Il paradigma energetico come generatore di modelli The energy paradigm as a model generator

This paper proposes a reflection about the influence that the goal of reducing energy consumption in the building sector has on the formation of models and building types. The ‘energy paradigm’ is now in the common thought. Our society needs energy sources because every single sector of our economy and, consequently, of our daily life, requires energy. The building types that can be found in the vernacular culture, according to studies of ‘bioclimatic’, are largely related to the availability of resources (materials for building) and local climatic conditions. The bioclimatic design approach has generated, in the 70s and 80s of the twentieth century, the model of the ‘solar house’: the model generally has a south glass façade, an opaque façade to the north side with few openings, with east and west facades of limited extension. The south facade hosts ‘passive solar systems’, such as greenhouses and Trombe-Michel walls, for the exploitation of solar radiation. Ventilation chimneys, or the position of the openings on opposite sides at different heights, allow cooling in summer and, in general, a good air exchange. In 2002 the European Directive n. 91 has as objectives the reduction of energy consumption in buildings and the comparability of performance in the European countries through a homogenization of descriptive parameters of the energy performance of the building. This leads to the consolidation of a different approach, one more ‘conservative’, determined by the availability of new materials and equipment plant and the lower limit values of energy consumption required by the regulations: the Passiv Haus model. Buildings are constructed more compact, therefore, to reduce dispersant surfaces (at equal volume). The openings to the outside are limited in size and are positioned so as to allow a good natural lighting. The cooling and air exchange is assigned to heat pumps and mechanical ventilation. The photovoltaic panels, in addition, sometimes, to thermal solar panels already in bioclimatic model, become a constant presence on the roofs of buildings. The promulgation of Directive 2010/31/EU – recasting of the previous Directive 2002/91 /EU –introduces new objectives and a new energy model: the Near Zero Energy Building (NZEB). The focus shifts to the need to have a null balance between demand and local energy production from renewable sources; to integrate microgeneration plants (PV, micro wind generators) in the architectural language becomes increasingly important, as well as to make use of evolved plant design (eg. geothermal heat pumps). The building becomes ‘energy active’. The paper presents some considerations, highlighting the need to address the architectural project knowing metabolize energy saving objectives without falling into mere diagrammatic translation of the principles mentioned above.