Gas Insulated Substations (GIS) have demonstrated their superior reliable performances over the last 40 years and are widely used from medium voltage up to high voltage ranges. Among many reasons for a preferential application, their reliability and the compact dimensions are probably the most attractive. Based on the experience gathered during the last 40 years and the new tools developed by the industry in the last decade product designers have the capability of integrating the environment constraints at the beginning of the conception of the new product. This ECO Design approach has for its main goal to develop products consistent with the needs of the customers in reducing the environmental impact of the product during its life cycle from raw material extraction to the end of life. The paper presents the design efforts performed in order to conceive a new GIS range in line with requirements of minimal impact on the environment. Aspects of the design evolution are discussed on the example of a new 72.5-145kV GIS. The ecologically improved solutions are shown under consideration of relevant design parameters such sizing, materials and technologies used. The environmental evaluation and comparison of GIS components in respect of used resources is supported also with EIME software. ECO Design proceedings do not only concern the final industrialized product hut include already the development phase. Thanks to the progress in design tools modelling and simulation it is possible to replace partly time consuming and expensive prototyping and testing. The authors see the advantage of the ECO Design oriented product realization, even though this process is demanding and complex. Its consequent application, however, leads to economically and ecologically balanced solutions.