Traditional accounting systems are not routinely designed to provide companies with information about total costs related to the use of resources and generation of waste and emissions. When a company is able to calculate and allocate costs on so-called non-product outputs, it can better monitor the real efficiency of materials and energy use that leads to better management of resources and financial savings.

For SMEs, it is recommended to use a simple input-output analysis based on 'TOP 20' methodology. TOP 20 materials analysis quantifies potential for improvement in non-product output costs.

TOP 20 collects data on the most significant process inputs, e.g. energy, water, raw materials, materials, auxiliaries and packaging, and their significance to the final product. The calculation is based on annual figures from the previous business year.

TOP 20 analysis has been widely used in 'clean' production projects since the 1990s; recently, it became an integral part of the 'EDIT Value' system developed by the Presource project. EDIT Value, which stands for 'Eco-innovation Diagnosis and Implementation Tool' for increased enterprise 'Value' and includes an updated list TOP 20 inputs, was piloted in 18 companies across six European countries.