Yes, but one day they will have - hopefully - results. And a commitment to publish in open access journals should have been part and parcel of a funding round like this. A billion is not exactly pocket change.
Henry Markram, the coordinator of the Human Brain Project, is also one of the founders of Frontiers (http://frontiersin.org), a scientist-led, open-access publisher, so I think it's fair to say there is already a strong commitment to open access publishing within the project.
For some projects it is already mandated in the grant agreement. I've heard that this will be extended to all project for Horizon 2020. I am also under the impression, that the EU protects researchers who post the full version of their papers on their websites even when the publisher does not permit it. I could be wrong on the latter.