Neighbourhood Revitalisation and Heritage Conservation through Adaptive Reuse: Assessing Instruments for Commoning

ABSTRACT This contribution discusses experiences of civic initiatives with adaptive reuse in urban and rural settings. The contribution aims at understanding the implications of formal ownership instruments of commoning projects to address social needs and conserve heritage. In particular, we examine cases in which Heritable Building Lease (HBL), Community Land Trusts (CLT), and Community Ownership (CO) have been used as instruments for such commoning processes. These instruments are increasingly implemented for adaptive reuse projects with heritage buildings and sites to promote a long-term perspective of use. The case studies have an explicit ambition in opening up the site’s heritage to community engagement and to contribute to positive impacts on equitable and participatory neighbourhood development. The paper argues that the instruments play an important role in institutionalising commoning initiatives, but that formal tools are not enough as they have to mesh with informal processes. Moreover, professional expertise, time resources for volunteer engagement and idealistic motivations, are necessary preconditions for the use of these tools, yet they also show a selective bias towards the involvement of middle-class activists.


Introduction
In metropolitan areas, geographically uneven development dynamics have produced rising land and real estate prices in growing metropolitan centres fostering gentrification dynamics, on the one side, and shrinking areas, with several abandoned historical buildings in a vicious circle of disinvestment and vacancy, on the other. In this context, projects of adaptive heritage reuse find increasing attention in research and practice. Civic or community engagement is seen as a vehicle against gentrification or neglect. As we will argue, common ownership, finance, management, and use, support long-term stewardship of the heritage sites.
Drawing on the experiences of case studies in the EU-funded Open Heritage research project (2018-2022), we discuss how projects have dealt with the challenge of promoting investment and (re-)use of a particular heritage site, while simultaneously addressing the needs and concerns of the neighbouring area. 1 In particular, we want to discuss three

Neighbourhood Revitalisation through Adaptive Reuse
Adaptive reuse is not only conceived of as an approach to revitalise individual buildings or plots, but also to provide spaces and services that address important social needs in rural or urban neighbourhoods. Such social needs may become particularly urgent due to social and economic change, whether in terms of growth or decline. In the context of growing capital interests in land markets due to the 'rent gap,' the need for affordable housing and community spaces becomes acute, particularly for low-income residents to avoid gentrification and displacement. 2 In the context of shrinkage, the needs for public transport, childcare, pubs or markets gain significance for residents. 3 Some scholars have framed the contribution of such social services and the provision of alternative space in terms of 'equitable development,' 4 'community development' 5 or 'socially sustainable urban development.' 6 Jason Reece defines revitalisation as a strengthening of social ties in a neighbourhood together with an expansion of institutionalised networks and services, supporting existing neighbourhood-based businesses and creating additional opportunities for residents. 7 More concretely concerning adaptive reuse, newly refurbished heritage sites could contribute to more (high quality) spaces for social services in the area and extend spaces for neighbourhood-based companies and entrepreneurs, all of which may enhance social and economic opportunities for the existing residents. A crucial question to adaptive reuse projects from this vantage point is how such neighbourhood revitalisation can avoid advancing gentrification threats, in one instance and compensate for the negative trends of shrinkage, in the other.
Critical and political-economic research on gentrification has highlighted the process of land speculation that runs through different phases, moving from strategic disinvestment to investment. 8 In the classical description, the first phase of gentrification commonly involves the appropriation of run-down buildings in urban neighbourhoods by people, such as young students, artists or other creative and alternative groups with high cultural capital. 9 In her New York case study, Zukin studies the refurbishment of old run-down apartment buildings and the adaptive reuse of former warehouses or small manufacturing sites. 10 Eventually, in this process of creative engagement with and care for the existing built and natural environment in the area, the public perception of the neighbourhood changes as it is less and less identified with urban blight. Instead, it becomes valued because of its unique characteristics marked by old refurbished buildings and the intriguing palimpsest of several layers of history in the built environment. 11 Such characteristics are increasingly favoured over new urban developments that lack this sense of place and history. 12 In dynamic urban economies such as New York City or Manchester, 13 such processes have contributed to a revalorisation of land and real estate, addressing a 'cosmopolitan' elite rather than working-class residents and ultimately contributing to the displacement of inhabitants who can no longer afford the growing rents and other expenses. There is, indeed, little in terms of explicit research on how adaptive reuse can foster revitalisation, while simultaneously defending against gentrification. 14 In shrinking areas, the issue is not the displacement of the residents by wealthier populations but rather of depopulation of the residents due to a lack of opportunities in or attachment to the area. 15 The biggest concern is maintaining the social and public infrastructure which requires increasing efforts and financing per capita as inhabitants move away. This growing burden on the residents that remain can develop into a downward spiral, and the question of infrastructure thus becomes key to avoiding a further loss of the population and the abandonment of buildings. 16

