Are partial deductions allowed for building subsystems instead of a whole building deduction?

In the case of a building that does not meet the whole building requirement of a 50 percent energy savings, a partial deduction is allowed with respect to each separate building system that comprises energy-efficient property and which is certified by a qualified professional as meeting or exceeding the applicable system savings targets established by the secretary of the treasury. The applicable system savings targets to be established by the secretary are those that would result in a total annual energy savings of 50 percent for the whole building, if each of the separate systems met the system target; note that the maximum allowable deduction is $0.60 per square foot.  more