The article discusses the importance of considering environmental value in project evaluation. It suggests including the full price, which incorporates environmental value, in the assessment. The paper also talks about the theory of social discounting rate and how to balance ethical and economic factors within this theory. It concludes that a comprehensive social discounting rate should not be used, and environmental and non-environmental factors should be treated separately in project evaluation. The sum of the Net Present Value of these two sections should be used to make decisions.