Semi-underground buildings: design models for the contemporary cities

The contemporary interest, on the one hand for a renewed relationship between city and natural landscape, on the other hand for settlement type intrinsically efficient from an energy standpoint, refocused the attention on the design of the city dug, or rather, almost completely plowed into the ground. This is an emblematic model of dealing with the factors of atmosphere, like sun, wind, the terrain, the hills and flora shadows, forcing some designers to migrate from methodologies indifferent to the design characteristics of the site, in search of fine calculation tools to optimize the configuration and the structure of buildings to get in a more "passive" possible way (with the lowest intake plant) to ensure the best meeting of comfort and psychological needs of users: not only lighting, sunbathing, ventilation, thermal comfort in summer and winter, acoustic comfort, but also with a view to characteristics of lighting and sociological aspects. The research revisits, in a modern consideration (related to the experiences, ideas and tools already investigated by researchers and designers of the seventies), the carved architecture of the past (such as the underground structures of Matmata in Tunisia, Gharyan in Lybia, but also the cities of Cappadocia in Turkey and the artificial cavities of the perfect ecosystem of Matera in Italy). So, the semi-underground buildings proposed, while applying bioclimatic "classic" techniques as direct gain or the solar greenhouse (with external sun protection), passive ventilation (with underground channels that act as geothermal heat exchangers) and a review of the Barra-Costantini system (for preheated air distribution in the rooms not directly exposed to the sun), offers new suggestions for forms, an aesthetic approach new and opposite: for example, the convex volume of the solar greenhouse, for example, is reflective, modern and technological opposed to the concave, opaque, archaic vernacular surface made with a ventilated stone wall.