Note that in these non-hygroscopic layers, the RH values are still real and accurate and these typically represent the critical values that you should be looking at for mould growth, rather than water content.
From what I have found out during my research of fully breathable timber frame walls is that the choice of insulation is critical and must be hygroscopic. Therefore I am simulating the case with Cellulose insulation. Is it right to say that as a result of the hygroscopic properties of the insulation that condensation will not be a problem? I should also mention that there is a softwood fibre board replacing where the OSB would normally be on the external side of the timber frame. In theory any moisture in the construction should be absorbed by the insulation and the under pressure in the cavity will cause any moisture to be drawn outwards.
I think this system is very interesting which is why I am basing my dissertation on it, although it is yet to stand the test of time in the Irish climate.
Many thanks again Calina and Daniel for taking the time to answer and steer me in the right direction, I really appreciate it.