Ember: exclude folders from ember-cli-build

Is there a way to exclude folders from an ember-cli build - so you can put some working code in it and not have it compiled?

I've seen a few similiar questions on stack overflow eg Exclude folders from builds in Brocfile but this seems to be talking about a pod structure which I'm not using. I would have thought that this should be simple to achieve, but haven't found any solution as of yet.

Many thanks in advance!