Yes, it can be depreciated as a rental asset as five year property.

How did he claim the credit?  Did he claim 40% on Form 5695 and 60% on Form 3468?

The personal credit reduces the Basis by the amount of the credit.

The business credit reduces the Basis by HALF of the amount of the credit.

But it gets a bit weird if (a) you reduce the entire Basis by those two things or (b) if you treat it as two separate items (rental item and personal item) and then just do the half credit Basis reduction on the rental portion.  While my first inclination would be to do the second method, it gets much more difficult if the rental percentage changes every year.