Built Religious Heritage, Circular Economy, and Life-Cycle Assessment: A Case Study of a Convent Property in the Province of Quebec, Canada

Abstract

When it comes to the circular economy, studies devoted to religious built heritage focus mainly on the interest of the adaptive reuse of buildings, e.g., recycling a building for new contemporary uses. The present study proposes to go a step further by deploying, for the first time in the literature, a life-cycle assessment (LCA) to a monastery-type religious building located in the province of Quebec, Canada. To this end, this study takes into account the embodied and operational energy consumption and greenhouse gas (GHG) emissions of the building’s entire life cycle, from its construction, in 1907, to the rehabilitation scenario currently under analysis. It also compares this scenario to a new building to determine the best option from an environmental point of view. The article concludes with the importance of using LCA in the context of religious buildings. It also calls for qualitative factors to be taken into account, which could enhance the results of the LCA by better integrating the precepts of the circular economy, in particular the attitudes and coping strategies of occupants with regard to operational energy consumption.

1. Introduction

In the context of the fight against climate change, it is becoming increasingly necessary to work on improving the energy performance of buildings, given that the building sector is a major cause of greenhouse gas (GHG) emissions. With this in mind, the adaptive reuse of buildings, a trend that is gaining in popularity and which postulates that new uses can be assigned to old buildings, becomes a necessary hypothesis for action to consider, insofar as it can lead to environmental as well as economic and social benefits [1].

The adaptive reuse of historic buildings is based on a number of approaches and working methods, which were largely addressed in the scientific literature. These methods can include empirical approaches based on case studies, field measurements, simulations, modelling, literature reviews, and life-cycle assessment (LCA) [2,3,4,5,6,7,8,9,10,11,12]. However, studies that addressed historic buildings of a religious nature using specifically an LCA method are almost inexistant. This gap needs to be filled, given both the scope and importance of LCA methodologies and the scope of historic religious buildings, which constitute a very important part of heritage today [13].

The present article puts forth an LCA methodology to a monastery-type convent property located in the province of Quebec, Canada. This study is based on aspects relating to the building’s embodied and operational energy and GHG emissions, from its construction (1907) to the scenarios currently under analysis of adaptive reuse compared to a new construction (2023–2083). It asks the following questions: What are the embodied and operational GHG emissions of a historic religious building in the province of Quebec? Between two future scenarios for the building—adaptive reuse and new construction—which option is the most environmentally sustainable in terms of GHG emissions? It uses a hybrid approach, meaning that GHG emissions were estimated with the use of standardized hypotheses and historical materials for the historic structure, and that the GHG emissions of the future scenarios were determined using specific software.

This study is naturally in line with the circular economy in its interest in the adaptive reuse of a convent property. But it also opens up analysis perspectives complementary to those provided by LCA, notably by taking into account the attitudes and adaptive strategies of building occupants to modulate their past operational energy consumption. In this way, it adds a qualitative perspective to the quantitative approach of LCA, giving greater scope to circularity practices linked to adaptive reuse.

This article begins with a review of the literature on cultural heritage, religious built heritage, and the adaptive reuse of religious heritage buildings. Next, we present the methodology of this study, namely LCA. Thirdly, we present the results of the case study, the Abbey of the Benedictine Nuns in the city of Joliette, province of Quebec. We conclude with a discussion of the results in terms of the circular economy.

1.1. Literature Review

1.1.1. The Significance of Heritage Buildings: Core Principles

In its distant legal roots, patrimony referred to property handed down from generation to generation. However, since Western modernity (18th and 19th centuries), heritage has acquired a symbolic value and a profound cultural and identity-related significance for various communities, particularly on a national scale [14,15,16]. Not surprisingly, the field of heritage studies today is vast and, so to speak, teeming.

Among the established and recognized approaches to heritage studies is the study of built heritage, based on architecture, architectural history, and urban planning [17,18]. There is also the study of intangible cultural heritage. Defined by the Convention for the Safeguarding of the Intangible Cultural Heritage (UNESCO, 2003) as the living cultural heritage of communities, this type of heritage is based on characterizing the wealth of intangible elements of everyday life, such as languages, customs, and traditions. It lies, among other things, in the hands of specialists in anthropology and history [19].

Finally, it is important to emphasize that much research focuses on cultural heritage, whether tangible or intangible, from the angle of the so-called processes of patrimonialization that lead to the recognition and designation of heritage status. These studies, centered around a critical perspective, essentially help to shed light on the ideological, cultural, and normative contexts that underlie the heritage phenomenon [20,21].

Given the abundance of the literature on heritage, and in particular the critical perspectives that highlight the evolving nature of heritage enhancement, it is hardly surprising that the relationship between the circular economy and heritage is now beginning to be better understood.

To gain a better understanding of the relation between heritage and circular economy as well as various methods used to study them (such as LCA), a literature review was conducted. For this purpose, we used the following databases: Google Scholar, Web of Science, Sofia (the search engine of Laval University Library), Science Direct, and Academic Search Premier. The keywords used were as follows: “Circular economy AND Cultural Heritage”, “Circular economy AND Tangible heritage”, “Circular economy AND Religious heritage”, “Circular economy AND Ecclesiastical heritage”, “Circular economy AND Life-Cycle Assessment AND Historical building”, “Circular economy AND Life-Cycle Assessment AND Heritage building”, and “Circular economy AND Life-Cycle Assessment AND Historic Building”. We excluded research that applied LCA or a circular economy perspective to anything else than the built environment. As for our inclusion criteria, basically, they concerned any article that studied the circular economy in relation to any historical or heritage building (be it religious or not) (see

Table 1. Methodological clarifications regarding our literature review.

Methodological Clarifications
Selected databases (n = 5)	Google Scholar Web of Science Sofia (the search engine of Laval University Library) Science Direct Academic Search Premier
Used set of keywords for Boolean search (n = 7)	Circular economy AND Cultural heritage Circular economy AND Tangible heritage Circular economy AND Religious heritage Circular economy AND Ecclesiastical heritage Circular economy AND Life-Cycle Assessment AND historical building Circular economy AND Life-Cycle Assessment AND Heritage building Circular economy AND Life-Cycle Assessment AND Historic building
Search dates	February to March 2025
Exclusion criteria	LCA applied to anything else than the built environment
Inclusion criteria	Topic: LCA applied to the built environment which includes a circular economy perspective Publication language: English or French Time period: Recent articles (from 2015 until present)
Number of retained articles	21 (see Table 2, Table 3 and Table 4)

). In addition, we must specify that our aim was not to conduct a systematic literature review, but rather to highlight recent development in our field of research in order to better ground our study.

1.1.2. Adaptive Reuse and Circular Economy of Built Heritage

The circular economy is defined by the Ellen MacArthur Foundation as “a system where materials never become waste and nature is regenerated. In a circular economy, products and materials are kept in circulation through processes like maintenance, reuse, refurbishment, remanufacture, recycling and composting” [22]. The vast majority of studies examining the relationship between the circular economy and heritage have approached the subject from the angle of the adaptive reuse of buildings. It consists of the renovation, rehabilitation, and redevelopment of buildings, which also give them modern use. It is aligned with circularity due to the extension of the lifespan of already existing buildings (underlying the idea of reuse), the reduction of land consumption, and the slowdown of the extraction of natural resources that would have been necessary for a new construction [3,23,24] For instance, as stated by Dell’Ovo et al. (2021, p. 1), “the adaptive reuse [of cultural heritage] matches the main points of the circular economy, seen as the sustainable economy, which is aimed at the reduction of natural resource extraction and environmental impact by extending the useful life of materials and promoting recovery, reuse, and regeneration processes” [25].

This approach, which is based on the premise that new contemporary and modern uses of an already existing building can tie in with the preservation of heritage through a process of rehabilitation focusing on built heritage, also draws on largely immaterial and social dimensions, such as the meanings and values given to place [1]. It is therefore very inclusive and promising in terms of the circular economy.

Regarding the papers that tackle the relations between heritage, adaptive reuse, and the circular economy, authors mostly focused on finding the best practices of adaptive reuse [2,8,25,26], on assessing how adaptive reuse and the circular economy could better align with public policies, stakeholders objectives, or investment opportunities [23,25,26,27,28], and on evaluating the relation between the circular economy and the conservation of heritage (such as adaptive reuse) to determine if they are always compatible [3,4,29,30]. In this field, some authors have deployed methodologies of an inductive nature, consisting in identifying fundamental findings of adaptive reuse processes on the basis of specific case studies [2,8,25,26,29,30]. Other researchers have preferred to conduct literature reviews in an attempt to identify and cross-reference variables that are likely to intersect with the circular economy and adaptive reuse [3,4]. Finally, rarer scholars have developed indicator-based research approaches in order to support decision-making processes with regard to the circular economy, from an adaptive reuse perspective [23,27] (see

Table 2. Heritage, adaptive reuse, and circular economy.