Heritage Conservation through Adaptive Reuse
The adaptive reuse of the heritage sites -not always but often acknowledged as designated heritage -serves as an alternative to demolition and new construction. Sites may thus turn into spatial experiments, allow temporary uses, and become auratic places. 17 Combined with experimental preservation approaches, adaptive reuse is vital for new cultural production not only of spaces but also of heritage interpretations, which intersects historic, contemporary, and future layers. 18 The identification and interpretation of heritage values in adaptive reuse projects might include historic, aesthetic, and use values, 19 which are most relevant in authorised heritage conservation practices. Community or societal values 20 and emotional values correspond to feelings, embodiment, and memory or nostalgia. 21 Heritage values are not, however, a matter of neutral scientific discussion but are deeply interwoven with the interests, motivations, and objectives of stakeholders. Most critically discussed are aesthetic values which are often used as unique selling points in marketing. 22 In this context, critical approaches to the heritage industry reach back to the 1980s. 23 Heritage assets and values might intensify gentrification or other processes of exclusion 24 and thus the heritage project becomes disconnected from the neighbourhood or other local communities. 25 At the EU level, the Faro Convention of 2005 highlights the 'importance of a wider understanding of heritage and its relationships to communities and societies'. Heritage sites can tell a lot about urban and communal history, memory, identity, and local pride. Several EU-funded research projects, such as OpenHeritage, 26 CLIC (Circular Models Leveraging Investments in Cultural Heritage Adaptive Reuse) 27 or ROCK (Cultural Heritage leading Urban Futures) 28 -funded through Horizon 2020 -introduce adaptive heritage reuses as an approach to produce space with a positive social impact, a low intervention scheme and an engagement of neighbourhood and heritage communities to define and manage what people consider important about the buildings and sites.
The dilemma is that to the extent that adaptive reuse projects are successful in fostering civic engagement and the securing of heritage need civic engagement, they generate cultural heritage objects as assets and unique selling points. Designated or listed buildings and cultural heritage objects can trigger economic valorisation processes when increasing the expected return of investment in an area may be due to place-making and aesthetic attraction. 29 This happens when spectacular reuses bring heritage back to life as, for example, in the case of the High Lane in New York or the Tate Modern, a former power station, in London. But also in relation to smaller adaptive reuse of industrial heritage sites such as those in Budapest which document this phenomenon. 30 Furthermore, economic valorisation affects buildings with continuous uses for example where residential settlements have become World Heritage Sites, such as the Berlin Modernism Housing Estates. Adaptive heritage reuse, therefore, could thwart equitable neighbourhood revitalisation posing the question as to how civic initiatives of adaptive heritage reuse can avoid becoming a victim of their own success?

Solutions through Civic Engagement and Commoning?
Community engagement in heritage is well known. While Sophia Labadi and William Logan 31 concentrate on frameworks, management, and strategies, and consider diverse scales from international to local in relation to community engagement for heritage conservation, Gill Chitty 32 in contrast provides a good overview of different approaches and introduces case studies. Oevermann and Gantner 33 discuss examples of heritagerelated community engagement through physical access and digital tools.
However, one basic question remains: Who is the community when speaking about community engagement? Starting from the premise that a community is defined by a commonality, Nils Scheffler defines geographical communities as 'people that live in the same area, such as the neighbourhood,' and social communities as 'people that have similar interests, beliefs, attitudes, and objectives, such as a heritage community.' 34 In the following, we focus on (geographical) neighbourhood communities, on the one hand, and the (social) community on the other.
An important focus of the debate around community engagement and heritage has acknowledged urban commons as an approach to citizens' self-organising. 35 Urban commons consist of three key aspects: The common and shared resource, the commoning institutions and rules that regulate care, management, and use of the resource, and the community of commoners. 36 Neighbourhood revitalisation becomes a commons insofar as communities articulate a shared interest and organise around the provision and management of affordable housing, public infrastructure for transportation, health care, education, or promotion for employment and local business opportunities. Similarly, heritage conservation becomes a commons when communities define a heritage of interest and appropriate and care for a heritage object or site.
In recent years, recognising the embeddedness of actually existing commons within markets and political-administrative structures, researchers have studied legal and organisational models for commoning in order to understand the potential of civic engagement as a form of democratic empowerment. 37 In the context of land and real estate models that promote commoning, particular attention has been paid to Heritable Building Lease (HBL), 38 Community Land Trusts (CLT), 39 as well as Community Ownership (CO). 40 However, a comparative approach to understanding these models concerning community engagement and adaptive heritage reuse has been lacking so far.
Based on case studies, we consider how these instruments of HBL, CLT, and CO that formalise ownership and management have been linked to community engagement about social needs and heritage. At the beginning of our research, to guide our research interest, we hypothesised that these instruments facilitate commoning around (1) social needs of neighbourhood residents and (2) heritage and heritage conservation; but also that (3) the use of the instruments has social preconditions and implications. Consequently questions relevant to the historic environment include what these instruments imply for defining community and heritage, and for projecting long-term neighbourhood development. As we shall see, these instruments play an important role in institutionalising commoning processes though we will highlight persisting challenges. For commoning processes, formal tools are not enough, informal processes and idealistic motivations are an essential element. Best practice examined in our case studies shows that both, formal and informal aspects, have to be engaged.

