BIPV meets history. Value-chain creation for the building integrated photovoltaics in the retrofit of historic buildings

Photovoltaic (PV) systems are usually not recommended in heritage buildings for preserving their values and aesthetic features. However, these buildings are widespread in Europe and their energy requirements, due to heating, cooling, and electrical energy, can be significantly reduced with PV modules and hybrid systems. Also, recent aesthetical and technological innovations focus on more compatible systems, thanks to low-rate reflection, mimetic appearance, compact shape, and geometric flexibility. The paper aims at checking the opportunities for PV integration in heritage buildings. The study is applied to the “Rustico Macchi”, an Italian heritage building that need a complete retrofit for hosting exhibitions and didactic activities. To do so, a dynamic building energy model (BES) is created considering the data from on-site tests. This model is tested adding various types of PV modules on roof, façade, or windows, and integration levels, checking, for each case, the reduction of non-renewable input primary energy and self-consumed electrical energy produced by PV. The results highlight that a balance between conservation and energy production is possible integrating advanced PV systems and considering the traditional principles of architectural restoration: heritage significance of the building and its settings, minimum intervention, reversibility, and technical compatibility.KeywordHeritage buildingSolar energyPhotovoltaic systemsDynamic energy simulation

The paper presents an overview of existing urban sustainability rating tools for their possible application in historic urban environments, facing the debate between environmental sustainability and urban heritage conservation. This critical study focuses on Urban Green Rating Systems (UGRS) that make a transparent and systematic decision-making support tool for evaluating the sustainability in urban planning, combining environmental, economic, and social aspects. The research aims at comparing different UGRS approaches for cities and neighbourhood renovation, highlighting main themes, criteria, indicators, pros, and cons to balance heritage preservation and sustainable development. All the UGRS give high importance to environmental aspects while lower or no consideration is dedicated to heritage conservation. Thus, gaps in the methodological approaches to be addressed in the future have been identified, to serve as a guideline and reference for developing a comprehensive, international assessment system to bridge this knowledge and applicability gap.

The launch on the market of innovative highly customized products, with a low visual impact colour and aesthetically wise promoted the integration of photovoltaic (PV) systems in protected areas. Despite the aesthetic, economic and energy advances, their integration therein is hampered by several legislative, and procedural barriers. For this reason, the study aims at reconstructing a European, Italian, and Swiss legislative and authorization framework to highlight prospects, potential, limits, and points of contact among such territories. The working methodology is structured in four parts: (i) the reference context's legislative analysis; (ii) definition of authorization processes; (iii) discussion with stakeholders; (iv) critical summary of the results. Thanks also to the introduction of specific targets and economic incentives, policies implemented in all territorial contexts push the use of solar energy in new buildings and restructuring. Several focus groups have been organized to discuss the existing legislation with different professional target groups (Heritage and Public Authorities, Designers). The results show that in Italy, due to the complex and fragmented authorization process, PV implementation slowed down over the years. In Switzerland, however, clearer criteria and simpler procedures encouraged their diffusion. In both territories, stakeholders need more training and updating about PV technologies, integration criteria, and implementation processes.

Within the framework of IEA-SHC Task 59, a multidisciplinary team of experts from around the world has come together to investigate current approaches for energy retrofit of the built heritage with energy efficiency conservation-compatible measures, in accordance with cultural and heritage values, and to check and adapt the new standard EN-16883:2017 for historic buildings. This paper introduces activities within IEA-SHC Task 59 (Subtask C) focused on retrofit solutions with high impact on sustainability, energy efficiency, and the integration of renewables, which is the main goal of the solar group, focused on the integrated solar systems for historic buildings. Relying on an extensive, detailed, and accurate collection of case studies of application of solar photovoltaic and thermal systems in historic buildings, the assessment criteria of the standard have been reviewed and tailored for better solar implementation evaluation in a heritage context. All this is studied based on technical compatibility, the heritage significance of the building and its settings, the economic viability, the energy performances and indoor environmental quality and use, as well as the impact on the outdoor environment of solar renewables.

