There are three main ways in which ES can be valued: Direct-Market Valuations, Indirect Market Valuations, and Non-Market Valuations. Each category serves a purpose and targets a different aspect of the total value, this is why if the desired outcome is a total economic valuation, then a multi-method approach is required.
Direct Market Valuation Methods:
These methods utilize data from already existing markets as their basis for ES valuations, in order to use these methods they must already be traded in real markets.
Indirect Market Valuation Methods:
These methods posit that the values of ES can be derived from observable consumer behaviors in relevant markets.
Non-Market Valuation Methods:
These methods are used when there are no available market prices and when other methods cannot be applied. Typically they require individual respondents to estimate their changes in utility associated with an increase in quality or quantity of ES. This is done through surveys or interviews.
More on this in the full report.