Energy conscious refurbishment of the village of Montieri (Gr,It). A urban strategy for retrofitting historic architecture

The European energy policy aims at reaching the target of quasi-zero energy buildings for new constructions in 2020, member states are also asked to set new energy requirements for existent buildings. Historic architecture has always been dispensed with the fulfilment of energy requirements but by the rising price of energy, historic residential buildings of urbanised areas will be more and more characterised by high running cost and low comfort standards if compared to newer building estate. If within a city the contribution of historic areas and city centres on the general energy demand for heating, domestic hot water, electricity and on CO2 emissions is reduced, in the case of small historic towns as Montieri the situation is reversed because the extension of the historic or cultural area almost corresponds to the whole built environment, therefore the contribution of these areas to the general urban energy balance is relevant. Therefore in small historic towns, in order to keep acceptable living standards and affordable running cost of buildings and to avoid phenomena of abandonment, facing the issue of energy saving also on historic architecture is becoming more and more relevant. The urban dimension of a small historic town presents several strengths for the application of urban energy policies: compact shape and the reduced number of buildings simplify the collection of information needed for and accurate description of cultural value of the built environment and of energy behaviour of buildings direct relationship with the surrounding natural environment enhances the exploitation of local renewable energy resources for sustainable management of the energy demand through and the integration of passive systems for improving indoor comfort of buildings the presence of a small community made up of few inhabitants allows a major cooperation with local administration in the design and implementation of refurbishment actions at village scale. The research gives a contribution on this topic trying to mediate between energy efficiency requirements and the respect of cultural value of architecture by proposing a cautious and accurate procedure to set achievable targets of reduction of buildings’ energy demand at urban scale. Principles from the discipline of building renovation and methods for the assessment and improvement of energy performances of urban building stocks are crossed to define a repeatable procedure for setting reliable strategies of retrofit interventions on historic areas. The tool implemented is the matrix of transformability that classifies the built environment according to the historic character of buildings and to those features that influence building energetic behaviour. The aim is to subdivide the urban fabric in classes characterised by similar suitable possibility of transformation. The procedure becomes an important tool in the hand of the municipality useful to set a plan for energy retrofit actions on buildings of the village, where to each construction is assigned a reachable level of energy performance and allowed technical intervention according to the cultural character and the relationship with the urban texture. In fact the cultural value of buildings is read as limitation to the transformability of buildings and the general scenario of urban renovation takes into account the peculiarities of all building classes in the village levelling the energy efficiency target on the characteristic of local architecture. The procedure provides to homeowners and building designer a first general direction to schedule retrofit interventions according to the energy refurbishment criteria already foreseen for each building. The procedure is tested on the small historic town of Montieri where the Geothermal Communities Project has set European fundings to implement energy retrofit actions on the medieval built estate. Criteria for the choice of suitable energy retrofit technologies respectful of the cultural value of buildings are outlined and collected in a guideline document that represents the practical result of the research work since is going to be integral part of the soon to be published Public Call for energy retrofit interventions in the village of Montieri, funded by the Geothermal Communities project. In Montieri, the involvement in the European project is the hint to set a clear position on energy efficiency requirements. In the guideline document minimum standards of energy performance for building elements, characteristics of local traditional building technology, are defined and their application demonstrates to be an effective solution for controlling the architectural quality of energy retrofit projects and to extensively reduce the general energy demand for heating of the historic village. Selected case studies of each class demonstrate the achievable level of improvement of energy performances for each group of buildings. In this way the application of tailored technical solutions on individual buildings is supervised by a general control of the effects of each measure at urban scale and the evaluation of the general reduction of energy demand at urban scale due to the proposed retrofit scenarios.