Materials and Methods
This research is based on an explorative analysis 41 of four case studies, with two cases on HBL, one case on CLT, and one case on CO. It should be noted that the use of HBL, CLT, CO in adaptive heritage reuse is rather the exception than the rule, thus the range of possible case studies was limited. In Germany, the HBL has experienced a renaissance among housing activists and housing cooperatives unlike Great Britain, where CLTs and CO, by contrast, have seen a significant rise. 42 Meanwhile, in Germany, there are only first attempts at establishing a CLT. 43 Thus, while the use of these instruments differs for each country, there are underlying legal principles to prevent market speculation that can be found in both countries. In Great Britain and Germany, we sought one case study in an urban setting where gentrification is a real threat and a case study in a peripheral setting that struggles with economic and demographic decline.
As explorative research, we acknowledge that the case studies are not representative of each instrument, but rather they act as vantage points to understand how these ownership instruments have been related to civic engagement and commoning around social infrastructure and heritage. In particular, when selecting case studies, we sought to find examples of good practice 44 to explore the potential of using these ownership instruments in conjunction with civic engagement and commoning.

Data Collection
We draw on findings from the OpenHeritage research project (funded by the European Union through Horizon 2020 from 2018-2022) on case studies at Hof Prädikow, 45 ExRotaprint 46 and St Clement's. 47 To understand the Midsteeple Quarter case, we engaged in desk research and an online interview. 48 The authors visited cases of Hof Prädikow and ExRotaprint periodically for three years between 2018 and 2021, visits to St Clement's and Midsteeple Quarter had to be dropped due to the Covid-19 restrictions.
For the specific questions of this paper, the authors conducted interviews of about one hour with one expert involved in the case of ExRotaprint, St. Clement's and Midsteeple Quarter, respectively, and two interlocutors at Hof Prädikow. In addition, representatives of national institutions which provided support for the case studies in terms of implementing the ownership instruments, were interviewed. In our case, we spoke with leaders from the National Community Land Trust Network for Great Britain and the Stiftung trias for Germany. These interviews were indispensable in attaining specific insights into the practice of civic engagement and the relationship to neighbourhood revitalisation and heritage conservation. These are processes which until now have not been documented systematically. A semi-structured questionnaire guided the interviews and allowed for sufficient openness to explore the experiences and understand the dimensions and implications of civic engagement. Our interviewees kindly provided us with further documentation on the respective cases to complement these insights.

Ownership Instruments
Before presenting the case studies, we outline the characteristics of the three ownership instruments. Contains an overview of the distinctive features of the ownership instruments, followed by a brief elaboration for each.

Heritable Building Lease (HBL)
The Heritable Building Lease refers back to German law (Verordnung über das Erbbaurecht) that was codified in 1919. It is only recently that it has been rediscovered as an instrument to support sustainable development practices and to counter the speculation of land. Its historical origins reach back to the land reform movement of the mid-19 th century amid the industrial revolution, with thinkers such as Henry George 49 who thought about instruments to capture increases in land values for the common good. The key idea is to separate the ownership of the land and the ownership of the buildings. Hereditary building rights are longterm leases (often with a duration of 99 years) that include the right to erect and maintain buildings on a property. These buildings are recorded in the land register and can be encumbered with mortgages and land charges in the same way as full ownership. Every year, the leaseholder has to pay ground rent (Erbbauzins), the definition and size of which can be determined in a variety of ways in the lease contract. For civic initiatives of adaptive reuse, a key advantage of the heritable lease is that it allows for the development of buildings without the financial requirement to buy the land. For Germany, it is estimated that around 5% of all land properties are leased through the Heritable Building Right. 50 In the case of ExRotaprint and Hof Prädikow, the Stiftung trias (Foundation trias) owns the land. Founded in 2002, the Stiftung trias is the main advocate of the Heritable Building Right for co-housing and pursues three aims through the HBLs, namely promoting community-oriented living (based on participation and selforganisation), removing land from the speculative market and preventing the sealing of agricultural soil.
This heritable lease has several implications and potentials. First of all, land speculation and the selling of the buildings for profit can be prevented as the lease giver needs to consent to sales. The lease can define the uses of the land and thus prevent institutions from using the site solely for profit-maximising interests. Moreover, the ground rent may be adjusted with local price or average income indices which protects the leaseholder from unforeseen increases and the risk of defaulting. This ground rent is claimed to prevent the leaseholder from disinvesting since it means ongoing and continuous expenses. 51 Furthermore, the preservation of the built heritage can also be mandated in the lease. Trias, which is the lease giver in the two case studies ExRotaprint and Hof Prädikow monitors the compliance of the leaseholder with the lease contract.

Community Land Trust (CLT)
The Community Land Trust functions similar to the Heritable Building Right in that it separates land and building ownership. The key difference, however, is that the stewardship and management of the land is in the hands of a CLT which is a non-profit organisation. In CLTs, the general direction is decided by the membership that is open to anyone living in a geographically defined area, which may be a ward, a district, a parish, a town or such. The idea of a CLT implies that significant community organising (Interviewee London CLT) has already been done before developing the site, namely to determine collectively a proper location and to come up with a development plan. The CLT board is responsible for the management and is usually made up of a combination of representatives of three different kinds of groups: (1) CLT members who live in the geographic area, (2), residents and users of the CLT land, and (3), other local stakeholders and experts. In addition to housing affordability, CLTs also seek to further social or ecological objectives with priorities differing in each case, such as advancing education or vocational training, providing public services, offering recreational sites, community spaces or cultural activities and promoting environmental protection.
CLTs are a relatively new phenomenon in England and Wales, where actors have taken inspiration from the CLT movement in the US. 52 Pilot projects were supported in 2006 and 2008 by a 'National CLT Demonstration programme' and the support of the Carnegie UK Trust and Tudor Trust. In 2010, enjoying cross-party political support, 53 the National CLT Network was established to promote the CLT movement and offer professional advice. By now, there are more than 290 CLTs in England and Wales, with about half having formed since 2018. 54 The interviewee of the National CLT network claimed that one of the significant achievements in England and Wales is that the CLT is a legally defined concept. The experience of CLTs in the US and the UK has also influenced initiatives elsewhere in Western Europe to adapt this institutional model in their respective context. In recent years, the first CLTs have been set up in Belgium and France. 55

