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Acceptance of Building Integrated Photovoltaic (BIPV) in Heritage Buildings and Landscapes: Potentials, Barriers, and Assessment Criteria

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Abstract

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.
Construction Pathology, Rehabilitation Technology and Heritage Management
March 24-27, 2020. Granada, Spain
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CODE 553
ACCEPTANCE OF BUILDING INTEGRATED PHOTOVOLTAIC (BIPV) IN
HERITAGE BUILDINGS AND LANDSCAPES: POTENTIALS, BARRIER AND
ASSESSMENT CRITERIA
Polo López, Cristina S.1*; Lucchi, Elena2; Franco, Giovanna3
1: University of applied sciences and arts of southern Switzerland, Department for environment
construction and design Institute for applied sustainability to the built environment
e-mail: cristina.polo@supsi.ch, web: http://www.supsi.ch
2: Eurac Research, Institute for Renewable Energy
e-mail: elena.lucchi@eurac.edu, web: http://www.eurac.edu
3: University of Genoa, Department of Architectural Design
e-mail: francog@arch.unige.it, web: http://architettura.unige.it
ABSTRACT
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.
KEYWORDS: BIPV; photovoltaics systems; historic buildings; historic centers; heritage landscape.
1. INTRODUCTION
Improving energy efficiency in historic heritage, preserving their values and characters, is a topic of
great importance, even considering that historic buildings constitute a considerable part of the European
(EU) building stock. The promotion of Renewable Energy Sources (RES) has an important role in this
process, thanks to the Directive 2018/844 has introduced the concept of nearly zero-energy buildings
(NZEBs) [1] for new buildings and for existing buildings subjects to major renovations. Also,
Switzerland moves in this direction. Even if it is not always possible to comply with current energy
standards, it is considered essential trying to improve their energy efficiency as much as possible [2]. At
EU and international level this topic is gaining importance in recent years. Proofs of this increasing
interest is the constant growth of funded project at European level [3; 4; 5; 6; 7; 8]. At international
level, the main aim of the International Energy Agency (IEA) Task 59 [9] is to find conservation-
compatible energy retrofit approaches and technologies for historic (not necessarily protected) buildings
with low energy efficiency and comfort levels, also considering the integration of renewable solar
resources. Different methodologies and decision-making tools to determine the correct approach for
energy retrofitting and management of historical buildings have been investigated so far in EU Research
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Projects [3; 4; 5; 6; 7; 8; 10]. The final aim of most of these projects focused on reducing primary energy
consumptions as much as possible, to improve the level thermal and acoustic conditions, quality of the
internal air and natural lighting conditions, as well as preserving the historic architectural and landscape
values and minimizing the environmental impacts. The aim is to look for a balance between different
needs. Similarly, the International Scientific Committee on Energy and Sustainability within ICOMOS
and the new EU standard EN 16883 set the importance of consider a consensual and uniform approach
to be implemented [11]. The integration between solar energy systems and building components appears
very critical in sensitive historic contexts, especially for the protection of their constitutive materials,
aesthetical appearance and historical values [11]. In the recent past, the installation of photovoltaic (PV)
and solar thermal (ST) systems was not recommendable for historic buildings, to preserve the valuable
fronts and roofs, especially considering traditional PV panels. On the contrary, nowadays, the use of
integrated solar systems within these types of context to enhance energy efficiency becomes increasingly
possible due to the very high compatibility of new products. These products, thanks to advanced
customization with low reflecting and special glasses, colors, patterns and innovative low-cost
treatments, can be designed to appear similar to traditional architectonic materials [13], as already
demonstrated in some research projects [3; 4; 5; 6; 7; 8] and activities carried out within IEA SHC
program [14]. The most popular strategy is the insertion of Building Integrated Photovoltaics (BIPV)
systems into building components, despite the above-mentioned architectural barriers. The integration
of these systems in roofs was studied departing from existing guidelines and less visually intrusive
commercial products [3; 8]. The commitment of local and heritage authorities was introduced as an
important step to find unexplored solutions (i.e. localization on alternative structures close by heritage
sites) [3; 4]. Otherwise, BIPV market is dynamic and characterized by a wide spectrum of new
architectural products for [15; 16]. These products are suitable for the application in heritage context
with minor alterations of the original integrity or harming the aesthetics or cultural value of roofs,
facades, skylights and windows [8; 13; 15; 16; 17; 18]. The installation of solar technologies in these
sensitive contexts has not a unanimous approval in scientific circles and the motivations could be
different from the point of view of conservatives. The reasons for which being somewhat diverse
[16].Alongside evaluations of a technical-economic nature and considerations relevant to effectiveness
and efficiency, the installation of solar - supplied devices clearly contrasts with the “slippery” project to
safeguard cultural and material values, juxtaposing different weights unlikely to find common ground
[15]. However, a shared framework on the acceptability and compatibility of these products on historical
contexts and sensible landscape is still missing. This depends substantially on multiple meanings that
can be attributed to terms such as integrity, alteration, aesthetic and historical values and in the balance
among aims.