Author(s)	Objective(s)	Method(s)	Relation(s) Between Heritage and Circular Economy
Buglione et al., 2025 [2]	To explore “three best practices of cultural heritage adaptive reuse […] to understand in particular their business, financial and governance model and the impacts they generated in their territory” (p. 194).	Case studies of De Hoorn (Belgium), C-Mine (Belgium), and the Catacombs of San Gennaro (Italy). “Semi-structured interviews [were] conducted with the heritage sites/buildings managers, retrieving the needed information to define their adaptive reuse circular model. […] Three main domains were considered to structure the interviews and evaluate the practices: the auto-poietic capacity [capacity of economic financial self-sustainability], the generative capacity [capacity to generate resources] and the symbiotic capacity [capacity of establishing relations]” (p. 195).	“The ‘ideal’ circular model for cultural heritage adaptive reuse should be the achievement of all goals (cultural, environmental, social, economic)” (p. 194). “In De Hoorn, the circular economy was implemented in the recovery of building materials and adoption of high environmental standards for the reused building. […] Similar conditions were observed in C-Mine. […] A slightly different condition is showed in the Catacombs of San Gennaro, where the core business and revenue model are represented by guided visits to the archeological heritage site […]” (p. 219). “Another interesting common aspect observed in the best practices is the capacity to regenerate and ‘beautify’ the surrounding urban/rural areas” (p. 220). “Participation can be seen as one of the most important aspects of a circular and ‘human-centred’ model of cultural heritage adaptive reuse” (p. 220).
Dell’Ovo et al., 2021 [25]	This contribution aimed at “defining a methodological framework where the scenarios of adaptive reuse identified are evaluated by applying a compensatory approach, which will result in a rank of suitability and will assess the opinion of experts and policymakers, detecting their coalition and conflict through the use of the Novel Approach to Imprecise Assessment and Decision Environments (NAIADE)” (p. 3).	The aim of this article was to develop a new methodology. It consisted of three phases: 1. The intelligence phase, which assessed the “current context and conditions that people worldwide are facing due to the pandemic situation caused by COVID-19” (p. 5) and developed four different scenarios. 2. The design phase, which consisted of creating an evaluation framework “divided into two main dimensions, on-site and off-site, and then, further classified considering the aspects of the STEEP analysis, i.e.,, social, technological, economic, environmental and political [to determine factors that affect the building]” (p. 6). This was followed by the application of the NAIADE, which “allows users to evaluate the alternatives starting from a performative matrix considering a technical solution and consider the opinions of stakeholders involved in the decision problem [using a questionnaire]” (p. 7). 3. The decision phase, where “a sensitivity analysis has been performed, as well as a detailed ‘What if’ analysis, which allows users to present different scenarios by changing the level of importance of the criteria” (p. 8). “The methodological approach was tested on a case study in order to evaluate its effectiveness and relevance” (p. 8): the Castello Visconteno in Cusago, Italy (comparison of four adaptive reuse scenarios to determine the most suitable adaptive one).	“The adaptive reuse [of cultural heritage] matches the main points of the circular economy, seen as the sustainable economy, which is aimed at the reduction of natural resource extraction and environmental impact by extending the useful life of materials and promoting recovery, reuse, and regeneration processes” (p. 1). “In the last decade, cultural heritage has represented in the European debate one of the fundamental resources for sustainable development, capable of contributing to the economic growth of the territories in the circular economy perspective” (p. 2). “It is recognized that the conservation and reuse for new functions of the cultural and landscape heritage can have positive impacts on the quality of life and individual and community well-being, contributing to the creation of jobs, the conservation of natural resources, and the revitalization of cities hosting heritage” (p. 2).
Foster et al., 2020 [27]	“This article focuses on a subset of existing building renovations, the adaptive reuse of cultural heritage (ARCH) buildings. Its purpose is to contribute to better alignment between macro-level European Circular Economy (CE) policies with micro-level renovation and management of existing buildings and ARCH. With this aim, the article proposes a new ARCH Circular Environmental Impact Indicator Framework” (p. 1).	The aim of this article was to develop a new methodology. “1. Define the research question [what are the ideal CE environmental indicators for ARCH?], 2. Identify the causal network [European environmental policy micro-to-macro landscape that drives environmental outcomes, measured by indicators], 3. Select the best indicators [the underlying principles of the CE indicators chosen are related to cultural heritage and healthy ecosystems] […] The framework’s indicators were selected based on the literature reviewed by Foster (2020) and Foster and Kreinin (2020). The starting point was the list of most prevalent CE indicators” (p. 4).	“CE indicators for ARCH are examined in the context of the existing and forthcoming decision-making landscape in Europe” (p. 1). “The renovation of existing buildings, including ARCH, is central to achieving climate change, clean energy, resource efficiency and material reduction goals” (pp. 1–2).
Foster and Saleh, 2021 [23]	The ARCH buildings “in Europe’s cities [are] a ubiquitous yet poorly understood segment of existing building rehabilitation. To date, there is no systematic way of characterizing and measuring the investment opportunity at the city or regional level for ARCH. […] The purpose of this article is to propose a solution to this methodological gap […] by developing a novel dataset and aggregate index for identifying which European cities present the best investment opportunities for ARCH” (p. 1).	The aim of this article was to develop a new methodology. “To achieve a methodologically robust and transparent composite indicator, the authors apply the research method of the Composite Indicators and Scoreboards (COIN) Tool developed by the European Commission Joint Research center. […] The selection of the indicators was “guided by the literature review” (p. 2). […] “Following the creation of the Index dataset with the COIN Tool, the tabulated scores of the indicators and dimensions of the 190 cities of the Monitor were analyzed using descriptive statistics in Microsoft Excel [to] measure central tendencies, frequencies, rankings, and variances within the data” (pp. 1–2).	“The key contributions of ARCH to sustainable and circular cities are well established in the literature and are condensed here in four points: 1. ARCH contributes to extending the dynamic lifespan of heritage and slowing the extraction of natural resources and energy for new buildings; 2. ARCH projects can anchor social and economic hubs in cities and actively revitalize them by capitalizing on their local authenticity; 3. ARCH buildings ‘preserve social, cultural, and emotional values’; 4. Refurbishing ARCH buildings (which may have energy efficiency and thermal comfort challenges) is a critical path towards climate change mitigation and adaptation” (p. 2).
Girard and Gravagnuolo, 2017 [3]	“The aim of this paper is to review the current concept of circular economy, linking it with culture, cultural heritage and landscape as fundamental drivers of sustainability” (p. 37).	“Provides an overview of evaluation tools [through a literature review] for the assessment of the impacts of heritage regeneration, drawing a pathway for research on cultural and natural heritage as drivers of sustainable growth” (p. 35).	“It is more and more clear that investments in cultural heritage produce positive impacts in the economic, social, cultural and environmental dimensions. A regenerative development model, as proposed in the circular economy European policy documents, can be achieved introducing culture as one strategic area of investment” (p. 37). “The regeneration of abandoned or underused cultural heritage/landscape realizes operationally the circular economy, reducing land consumption and allowing the preservation of ecosystem services: the reduction of materials use—reducing the need of new land and buildings; reuse and shared use of existing goods with new functions; maintenance of exiting goods (buildings, cultural landscape) ensuring longer life; energy recovery—valorizing the embodied energy and using renewable energy sources; re-creation of value through the use of parts of exiting (ancient, historical) buildings (refurbishing/remanufacturing)” (p. 40).
