How can we make sustainable design?

Which are the characteristics of sustainable design? the more an object of design is used, the more sustainable it isand it is sustainable as it originates from an accurate design process. how can we make sustainable design"?observing people and things in order to recognize their needs; simplifying the form according to different functional ideas; decomposing and reordering the parts of the designed model in order to encourage new combinations resulting into new useful forms; selecting local materials so that the final product will be more convenient; communicating the ‘plus’ of the product whose value will be linked to the opportunity to reuse it in different ways;