1/4 mile radious from building boundary

I would use the one generated in CAD, since that seems to be the true offset of the building footprint (which seems like the building is your project boundary in this case). It's been a really long time since I used GIS, but from what I remember, that's better suited for large scale planning/mapping/etc. and therefore may take some liberties with features. Maybe there are some offset settings that could be adjusted in GIS to be more exact and not round the edges, if you'd rather stick with that.

I don't think the reviewers would be too picky about just the edges, unless your calculations/services end up being borderline for compliance. The first time I had this one documented for a project, we accidentally used a regular round radius from the site. The reviewer pointed it out, but because our project was in a really dense and diverse urban location, it didn't affect compliance, so I wasn't required to fix it or resubmit.

It would seem if the density boundary to be used is a 1/4 mile offset from the project boundary, it should be called an offset and not a radius.  It could be interpreted as a 1/4 mile radius circle taken from each of the corners of the building, which when made into a single boundary, is an ovalish shape.  The offset vs. radius creates quite different shapes, so would be beneficial to have a clearer definition.  As mentioned above, if it is a dense area it might not make a big difference, but would be good to have a consistent definition.

Any feedback on the conversation above? Is a regular 1/4 mile offset from the project boundary accepted by USGBC? As Ralph mentions above, I am in a situation where doing an offset from the project boundary encompasses enough density to meet the threshold but a simple circular boundary with a 1/4 mile radius does not.

Thank you in advance for any feedback! 

It is definitely an offset radius of your project boundary, not a circular radius like in previous versions. The Reference Guide is awkwardly worded. 

Thank you Emily! I appreciate it.

Yes, we were also told in reviewer comments it was a 1/4 mile offset from project boundary. Also the reviewer commented that where buildings intersect the 1/4-mile offset, if the intersected property is included within the projects density calculations, the entire building area and the entire associated property area must be included. Use a similar approach when excluding intersected properties. It is recommended that a narrative be provided explaining any inclusions or exclusions."