The LEED User "Powered Equipment Inventory" Worksheet, located under the "Documentation Toolkit" tab provides guidance on performance metrics as follows:
How to document performance based on the maintenance strategies at your building:
• If 100% of powered equipment is environmentally preferred, you don't need to track any usage metrics over the performance period. You can use this spreadsheet to demonstrate 100% compliance, just be wary of vendor equipment and be sure to include it in this inventory.
• If less than 100% of powered equipment is environmentally preferred, and you only wish to account for powered equipment (NO credit for manual equipment), you can use this spreadsheet to show that at least 20% of your equipment (by pieces of equipment) is environmentally preferred.
• If less than 100% of powered equipment is environmentally preferred, and you use a mix of powered and manual equipment, you'll need to track performance in runtime-hours and provide appropriate documentation showing that environmentally preferred equipment was used at least 20% of the time during the performance period. This spreadsheet can help you organize the different powered equipment you'll need to track over the performance period. Remember to track runtime-hours of manual equipment too (eg. push brooms and rakes) so you get credit for these strategies.
Our project submitted for preliminary review using the second outlined option. Our management plan detailed 11 pieces of powered equipment, 3 of which are environmentally preferable, leading to a 27% compliance rate. However, review comments were received as follows:
"The performance measurement method stated in the plan is the percentage of applicable pieces of equipment, but it is unclear how often environmentally non-preferable equipment is used versus environmentally preferable equipment. Provide a revised plan that includes a performance measurement method for maintenance equipment that describes how actual outcomes and sustainability performance for maintenance equipment practices will be measured and tracked over time. The performance measurement method must be able to quantify how the maintenance equipment is used rather than examine the pieces of equipment in the overall inventory. An example of a performance metric is the number of hours that each piece of environmentally preferable maintenance equipment is used during the performance period".

Based on the review comments, I don't see how they will find Option 2 from above acceptable. Please advise where GBCI/USGBC has the second option outlined, as I am unable to find reference to this approach in the EBOM Reference Guide.