Community Ownership
The legal construction of community ownership has a long history in rural Scotland, its application to the urban context was made possible through new legislative powers to urban communities in the context of Land Reform and Community Empowerment in 2016. In an interview, the interviewee from the Dumfries and Galloway Small Communities Housing Trust noted that despite a long and rich history of community ownership, land ownership in Scotland is one of the most unequal in Europe. 56 Half of the country's privately owned land is held by just 432 owners and 16 owners claim 10% of Scottish land. 57 In recent years, a movement has developed around this issue of land reform. Scotland's 2003 land reform brought about the first steps towards buyout assistance for CO. Founded in 2010, 'Community Land Scotland' is a publicly supported organisation that promotes community ownership of land and holds 10 Million Euros per year to support communities to purchase land. This is bolstered through the legislative efforts that give privileges to communities to buyout land, and particularly claim those properties by absentee landlords that are plagued by demise. By 2021, around 227,000 hectares of land have been transferred to community management, housing some 25,000 people. 58 In contrast to England, the separation of land and building ownership is not a legal option and CO in Scotland ownership thus entails both aspects simultaneously. The granting of Community Ownership presupposes a formally constituted community organisation, in the form of a Community Benefit Society, or a Company Limited by Guarantee, to manage the asset.

ExRotaprint
ExRotaprint was founded in 2007 by tenants of the former Rotaprint industrial complex located in Wedding, a traditional working-class district in central Berlin. When threatened with the sale of the area to a pension-fund investor, the tenants founded ExRotaprint as an association and eventually gained ownership of the site when put up for sale by the Berlin Municipality's Real Estate Fund. ExRotaprint set up a legal configuration comprising a nonprofit status. Based on an HBL, Stiftung trias bought the land and ExRotaprint as a charitable company with limited liability (ExRotaprint gGmbH) bought the buildings and manages the site. ExRotaprint thus became the owner of the 10,000 m2 complex and started a non-profit real estate development project setting a precedent in Berlin that inspired many experiments in cooperative ownership and a campaign to change the city's privatisation policy.
ExRotaprint offers affordable rents to small businesses, artists and social projects even as the inner districts of Berlin, including this neighbourhood, have seen a dramatic rise in real estate value and rents since the early 2000s. The association of the renters takes part in the decision-making of the project. It is not a duty for ExRotaprint tenants to participate in the operation of the association but an offer; the same is with the charitable company with limited liability (gGmbH). This gGmbH consists of eleven partners, including the initiators of ExRotaprint as well as the association. Votes in decision-making processes are distributed according to the money invested but the maximum is cut to 50% to avoid the domination by one partner. The association provided 10% of the money invested, most of the others have below 15 % (Interviewee ExRotaprint).

Hof Prädikow
Some 50 km outside of the city centre of Berlin, the Hof Prädikow site is centred around an aristocratic four corner farm with origins going back to the 14th century. It boasts of an inner courtyard of the size of about 3 football fields. Hof Prädikow site was converted within the land reform of 1946 to state-owned property. The entire estate of about 9.5 ha was still used for agricultural purposes during the time of the German Democratic Republic. After the German reunification in the 1990s, the Hof Prädikow site was used by a series of absentee owners leading more and more to abandone the complex. From the mid-1980s to the 2010s, the number of inhabitants in the village Prädikow was reduced by half to around 220 in the context of the economic demise of the area following German reunification.
In 2016 trias foundation purchased the site and concluded a building lease contract with the Mietergenossenschaft Selbstbau e. G., an umbrella cooperative that functions as the investor and developer of the adaptive reuse in January 2017. Selbstbau collaborates with the Hof Prädikow initiative, the cooperative on-site, comprised of a group of people who live there. A group of 24 adults and 12 children started organising the activities on the manor and the development of the farm site, by 2021 there were around 80 adults in the organisational activities. The first persons started moving in and living on the site in early 2022. The first project to be realised, however, is the Dorfscheune, a historic barn that is currently being transformed into a meeting space for activities of the village people and the Hof Prädikow. Around 80 residents of the village Prädikow, collaborate in fundraising for, programming and refurbishing the village barn. Whereas most of the work is voluntary, the construction phase involves a few paid jobs (manager of project Dorfscheune and facility manager) financed by the association and external funding.