2. AIMS AND METHODOLOGY
The paper aims at proposing a set of shared criteria on the application of BIPV systems for the renovation
of heritage buildings and landscapes, preserving their material, aesthetic, and natural values as well as
lowering energy bills, increasing comfort, and improving their technical quality. On the one hand, it is
possible to evaluate the efficiency and the effectiveness of an energy retrofitting intervention from the
quantitative point of view (in terms of energy and economic savings). On the other hand, it is more
difficult to express an assessment from a qualitative point of view, especially in the case of listed
building. The assessment of these interventions should take into consideration how much is lost, in terms
of material culture and historical value, and how much is gained, in terms of energy improvements and
sustainability, as well as perceptive impacts on buildings contexts and landscapes. However, material
loss and energy saving are two entities that are difficult to measure among themselves. It is therefore
necessary to overcome this dichotomy recurring to a systemic approach that could optimize and not
maximize one system over the other. The methodology is based on the literature review, the comparative
analysis of technical legislation and the proposition of a set of quantity-quality criteria. While the
comparative analysis of legislative framework is rather simple, more difficult is the formulation of a set
of shared criteria for the compatible use of BIPV on historic buildings and urban landscapes. It was
therefore necessary to open a light on different philosophies and methodologies to approach architectural
conservation and restoration. The research is structured in the following steps: (i) examination of
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existing criteria for acceptable use of BIPV on heritage contexts in the legislative framework; (ii)
examination of the point of view of architectural restorers and conservators; (iii) identification of a set
of criteria for compatible insertion of BIPV with particular attention to visual impacts; and (iv)
application of these criteria on case studies.
3. CRITERIA FOR COMPATIBLE BIPV APPLICATION
3.1. Criteria from the legislative framework
EU and Switzerland legislations emphasize the key role of combining energy efficiency and RES
integration in the building sector. RES are mandatory for the retrofit of existing buildings, providing
correct inclination and orientation [1]. This measure is not mandatory for listed buildings, when it can
have an impact on the aesthetic value of the building [1]. Important building renovations (in terms of
surfaces involved or energy consumption reduced) require a coverage of 50% for the energy produced
for domestic hot water, heating and cooling through RES [1]. It should also be noted that these energy
sources are one of the requisites needed for the achievement of the Nearly Zero Energy Buildings [1].
In general, the integration of BIPV in the landscape is encouraged reducing its aesthetical impact and
without ruin the heritage structures or natural sites [1]. The systems must be coplanar to the roof, not
protrude, and present a compact shape with a low rate reflection. Several EU Countries defined national
guidelines that include BIPV installation in sensitive buildings and landscapes [1]. Specificity, the
guidelines suggests several examples of best practices, but only in few cases specific aesthetic or
technical criteria for their assessment. Heritage authorizations are mandatory for RES installation on
cultural heritage, particularly for historical and rural buildings, historical towns and settlements, areas
of landscape protection. In this case the final advice of the Heritage Office for Cultural Heritage is
required. As stated, legislative framework in the different countries could approach the topic in a
different way. Nowadays, the authorities and the legal entities are taking positions with a more open-
mind approach. Initially, they established basic criteria and guidelines to respect. Recently, the tendency
is to greater permissibility, pushing to municipalities in searching appropriate and compatibility
solutions with the landscape and constructive characteristics of the urban areas and analysing specific
and singular cases in detail, when necessary. Furthermore, some important methodological premises lie
at the basis of these reflections. This situation is evident also from technical recommendations: (i) to
ensure the maximum material preservation it is preferable to intervene on traditional buildings if quite
degraded or in state of collapse, where completely new roofing is required; (ii) to minimize the alteration
to a landscape it is desirable to intervene on shelters, arbours, service access volumes annexed to the
buildings rather than on buildings which fully embody traditional characteristics; (iii) in urban
landscape, it is preferable to intervene on buildings already compromised by blatant, modifying stages
or on recent buildings, in which materials and building techniques are often employed already different
from traditional architecture regulations [19].
