding Oxford Brookes University award assessment is that if you are exempted from any of the papers i.e. F4 through F9 then for the same NO marks will be awarded to you. Therefore, this can be one of the disadvantages of exemptions from ACCA papers.