Our project is a model and protype shop at a private art and design institution. Our first sub-metered water use will be the electric water heater, which provide 100% of the building hot water.

The second use was going to be the exterior landscape irrigation. However, to keep the project within it's budget for the year, installing the landscape was VE'ed out for another year or two. There is a schematic design for the future and the owner would likely vouch that all landscape irrigation water will come form this metered source. Can we use this as one of our metered uses? 

Our other option would be submetering the qualifying plumbing fixtures and fittings. If we do that, do we need to meter the hot water going to those sinks or only the cold water?

Thanks in advance!