St. Clement's
St. Clement's is London's first CLT established in the former 19 th -century workhouse and later psychiatric hospital of St Clements, in the Mile End area. It is part of the larger housing complex that consists of 19 buildings or building parts housing a total of 252 homes. Supported by the Greater London Authority to work with a private developer and a social housing association, the CLT was allocated 23 homes that are dispersed throughout and alongside privately owned and social housing units. This CLT establishment was made possible by a section 106 agreement attached to the site. The legal provision required developers to create 30% of all housing provided as affordable, altogether 53 homes, part of which now belong to the CLT. The St Clement's CLT lease has a time Picture 2. Courtyard of hof prädikow, 2019. Image credit: Markus Kip. horizon of 250 years and provides affordable housing, allowing long-term residents who would be priced out to remain in the area, countering the tendencies of displacement and housing unaffordability in East London.
In the case of St. Clement's CLT, the land is owned by a charity with local stakeholders as trustees and the CLT owns the head lease to sell or underlease to residents. 59 The residents' payments to the CLT are adjusted to ensure the affordability of housing. At St. Clement's these payments are adjusted to the median income of the area and not to the open market prices in the gentrifying area. The establishment of a community centre is a key priority, and the attainment of these objectives is monitored and formally ascertained based on pre-defined social impact indicators. Due to conflicts with the private developer around the financial conditions for the CLT to appropriate the building, the establishment of the community centre has been in jeopardy for years until today.

Midsteeple Quarter
Community ownership at the Midsteeple Quarter project is arranged in a way that differs from the HBL and the CLT in England and Wales primarily since Scottish law does not allow for a distinction between land and building ownership. Here CO means that land and real estate are owned by a Community Benefit Society that is the Midsteeple Quarter or the formal name Dumfries High Street Limited as an independent organisation set up by the local community in 2017. The Community Benefit Society can be joined by local residents for a membership share of £1 and counts more than 400 members of two postal code areas. Members elect a board to direct the project. Community ownership stipulates particular usages, in the case of Midsteeple Quarter from affordable housing to education, cultural activities and the promotion of small entrepreneurship. Midsteeple Quarter covers a central area in the city of Dumfries that has experienced decline and the practical loss of housing while the suburban fringe has experienced growth. Within this area, several historic buildings are to be taken over for a variety of purposes, but centrally housing, particularly on the top floors over the High Street storefronts.
The ongoing Midsteeple Quarter project aims at CO as the vehicle for the strategic regeneration of Dumfries Town Centre. It is a reaction to economic town centre decline, but also the social needs of the community. The project aims to revitalise the urban core by providing spaces for business enterprise, creative professionals, and links to further education, business and housing. The project has recognised the need for housing as a key contributor to the vibrancy of the area. The intention is to provide affordable housing opportunities in the ownership of the community organisation and to overcome the lack of activities in the town centre.

Implications for Commoning
Overall, we saw the three hypotheses that we formulated at the beginning of the research confirmed: the ownership instruments studied show a positive effect on civic engagement and commoning in neighbourhood revitalisation and heritage conservation processes. However, these instruments have important preconditions for their successful implementation and also carry possible implications that require attention from the practitioners and actors. Throughout this research process, more detailed insights have been gained that throw a differentiated light on the three ownership instruments.

HBLs, CLTs and COs Allow for a Long-term Perspective of Affordable Spaces and Community Uses
A long-term vision of integrating the project with the social needs of the environment is emphasised by all interviewees. One interlocutor from Hof Prädikow, connecting the heritage of the site with the long-term plans for addressing the social needs of the geographic community, stated: "We want to return to the use of the farm from 100 years ago. The farm was the centre of the village. It's where people married, where they celebrated and where they earned money. Some people also lived there. It's where things were produced that were consumed in the village . . . That's the image we communicate." All three models have the main advantage of facilitating access to collective ownership. In the case of HBL and CLTs, the individual development of buildings is relatively cheap, since the land does not need to be bought. The separation of land and buildings allows for dividing costs among different actors. This separation is not a legal option in Scotland (Interviewee Midsteeple Quarter). CO, however, is legally promoted by giving the first 'right of refusal' to communities to appropriate properties in decay and neglected by absentee landlords. Moreover, the government of Scotland supports CO through 'Community Land Scotland' by providing 10 Million Pound per year for the purchase of such lands.
A formal construction of not allowing profit to be made from the land is possible in the case of HBL, and legally inscribed in the case of CO and CLTs. Through leases of 99 or even 250 years, these instruments guarantee financial stability and a long-term perspective of affordable spaces. Rents at Ex-Rota Print, as one example, are at around 3.00/3.50 € per square metre instead of the usual 10 € per square metre in this neighbourhood for small businesses and cultural organisations. Keeping rents low creates the possibility of making space for low-income businesses and services possible (Interviewee ExRotaprint). In conjunction with the legal construction of a non-profit with limited liability (gGmbH), this prevents the collectives such as ExRotaprint from breaking apart due to private profit interests within partnerships. In conjunction with the cooperative model, as in the case of Hof Prädikow, the financial risk of individuals can be reduced during the development phases by sharing unexpected rising prices, such as the boom in construction costs. In such instances, the collective decision-making model allows for innovative solutions that could not be handled by individualised approaches. At Hof Prädikow, members have responded by designing smaller units of private housing and by compensating for this reduction with larger communal spaces (Interviewee Hof Prädikow).
However, the potential for countering the effects of gentrification in the surrounding area is extremely limited, except for purchasing surrounding lots as well and transforming them into collectively managed sites, as our interviewees from the National CLT Network and Stiftung trias pointed out.