Gravagnuolo et al., 2025 [8]	“To collect, analyze and make available a large and dynamic set of heritage data for different users, a database of 126 cultural heritage adaptive reuse practices was built: [the CLIC Survey database].” (p. 128). “This article aims to present the methodology and tools used in the CLIC adaptive reuse of cultural heritage to collect, organize, analyze and interpret relevant data on European cultural heritage adaptive reuse practices, to identify good practices, success factors and barriers towards the implementation of the circular model for heritage reuse and regeneration” (p. 129).	“The CLIC methodological approach was based on the analysis of empirical evidence to explore whether and how the experiences of cultural heritage adaptive reuse have been able to turn abandoned heritage/landscape assets into a resource for new jobs, wellbeing, health, social cohesion, regional competitiveness and environmental regeneration—as advocated by all international policy documents and scientific literature […] The CLIC Survey on the adaptive reuse of cultural heritage was designed, developed, tested and implemented to collect useful information on the characteristics and impacts of adaptive reuse practices” (p. 129).	“The CLIC Survey on the adaptive reuse of cultural heritage was launched in 2018 engaging heritage adaptive reuse of cultural heritage, managers and authorities to collect relevant data for the assessment of performances in the perspective of the circular model” (p. 128).
Huuhka and Vestergaard, 2019 [4]	“The purpose of this paper is to present a discussion from a blue-sky perspective that brings together the ideas of CE with heritage conservation theories, in order to analyze when their principles are compatible and when they may contradict one another. The paper works with the concept of circularity and conservation in the context of the built environment and built heritage” (p. 30).	“The work draws from a comparative approach. The paper reviews a body of literature on architectural conservation and CE to establish an understanding on the state-of-the-art for both disciplines separately” (p. 29).	“To implement CE in its highest level in the built environment [including heritage], urban development and construction activities need to be based on the maintenance, repair and adaptation of the existing stock, not on its replacement” (p. 38).
Marika et al., 2021 [28]	1. “This paper focused on the adaptive reuse (AR) approach of underused or abandoned buildings, sites, and areas as a useful practice to generate new values by supporting innovative development dynamics” (p. 2). 2. “Within this framework, the present paper aims at exploring and understanding if and how the most widely used sustainability protocols in Italy (GBC and ITACA), currently address and enhance the practice of AR of underused or abandoned buildings in the broader context of CE. […] There is a huge underutilized and abandoned architectural heritage available within the Italian territory, this paper explores how it can be reused” (p. 2).	The method was separated into three different phases. 1. The intelligence phase—“Collection of materials and analysis of the key themes and tools of this paper (CE, AR, and the sustainability protocols)” (p. 2), 2. the categorisation phase—“An in-depth analysis of the protocols in terms of the proposed criteria and credits” (p. 2), and 3. the synthesis phase—“Provide a framework of results useful to understand the potential shortcomings in the sustainability protocols with respect to the investigated themes” (p. 2).	“The role of the built environment is fundamental to achieving the principles of circularity relating to the entire life cycle of buildings” (p. 1). “CE principles must permeate all stages of a building cycle, transforming the way they are designed and maintained over time by reducing the production of new construction and urban land use” (p. 4). “AR as a key element of the CE concept and in line with the concept of sustainable architecture emerges as a widely growing practice in favour of the three pillars of sustainability. […] From a social point of view, it strengthens the sense of community by promoting the preservation of architectural aesthetics and tangible and intangible values […] The environmental sustainability of the reuse practice lies mainly in the lower consumption of energy and new materials […]. Finally, from an economic point of view, two main benefits can be observed, the economic convenience of reuse compared to demolition and construction of a new building and the positive externality produced on the real estate value of the building itself and adjacent assets” (p. 4).
Nocca et al., 2021 [29]	“This paper is focused on the circular economy model and, in particular, on the functional reuse of cultural heritage as the entry point for triggering circular processes in the cities” (p. 105).	The aim of this article was to develop a new methodology. “The starting point for the proposed evaluation framework is the Level(s) as it is the only officially recognized evaluation tool to date.” (p. 118). “[It] provides a set of indicators to assess the environmental performance of office and residential buildings, considering impacts throughout life cycle. […] [It] is based on six macro-objectives that correspond to the three following different thematic areas: environmental performance for life cycle, health and comfort, cost, value and risk” (p. 119).	“The restoration, rehabilitation and functional reuse of cultural heritage and cultural landscape are part of the circular economy process” (p. 112). “The only more detailed and specific official evaluation tool adopted by the European Commission (in collaboration with various stakeholders, including different producers, associations and organizations) in the context of the circular economy is the Level(s), a tool referring only to the construction sector. Level(s) provides a set of indicators to assess the environmental performance of office and residential buildings, considering impacts throughout its life cycle” (p. 119)
Pintossi et al., 2023 [26]	“Numerous challenges hamper the [ARCH]; however, they lack a theoretical framework, and their identification is mostly case study based. To address this gap, the article aims at determining the common challenges to the ARCH from the stakeholders’ perspective with a comparative study” (p. 2).	“This research performed a multiple-case study comparing at multiple scales the cities of Amsterdam in the Netherlands, Rijeka in Croatia, and Salerno in Italy” (p. 3). “To [collect the data and] identify the challenges to ARCH, a series of three stakeholder engagement workshops was organized, one in each city” (p. 3). “The collected data was analysed by content analysis” (p. 5).	“The role of heritage within circular economy and circular cities is receiving attention. Prolonging the life cycle of cultural heritage through conservation, e.g., by reuse, aligns with the circular economy purposes of closing or slowing resource loops, reducing consumption of resources, and preventing waste production” (p. 1). “ARCH benefits the environmental, social, cultural and economic dimensions of sustainable development. For example, it can prevent/reduce the production of demolition waste, conserve the embodied energy, retain the heritage attributes and values, reduce costs at times, generate employment, prompt transit-oriented growth and contribute to placemaking” (p. 2).
Rudan, 2023 [30]	“To determine the willingness and ability of a local community [local administration and self-government, entrepreneurs, population, and destination management] to recognize the value of cultural heritage, and create new value based on the principles of a circular economy” (p. 2).	“This paper used the analysis of case studies of historical heritage that has been renovated and repurposed for the function of cultural attractions that draw tourists, but certainly local residents as well” (p. 6) in the Kvarner tourist destination in Croatia. “For each case study, the research focused on the information available to the local population and tourists about projects involving applied adaptive reuse, as well as their visibility in the tourism offer” (p. 6).	“The concept of circular economy encouraged the restoration and reuse of cultural and historical heritage, which is a valuable resource in the development of the cultural offer of tourist destinations” (p. 12). “Adapted cultural heritage can be used for various purposes, including tourist and cultural (interpretation centres, catering facilities, accommodation facilities, museums, libraries, etc.)” (p. 12). “Destination development needs to be defined on circular economy principles, with the aim of achieving sustainable tourism” (p. 12).

