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Abstract. The urban heat island (UHI) effect is constantly increasing the energy consumption of buildings, especially in summer periods. The energy gap between the estimated energy performance -often simulated without considering UHI -and the real operational consumption is especially relevant for institutional buildings, where the cooling needs are in general higher than in other kind of buildings, due to more internal gains (people, appliances) and different architectural design (more transparent façades and light walls). This paper presents a calculation of the energy penalty due to UHI in two institutional buildings in Rome. Urban Weather Generator (UWG) is used to generate a modified weather file, taking into account the UHI phenomenon. Then, two building performance simulations are done for each case: the first simulation uses a standard weather file and the second uses the modified one. Results shows how is it necessary to re-develop mitigation strategies and a new energy retrofit approach, in order to include urbanization ad UHI effect, especially in this kind of buildings, characterized by very poor conditions of comfort during summer, taking into account users and occupant-driven demand. IntroductionInstitutional buildings like: offices, universities, schools, hospitals, etcetera, constitute a very important part of the building stock. In Italy, Many of these buildings were built in the XIX and in the first half of the XX Century, without specific measures to reduce energy consumption. As a result, the institutional buildings are responsible of almost the 20% of the total building stock energy demand in the country (REF IS NEEDED). Moreover, the consumption profile of institutional buildings is different from the residential buildings stock: in 2008 institutional buildings consumed more electricity than residential buildings (39% versus 22% of the total consumption) due to more intensive use of air conditioning (19% versus 1%), appliances and lighting (9% versus 3%) [1]. Italy has today a good share of renewable energy contribution to electricity production (about 40%). However, the high demand of electricity that institutional buildings have poses a challenge for energy demand and urban sustainability.

The City of Rome is trying to come into line, culturally and strategically, with European standards of environmental health and energy savings. This study is designed as a roadmap for the retrofit of existing building stock, through the analysis of case studies of major significance in terms of building characteristics and period of construction. The recognition of the consistency of the existing school building stock and the subsequent selection of the buildings that are representative of general conditions allowed us to compare results and draw from them intervention guidelines that are applicable to almost all of the school building stock. The guidelines developed by the authors take into account the optimisation of the building envelope and plant system, as well as the pay-back period of each case. The interventions, with their low investment costs, have significant benefits in terms of energy efficiency, with a subsequent reduction in greenhouse gas emissions, and in terms of indoor and outdoor environmental quality, and propose a systemic approach to the retrofit of Mediterranean cities, which often have ancient and monumental historic centres that need to be protected and enhanced, as well as in the established suburbs, defined as those that appeared up to the 1970s-1980s. For these buildings, characterised by great potential for transformation and often with poor architectural and technological quality, the energy retrofit is also an opportunity to redesign and redefine the levels-objectives of indoor comfort. The reduction of energy consumption in school buildings, estimated at about 40% for the envelope and 20% for the plant, other than the evident environmental benefits to the territory, also has a significant impact on the education of the individual awareness of the users. Widespread retrofit of public structures at the disposal of young students, other than having a powerful impact in the reduction of greenhouse gases, constitutes a fundamental element in education on environmental issues and quality of the built, creating an unquantifiable extra value for sustainable development in the City of Rome and for the construction of more liveable and civilised cities. © 2012 WIT Press

This paper aims to provide an assessment of a part of school building stock in Rome, through analysis of qualitative and quantitative data referred to a sample of 684 buildings used as primary school. This research designs a start point useful for administration to defining possible strategies and policies to reduce consumptions in this sector. The study has been performed by describing the characteristic of buildings related to construction age and comparing buildings' energy label with the thermal consumption metering, in order to obtain a model with a high level of objectivity and accuracy. The results show the necessity of a spread and deep intervention on school buildings for its high potential in energy and costs reduction.

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