3.2 A common ground for discussion: multiple attitudes in architectural preservation and
restoration
Sustainability and historical heritage, both material and immaterial, seem to belong to increasingly
tangent (and interactive) spheres. This new condition may contribute to overturn cultural reference both
in terms of technical attitude and conservation/restoration principles. Since more than two Centuries,
Europe is discussing about the fate of an impressive amount of ancient monuments, of poor but
meaningful buildings, of urban fabrics and of rural hamlets that survived from the past and still
characterize our territories and built landscapes [20]. During the XIX century, the two recognized
‘fathers’ of the modern restoration theories elaborated two opposite ideas about the attitude to be adopted
in relation with the traces of the past that still influence our debates. Eugène Emmanuel Viollet-le-Duc
clearly declared that restoration was a modern word for a modern thing and that “[…] restoring it is not
preserving a building, but it could mean to bring it again to a state of wholeness that could have never
been existed in a given moment [21]. With a completely different approach, but agreeing on the modern
essence and origin of the problem, John Ruskin asserted that “[…] restoration is a lie; the worst lie
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which is accompanied by the destruction of the beloved artefact accompanied by the fake description of
the destroyed thing” [22]. Nowadays all over Europe it is possible to identify more or less codified
theoretical-doctrinal positions in accordance with Ruskin’s or Viollet’s thoughts, synthetized in the
following points: (i) the so named stylistic restoration”, focussed on the construction of a “history of
styles”, by selecting those parts of a monument that are considered consistent with the prevalent
architectural language recognized in the building; (ii) the presumed “philological restoration” [23]
recognized the essence of the monument considered as a document and stated the necessity to valorise
all the signs of succeeding phases of its history; (iii) the so-called critical and creative restoration”
[24], that implies the critical identification of the outstanding aesthetical values of a monument, its ‘true
form’ as the result of a genius’s creation. A parallel and more complex version of this approach brought
afterwards to the fundamental definition of the treatment of the so-called lacunae, i.e. the voids existing
within a figurative texture, in order to re-establish not the original and lost unity but only the potential
one, still suggested by the survived and remaining parts of the masterpiece of art and thus deciding which
instance should prevail between the historical and the aesthetical one [25]. Finally, (iv) the usually
identified as the modern “preservative approach” gave then the greatest relevance to the permanence of
the existing artefacts, recognised and accepted in their irreducible complexity and contradictoriness,
with no aspiration in transforming the existing buildings to match a coherent idea of them but trying to
safeguard all the past interpretations already embedded in the body of the monument and the possibility
for future ones [20]. In order to be effective in the safeguard of this legacy, we should overcome the
simple struggle between the extreme terms of the traditional debate. If the choice of ‘how’ to intervene
on existing buildings is a matter of decision, we must assume all the responsibilities about it, renouncing
to invoke metaphysical or legal reasons in order to diminish the role we play in determining the real
impact of our ideas and proposals. [26]. Material conservation, minimization of impacts, protection of
the landscape are the indispensable objectives of any new intervention. Whatever the attitude to critical,
stylistic or conservative restoration we can identify criticalities connected to impacts on historical,
landscape and environmental context, substantially summed up below: (i) visible intrusion, given
recipient chromatic characteristics, their shape, reflecting surface (generally contrasting with
morphological surfaces, matter and already existing colours); (ii) modification of soil structure, minute
territorial soil formation, vegetation etc.; (iii) replacing of existing materials and loss of matter
characteristics in traditional architectural presence; (iv) alteration of social perception of the places. On
these critical points, together with the results of previous investigation on legislative framework, the
identification of acceptable criteria could be based [19].
3. IDENTIFICATION OF A SET OF CRITERIA AND BIPV APPLICATION IN CASE
STUDIES
The compatibility criteria for architecture and landscape safeguarding, considering factors affecting the
visibility and impacts, could be sub-divided into: (i) “localizing” (focusing on territorial vocations,
panoramas, building and morphological characteristics of the network but also on the real conditions of
minor building preservation); (ii) “quantitative” (depending on whether it is a question of isolated
systems or repeatable/groupings, considering, hence, the question of scale, with implications for the so-
called cumulative factor); and (iii) “qualitative” (relating to the morphology of the device, its colour, the
possibility to mitigate on the visual impact). The factors affecting “quantity” (surface extent, rapport
with roof, width, height and slope) and “quality” type (shape in relation to the context, colour, texture,
anchoring, arrangement and alignment) are closely interdependent. Hence, compatibility criteria must
be read not so much, and not only, as an independent but as an integrated method as they take into
consideration principally the type of context and its visibility [26]. The first principle in evaluation of
intervention admissibility is the maximum surface extension of the panels on the roof. Roofing rapport
limit (surface of pitched roof/surface of panels) common to most technical regulations is 40% but there
are specific situations with a lower degree of tolerance (15%), with the further indication of the option
of covering only one slope. In small isolated or grouped rural buildings, considering the narrow
dimension of their roof, a dimensional relationship contained to respect 40% would reduce the surface
available for panel installation to limit an energy production – in short totally ineffective! It is, hence,
not unthinkable to propose integrated solutions covering the whole pitched roof, with careful reflection
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on employable materials, colour and panel shape, the way they are positioned, aligned and anchored,
criteria all of a quality nature and, therefore, more difficult to classify. Example of maximum surface
extension interventions are shown in Figure 1 and 2. In any case, elements of a quantity nature are to be
evaluated alongside “scale” and the cumulative effect issuing from repeated intervention on the
landscape, the latter causing greater alteration detection and upsetting proportion equilibria. Effects of
cumulative interventions are shown in Figure 3. As concerns shape, the arrangement of solar panels on
triangular pitched roofs approaches the critical; the roofs poorly adapt to the fixing of a device, or a
group of devices of generally rectangular shape. Consequently, panel-laying may be incompatible,
unless geometrically adaptable shaped panels are employed (“laser cut”); in the case of covering the
entire roof, be it triangular or rectangular, a fringe band of traditional roof covering could opportunely
be left intact. The market today boasts different materials (rigid or flexible panels) and colour schemes
(coloured panes, semi-transparent panes of glass) which constitute a valid alternative for better landscape
compatibility versus traditional photovoltaic panel – the drawback being slow performance and high
cost (Figure 4).
