PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture. Geneva, Switzerland, 6-8 September 2006 Energy Efficient Building Design: the “Borgo Solare” Case Study Niccolò Aste, Umberto Beneventano, Michela Buzzetti, Lavinia Tagliabue Department of Building Environment Science & Technology, Politecnico di Milano, Milan, Italy ABSTRACT: The purpose of the article is to describe the work carried out for an Italian project concerning the construction of a sustainable settlement named ‘Borgo Solare’. Borgo Solare is a residential complex situated in the outskirts of the town of Ferrara, constituted by buildings, squares, cycling tracks, green parks, water channels, fountains and a small lake. The main feature of Borgo Solare is that the whole project will be realized according to the criteria of sustainable architecture. This work consists in a specific analysis of the energetic aspects (loads and materials) of a small storey building. The purpose is an appraisal of the weight of the various factors related to environmental impact. The building is analysed in terms of energy performance, economic evaluation and environmental impact. Keywords: residential building, energy performance, quality, sustainable architecture 1. INTRODUCTION The project designing of Borgo Solare is carried out by a team of architects and researchers of Politecnico di Milano that have placed side by side the planning since the first steps and the real estate company Gambale that operates in the field of sustainable building components production. The purposes of the project were the realisation of a settlement near Ferrara, in Northern Italy. The sustainability should be the central theme of this work, with a specific attention to energy performance of the buildings, the relationship with sun, green spaces and water, the connection to the urban context and compliance with local building traditions. Preliminary studies have been focused to the distribution of the buildings in the site and to the consequent solar availability. The purpose was to realize the morphology and the configuration to optimise solar gains in winter and passive cooling in summer. Figure 1: Solar evaluation of the settlement. The relationship with water and green spaces has been studied to pursue a favourable external microclimate with benefits also on built environment. In figure 1 it is shown a preliminary study about solar influence on the settlement. The present study is focused on a specific building of the settlement, currently in phase of project and development. The building is constituted by three plans and is subdivided in to 15 apartments. The specific morphology permits access to ventilation and irradiation for all apartments to achieve indoor air quality and use of environmental factors to minimize energy needs. The ratio of transparent and opaque envelope is nearly 20%. The balconies have been dimensioned to protect windows during summer and permit sun penetration in winter period. Until 2005 the energy law in the Italian normative context was represented by the Law 10/91 which was an interesting and articulated energy law also with a first proposal of energy certification for built energy quality [1]. Since October 2005 the new Italian “energy efficiency in building” law, DL 192/05, is referred to the Directive 2001/91/CE and is mainly focused on heating loads that are restricted respect of the values indicated in the L10/91. The DL192/05 is related to increment in energy efficiency of buildings and introduces some control principles on summer load cooling [2]. The aim of Borgo Solare project is to realize higher performance energy buildings which respect both the old and actual limits by law, and in this work the planning choices are verified in an optic of economic feasibility and environmental sustainability, compared with the energy laws standards. The summer cooling load in building is not considered in the L10/91 and is marginally mentioned in DL192/05, therefore the present work is focused only on the theme of building heating load.