Neighbourhood Engagement Is Differently Defined in CLT and CO Compared to HBL
St. Clement's in London and the community development trust in Dumfries, both have a clear objective in neighbourhood engagement and have established binding rules for engagement and inclusion in decision-making processes. In general, CLTs and COs define the community of (potential) members geographically, mostly along administrative borders of wards, districts or towns. This secures that both models are open and accountable to the membership of the neighbourhood in this geographical sense. The elected board is responsible for decision-making, but both, members and the board can propose new initiatives. Both representatives of St. Clement's and Midsteeple Quarter highlight the importance of early community consultation to facilitate neighbourhood engagement. Our interviewee from CLT London points out that there was community involvement from the first layouts of plans.
By contrast, HBL does not entail binding rules for community engagement. Though not formalised, neighbourhood engagement with this instrument may also be promoted and could also prove to be effective. In the HBL case of Hof Prädikow, neighbourhood engagement is a goodwill agreement (Interviewee Stiftung trias). Here, the ambition of the Hof Prädikow initiators is to bring back the historic function of the farm as a meeting point and provider of small services and the village barn is to be used by the village residents and the farm's new inhabitants. In the case of ExRotaprint, neighbourhood engagement is ensured through usages defined for the compound. The objective of ExRotaprintt is to use 1/3 of the space for small businesses that offer jobs and trainees for the neighbourhood, 1/3 for community work and social services, and 1/3 for artist studios. It should be noted that ExRotaprint, in the form of and its gGmbH as the managing company of the HBL construction has set in place decision-making structures that allow for broad participation of stakeholders (renters) of the site, however, that also operate well without requiring formal participation of everyone in these processes. The use of the place by the neighbourhood for its activities and the creation of moments of social encounter is considered to be of greater importance for civic engagement than formal participation processes.

Heritage Conservation Can Be Promoted through the Ownership Instruments Studied
None of the models studied has an intrinsic connection to heritage conservation. In all cases, any inclusion of heritage concerns is an add-on to these instruments. However, the benefit of these instruments for adaptive heritage reuse projects is that the purpose of heritage conservation can be specified in the HBL, CLT and CO. HBL, CLT and CO are not instruments for heritage conservation per se. Many of the initiatives operating with these instruments are new construction projects (interviewees National CLT Network and Stiftung trias). However, other projects such as the ones covered in this study have combined these instruments with self-imposed obligations of heritage conservation. Such binding agreements can be added to the leases of a specific project for HBL, CLT and CO and thus cannot be revoked within the length of the contract. In the case of listed buildings, stipulations may be added on top of the requirements of heritage authorities. Alternatively, such heritage stipulations in these instruments could also address forms of heritage that have not (yet) been listed officially. The problem, however, is that these agreements can be difficult to monitor; therefore, in the context of HBL they often come down to 'goodwill agreements' (Interviewee Stiftung trias).
To be sure, even when the projects under investigation emphasised the heritage base of their initiatives, the use of these instruments did not spare them from challenging decisions to do justice to both heritage conservation and urban development to address modern functions and needs. The interviewee from Midsteeple Quarter stresses the overall social and political cohesiveness of the process to develop a new Masterplan for the city centre, however, he also acknowledges that 'around the heritage element, there are probably difficult conversations still to come around buildings that may have to be removed, rather than saved.'

Heritage Definition and Use are Promoted as a Commoning Process
Besides formal requirements for heritage conservation, it is also possible to find an intrinsic connection between the heritage of the site and the implementation of one of the ownership models. It would be misleading to consider the heritage and the demands of heritage conservation as an additional effort that is placed on top of the other requirements. Oftentimes, it is precisely the interest in the heritage as a unique feature of the site, that galvanises the broader support for engaging in such complex and demanding processes that are part of these ownership models. The heritage gives project initiators, neighbourhood residents, heritage communities and other public stakeholders a concrete reason to focus their attention on one particular site. In an evolving circular process, as heritage is addressed for its aesthetic, historical or communal value, heritage becomes defined, used, and ideally conserved by these actors as a process of commoning.
In all four cases, the projects have created a heightened awareness in the respective neighbourhoods of the heritage of the site. At Midsteeple Quarter, the focus on the heritage also triggers a growing sense of pride for the town centre after a prolonged period of economic decline. The CLT London, as one example, launched a campaign to develop and open up the site and took initiative to establish a Cultural Heritage Community. This group was needed to apply for the Heritage Lottery Fund. Our interviewee from the London CLT mentioned a community engagement process in 2018 to determine the use of the envisioned community space that also brought out the heritage of the building: "The theme that came out of that survey was mental health and wellbeing. So, all of the activities that were planned could link to that. And that ties in with the historical use of the building as a psychiatric hospital and as a workhouse as well. There has always been an awareness of how fortunate we are, being in a space that is so rooted historically to the area and in any project that we run we want to make sure that we are respectful of that and that we educate people around that." The project partnered up with Historic England to develop a plan for refurbishing the building and the inclusion of residents, local architects and construction companies. The Prädikow example shows that the status of a listed building demands the integration of the heritage authorities to reach a building consent. On top of that, the Hof Prädikow group also works on the history of the site by involving village residents through oral interviews, collecting documents etc. to produce a common understanding of the farm's heritage. This process has heightened the awareness of the heritage even among established residents who according to our interviewees had lost interest in the history of the site over the past decades. At ExRotaprint, the project initiators have engaged in heritage conservation beyond the legal requirements from the heritage protection authority posed on the listed buildings. This process also involved research on the architects Kirsten & Nather of the complex and the publication 60 created a new appreciation of his works that had previously been rather unknown. While this heritage making through the neighbourhood opens opportunities that might be beneficial for residents and small businesses, it also attracts investors and profit-driven development schemes. The instruments may become a helpful tool but they are not sufficient in fostering a commoning process around heritage. Social preconditions of commoning and the use of these instruments require a critical look.

