Abstract:The urban canyon model has been recurrently used as a basis for many solar access studies. However, its conception as endless structures disregards the effect of street intersections, despite being characteristic elements of urban fabrics. This paper aims to evaluate the impact of street discontinuities on solar access over building façades. The potential of crossings to increase the available radiation has been assessed through computer simulations in dense urban environments in a Mediterranean location. For the cases studied, results show that local effects of an intersection almost disappear beyond a specific distance for each aspect ratio, which can be helpful to determine the suitable level of detail for solar analyses at an urban fabric scale.

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The ability of our societies to reach and maintain housing conditions consistent with the right to decent habitat is inevitably related to the integration of the sustainability challenge into the mechanisms for housing, neighborhood and city generation, since it directly depends on both available resources and the production of waste.Based on this relation, the sustainable building concept is thoroughly explained through the transposition of the sustainable development defi nition proposed by the Bruntland report, which allows the linkage of human needs satisfaction with the use of resources. In this way, sustainable housing should address the

Habitabilidad, un concepto en crisis. Sobre su redefinición orientada hacia la sostenibilidad RESUMENLa inaplazable respuesta a la crisis ambiental provocada por el sistema productivo industrial, supone el primer y mayor reto que debe afrontar el sector de la edificación, pues conllevará transformaciones profundas en sus objetivos y en sus procedimientos de actuación.La consecución de la condición de edificación sostenible se aborda en el presente artículo a partir de la aproximación a una redefinición de la misma utilidad social que debe procurar el sector: la habitabilidad. En primer lugar, se analiza la concepción normativa actual y se detectan las barreras que opone frente a las demandas de sostenibilidad. En segundo lugar se exploran alternativas disponibles en el mismo contexto legislativo español que permiten adecuarlo al nuevo paradigma ambiental.En último término, el artículo también presenta los cambios que la redefinición del concepto de habitabilidad conlleva en la misma dinámica de sector y, concretamente, en la rehabilitación del parque construido. 113-113Palabras clave: Sector de la edificación, edificación sostenible, habitabilidad, rehabilitación. SUMMARY

The causal relation among building typology and building energy demand is a complex balance of climate, morphology, technology and use. The assessment of the relation between mass of building elements and energy demand in different housing typologies is the main goal of this study. A novel indicator, namely the Buildingmass, is introduced and tested in the Mediterranean climate region. Explorations on nine conventional housing typologies in Barcelona and Rome are carried out. Buildingmass evaluation is based on the calculation of the mass of building elements. Energy demand is assessed by modelling on multi-space dynamic thermal analysis tool. Our results point out that the Buildingmass has a strong relevance on energy, playing an important role in reducing heating and cooling demand in the Mediterranean city, as described by the proposed correlation (R 2 = 0.88). Moreover, this indicator gives a more detailed characterisation of the housing stock of the Mediterranean city. The study aims at bridging the gap between urban physics and urban metabolism studies and fostering energy conservation measures for the built environment.