In the D4S approach, generic strategies and guidelines are recommended to create more sustainable products [3]. Within the Delft program, this approach is now being further elaborated and scientifically grounded with respect to the modelling of the specific group of PV powered consumer products. Therefore, no specific design guidelines could be applied by the young designers involved in this project. However, in the application of D4S in almost 20 years of ecodesign of industrial products, the most significant guideline undoubtedly has been the advice to use ecobenchmarking as much as possible as one of the most powerful design tools.

In the D4S approach, benchmarking is defined as follows: “Benchmarking is the process of improving the performance of an existing product by continuously identifying, understanding, and adapting outstanding practices and processes found both within and outside of the organisation. Benchmarking is a structured approach to compare the environmental performance of a company’s products against competitors’ products and to generate improvement options” [3]. In the D4S manual and the book ‘Adventures in EcoDesign of Electronic Products’ [4] specific guidelines and a stepwise planning of ecobenchmarking have been described.

The phase model of Buijs & Valkenburg [1] also indicates the importance of creating an inventory of similar products to improve a specific product design.