The Local Embedding of the Instruments Requires Informal Action
Besides formalised structures and commitment, a key to success in stimulating civic engagement is the building of trust between the project and the surrounding area or neighbourhood. In some instances, particularly visible in Hof Prädikow, the initiation of a new project and the related arrival of new residents with a distinct 'urban' occupational and educational background in the rural area is met with scepticism among the established residents: 'Who are these people? Why do they come here? What changes will they bring to the area? What if, I don't like these changes . . . ?' Trust-building is pro-active and patient work and becomes more important, the greater the prejudices are. Trust is the precondition for formal arrangements, such as representation in board structures, however, all experts we interviewed agree that formal structures of participation are not sufficient to create meaningful civic engagement.
The Midsteeple Quarter project and the London CLT have built on significant efforts of community organising early on, to identify a site and the needs of the neighbourhood that the project would address. In the case of HBL, one interviewee from the Stiftung trias and another from Hof Prädikow agreed that the reservations of the local population have been lowered, once people found out about the HBL construction of the project. The idea of building something on land that is not owned seemed strange to several inhabitants in rural Prädikow. However, the fact that a not-for-profit foundation monitors the public benefits of the development reduced the fears that the Hof Prädikow collective would aim at closing themselves and the heritage site off from the rest of the village. Furthermore, a rural project such as Hof Prädikow, which is still in its initial phase, indicates a specific pitfall when large projects open up and create the prospect of turning majorities in political processes and elections. Established decision-makers in the area react with a defensive attitude towards new initiatives for fear of losing authority. For this reason, Hof Prädikow group as well as sympathising villagers try to motivate doubting political actors to proactively engage and become part of the processes that shape the site and the neighbourhood development.
In the case of ExRotaprint, participation of the surrounding population in the site is primarily facilitated through usages of the social services provided on the site or the small business and workshops. Our interviewee explains this intertwining of formal and informal processes of community participation in these terms: "This school for dropout teenagers, the advice for refugees, the advice (services) for long-term unemployed people, and the German classes, they are so integrated into this Wedding (district) community. . . . [Regarding community engagement] I would say it is kind of to curate a compound like this through choosing the renters and what kind of offers they bring to the neighbourhood. They are doing the job much better than us at ExRotaprint could ever do. It is so concrete. It is more important to look at these kinds of things for us than if [a project within the compound] is actively engaged in ExRotaprint and the [formal] process. But the work they do is so important for the whole compound and gives an important aspect to the daily life here." Through direct local benefits, the relationships with the surrounding area have been perceived as constructive, and in contrast to other gentrifying areas in Berlin, this project does not face animosity from the neighbourhood as a bridgehead for gentrification dynamics.

The Instruments Require Professional Skills or Support, a High Degree of Volunteer Labour and Idealist Attitudes
The purpose of the charity National CLT Network in England and Wales, as one example of a supporting organisation, claims: 'We provide funding, resources, training and advice for CLTs and work with the Government, local authorities, lenders and funders to establish the best conditions for CLTs to grow and flourish.' 61 A key objective of the charity is to 'promote the voluntary sector for the public benefit' (Constitution 3.1 of the National CLT Network). Both the London CLT and the Midsteeple Quarter CO count on professional staff to coordinate the efforts, provide administrative support and motivate community organising and engagement.
Similarly, the trias foundation offers help to the HBL arrangements at ExRotaprint and Hof Prädikow for financial advice and monitoring. There is, however, a slight difference in the way these projects commit to the foundation and its framework support: 'To work with us is an act of solidarity: after 30 years, when they [the lease taker] repaid all their bank loans and do not have any debts anymore, they continue paying the land lease fee into a solidarity fund. It is an idealistic step: not only do we help projects, but projects also help us by building up a structure for the next project.' 62 This means that value capturing through the ground rent is used to fund other projects.
Even with such professional support, all four projects studied make clear that voluntary work required by community members is intensive. Within the approximately five-year phase from initiating the project to moving in for housing, the Prädikow project participants worked on planning and on building consent, which required programme, architectural interventions and funding to be adapted frequently. Inspired by a sociocratic decision-making model, 63 each member of the Hof Prädikow group is expected to take proactive engagement to follow the debates and take part in decision-making, as an interviewee emphasises in these terms: "Everyone carries the responsibility and risk to evaluate constantly within the project phase, whether this is still one's project or not. And there is this basic attitude towards information. It is not about bringing information to people. People are expected to seek the information they need. It is absolutely essential that people are proactive in this project. Of course, there are transparency and digital tools. But if I don't use them, I am simply out of luck." Instead of voting on yes/no basis, objections to proposals have to be substantiated and the degree of resistance is measured on a scale from 1 to 10. The idea is that the better argument decides and the level of resistance to new proposals has to be low. Throughout these communicative processes, the members work on common values, establish approaches and formats of communication, learn from mediation sessions, and implement inner-group and public activities. All of this is to say that while these processes promise to strengthen group cohesion and bring about a sustainable decision, they require a significant degree of engagement, energy and skill.
Institutionalising voluntary work, for example, by the community boards in the CLTs, ensures that neighbourhood engagement is not only part of the project preparation or implementation phase, but also constitutive of the long-term stewardship of the project and the neighbourhood (Interviewee National CLT Network). Group members' skills in financial, legal, and architectural issues are important to draw on, but sometimes these skills need to be brought in by supporting organisations or possible local cooperation partners. All adaptive heritage projects, in conclusion, require a high degree of support, voluntary work, and idealism from their members.

