using HPD as supporting documentation

As per my limited experience, I will say that it can be used for VOC content as it counts as a manufacturer declaration with indication of content expressed as g/l and reference to testing standard. For VOC emission evaluation it will not be accepted and you should try and obtain the cited test report or certification (e.g. Greenguard Gold).

yeah I would agree with Muhammad....GBCI would probably not accept a declaration unless it also included confirmation that the product met the VOC Emissions Evaluation / VOC Content Evaluation....and noted the specific requirements (e.g., CDPH, Table 4-1, range of VOCs, classroom/office scenario, etc.) In my experience I have not seen a manufacturer combine declaration and emissions/content evaluation into one document.  to Erin's point, if this document could be combined then it would be a tremendous help in streamlining our documents for the LEED application. 

From my experience it is best to upload the actual testing document, from a lab accredited under ISO/IEC 17025, that indicates GEE compliance (Greenguard Gold). In the past I have tried to submit a Declare label that indicated CDPH compliance, and TVOC Range, however this was not accepted by the reviewer. Some manufacturers, Sherwin WIlliams for example, do provide great LEED compliance documents that indicates what compliance they provide. These are great references for knowing what documentation is available; however, you still need to provide the actual document for compliance. https://images.sherwin-williams.com/content_images/sw-pdf-leedv4-guide.pdf