Figure 1: Example on solar BIPV integration in a Glaserhaus, built in 1765 in Affoltern in the Emmental / BE
(CH). Left picture shows the front view of the house from 1765, in the last decades mostly uninhabited before
the renovation. Right picture the illustrates the Plus Energy renovated building using BIPV solar technology in
the roof, where tradition, modernity, sustainability and aesthetics complement each other and significantly
improve the urban landscape (Source: Swiss solar prize 2016 and SUPSI-BFE database)
Figure 2: The 1939 built residence Villa Carlotta in Orselina / TI (CH), was recently renovated. The old oil
heating has been replaced with a 38 kW heat pump solar-powered (BIPV in roof) with six geothermal probes
ranging from 140 to 165 m in depth. The entire 350 m2roof area was equipped with a 51 kW PV system which
covers the total energy requirement 87% (Source: Swiss solar prize 2018)
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Figure 3: MFH-Multi-Family House, SanierunG Feldbergstrasse 4+6 BS (CH). Refurbishment of two houses in
the protected area of Basel-Stadt. The solar roof on the south side provides more energy than is necessary for
heating and hot water (Source: Swiss solar prize 2009, Viridén+Partner AG Zurich)
Figure 4: The Ecuvillens / FR (CH) rural house pilot project, dating back to 1859, uses clay-colored modules
developed by the CSEM and Issol for sites protected by cultural heritage (Source: Swiss solar prize 2018)
The arrangement of the panels in relation to the lay of the pitched roof is another factor to be considered
carefully. As to simple overlapping, it is preferable to select solar device integration with the roof surface
material of the whole pitch, made possible in intervention of complete reroofing. To permit roof
visibility, on the edges of the roof it is advisable to retain a fringe surface strip in traditional material. In
the case of partial pitch covering, another delicate factor affecting the intervention impact is the method
of panel grouping and aligning: care for detail, especially at the junction between panels and roof
covering, remains indeed one of the most delicate aspects in relation to intervention detection.
The application of fortuitous and irregular types should be avoided in favour of solutions retaining or
improving the building’s proportional status freeing, for example, the part of the roof nearest the eaves
and assembling the panels close to the ridge - even if this might contradict some of the technical canons
examined. Co-planarity of the panels to the pitch, referring to alignment, regular shape, grouping and
precision in integrated installation, is another point for roofing panel interaction. When, in the case of
total surface reroofing, elements of small dimensions are chosen (tiles or solar curved tiles, for example)
other factors to be considered besides efficiency (certainly less so than in the case of panels) are the type
of material and texture, in keeping with the method of solar element laying (Figures 5; 6). Available
pitch surface area certainly affects the quantity of the solar or photovoltaic product to be laid and,
consequently, visibility or mimesis; technology, moreover, is making great strides towards the almost
total invisibility of solar cells.
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Figure 5: The refurbishment and addition of new building in the Doragno Castle, Rovio / TI (CH). It uses a BIPV
on the roof (16’000 kWh/y), testing an innovative and sustainable solutions for multifunctional building
envelope to achieve NZE standard, using ST and PV modules (Source: deltaZERO SA Architects, pictures
Luciano Carugo)
Figure 6: Hotel des Associations, Neuchâtel / NE (CH). The building is located in a ISOS protected area. Based
on special and opaque modules, it integrates perfectly with the entire roof surface and preserves the historic
character of the building (Sources: Swiss solar prize 2015).
4. CONCLUSIONS
A first analysis where made to identify compatibility criteria for architecture and landscape
safeguarding, when integrate solar systems in heritage buildings or in protected urban landscapes,
considering factors affecting the visibility and impacts. In parallel, in the growing sector of sustainable
architecture, solar energy represents one of the main challenges that are progressively changing the
building sector with the tangible revolution of solar architecture. The possibilities of new and emerging
solar products, unfortunately not yet well-introduced in the market, thanks to the advanced
customization possibilities (for example, low-reflection and special glasses, colors, patterns, different
shapes and sizes) will offer new opportunities to better insert into contexts of special heritage protection
buildings to preserve their cultural and essential values.
ACKNOLEDGMENT: The research has been co-financed by the European Union (Fondo Europeo di
Sviluppo Regionale), Stato Italiano, Confederazione elvetica and Cantoni, in the Cooperation Program
Interreg V-A Italia-Svizzera for the Project “BIPV meets history. Value-chain creation for the building
integrated photovoltaics in the energy retrofit of transnational historic buildings” (ID n. 603882). The
authors wish to express their gratitude to the IEA SHC and EBC Executive Committees for supporting
the Task59/Annex76.
5. BIBLIOGRAPHY
[1]European Parliament (2018) Directive (EU) 2018/844 of the European Parliament and of the Council
of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive
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Heritage. Guidelines for Improving the Energy Performance of Historic Buildings, British Standard
Institution; Brussels, Belgium, 2017.
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[3]3ENCULT- Efficient Energy for EU Cultural Heritage, http://www.3encult.eu (accessed:
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[4] EFFESUS: Energy Efficiency for EU Historic Districts’ Sustainability. Seventh Framework
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[23] G. Giovannoni, ll restauro dei monumenti, Roma: Cremonese; 1931.
