Ratho Libray in Edinburgh is planned to be demolished and will be replaced by a new building. However, fully demolishing the existing building and replacing a new one is a waste of resources, which is not sustainable. This project discovers the way of building a sustainable proposal that responds to the urban context and environment. The methods include researching the way of reusing the existing material in the new proposal and discovering new materials that are potentially sustainable to be used. It is a proposal with appropriate atmospheres in relation to the building functions.