The Dilemma of Civic Engagement Is that the Required Expertise Has a Selective Bias Towards Participants with Middle-class Background
The immense expertise that all three models require for setting up and maintaining explains an overrepresentation of a middle-class professionals who are involved in these decision-making processes -whether because of the expertise they bring in for such complex formal planning processes or because of the required resources to allow for consistent participation. While organisations such as the National CLT Network and Stiftung trias provide important professional advice to such initiatives, this advice does not eliminate the need for the project groups to develop significant expertise themselves.
An interviewee from Prädikow emphasised a selective bias as evident in the case of the group of initiators, several of which who are academically educated and professionally experienced in project planning. In her account, she juxtaposes this group with the working-class background of the long-term residents who have engaged much less proactively around matters of planning and politics over the past decades. In the case of ExRotaprint, the members of the managing gGmbh are professionals, too, quite in contrast to the working-class environment of the Wedding district. However, given the emphasis on informal and usage-driven forms of participation, the social and educational discrepancy between managers and users does not create unsustainable resentments or conflicts. The selective bias is less obvious in the case of St. Clement's CLT where CLT residents must demonstrate a need for such affordable housing. In this London case, however, the support from an organisational team is particularly strong as a way to ensure the logistical and organisational flow of the processes, the outreach and others. Generally, for the CLTs' membership, Jennifer Aird observes that CLTs 'target the intermediate market of households who are not provided for by either social (public) housing or the open market.' 64 If these selective biases are not managed well, the challenge of any given placefocus in adaptive heritage reuse sites is that its effects on and relationships to the surrounding area may eventually fall out of view. The risk is thus that the project develops as a social and cultural Island that sets itself apart from the neighbourhood and because of its unique selling point of place-making propels gentrifying dynamics in the surrounding area.

Conclusion
All three ownership instruments show significant potential for adaptive reuse initiatives of cultural heritage in view of enabling civic engagements. However, as the case studies demonstrate, these formal processes are not sufficient by themselves. For these instruments to be used successfully an interplay between formal and informal processes is necessary for any meaningful civic engagement.
However, there are differences in how informal and formal processes have been integrated in our case studies, particularly how neighbourhood integration in decision-making processes is formalised. The involvement of a neighbourhood in CLTs and COs is formally defined, and in the cases considered there are clear strategies and benchmarks for creating a pre-defined social impact. Therefore, the accountability of CLTs and COs towards public stakeholders appears greater, however, further research would be needed to explore how formal rules and impact measurements in these institutions relate to the actual needs and interests of neighbourhood inhabitants at large.
In the case of the HBL, social purposes may be defined but monitoring this process through the lease giver cannot ensure the same level of formal enforcement. As a result, HBL requires ongoing self-motivation of the project to do civic engagement and the risk is that it may fall by the wayside eventually when only considered 'optional.' At the same time, the HBL instrument allows for greater flexibility and freedom in designing these processes.
Another condition for embedding the formal instruments relates to the skills and resources they afford. In the case of HBL at Hof Prädikow and ExRotaprint, the skills required for implementing the tools and moderating informal processes are brought in by idealistic and passionate project initiators. These demanding processes, however, create a selective bias towards middle-class professionals or creative entrepreneurs who have acquired these skills. Such selection, in turn, creates a new challenge to avoid the project from attaining a more general bias within civic engagements and to open up these processes also to other participants in the neighbourhood who may not have such skills and resources. In the CLT case of St. Clement's and the CO case of Midsteeple Quarter, the formal character of the rules for membership and civic engagement goes some way to avoid this bias. It needs to be noted, however, that both cases count on a small team of staff including community managers.
The most critical issue in the use of these instruments relates to the issue of their sociospatial impact, especially in already densifying areas. As discussed, neighbourhood revitalisation and heritage conservation may counteract the original intention of creating benefits for the neighbourhood. All tools do not entail approaches for value capture in the area. The political question that emerges from this dilemma is how can such formal tools be extended territorially and scaled up to have a broader impact on neighbourhoods beyond creating Islands for the few.
Within these broader limits, however, the explorative study shows promising effects. The awareness of shared heritage is an important motivating factor for residents and other stakeholders to become involved. In all cases considered, heritage was a key to bringing people together to discuss and commonly define the meaning of the site, what its relevance is for the neighbourhood and what future uses it should enable.
The CLTs, COs and HBLs can be useful tools for energetic (non-profit) initiatives to access and control their development, promote local heritage without commercialisation and create places for social encounter in the neighbourhood. As a follow-up, a systematic comparative analysis could elucidate the current obstacles to instituting CLTs, COs and HBLs on a broader scale and the conditions for these instruments to gain greater mainstream support and political traction.