). While these methods are sufficient to meet the objectives of the previously mentioned research, for instance, to evaluate the best practices in the adaptive reuse of cultural heritage [2,8,25,26], they do not allow for assessments of the environmental impact of the studied building throughout its life cycle, from the construction of the historical structure until its transformation.

1.1.3. Adaptive Reuse and Circular Economy Specifically Applied to Religious Heritage Buildings

Few studies have been devoted directly to religious heritage in relation to adaptive reuse and the circular economy. However, those that are available focused on exploring the potential of historic structures to accommodate new functions, while aligning with the circular economy [24,31], on analyzing how the management of a historic building perceived the circular economy [32] and on identifying the challenges of adaptive reuse [5]. Their methodologies are divided between the first two branches mentioned in Section 1.1.2. On the one hand, Mutmainah et al. (2024), Lo Faro and Miceli (2021), as well as Disli and Ankaraligil (2023) [24,31,32] have used case studies to illustrate the benefits, issues, and challenges associated with the circularity of adaptive reuse. On the other hand, Popescu and Staicu (2022) [5] preferred to deploy a literature review (see

Table 3. Religious built heritage and circular economy.

Author(s)	Objective(s)	Method(s)	Relation(s) Between Heritage and Circular Economy
Disli and Ankaraligil, 2023 [24]	1. “To investigate the contribution of historical architectural solutions and functional systems that have already been designed using passive methods and to explore their potential for adaptation to contemporary structures” (p. 1), 2. “To present the degree of circularity and the contribution of historic buildings to the circular economy” (p. 2).	The aim of this article was to develop a new methodology. “This study proposed a method to determine the contribution of existing historic buildings to the circular economy” (p. 4). 1. The circular economy information [was] collected from the literature and the data obtained during the field study [of the Yakub Celebi Complex—The Great Mosque, Turkey] were analyzed together to determine the contribution of historic buildings to the circular economy” (p. 4). 2. “A score table was created according to certain criteria [e.g., growth and resource utilization, closed loop, increased efficiency]” (p. 4) 3. “[The score table] was tested on the historic mosque” (p. 4).	“In addition to their heritage value, historic buildings also contain functional systems consisting of heating, cooling, ventilation, lighting, cleaning and wastewater systems, and roof and surface drainage systems, depending on the purpose and user for which they were designed. […] When they provide optimal conditions, they also extend the life of buildings and contribute more to the circular economy” (p. 1). “The circular economy has become a key factor in the sustainable management of cultural heritage in the last decade, especially in developed countries, and the number of studies on cultural heritage and the circular economy has increased greatly” (p. 3). “The idea of reuse is at the heart of the existing built heritage” (p. 3). “The preservation and reuse of historic heritage is an economic solution to the use of materials, resources, and land. It also provides social sustainability by providing information about the past to those who work in historic buildings and their occupants/users. Consequently, cultural heritage plays an active role in the transition to circular economy” (p. 11).
Lo Faro and Miceli, 2021 [31]	“To focus on the role of [religious] heritage in promoting social sustainability: in order to do so, a high degree of preference has been granted to new uses that appeared to be more socially valuable in terms of increasing engagement among different communities and promoting positive social values” (p. 7).	The aim of this article was to develop a new methodology. 1. Recollect “all the information—history, dimensions, constructive techniques and materials, conservation status, decays—to be critically discretized, systematized and represented in order to support accurate levels of reading in the following steps” (pp. 6–7). 2. Diagnosis—“define a plan of non-destructive analyses such as infrared thermography, sonic and ultrasonic methods, radiography and moisture measurements” (p. 7). 3. Interview selected interlocutors to detect “the needs that the community perceives as the most relevant, and therefore, addressing those needs in a renewed function” (p. 8). 4. Apply the methodology to “some case studies with the proposal of new uses for former ecclesiastical buildings [the Capuchin Convent of Villagonia, the Convent of the Friars Minor in Grammichel, the Convent of San Francesco in Troina, Italy]” (p. 8).	“High quality conservation projects preserve cultural heritage and community values at the same time” (p. 5). “The aim is to raise awareness and sensibility that supports public administrations, religious institutions and private investors in designing appropriate interventions with the purpose of exploiting the value of the asset, particularly according to the social dimensions of sustainability, and supporting virtuous processes of circular economy” (p. 5).
Mutmainah et al., 2024 [32]	“To analyze how mosque [a heritage building] management understands the concept of circular economy and mosque empowerment programs that have been carried out so far” (p. 5). To “propose a model for optimizing mosque-based circular economic empowerment to achieve a sustainable economy” (p. 5). Empowerment means that in addition to worship, mosques also offer cultural, historical, and tourists experiences to the community.	“This study used a qualitative approach with descriptive analysis through observation and interviews” (p. 8) with the case studies of the Great Mosque of Al Jabbar Bandung and the Great Mosque of Tasikmalaya City, Indonesia.	“It is hoped that optimizing the empowerment of a mosque-based circular economy can create a sustainable economy, not only for the current ummah but also for the ummah in the future” (p. 21). “The reuse of existing mosque facilities and infrastructure can be optimized so that they can provide added value that can create jobs or improve the welfare of the people through joint programs with the local government, community, and universities” (p. 21).
Popescu and Staicu, 2022 [5]	“The aim of this research is to establish an understanding of the challenges of adaptive reuse and to identify how the circular economy practices are already embodied in this practice” (p. 40).	“Literature review related to religious sites revival with adaptive reuse technique. Through a review of 23 papers and studies published in the past 30 years, the authors seek to showcase the challenges met in adaptive reuse for religious sites and the circular economy practices embodied in the process” (p. 40).	“Many papers recognize that adaptive reuse of religious heritage is facing more challenges than opportunities, and when it comes to circular economy practices in adaptive reuse, there are rare and connected only to materials reuse and energy efficiency” (p. 46).

). While these articles make a valuable contribution to the relation between adaptive reuse, the circular economy, and religious heritage buildings, they do not comprehensively assess the GHG emissions from the construction of the historical structure to the adaptive reuse scenario, as we aim to do in the present research.

1.1.4. Life-Cycle Assessment (LCA): A Method to Measure the Environmental Impact of Adaptive Reuse of Heritage Buildings

To meet the shortcomings mentioned in the above section, the LCA method has started to flourish in the context of the adaptive reuse of historic buildings. Some authors used LCA to account for the embodied carbon in a building in order to reduce GHG emissions. For instance, Mahmad et al. (2024), Huang et al., 2024, as well as Wise et al. (2019, p. 8) conducted literature reviews to expose the relevance of this consideration [33,34,35]. The latter put the emphasis on the fact that “embodied carbon affects the best retrofit choices for heritage buildings and should be [more] considered in these projects” [34].

More globally, LCA was used in order to study the environmental impacts of buildings in terms of the carbon footprint, among other things, in relation to the structural transformations made to buildings over the years. Some authors focused on the entire building [6,7,36,37], while others put the emphasis on a specific part (e.g., wall thermal insulation, finishing materials, etc.) [38,39]. As

Table 4. Life-cycle assessment (LCA) applied to circular economy of historic buildings.

Authors	Objective(s)	Method(s)—Life-Cycle Assessment (LCA)	Circular Economy (CE)		Period	Type(s) of Historic Building(s)
			Principles Applied to the Built Environment	Use of LCA
Angrisano et al., 2021 * [38]	“To understand how historic buildings’ energy retrofit projects [can contribute to decarbonization and resource conservation while focusing on walls’ thermal insulation]” (p. 1).	“Evaluates an energy retrofit project with the case study of Villa Vannucchi” (p. 1) in San Giorgio a Cremano, Italy. Compares various materials for walls’ thermal insulation using LCA.	“The circular economy for the built environment follows some specific actions: encourage optimization of resources and materials, support the reuse of existing assets and recovery of materials, support longevity through design for modularity and flexibility, support rigorous waste segmentation and treatment and design for deconstruction, and embed the use of LCA and lifecycle costing in the sector” (p. 3).	To assess “different design scenarios […] [that] can be of high utility to designers to compare and choose efficient solutions for the sustainable/circular renovation of historic buildings” (p. 1).	60-year period	A current university that was a former residential building
Bonoli and Franzoni, 2019 [39]	To evaluate the sustainability of conservation interventions on historic buildings while “focusing on the finishing materials currently used in this kind of intervention, namely coarse and fine mortars and paints” (p. 2).	Compares “alternative mortars and paints for the rendering of historical buildings during repair and retrofitting works” using LCA (p. 3).	“Conservation and ‘re-manufacturing’ represent a correct approach to reduce buildings’ impacts in a circular economy perspective” (p. 1).	To evaluate the sustainability of conservation intervention that could reduce the buildings’ impacts in a circular economy perspective.	N/S	Historical buildings in general
Foster, 2020 * [6]	To explore the benefits of extending the useful lifespan of cultural heritage buildings.	Four phases that consisted of the following: 1. Conducting a [systematic] literature review, 2. selecting a CE framework appropriate to the topic, 3. defining the phases of the buildings life cycle that best reflects the elements of the industry and possible interventions to realize a CE model, and 4. synthesizing discreet intervention from the literature according to the new model (p. 3).	“Circular economy is a production and consumption process that require the minimum overall natural resource extraction and environmental impact by extending the use of materials and reducing the consumption and waste of materials and energy. The useful life of materials is extended through transformation into new products, design for longevity, waste minimization, and recovery/reuse” (p. 2).	To define the life-cycle phases of a building’s lifespan to “facilitate mapping CE strategies as interventions/practices at each phase” (p. 5).	N/A (a literature review, not a case study)	N/A (a literature review, not a case study)
Fufa et al., 2021 [36]	“To provide a holistic picture of refurbishment and adaptive reuse of existing buildings (including buildings with heritage values, seen from an [LCA] perspective” (p. 1).	Case studies of 4 Norwegian refurbishment projects, namely a residential building and three office buildings: 1. Villa Dammen, 2. Powerhouse Kjørbo, 3. Bergen city hall, and 4. Statens bygg Vadsø. LCA was used on these buildings considering both their materials and their energy used.	“Three core elements of circular economy [applied to the built environment]: 1. Prioritize regenerative resources (reuse, reduce, rethink), 2. Service life extension (reuse, repair, refurbish, remanufacture) and 3. Use waste as a resource (repurpose, recycle, recover)” (p. 12).	To evaluate the environmental performance of existing buildings while applying circularity principles (refurbishment and adaptive reuse).	60-year period	Residential and office buildings
Gravagnuolo et al., 2020 * [7]	To “test the LCA methodology for the evaluation of environmental impacts of historic buildings towards a circular economy approach and promote the adaptive reuse of cultural heritage [which could be a better environmental option than new constructions]” (p. 241).	Case study of the ex-Monastery of San Pietro a Maiella e San Giacomo in Salerno, Italy. Compares two scenarios using LCA: “A. Maintenance of the building in the current state vs. B. Retrofit and reuse intervention” (p. 255).	The LCA that considers greenhouse gas emission through the entire life cycle of a product is in line with the circular economy approach that “strives for the reduction of natural resources depletion and greenhouse gas emissions through reuse, repair, refurbishment of existing products and buildings” (p. 243).	To evaluate the environmental impacts of historic buildings towards a circular approach and promote the adaptive reuse of cultural heritage.	60-year period	Religious buildings (a monastery)
Hu and Swierzawski, 2024 [37]	To empirically quantify the “adaptive reuse benefits across five impact categories using a historical edifice in Zabrze, Poland as a case study” (p. 1).	Case study of a former elementary school in Zabrze, Poland. 1. “Create two BIM models using Autodesk Revit to represent the historical building and the adaptive reuse project separately” (p. 6). 2. Perform an LCA analysis using the software Tally. 3. Calculate the environmental impact using the two LCAs from the second step.	The adaptive reuse is “not only a conservation tactic, but also […] a viable alternative to new construction, reflecting its alignment with sustainability and circular economy principles” (p. 3).	To calculate the environmental impacts of the two BIM models to measure efficiency of adaptive reuse (in a circular economy perspective).	N/A	Educational building (a former primary school)

* These articles elaborate extensively on circular economy. As for the others, circular economy is only briefly mentioned.

illustrates, LCA studies applied to historic buildings essentially address circularity by taking into account the environmental impacts associated with adaptive reuse, retrofitting, and rehabilitation, which highlights the recycling and perpetuation of buildings [6,7,37]. Therefore, while adaptive reuse supports the principles of circularity, LCA allows for measuring the environmental impact of this practice and comparing it to other scenarios in the construction industry, such as a new building.