The integration between solar energy systems and building components is highly critical in sensitive heritage contexts. On the one hand there is the need for finding a balance between the preservation of the aesthetic appearance and the historical values, but on the other hand, finding the space where to effectively integrate the systems might be quite challenging. The solar systems can be divided in photovoltaic (PV) and solar thermal (ST) systems. Building Integrated Photovoltaics (BIPV) and Building Integrated Solar Thermal (BIST) are PV or ST panels integrated into the building envelope, combining the energy generation with other functions, such as noise, weather protection, thermal insulation, sun shadow, and other aspects. Nowadays, the dynamism of the market allows to design highly compatible products which look like traditional architecture materials. This situation fosters the integration of these products in the BIPV and BIST systems within the heritage sites, especially thanks to the use of advanced customisation processes, special and low-reflecting glasses, and innovative cost-competitive coatings. There is a limited number of studies on the application of these technologies in heritage contexts, due to the presence of architectonic, conservative, and cultural barriers. This paper aims to conduct a comprehensive review of the available literature on the integration of renewable energy sources (RES) in heritage sites and buildings, which would foster the preservation of their cultural and natural values as well as reducing primary energy consumption, increasing comfort levels, minimizing environmental impacts, and improving technical quality and economical outlays. A common framework will thus defined to support restorers, historic conservators, and energy experts and to facilitate the diffusion and application of RES in heritage contexts. This conceptual framework will provide industries and academics with operative strategies and will encourage their diffusion and application in sensible contexts.

The integration between solar energy systems and building components is highly critical in sensitive heritage contexts. On the one hand there is the need for finding a balance between the preservation of the aesthetic appearance and the historical values, but on the other hand, finding the space where to effectively integrate the systems might be quite challenging. The solar systems can be divided in photovoltaic (PV) and solar thermal (ST) systems. Building Integrated Photovoltaics (BIPV) and Building Integrated Solar Thermal (BIST) are PV or ST panels integrated into the building envelope, combining the energy generation with other functions, such as noise, weather protection, thermal insulation, sun shadow, and other aspects. Nowadays, the dynamism of the market allows to design highly compatible products which look like traditional architecture materials. This situation fosters the integration of these products in the BIPV and BIST systems within the heritage sites, especially thanks to the use of advanced customisation processes, special and low-reflecting glasses, and innovative cost-competitive coatings. There is a limited number of studies on the application of these technologies in heritage contexts, due to the presence of architectonic, conservative, and cultural barriers. This paper aims to conduct a comprehensive review of the available literature on the integration of renewable energy sources (RES) in heritage sites and buildings, which would foster the preservation of their cultural and natural values as well as reducing primary energy consumption, increasing comfort levels, minimizing environmental impacts, and improving technical quality and economical outlays. A common framework will thus defined to support restorers, historic conservators, and energy experts and to facilitate the diffusion and application of RES in heritage contexts. This conceptual framework will provide industries and academics with operative strategies and will encourage their diffusion and application in sensible contexts.

The paper refers to the application of Building Integrated Photovoltaic (BIPV) systems for the renovation of heritage buildings and urban landscapes, preserving their historic, material, aesthetic and natural values as well as lowering energy bills, increasing comfort, and improving their technical quality in terms of economic and environmental sustainability. Several criteria for the compatible use of BIPV systems in heritage context are proposed, also taking into account the perspective of architectural preservation, legislative framework, research projects, and the scientific literature. The research is structured in the following steps: (i) examination of existing criteria for acceptable use of BIPV on heritage sites; (ii) examination of the theory of architectural preservation and restoration; (iii) identification of a set of criteria for compatible insertion of BIPV; and (iv) assessment of these criteria on case studies. The study shows new opportunities of inserting new and emerging solar products in these contexts, especially thanks to the advanced customization possibilities to preserve their values by resembling other known building materials.

Energy flexibility in buildings is gaining momentum with the introduction of new European directives that enable buildings to manage their own energy demand and production, by storing, consuming or selling electricity according to their need. The transition towards a low-carbon energy system, through the promotion of on-site energy production and enhancement of self-consumption, can be supported by building-integrated photovoltaics (BIPV) technologies. This paper investigates the aesthetic and technological integration of hidden coloured PV modules in architecturally sensitive areas that seem to be the best possibility to favour a balance between conservation and energy issues. First, a multidisciplinary methodology for evaluating the aesthetic and technical integration of PV systems in architecturally sensitive area is proposed, referring to the technologies available on the market. Second, the experimental characterisation of the technical performance specific BIPV modules and their comparison with standard modules under standard weather condition are analysed, with the aim of acquiring useful data for comparing the modules' integration properties and performance. For this purpose, new testbeds have been set up to investigate the aesthetic integration and the energy performances of innovative BIPV products. The paper describes the analyses carried out to define the final configuration of these experimental testbeds. Finally, the experimental characterisation at standard test conditions of two coloured BIPV modules is presented and the experimental design for the outdoor testing is outlined.