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[24] R. Bonelli, Restauro – restauro architettonico. In Enciclopedia Universale dell’Arte, XI. Venezia-
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... Retrofitting heritage buildings is a complex task where many criteria are weighed against each other, and transiting them towards clean energy utilization needs special attention [2,8]. Accordingly, conservation-compatible energy retrofitting strategies and scenarios that integrate renewable energy resources (RES) utilization in those strategies [9,10] need to be developed. Martínez-Molina et al. (2016) revealed that several energy retrofitting projects and studies in heritage buildings were carried out in cold zones, e.g., the UK and USA, while hot zones, e.g., Libya and Morocco, had few initiatives in this field [11], although climate is an important factor in such contexts since it influences energy use in the achievement of comfort [12]. ...
... The studies also emphasized that the applications of solar energy need lower operating and maintenance costs, and no significant operational pollution is expected [15][16][17]. Both Lucchi et al. (2020) and Polo Lopez et al. (2020) [10,31] are consistent with the work of Salameh et al. (2020 and 2021) [15][16][17] in terms of the importance of the integration of RES, i.e., solar energy applications, to cover demand for energy in existing buildings. Additionally, they pointed out that the applications of solar energy (e.g., photovoltaics (PV) and solar thermal (ST)) can be perfectly integrated with the building envelope components of heritage buildings [10,31]. ...
... The studies also emphasized that the applications of solar energy need lower operating and maintenance costs, and no significant operational pollution is expected [15][16][17]. Both Lucchi et al. (2020) and Polo Lopez et al. (2020) [10,31] are consistent with the work of Salameh et al. (2020 and 2021) [15][16][17] in terms of the importance of the integration of RES, i.e., solar energy applications, to cover demand for energy in existing buildings. Additionally, they pointed out that the applications of solar energy (e.g., photovoltaics (PV) and solar thermal (ST)) can be perfectly integrated with the building envelope components of heritage buildings [10,31]. ...
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Retrofitting "nearly-zero energy" heritage buildings has always been controversial, due to the usual association of the "nearly-zero energy" target with high energy performance and the utilization of renewable energy sources in highly regarded cultural values of heritage buildings. This paper aims to evaluate the potential of turning heritage building stock into a "nearly-zero energy" in hot, dry climates, which has been addressed in only a few studies. Therefore, a four-phase integrated energy retrofitting methodology was proposed and applied to a sample of heritage residential building stock in Egypt along with microscale analysis on buildings. Three reference buildings were selected, representing the most dominant building typologies. The study combines field measurements and observations with energy simulations. In addition, simulation models were created and calibrated based on monitored data in the reference buildings. The results show that the application of hybrid passive and active non-energy generating scenarios significantly impacts energy use in the reference buildings, e.g., where 66.4% of annual electricity use can be saved. Moreover, the application of solar energy sources approximately covers the energy demand in the reference buildings, e.g., where an annual self-consumption of electricity up to 78% and surplus electricity up to 20.4% can be achieved by using photo-voltaic modules. Furthermore, annual natural gas of up to 66.8% can be saved by using two unglazed solar collectors. Lastly, achieving "nearly zero energy" was possible for the presented case study area. The originality of this work lies in developing and applying an informed retrofitting (nearly-zero energy) guide to being used as a benchmark energy model for buildings that belong to an important historical era. The findings contribute to filling a gap in existing studies of integrating renewable energy sources to achieve "nearly zero energy" in heritage buildings in hot climates.
... RES contributions play an important role for achieving these goals in energy renovations of existing buildings, as the legislation requires covering 50% of energy produced for domestic hot water, heating, and cooling by RES [23]. Their implementation in historic buildings, referring both to listed and unlisted buildings with significant elements worthy of preservation and symbol of exceptional cultural significance, has several constrains, mainly related to the aesthetic impact [24][25][26]. In recent or past years, it has been a topic of controversy and interest [1, [27][28][29][30]. ...
... In parallel, the application of RES in architecturally sensitive areas and buildings is studied by several international and national research projects [29,30,[32][33][34][35][36][37][38][39][40][41][42][43][44], demonstrating their technical and economic advantages as well as the compatibility with heritage shapes, features, and values [24]. Several studies demonstrate the feasibility of RES and solar systems integration in historic buildings, documenting their integration in real case studies [25,45,46], which represent an opportunity to gain an overall understanding of solar technologies and heritage preservation procedures and priorities and point out the opportunities and constrains [24][25][26]47]. ...
... In parallel, the application of RES in architecturally sensitive areas and buildings is studied by several international and national research projects [29,30,[32][33][34][35][36][37][38][39][40][41][42][43][44], demonstrating their technical and economic advantages as well as the compatibility with heritage shapes, features, and values [24]. Several studies demonstrate the feasibility of RES and solar systems integration in historic buildings, documenting their integration in real case studies [25,45,46], which represent an opportunity to gain an overall understanding of solar technologies and heritage preservation procedures and priorities and point out the opportunities and constrains [24][25][26]47]. ...
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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.
... Innovative design characteristics of solar technologies nowadays, already in t market (i.e., solar modules with patterns and colours, or that are geometrically adaptab and economically feasible), can enable new possibilities of integration into old building historical sites, the urban space and landscapes [31]. Moreover, the colouring of PV has recently been considered an essential requireme for market acceptance [32,33] and, for the rest, this aspect would allow a better integrati in the landscape and in historical buildings and contexts [34]. Coloured glass, pattern coa ings or printing on front glazing treatments or coverings are new solutions for solar BIP or BAPV (Building Applied Photovoltaics) modules. ...
