We have a library project that is reusing metal shelving. Since it is being used for the same purpose this credit indicates it should be part of MR1.2. Should the surface area be calculated as if it were a solid box? (i.e. top and sides) or should I calculate actual exposed surfaces area (i.e. each top and bottom of each shelf, all the parts of the bookcase that touches the air)? I hope that makes sense. Thank you.