As seen in the previous tables, there is a scarcity of research that has attempted an LCA approach applied specifically to religious heritage buildings, and even less that considered both the past emissions of the historical structure and future reuse scenarios. The one that is the most related to our research is by Gravagnuolo et al. (2020) [7]. These authors applied LCA to a historic building of a religious nature, a disused monastery in Salerno (Italy). Their robust approach focuses on the embodied energy that has been injected into the building, essentially through the construction materials. The current article goes a step further, taking into account the embodied and operational carbon in an LCA perspective, which was also applied to a conventual property.

According to the objective of this article, the next section presents the methodological approach of the LCA of a religious heritage building, based on the case study selected. This LCA is intended to document the carbon footprint of the building throughout its entire life cycle. In other words, it encompasses both the building’s past, a conversion scenario, and its comparison to a new use scenario, from a carbon balance point of view, which is directly in line with a circularity perspective.

2. Materials and Methods

2.1. Life-Cycle Assessment: Theoretical Principles

LCA quantifies the environmental impacts throughout the life cycle of a specific product, from the extraction of the resources used to make it to its end-of-life. When applied to buildings, this method allows for comparing different scenarios or strategies in addition to playing a key role in decision-making related to material impacts and energy performance. These scenarios can involve, for instance, the adaptive reuse of a historical building or its demolition followed by new construction, to determine the best environmentally friendly option [40,41,42,43].

LCA allows for the presentation and comparison of various quantitative data on environmental impacts during the life cycle of buildings. More specifically, it consists of listing the materials used in constructive assemblies and the energy consumed by the building during its life cycle. The results help to quantify various categories of environmental impacts such as global warming potential, acidification potential, eutrophication potential, ozone depletion potential, photochemical ozone creation (smog) potential, use of nonrenewable energies, and consumption of fossil fuels. In our research, we focus on the global warming potential, which consists of the mass of greenhouse gas emitted (such as carbon dioxide, methane, and nitrous oxide) in tons of CO₂ equivalent [36,40,41,42,44].

Two main elements are included within LCA: embodied greenhouse gas (GHG) emissions and operational GHG emissions. Embodied GHG emissions represent the environmental impacts associated with the tangible elements of a building, from the extraction of materials to their end-of-life, including transportation. Each material has a CO₂ equivalent coefficient, for example, the production and installation of concrete emit much more than that of wood. As for operational GHG emissions, it encompasses the energy used for heating, cooling, lighting, ventilation, and other mechanical systems during the building’s use phase. The environmental impact of operational GHG emissions depends on the energy source. For instance, natural gas has a higher CO₂ equivalent coefficient than that of electricity, if one considers that in Quebec, the use of hydroelectricity predominates [40,45,46,47].

The phases in LCA calculation are universally defined, but their extent may vary slightly depending on the methodology, whether cradle-to-gate or cradle-to-grave. The first phase is the production of materials, which includes the energy required for extracting raw materials (A1), transportation to the factory (A2), and the fabrication of construction materials (A3). The second phase involves the construction of the building, which includes the transportation from the factory to the site (A4), and the energy used during construction (A5). The third phase is the building’s utilization, which includes the embodied GHG emissions of the installed product in use (B1), maintenance of the building (B2), as well as periodic repair, component replacement, and refurbishment (B3; B4; B5). To these can be added the operational energy use (B6) and the operational water use (B7). The fourth phase is the end-of-life, which involves GHG emissions during demolition (C1), the transportation of materials to have them recycled, reused, or incinerated (C2), the collection and sorting of waste up to landfill (C3), and their elimination (C4). The last phase is the recycling of specifically aluminum and iron (D) [40,43,48,49,50].

It is possible to use software to facilitate LCA calculations, such as the Athena Impact Estimator for Buildings (IE4B v5.5). This software, developed by the non-profit research group Athena Sustainable Materials Institute, aligns with North American Standards and complies with both ISO and EN methodologies. By entering the assembly quantities of the various materials inventoried in a building, the software generates results related to multiple environmental impact parameters. Athena calculated the embodied and operational GHG emissions (in CO₂ equivalent coefficient) for the life cycle of a building using regionalized data. This means that the software offers data about fifteen Canadian and American cities, such as Montreal and Quebec, and estimates their probable energy sources based on their location. For instance, for cities within the province of Quebec, it assumes buildings are powered by hydroelectricity. Using a similar approach, it determines the potential transportation mode, estimates average travel distances, and suggests appropriate manufacturing technologies [40,46,49,51,52,53,54].

2.2. LCA of a Historical Building

In this article, we first estimate the GHG emissions of a historical building using LCA applied to standardized hypothesis, databases, and historical research. After, still using LCA, we compared the emissions of a potential adaptive reuse scenario to a new construction scenario using Athena software (IE4B v5.5). Due to the combination of these methods, our approach can be qualified as hybrid.

Regarding the LCA of the historical building, the method used consisted of several steps to calculate both the embodied and the operational GHG emissions of the Abbey of the Benedictine Nuns in Joliette from 1907 to 2023 (see Section 3 for description of the case study). Regarding the embodied GHG emissions, we first quantified the various materials used in the construction of the building. To do so, we used a 3D model of the Abbey developed with Rhino software (v.7). This model allowed us to obtain the total volume of each material used in the construction. Second, a list of all materials was entered in an Excel Spreadsheet, and a carbon coefficient was determined to convert their GHG emissions into the CO₂ equivalent (it is not possible to use LCA software for historical materials). For materials where the carbon coefficient might be similar between past and present, the Athena coefficient was used. However, for other materials, complementary sources were consulted, such as various databases (see

Table 5. The method used to calculate the embodied GHG emissions of historical buildings.

Examples of Materials	Examples of Documentary Sources	Used Software
Mortar	ICE v3.0 Database	Rhino modelling + Excel calculations
Rubble stone	ICE v3.0 Database
Reinforced concrete	Consider the average proportion of steel in reinforced concrete based on One Click LCA

) [40,55]. It should be noted that these sources must be used with caution and be supplemented with historical knowledge. For example, we know that, for rubble stone, proximity to the raw material was an important criterion for past constructions. So, it probably was transported from a local quarry by animal traction or rail transportation to the construction site. Based on this information, we can conclude that the CO₂ coefficient of ancient rubble stones might be lower than that of contemporary rubble stones [40].

For the operational GHG emissions, a software was used: RetScreen Expert—Professional—version 9.0.0.94, developed by Natural Resources Canada. The software allows users to input various parameters detailing a building’s characteristics in order to simulate its energy consumption under predetermined operational conditions. As for other data such as climatic information, those used are contained in the software’s database. They include results from decades of data collected from multiple locations across Canada. For the studied buildings, the closest meteorological station is selected to ensure data accuracy [40,56,57]. As mentioned earlier, before using the software, we must determine the building’s operational conditions.

The occupation and operation of buildings in the past greatly varied depending on the building’s type and the specific historical period. Based on a historical review, we determined that the heating method switched to fuel oil in the 1950s and to gas around 1995. The surrounding temperature was established in a similar manner. When wood or coal was used for heating (prior to the 1950s), an indoor operative temperature of 17 °C was assumed. In the period when fuel oil became predominant, an indoor operative temperature of 18 °C was considered.

The difference of one degree Celsius between the two operational temperatures is due to the higher calorific value of fuel oil compared to coal. However, the estimation of the operational temperature is not arbitrary; it is based on a qualitative approach and supported by an empirical study. For the period spanning from 1908 to 1937, we investigated on three occasions the perceptions of the thermal sensation of the occupants of the Abbey of the Benedictine nuns in Joliette, using archive documents, namely the Annals. The Annals constitute a kind of daily logbook of community life and of the various events associated with it. From the thermal perceptions written in these archives, we were able to assess the thermal sensation vote (TSV). This is defined as a subjective index that measures the actual thermal sensation of individuals and grades them on a seven-point scale ranging from −3 (cold) to +3 (hot) (see

Table 6. The seven-point scale of the thermal sensation cote (TSV). Refs. [58,59,60,61,62,63].

