1. Single-dimensional approaches

Single-dimensional approaches assume either that all dimensions of evaluation are commensurable (economic, social, environmental), meaning that it is possible to find a common unit to aggregate them), or that each dimension can be completely isolated, to analyze one side of the problem.

This type of assessment consists of reducing all information type to one common dimension and measuring the equivalence in that dimension type, which can be:

• money (dollars, or euros, or another currency)
• energy (KJoules for example)
• matter (specific elements: carbon, or a table of elements through lifecycle analysis)

As long as monetary approaches are restricted to markets of good and services (including finance), monetary approaches are justified, for instance. However cost-benefit analysis (CBA) often extends the use of monetary analysis to non-existant markets (such as wildlife, for instance). The characteristics of CBA are analyzed in the following grain.

Physical indicators are concerned with the flow of matter or energy within the economy. Matter can include (virtual) water, CO2, etc. In ecological economics, those indicators allow to measure the social-metabolism of a country.

The ecological footprint is an aggregate physical indicator, which measures the impact of a person's or a nation's lifestyle in terms of biologically productive land (measured in hectares). 

As a summary, single-dimensional approaches comprise, for instance

• Cost-benefit analysis
• Energy footprint
• Carbon footprint
• Other physical measure