Solar districts: design strategies to exploit the solar potential of urban areas

The new EPBD (2010/31/EU) requires that new buildings comply with the “nearly zero energy” standard by 2020: this means first of all a very high energy efficiency of fabric and services, and then the production of most of the remaining energy from renewable sources. The sun is obviously the main renewable energy source for buildings, considering the large surfaces these typically expose towards the sky; prototype buildings exist, generating all the energy they need through photovoltaic or solar thermal panels. These examples are generally isolated buildings, but it should not be underestimated that the European trend in urban policies goes towards a reduction in the use of new land and the redevelopment of areas through demolition and rebuilding. This paper investigates what sort of influence energy issues can have on the design of new districts or buildings in urban areas, where the overshadowing by existing constructions can reduce the potential for solar energy production. This paper is a part of a wider study aiming to provide guidelines for the assessment of solar potential in urban areas: as a first step, simple models were analysed in order to understand energy needs versus potential energy production under different design conditions (height and size of buildings, distance between blocks, cladding materials, etc.) and then a real case study was assessed.