The sustainable white city

The history of architecture and urban planning tells of white cities, whose chromatic characteristic derives from the use of local resources (stone, lime) and which unconsciously responded to principles of environmental sustainability. During the first half of the twentieth century, some European countries undertook economic and social policies aimed at the agricultural development of the territories and a consequent repopulation of the countryside. Especially in the south of Spain, numerous white-colored cities were founded. Global warming issues call into question the current organization of the city, which must renew itself and create comfortable and compatible living conditions with long-term development. Today the importance of color is reaffirmed in the possibility of re-establishing the contemporary city according to principles of environmental and economic sustainability. In the field of architectural design, one of the central aspects to consider is the amount of energy that buildings need to cool down, and the amount of heat they emit into the atmosphere. Especially in areas with warm climates, the energy consumption of a building is determined by its thermal insulation properties, which mainly depend on the material and color of the external surfaces. The use of white color allows to reduce the heat absorbed by buildings, with lower energy consumption and emissions; furthermore, the amount of heat re-emitted in the atmosphere is reduced, with the possibility of reducing the urban heat island effect. This simple chromatic principle of architecture can be extended to the urban scale thanks to a wide range of products and technologies, so that some cities have already undertaken a chromatic conversion. The contribution tells the idea of ​​a sustainable white city and, starting from examples of built architecture, it defines the possible principles, materials, techniques and technologies available for the design of architecture and the contemporary city.