... Architecture has always been considered the mirror of the civilization, which cr ates it, in continuous relation with the environment. Moreover, the colouring of PV has recently been considered an essential requirement for market acceptance [32,33] and, for the rest, this aspect would allow a better integration in the landscape and in historical buildings and contexts [34]. Coloured glass, pattern coatings or printing on front glazing treatments or coverings are new solutions for solar BIPV or BAPV (Building Applied Photovoltaics) modules. ...
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This paper proposes to identify an approach methodology for the incorporation of building- integrated photovoltaic systems (BIPV) in existing architectural heritage, considering regulatory, conservation and energy aspects. The main objective is to provide information about guidance criteria related to the integration of BIPV in historical buildings and about intervention methods. That will be followed by the development of useful data to reorient and update the guidelines and guidance documents, both for the design approach and for the evaluation of potential future interventions. The research methodology includes a categorization and analysis of European and Swiss case studies, taking into account the state of preservation of the building before the intervention, the data of the applied photovoltaic technology and the aesthetic and energy contribution of the intervention. The result, in the form of graphic schedules, provides complete information for a real evaluation of the analyzed case studies and of the BIPV technological system used in historical contexts. This research promotes a conscious BIPV as a real opportunity to use technology and a contemporary architectural language capable of dialoguing with pre-existing buildings to significantly improve energy efficiency and determine a new value system for the historical building and its environment.
... In [26], a comparison among the installation of building-integrated PV/T air collectors and side-by-side PV modules and solar thermal collectors is presented, whilst in [27] a BIPV/T has been used as the roof top of a building in order to increase the electrical energy per unit area figure and to meet thermal demands. Additionally, ΒIPV systems are noted as an interesting approach for newly built and refurbished residences, because they operate as multifunctional building construction materials (they produce energy and serve as part of buildings envelope) [28][29][30][31][32]. BIPVs are usually used as glazing and windows for transparent openings; moreover, they can be used instead of ceramic tiles on the roofs of buildings. ...
... Both types of building PV products do not require the existence of free building surfaces or free land space for installation, compared to usual residential PV plants. In addition, from an architectural perspective, the ability to add color to PV cells (with the addition of suitable coatings) as well as to PV modules frames, reduces any optic nuisance, allowing the aesthetic integration of PV technology into the shell of buildings [29][30][31][32][33][34]. Additionally, lightweight fibre reinforced composite BIPV and BAPV modules are able to be curved (maintaining high mechanical strength) and thus various surface finishes are possible [28]. ...
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Cost-effective energy saving in the building sector is a high priority in Europe; The European Union has set ambitious targets for buildings’ energy performance in order to convert old energy-intensive ones into nearly zero energy buildings (nZEBs). This study focuses on the implementation of a collective self-consumption nZEB concept in Mediterranean climate conditions, considering a typical multi-family building (or apartment block) in the urban environment. The aggregated use of PVs, geothermal and energy storage systems allow the self-production and self-consumption of energy, in a way that the independence from fossil fuels and the reliability of the electricity grid are enhanced. The proposed nZEB implementation scheme will be analyzed from techno-economical perspective, presenting detailed calculations regarding the components dimensioning and costs-giving emphasis on life cycle cost analysis (LCCA) indexes—as well as the energy transactions between the building and the electricity grid. The main outcomes of this work are that the proposed nZEB implementation is a sustainable solution for the Mediterranean area, whereas the incorporation of electrical energy storage units—though beneficial for the reliability of the grid—calls for the implementation of positive policies regarding the reduction of their payback period.
... The new emerging solar products offer customization possibilities and thereby could provide better possibilities for the integration of solar products in heritage buildings without compromising the aesthetical and heritage value of such buildings [125]. Since the lifespan of solar collectors and PV systems is considerably shorter than that of a building, the removal or replacement of the systems must be taken into consideration during planning and installation [105]. ...
Article
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For heritage buildings, energy-efficient retrofitting cannot be applied with the same range of possibilities as with existing buildings. Applying such improvements to heritage buildings can be challenging due to their historic and/or cultural significance and non-standard construction methods. This paper reviews the technical challenges and potential of applying energy efficient retrofit elements in heritage buildings. The retrofitting measures reviewed are draught-proofing, windows, insulation, ventilation, heating, solar photovoltaics and phase change materials. It is possible to significantly reduce energy use in heritage buildings with such retrofits. However, there is no universal way to apply energy-efficient retrofitting in heritage buildings, which is apparent in the literature, where case studies are prevalent.
... Along this line, several authors affirmed that the renewable energy integration in heritage buildings could be challenging, since the lack of space is often a constraint in the projects of refurbishment [188,190,191]. In the case of BIPV systems (Building Integrated Photovoltaic), the integration of them in heritage buildings depends on: the state of the roof, visual impact and preservation of the structures [192]. ...