Seven-Point Scale	Thermal Sensation
−3	Cold
−2	Cool
−1	Slightly cool
0	Neutral/Comfortable
+1	Slightly warm
+2	Warm
+3	Hot

). Having these data in hand, it was possible to estimate the operational temperature of the building using the predicted mean vote (PMV) equation or psychrometric chart (such as the CBE Thermal Comfort Tool) [58,59,60,61,62,63,64]. The PMV is defined by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) as a model that “predicts the mean value of thermal sensation votes of a large group of persons, expressed on a seven-point scale” [65]. Usually, it is possible to calculate the PMV using objective data (operative temperature, air speed, humidity, clothing insulation, and metabolic rate) [58,63,65]. In the present case, because we were able to estimate the TSV based on thermal perceptions written in archive documents, we were also able to estimate the PMV. Having in hand all the aforementioned objective data, except for the operative temperature (linked to the operational temperature), it was possible to infer it.

One of the major points of circularity is to take into account not only the building’s relationship with its environment, but also the attitudes and strategies adopted by its occupants with regard to operational energy consumption (see discussion for more details). In this respect, the empirical study carried out at the Joliette monastery demonstrated that part of the occupants’ thermal sensation was modulated by strategies aimed at coping with fluctuations in the building’s operational temperature during the winter season, using adaptive strategies to modulate thermal sensation by increasing clothing or exposure to sunlight near windows, all to compensate for deficient heating systems or the frequent shortage of coal. The circularity of such adaptive practices is reinforced, in the case of clothing, by the fact that the occupants’ garments were essentially made on site, relying in part on local and regional resources (the textile industry was very present in several localities in the province of Quebec, including the town of Joliette in the early 20th century).

To go back to the calculation of operational GHG emissions, the outdoor temperature used to determine the heating period followed the same pattern as that for the indoor temperature. For other energy consumption, such as lighting, it was only taken into account for the modern period, while other parameters were not considered, such as ventilation systems or hot water consumption. As a complement to these standardized hypotheses, historical materials were used, such as archives (see

Table 7. The method used to calculate the operational GHG emissions of the historical building.

Operational GHG Emissions	Examples of Documentary Sources	Used Software
Building envelope	Historical research to determine the insulation capacity of past envelopes	RetScreen modelling (9.0.0.94) + Excel calculations
Energy and heating system	Visits of historical buildings and archival research (plans, submissions, health records)
Ventilation	Not considered for simplification purposes
Lighting	Considered only with the arrival of fuel oil for heating (estimated around the 1950s)—Based on statements obtained for a specific historical building, namely Chambord church.
Other electric charges	Considered only with the arrival of fuel oil for heating. Average of 200 W.
Hot water	Not considered for simplification purposes.
Air conditioning	Not considered for simplification purposes.

). Finally, with this information at hand, energy modelling was made for the studied building with RetScreen.

As could be seen with our method, it is more difficult to estimate the past GHG emissions of a historic building as we cannot use LCA software such as Athena due to technical limitations, meaning that it does not calculate historical materials. We had to rely on another method based on a standardized hypothesis, databases, historical research (such as in the Annals), and Excel calculations. Therefore, we reached the same limit as Bin and Parker (2012, p. 30) [48], who used a similar approach, meaning that “the coefficients of embodied […] carbon come from multiple sources; thus, inaccuracy and inconsistency exist. However, using these sources seems to be the best solution because there is only poor documentation of LCAs for particular products and processes of old [buildings]”. Iyer-Raniga and Wong (2012) [66] also assessed a similar constraint using a bill of materials to document the past embodied energy of heritage buildings. Perhaps these shortcomings could favor new constructions due to the ease of calculations, but we believe that such a possibility would overlook a way to have greener buildings.

2.3. Comparison Between the LCA of the Adaptive Reuse of a Historical Building and of a New Construction

2.3.1. The Adaptive Reuse Scenario

In one of our studied scenarios, we extend the lifespan of the Abbey of the Benedictine Nuns in Joliette by giving it a new use, which can be referred to as the adaptive reuse scenario (considered from 2023 to 2083). This building could serve many new functions including artistic, cultural, leisure, and tourism-related activities. For instance, it could house creative studios, a multipurpose hall, an exhibition space, a café restaurant, workshops, and artist residencies (see Section 3). However, before acquiring these new functions, architectural interventions should be conducted, such as new partitions and extensions. Some elements might also have to be demolished (see

Table 8. List of materials to be entered in Athena IE4B to calculate the embodied GHG emissions for the adaptive reuse scenario.

Typology of Design—Fully Glazed Exterior Walls	List of Assemblies
Concrete footing (S1) and concrete slab (P1 and P2)	S1—0.4 m width, 200 mm thick, 85 kg/m3 frame, 30 MPa P1—100 mm concrete, 30 MPa, 50.762 mm (2″) extruded polystyrene, 6 mil polyethylene membrane P2—Uninsulated concrete slab, 100 mm concrete, 30 MPa
Steel column and beam structure in I-Beam profile
Exterior walls in glazed curtain walls, with glazed aluminum-framed exterior doors (MR)	MR—Approx. 90% glazed, metal tympanum, fiberglass 5.5″
Steel stud interior walls, with hollow-core wood interior door (C1)	C1—Latex paint, regular gypsum of 5/8″, steel stud non-load bearing, spaced c/c every 400 mm (16″), heavy (20 Ga), 39 × 152 mm, regular gypsum 5/8″, latex paint
Steel stud exit walls, with steel interior doors (Cx1)	CX1—Latex paint, 2 regular 5/8″ gypsum, steel studs non-load bearing, space c/c 400 mm (16″), lightweight (25 Ga), 39 × 92 mm (1 5/8 × 3 5/8″), 2 regular 5/8” gypsum, latex paint
Open-web steel joist floors (P3)	P3—With concrete screed, 5/8″ regular gypsum, latex paint
Open-web steel roof (T1)	T1—Standard double-layer bituminous membrane, for slope: polyiso panel with 3″ (76.143 mm) fiberglass coating (0 to 6″ to create an average 3″ slope), 6″ (152.286 mm) polyiso board with fiberglass coatings, without concrete screed, 6 mil polyethylene vapor barriers, 5/8″ regular gypsum, latex paint
Interior staircases	One flight of 7 treads 1100 mm wide, 280 mm high (treads made of steel and reinforced concrete, railings made of steel)
Interior staircase landing	Typical model of 1100 mm × 1100 mm (steel and reinforce concrete)
Above-ground outdoor staircase	One flight of 7 treads 1100 mm wide, 280 mm high
Above-ground exterior stairs landing	Steel structure with 50 % perforated mesh steel
Ground-level stairs	Reinforced concrete
Ramps and landings	Steel structure with 50% perforated mesh steel
Railings	Steel

). We must emphasize that the elements taken into account in the calculations of the GHG emissions for the adaptive reuse scenario exclusively concerned the additions (e.g., new partitions) to the already existing building. The GHG emissions of the historical structure were already taken into account in the previous section [40].

To facilitate the choice of materials in adaptive reuse, we created typologies of predefined designs. Similarly, typical assemblies were developed with the help of an engineer and an architect to standardize the selection of materials for interior partitions, floors, and ceilings. The typologies and assemblies are inspired by current construction methods in the province of Quebec. For example, they take into account a summary analysis of community centers, gymnasiums, libraries, as well as multifunctional spaces built in Quebec ovIer the last ten years, mostly in a rural area. Using a 3D model created with Rhino software, the volume in cubic meters (m³) for each material was calculated. With these data in hand, the embodied GHG emissions of the adaptive reuse scenario were calculated using Athena. It is important to note that staircases, handrails, and balustrades do not have predefined assemblies in Athena IE4B. Thus, these elements were added as “Extra Materials” [40].

To calculate the operational GHG emissions of the adaptive reuse scenario, we did not consider the presence of building users, due to their potential variation. The occupancy schedule was set to 12 h per day, 7 days per week. An average indoor temperature of 20 °C was established, while the outdoor temperature for determining the heating period was 18 °C. The ventilation system operated according to the occupancy schedule. The lighting usage, as well as other electric loads (1 W/m²) were estimated at 8 h per day. Hot water consumption was determined to be 0.8 L/m² per day (see

Table 9. The elements considered to calculate the operational GHG emissions of the adaptive reuse scenario.

