Common Auditing

Avoiding the question of human capital and its intangibles, the focus in ISO standards for performance audits suggests that capital assets can be evaluated first for what they do and only second for what they are worth. That is, building a model of what activities or service economy or service product the capital asset supports, makes it easier to compare unlike physical goods. Consider two different ways to pollinate an orchard: by paying people to do it, or by letting bees do it. The beehive or meadow, and the road or truck, each bring in those who do the pollination, so should be treated equally.
The ISO 19011 standard may be a step in this direction, as it combines environmental management (for natural capital assets) with quality management (for humans) into a single audit. It is however not clearly a method suited for capital asset valuations, though it provides a framework to distinguish types of assets based on what activities they support. This would permit an activity-based costing or throughput accounting model to be quite easily constructed.
The Natural Capitalism approach goes further and advises a single uniform way of dealing with natural capital as an asset equivalent to infrastructural capital, financial capital and human capital. Though it says nothing about how to combine these into a single total cost of operations.