Article
It is estimated that EU cultural heritage (CH) buildings represent 30% of the total existing stock. Nevertheless, all actions in terms of refurbishment need a deep knowledge based on the diagnosis of the built quality. For this reason, the paper aims to provide a comprehensive review about the applicability of non-destructive techniques (NDT) and advanced modelling technologies for the diagnosis of heritage buildings. Considering a time span of two decades (2001-2021), a bibliometric analysis was performed, using data statistics and science mapping. Subsequently, the most relevant studies on this topic were evaluated for each technique. The main findings revealed that: (i) most of studies were conducted on Southern European countries; (ii) 36% of publications were journal papers and only 2% corresponded to reviews; (iii) “photogrammetry” and “laser applications” were identified as consolidated techniques for historic preservation, but they are only linked with HBIM and deep learning; (iv) a significant gap on quantitative NDT was detected and consequently, future researches should be performed to propose a common diagnosis protocol; (v) artificial neural networks have several barriers (i.e. data privacy, network security and quality of datasets). Hence, a holistic approach should be adopted by the European countries.
... All system characteristics that influence the building's appearance have an impact on the quality of integration and therefore, should be congruent with the overall design. The assessment of the multiple qualities of the integration of BIPV technologies is, however, not easy to implement, as there are no univocally shared tools to support the (propositional) work of designers, and (evaluative) work of Public Authorities, such as Superintendencies and Public Administrations, especially in the case of listed buildings, with an architectural value or located in historical contexts or with a high landscape value [21][22][23]. Among other things, these criteria, in relation to the concept of qualitative perception, are linked to interpretative and subjective considerations, and therefore always refer to the specific nature of the building or to a broader idea of architecture, typical of a given sociocultural context and a given era. ...
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The scenario that emerges from scientific research on the use of BIPV systems in architecture shows that photovoltaic technologies and systems have reached a significant development in production and installation, becoming a strategic approach in the field of energy efficiency and enabling a progressive decarbonisation of the building stock. Still, knowledge and methods of architectural integration are not fully developed, especially in Italy. The present paper reports the results of a research activity that, systematising the main criteria and indicators for assessing the integrability of BIPVs in architecture, has led to the development of BIPV Product and Case Study Catalogues that define an up-to-date state of the art on aspects of design and technological innovation using BIPV systems and components. Catalogues have been created with the objective of contributing to the growth of knowledge on the most up-to-date methods of design by implementing a ‘technology transfer’ from good practice, in which photovoltaic systems are an integral part of the design concept and construction techniques of the architecture. The analysis related to the production of BIPV systems and components and their application in architectural projects allows one to highlight the main critical factors in the diffusion throughout the country and to identify the main research demand arising from the specific national situation.
... However, national and local guidelines define clear criteria and rules for RES integration, trying to balance preservation and energy efficiency requirements. These guidelines suggest three different criteria [6]: (i) "localising criteria", related to project siting and location; (ii) "qualitative criteria", mainly referring to the minimal intervention on materials, features, spaces, and spatial relationships and to the mitigation of the visual impact, with the correct selection of colours, texture, anchoring, arrangement and alignment; and (iii) "quantitative criteria", driven by system performance (dependent on weather, type of technology, site characteristics, impact of shade, and orientation, tilt angle, surface extension) and economics (related to initial, operating and maintenance costs, availability of incentives, discount and fuel escalation rate). These criteria show different approaches to maintain the balance of preservation, usage of energy sources, and economic and energy cost in different levels. ...
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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.
... However, national and local guidelines define clear criteria and rules for RES integration, trying to balance preservation and energy efficiency requirements. These guidelines suggest three different criteria [6]: (i) "localising criteria", related to project siting and location; (ii) "qualitative criteria", mainly referring to the minimal intervention on materials, features, spaces, and spatial relationships and to the mitigation of the visual impact, with the correct selection of colours, texture, anchoring, arrangement and alignment; and (iii) "quantitative criteria", driven by system performance (dependent on wheather, type of technology, site characteristics, impact of shade, and orientation, tilt angle, surface extension) and economics (related to initial, operating and maintenance costs, availability of incentives, discount and fuel escalation rate). These criteria show different approaches to maintain the balance of preservation, usage of energy sources, and economic and energy cost in different levels. ...
Conference Paper
Full-text available
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.
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Reduction of the carbon footprint of historic buildings is urgent, given their exceptionally large energy demand. In this study, the performance and cost of a roof mounted photovoltaic system has been simulated for Bath Abbey, a grade I listed building, to test the financial viability of installing such a system. The electrical output of the panels was generated by the software package PVsyst with inputs such as the known dimensions of the Abbey, historical weather data, the orientation of the Abbey's roof, module azimuthal and tilt angles and shading by the spire and roof features. An important result is that even though the roof is not shadowed by other buildings, shading causes a 19% loss of peak power. This model was used to determine a recommended configuration comprising 164 solar panels, separated into two subsystems located on two parts of the roof, each with an inverter. Its predicted electrical output, 45 ± 2 MWh generated in the first year of operation, formed the basis of a cost–benefit analysis. This system will become profitable after 13.3 ± 0.6 years and provide a profit of £139,000 ± £12,000 over its 25‐year lifetime. Financial stress tests were performed for key assumptions to ensure that this result was true in all likely scenarios. This result shows that it is likely to make financial sense to install a photovoltaic system on a historic grade I listed building. A model of the grade I listed building Bath Abbey showing solar panels installed on the south side of the nave roof. This model was produced by software that generates a prediction for the electrical energy produced by the system each year. These data show that it makes financial sense to install solar panels on the Abbey roof.