Operational GHG Emissions	Elements Considered	Used Software
Building envelope	Remains essentially the same as that of the original building.	RetScreen modelling (9.0.0.94) + Athena calculations (IE4B v5.5)
Energy and heating system	Electricity/Dual energy (70% of electricity, 30% of a fossil energy system)
Ventilation	Use of electricity
Lighting	Power consumption of 6 W/m2.
Other electric charges	Power consumption of 1 W/m2. *
Hot water	Use of electric tanks.
Air conditioning	Not considered.

* We did not take into consideration the equipment required for the building’s future use (such as equipment needed to operate a café). Our objective was to compare two scenarios rather than make assumptions about very specific future appliances.

for more details) [40].

2.3.2. The New Construction Scenario

As for the new construction scenario (considered from 2023 to 2083), the building intended to replace the Abbey of the Benedictine Nuns in Joliette is designed to reflect contemporary construction practices and is conceived for the same functions as those of the adaptive reuse scenario. The building layout brings together all the proposed functions (creative studios, multipurpose hall, exhibition space, etc.) in a two-story structure. While its surface area is smaller than that of the adaptive reuse scenario, it offers the same activities and can accommodate a few more people. The same method was used for the adaptive reuse scenario to calculate the embodied GHG emissions, but with some other elements considered (see

Table 10. List of materials to be entered in Athena IE4B to calculate the embodied GHG emissions for the new construction scenario.

Typology of Design—A Steel Structure with Metal Cladding and Masonry	List of Assemblies
Concrete footing (S1) and concrete slab (P1 and P2)	S1—0.4 m width, 200 mm thick, 85 kg/m3 frame, 30 MPa P1—100 mm concrete, 30 MPa, 50.762 mm (2″) extruded polystyrene, 6 mil polyethylene membrane P2—Uninsulated concrete slab, 100 mm concrete, 30 MPa
Steel column and beam structure in I-Beam profile
Exterior wall R-20.5 (RSI 3.6) steel studs and masonry cladding (M2)	M2—Exterior natural stone cladding system, air barrier, Rockwool exterior insulation R11-15 3.5″ (88.8335 mm), steel studs load bearing with plywood spaced c/c every 400 mm (16″), lightweight (25 Ga), 39 × 92 mm (1 5/8″ × 3 5/8″), R11-15 fiberglass cavity insulation 3.5″ (88.8335 mm), 6 mil polyethylene vapor barrier, 5/8″ regular gypsum, latex paint *
Exterior walls in glazed curtain walls, with glazed aluminum-framed exterior doors (MR)	MR—Approx. 90% glazed, metal tympanum, fiberglass 5.5″
Steel stud interior walls, with hollow-core wood interior door (C1)	C1—Latex paint, regular gypsum of 5/8″, steel stud non-load bearing, spaced c/c every 400 mm (16″), heavy (20 Ga), 39 × 152 mm, regular gypsum 5/8″, latex paint
Steel stud exit walls, with steel interior doors (Cx1)	CX1—Latex paint, 2 regular 5/8″ gypsum, steel studs non-load bearing, space c/c 400 mm (16″), lightweight (25 Ga), 39 × 92 mm (1 5/8 × 3 5/8″), 2 regular 5/8 gypsum, latex paint
Open-web steel joist floors (P3)	P3—With concrete screed, 5/8″ regular gypsum, latex paint
Open-web steel roof (T1)	T1—Standard double-layer bituminous membrane, for slope: polyiso panel with 3″ (76.143 mm) fiberglass coating (0 to 6″ to create an average 3″ slope), 6″ (152.286 mm) polyiso board with fiberglass coatings, without concrete screed, 6 mil polyethylene vapor barriers, 5/8″ regular gypsum, latex paint
Interior staircases	One flight of 7 treads 1100 mm wide, 280 mm high (treads made of steel and reinforced concrete, railings made of steel)
Interior staircase landing	Typical model of 1100 mm × 1100 mm (steel and reinforce concrete)
Above-ground outdoor staircase	One flight of 7 treads 1100 mm wide, 280 mm high
Above-ground exterior stairs landing	Steel structure with 50 % perforated mesh steel
Ground-level stairs	Reinforced concrete
Ramps and landings	Steel structure with 50% perforated mesh steel
Railings	Steel

* The underlined element is to demonstrate the difference between the adaptive reuse scenario and the new construction scenario.

) [40].

Regarding the operational GHG emissions, the occupancy schedule was set to 12 h per day, 7 days per week. During the heating period, an indoor temperature of 22 °C was considered when the building was occupied and 18 °C when it was unoccupied. During the cooling period, an indoor temperature of 24 °C was maintained at all times. The outdoor temperature used to determine the heating period was 18 °C. The ventilation system was operated according to the occupancy schedule. The lighting usage, as well as other electric loads (1 W/m²), were estimated at 8 h per day. Hot water consumption was put at 0.1 L/m² per day (see

Table 11. The elements considered to calculate the operational GHG emissions of the new construction scenario.

Operational GHG Emissions	Elements Considered	Used Software
Building envelope	Modeled according to the most recent standards.	RetScreen modelling (9.0.0.94) + Athena calculations (IE4B v5.5)
Energy and heating system	Electricity/Dual energy (70% of electricity, 30% of a fossil energy system)
Ventilation	Use of electricity. Central unity combining heating, air cooling and air treatment.
Lighting	Power consumption of 6 W/m2.
Other electric charges	Power consumption of 1 W/m2.
Hot water	Use of electric tanks.
Air conditioning	Considered.

) [40].

3. Results—Case Study

Our case study is the Abbey of the Benedictine Nuns, which was built in 1907 in Joliette, a city located on the north shore of the St. Lawrence River (some 40 km northeast of Montreal). The convent was the home of the Congregation of the Sisters Adorers of the Precious Blood (Adoratrices du Précieux-Sang), which was renamed the Benedictine Nuns around the 1970s. They are Canada’s first contemplative religious congregation, meaning that their spiritual and social action are essentially devoted to prayer and the adoration of Christ. Like other traditional religious congregations in Canada, the members of the Benedictine Nuns congregation are aging and becoming fewer in number. This reality has led to the convent’s closure in 2021 and the search for rehabilitation scenarios.

The Abbey has a total area of 4517.6 m². Throughout its life cycle, several modifications were made to the building envelope. These included the central part (1907–1913), the south wing (1913–1924), the north wing (1924–1947), the central and southern isolation (1947–1959), as well as the rear annex (1959–1995). The types of heating energy also changed over time. The building was first heated using coal (1907–1959), then switched to fuel oil (1959–1995) and later to gas (1995–2023). As a result of these changes, the building’s energy efficiency improved. It went from 65% to 70% and finally reached 85%. Beginning in 1959, electricity was used for lighting the building. The indoor temperature was set at 17 °C from 1907 to 1959 and to 18 °C from 1959 to 2023. The outdoor temperature to determine the heating period was also set at 17 °C and then at 18 °C beginning in 1959 [40].

The embodied GHG emissions for the Abbey of the Benedictine Nuns were 703 tons of CO₂ equivalent over its 116 years of existence. As for the operational GHG emissions, they average 158.42 tons of CO₂ equivalent per year, for a total of 18,376 tons of CO₂ equivalent for its entire life cycle [40].

To obtain more precise data on the operational GHG emissions depending on the energy used for heating and the modifications made to the building envelope, the life cycle of the building was divided into six periods: 1907–1913, 1913–1924, 1924–1947, 1947–1959, 1959–1995, and 1995–2023 (see above). For these periods, the tons of CO₂ equivalent were, respectively, as follows: 681, 1568, 5344, 2259, 5525, and 2999 (see

Table 12. Characteristics of the Abbey of the Benedictine Nuns in Joliette and its operational GHG emissions.

Periods	Modifications to the Envelope	Type of Energy for Heating	Heating System Efficiency (%)	Indoor Temperature (°C)	Thermal Losses of the Envelope (kWh)	Lighting (kWh)	Total Electricity Consumption (kWh)	Total Wood Consumption (kWh)	Total Fossil Energy Consumption (kWh)	Operational GHG Emissions (Tons of CO2 eq.)
1907–1913	Central part	Coal	65	17	204,982	0	0	0	315,357	681
1913–1924	South wing	Coal	65	17	257,309	0	0	0	395,861	1568
1924–1947	North wing	Coal	65	17	419,531	0	0	0	645,432	5344
1947–1959	Central and southern isolation	Coal	65	17	339,907	0	0	0	522,934	2259
1959–1995	Rear annex	Fuel oil	70	18	397,344	19,288	20,656	0	548,447	5525
1995–2023	N/A	Gas	85	18	397,344	19,288	20,656	0	479,891	2999

) [40].

Regarding the adaptive reuse scenario, the embodied GHG emissions are calculated at 1.52 tons of CO₂ equivalent per year, assuming no recycling of materials. The total embodied GHG emissions for a 60-year period is 91.33 tons of CO₂ equivalent.

As for the operational GHG emissions, if the Abbey is heated solely using electricity, the emissions are calculated at 10.24 tons of CO₂ equivalent per year, resulting in a total of 614.34 tons of CO₂ equivalent over a 60-year period. If the dual energy option is considered (70% electricity, 30% from fossil energy system), the operational GHG emissions would be 19.45 tons of CO₂ equivalent per year, amounting to a total of 1167.06 tons of CO₂ equivalent over 60 years (see

Table 13. Characteristics of the Abbey of the Benedictine Nuns in Joliette and its operational GHG emissions (according to the adaptive reuse scenario).

Type of Energy for Heating	Heating System Efficiency (%)	Ventilation, Fresh Air (cfm)	Thermal Losses of the Envelope (kWh)	Heat Required for Fresh Air (kWh)	Electricity for Ventilation Motors (kWh)	Electricity Lighting (kWh)	Total Electricity Consumption (kWh)	Total Fossil Energy Consumption	Operational GHG Emissions (Tons of CO2 eq.) for 60 Years
Electricity	100%	7828	384,872	97,128	34,295	71,814	543,704	0	614.34
Dual energy (electricity + gas)	100%/85%	7828	384,872	97,128	34,295	71,814	444,176	117,092	1167.06

) [40].

Finally, for the new construction scenario, the embodied GHG emissions are calculated at 10.7 tons of CO₂ equivalent per year, for a total emission of 640.5 tons of CO₂ equivalent over a 60-year period.

Regarding the operational GHG emissions, if the new building is heated solely using electricity, the emissions are calculated at 6.32 tons of CO₂ equivalent per year, for a total of 379.44 tons of CO₂ equivalent over 60 years. If the dual energy option is considered, then the operational GHG emissions would be 9.94 tons of CO₂ equivalent per year for a total of 596.36 tons of CO₂ equivalent over 60 years (see

Table 14. Characteristics of a new building to replace the Abbey of the Benedictine Nuns in Joliette and its operational GHG emissions (according to the new construction scenario).

Type of Energy for Heating	Heating System Efficiency (%)	Ventilation, Fresh Air (cfm)	Thermal Losses of the Envelope (kWh)	Consumption of the Air-Conditioning (kWh)	Heat Required for Fresh Air (kWh)	Electricity for Ventilation Motors (kWh)	Electricity Lighting (kWh)	Total Electricity Consumption (kWh)	Total Fossil Energy Consumption	Operational GHG Emissions (Tons of CO2 eq.) for 60 Years
Electricity	100%	7410	105,603	21,836	101,984	116,858	51,929	335,815	0	379.44
Dual energy (electricity + gas)	100%/85%	7410	105,603	21,836	101,984	116,858	51,929	296,754	45,954	596.36

) [40].

In short, we can observe that the embodied GHG emissions are lower for the adaptive reuse scenario than for the new construction scenario. We therefore see the relevance stated by Mahmad et al. (2024), Huang et al. (2024), as well as Wise et al. (2019) of taking into account the embodied emissions (and not only the operational ones) [33,34,35]. Indeed, considering only the operational energy would have changed the situation a little, meaning that it is the contrary whether we consider only electricity for heating or dual energy (electricity and gas). These emissions are higher with the adaptive reuse scenario (see

Table 15. Comparison of the GHG emissions of two scenarios: adaptive reuse and new construction.

Scenario	Embodied GHG Emission (Tons of CO2 eq.)	Operational GHG Emission (Tons of CO2 eq.)
Adaptive reuse	91.33	Electricity: 614.34 Dual energy: 1167.06
New construction	640.5	Electricity: 379.44 Dual energy: 596.36

and Figure 1) [40]. To sum up, if electricity is being used for heating, the total GHG emissions (both embodied and operational) of the adaptive scenario are lower than the new construction scenario. However, if we use dual energy, they are higher. According to our results, using electricity with an adaptive reuse scenario is therefore the best environmentally friendly approach.

Another observation is that the past GHG embodied emissions (the historical building) were much higher than the modern intended scenarios. The same conclusion applied to the operational emissions, which were emitted much more from a historical point of view. Thus, no matter which scenario is chosen, it is primordial to remove fossil fuel-based heating sources, which historically supplied these buildings (see Figure 2) [40]. Figure 2 allows for the visualization of the total GHG emissions during the entire lifespan of the building, from its construction (1907 to 2023) to various scenarios (2023 to 2083), if we consider electricity for heating.

4. Discussion

The case study of the Joliette Benedictine Nuns monastery from an LCA point of view is interesting in several respects. Firstly, to our knowledge, it is one of the first studies of its kind applied to the field of religious built heritage. In this respect, the case study supports the main findings of other studies that have carried out LCAs on historic buildings, namely the significant carbon footprint benefits that can be derived from an adaptive building reuse operation [6,7,36,38,39]. It should be noted, however, that according to our foresight derived from the comparison between the conversion scenario and the new-built hypothesis, this case study suggests a possible disadvantage for the converted building in terms of operational energy, mostly if the choice of energy source is not electric, but rather some form of dual energy. Needless to say, this clarification is situated very precisely in the context of the natural resource energy of Eastern Canada, which abounds in hydroelectric power, an energy that is not necessarily clean but which, all the same, demonstrates a lower carbon footprint than other forms of energy released directly from fossil fuels (natural gas or fuel oil, for example) [67]. Even if placed in this context, such a nuance is important, since it can potentially allow us to question a very important dimension of LCA, namely operational energy.

Our research also has its limits. For instance, it would have been interesting to evaluate different kinds of adaptive reuse scenarios (e.g., other uses of the building and/or other architectural modifications) to determine if a certain one is more environmentally friendly than another. However, for the purpose of our research, which aims to determine the best option from an environmental point of view between the adaptive reuse and a new construction, only one scenario was sufficient. Additionally, to strengthen our results, it would have been relevant to conduct a sensitivity analysis, though it could not be completed during the course of the project.

Beyond the benefits derived from the adaptive reuse of the building, the circular economy can also be observed in the building’s relationship with its environment, and in the attitudes and strategies adopted by its occupants with regard to operational energy consumption [68,69,70]. Operational energy consumption and operational GHG emissions provide a complementary link to circularity insofar as it can, as in this case, be partly influenced by the attitudes and strategies of building occupants. As mentioned above, determining the level of operational energy consumption for the Joliette monastery’s past was largely dependent on a qualitative study. The aim was to estimate an operational temperature based on the thermal sensation and coping strategies of the occupants, in this case a religious community.

This important element suggests that the circularity of the LCA of historic religious buildings can be better understood by taking into account, in a precise way, factors related to the optimal use of resources, insofar as the attitudes and strategies of occupants can be documented both historically and in contemporary times. It follows that when it comes to LCA studies of religious buildings of the convent or monastery type, it is necessary to take into account the attitudes and strategies of religious congregations. Based on the vows of obedience, chastity, and poverty, religious congregations are inherently inclined to a form of circularity with regard to their day-to-day environment. This circularity is ascetic and demands a sober approach to consumption, namely operational energy [71].

Taking into account, in a qualitative way, the occupants of historic buildings with a religious character and their adaptation strategies can only enrich the methods and approaches of LCA and, ultimately, enshrine a better understanding of the social sustainability of adaptive reuse. From this point of view, LCA can join what Lo Faro and Miceli (2019) [72] point to be a success factor for the adaptive reuse of convent properties: an authentic match between the spirit of a place and past and anticipated (or future) meanings.

The development of both quantitative and qualitative approaches to the LCA of historic religious buildings may enrich the literature on the circularity of adaptive reuse practices. Indeed, there are at least two relatively distinct but complementary ways of approaching adaptive reuse. On the one hand, adaptive reuse may be approached by focusing on a building or group of buildings. Such an approach tends to consider the uses underlying the conversion process on the basis of a number of variables linked to the building, e.g., preserving the spirit of the building (commonly referred to as the spirit of the place), upgrading (reusing) original materials, and increasing energy efficiency [1,73]. On the other hand, adaptive reuse can also be approached on a broader scale, whereby heritage conversion is linked to more specifically urban variables, e.g., strengthening social cohesion, devaluing places of belonging, contributing to the development of the municipality’s land base, contributing to the area’s economic vitality, gentrification, etc. [74,75]. Neither of these two approaches to adaptive reuse is entirely quantitative or qualitative. Rather, they have a mixed character that must command a combination of quantitative and qualitative studies in order to consolidate the principles of circularity (the building in its environment, the optimal use of resources, the adaptability of building occupants) without which heritage cannot fully play its role in a vision of sustainable development.