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The need to achieve energy efficiency standards in new and existing buildings has triggered both research and design practice aimed at reducing their carbon footprint and improving their indoor comfort and functionality conditions. In this view, a dedicated scientific effort has to be spent while dealing with historical architectures needing to preserve their key testimonial knowledge into the society. Therefore, tailored retrofit strategies have been investigated and implemented without compromising their architectural value, especially when new uses are foreseen in those buildings. This review classifies different examples of the use of energy efficiency approaches and the integration of renewable energies in historical buildings, including solar and geothermal energy, and the use of heat pumps and other high-efficiency heating ventilation and air conditioning systems.
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When facing a retrofitting project which tries to improve the energy performance of a cultural heritage building it is necessary to weigh carefully different aspects such as: energy efficiency, modernization and comfort. These energy improvements are desirable, but are not always possible without compromises. The situation may become slightly problematic when solar energy systems should be installed in historic buildings. The first step to overcoming barriers successfully, is to better understand the processes for both, historic preservation and solar PV project implementation, and to foster working with professionals in each sector to receive appropriate support and guidance. Establishing an assessment criterion for each step was the top priority of the research project presented here to assist in achieving a successful result.
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Many municipalities, particularly in older communities of the United States, have a large amount of historic buildings and districts. In addition to preserving these historic assets, many municipalities have goals or legislative requirements to procure a certain amount of energy from renewable sources and to become more efficient in their energy use; often, these requirements do not exempt historic buildings. This paper details findings from a workshop held in Denver, Colorado, in June 2010 that brought together stakeholders from both the solar and historic preservation industries. Based on these findings, this paper identifies challenges and recommends solutions for developing solar photovoltaic (PV) projects on historic buildings and in historic districts in such a way as to not affect the characteristics that make a building eligible for historic status.
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The reduction of energy consumption and of polluting emissions as well as the improving of residential standards (potentially contrasting outlooks) are more and more frequently involving the architecturally created environment and landscapes of considerable renown - initially excluded from obligatory compliance with existing regulations. Conflicts tend to increase in such circumstances, since technical knowhow must aim at reconciling with objectives of a more widely cultural nature (safeguarding of and respect for the environment, authenticity of material and identification of built heritage). The experience of the research presented refers to a particularly sensitive site, placed under the protection of the state and interested international agencies. It is among the most representative of the whole of Italy: The National Park and UNESCO site of the Cinque Terre, Porto Venere and the archipelago of the islands Palmaria, Tino and Tinetto in the extreme east of Region Liguria. The research, both methodological and operative, offers elements useful to the understanding and solution of issues relating to the recovery of simple rural buildings and the improvement of thermal performance and energy supply, especially on sites isolated from network installations. Particular in-depth study is dedicated to 1) identification of criteria to better integrate solar technologies for energy production in rural buildings, for end consumer utilization (owners and technicians), as well as 2) local government and safeguarding agencies called upon to evaluate acceptability.
Book
This book provides a methodological framework to set properly the thermal enhancement and energy efficiency in historical buildings during a renovation process. It describes the unique thermal features of historical properties, closely examining how the building materials, structural elements, and state of conservation can impact energy efficiency, including sample calculations and results. It also describes means and aims of several fundamental steps to improve energy efficiency in historical buildings with an experimentation on a case study. This timely text also introduces leading-edge technologies for enhancing the energy performance of historical buildings, including the potential for integration of co- ad tri-generation though micro-turbines, photovoltaics and solar collectors and their compatibility with architectural preservation. • Discusses the unique considerations for energy efficiency that are necessary when planning preservation and update work on historical buildings; • Provides tools to help undertake such projects, including methodological frameworks, sample calculations, and the results of technical feasibility studies; • Includes one complete case studies from work recently conducted on a listed building.
Chapter
New challenges in contemporary age are facing the discipline of architectural restoration. These challenges do not mean that the traditional questions and issues have been definitely solved or that they have lost their relevance: the problems of “why?” and, consequently, of “how” to intervene on existing architectures maintain their actuality. In the same time, some new and additional reasons to affirm and pursue the safeguard of our built environment have come to the fore. Among them we may highlight: the informative potential of ancient architecture, from which we can derive several interesting lessons about smart technological solutions to build in a more ecological and respectful way for the environment and the limited resources of our planet; the need for sparing resources (economic, energetic, territorial, human, social, environmental) because of the energetic crisis and the fragile ecological situation of the Earth. The essay proposes a deep reflection around theoretical and methodological issues on the terms conservation and restoration.
/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency (Text with EEA relevance)
European Parliament (2018) Directive (EU) 2018/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency (Text with EEA relevance), Official Journal of the European Union.
Energy retrofit and conservation of built heritage using multi-objective optimization: Demonstration on a medieval building
  • F Roberti
  • U Filippi
  • E Oberegger
  • A Lucchi
  • Gasparella
F. Roberti, U. Filippi Oberegger, E. Lucchi, A. Gasparella, Energy retrofit and conservation of built heritage using multi-objective optimization: Demonstration on a medieval building, Building Simulation Applications (2015) 189-197.