The Impact of Contemporary Housing Functions on Its Social Sustainability

Social housing functions are interrelated in manifold ways, expressing different needs and preferences of heterogeneous and socially unequal modern societies. The home as a place of individual shelter and privacy and as a node of interaction in social networks interferes with activities that had been spatially outsourced in the past and reintegrated again in recent times, such as productive labor, care or supply. In addition, social housing functions compete with economic functions of capital accumulation and profitmaking, transforming the dwelling into a tradeable commodity. Likewise, ecological functions of saving land and resources and reducing greenhouse gas emissions have to be satisfied. These interdependencies challenge sustainable housing politics, most prominently signified in the UN’s Sustainable Development Goals 1, 10, and 11. The contribution captures this network of housing functions by advocating to strengthen social housing functions against economic functions. Political and philosophical justification of this position refers to theories of social capital and relational justice. Political measures feasible of being applied within the neoliberal system will be delineated, aiming to sustain social housing functions.


Introduction
Sustainable Housing is a significant challenge of contemporary societies worldwide, addressed explicitly by the Sustainable Development Goals 1, 10 and 11 of the United Nation's Agenda 2030 [1]. By taking the triangle model of sustainability as a reference, the economic sustainability of housing rests upon the idea to push back a dominant profit-making strategy of capital accumulation and claiming a social infrastructure approach of housing instead. Ecological sustainability deals with eco-sensitive products and property-protecting housing construction without losing the practical needs of availability and affordability of income-poor households. While ecological sustainability is considered here rather implicitly, the contribution focuses on the conflicting interlinkages between the social sustainability of housing and the growing meaning of economic housing commodification.
Housing in its social dimension does not only provide a place for individual shelter and privacy that help humans survive physically. Moreover, it offers opportunities for community engagement and social inclusion. The neighborhood represents a significant institution to embed residents in social networks, enabling social capital creation such as trust, solidarity, and mutual support. From a theoretical perspective, the paper primarily though not exclusively refers to Bourdieu's concept of social capital and Rosanvallon's relational equity approach, with its ingredients of 'singularity' , 'reciprocity' and 'community' .
However, the mentioned social functions of housing are challenged by a significant transformation and pluralization of lifestyles, labor conditions, family structures, and cultural aspirations of living, affecting sustainable housing policies. Housing has become more flexible, fragmented, multi-located and biographically dependent. More single (parent) households of younger and older people ask for social co-housing and intergenerational living solutions. Increasing housing prices are a big problem for low-and middle-income households, and the current COVID-19 pandemic crisis contributes to a massive relocation of functions to the home (working, consumption, schooling, and leisure). These multiple and conflicting housing functions induce a search for tailored political solutions to socially sustainable housing.
The paper delineates the outlined challenges by, firstly, discussing the numerous and different housing and neighborhood functions of contemporary modern societies. This section is meant to be a plea for considering the social functions of housing primarily. Secondly, a political and philosophical justification for this plea is presented, with reference to the theories of social capital and relational equity. Social functions of housing will, thirdly, be confronted with neoliberal economic housing functions to argue for political interventions that encourage social sustainability of housing. Several political measures will then be presented, which deemed suitable and necessary in this regard. Examples from European countries and cities are used to illustrate and elucidate the arguments raised throughout the contribution.

Housing and neighborhood functions
Housing functions are diverse and assessed differently by people and social milieus of varied socio-economic and socio-demographic status. Housing functions' appraisal depends, on the one hand, on individual needs, expectations and aspirations, which, in turn, are influenced by biographical and cultural circumstances as well as economic conditions. Housing biographies change in phases of commencing work or study, growing or shrinking households, new job or family opportunities, or after retirement. These phases often affect residential movements, along with shifting expectations towards housing needs. Also, changing earning capacities (growing or falling) affect a household's autonomy concerning the housing situation. The housing culture shapes different imaginations of how people live -in a detached house or an apartment in a multi-story housing block -and thus how housing contributes to the production of personal identity.
Beyond individual needs, housing functions' appraisal is subjected to social and cultural aspects. Until today, prevailing housing architecture is designed for the traditional two-generational family, represented in separated housing units without or few commonly shared spaces. Moreover, an increase of single-person households, both younger (voluntarily intended) and older (involuntarily accepted) persons, is to be considered. Alternative forms of housing such as social co-housing [2], or housing associations that include jointly used spaces (e.g., kitchen, gym, library, co-working spaces), are growing but still marginal compared to mainstream architecture. While standard housing architecture designs rooms to be used more or less mono-functionally, co-housing concepts promote ideas of rooms that allow to integrate different functions in one room or to provide spaces that are used by multiple households (e.g., a room for taking care of children or a kitchen that is used by several families). Social housing functions are also influenced by a transformation of how living spaces are utilized. The change of (global) labor markets and the digitization of almost every aspect of our lives contributes to a spatio-temporal intersection and decentralization of activities of work, provision, education and recreation at home, which manifests in a functional mix of living spaces (e.g., working in the kitchen).
Historically, the spatial interference of domestic work had been the norm; farming, handcraft, and trade had been tied locally to the home [3]. The system of the estates of the realm, political sovereignty of aristocracy and the church inhibited social mobility by and large. Industrialization provoked an increasing spatial separation of productive and reproductive labor, which led to an extensive functional fragmentation and spatial specialization of activities to date. Today, we face spatialfunctional re-unification processes, which results in a complex amalgamation of housing needs. Ongoing COVID-19 pandemic measures (homeschooling, home office, online delivery services) boost and exacerbate this development, affecting the home and the neighborhood. It is assumed that this development will become a sustainable housing trend, not least due to requirements to mitigate climate change effects [4]. However, not all households will be able to cope with these housing functions' transformations.
The neighborhood with its opportunities for social interaction is likewise relevant to satisfy the requirements of accommodation. Public spaces provide chances to establish and strengthen mutual recognition to enhance social inclusion opportunities to both new and long-established residents [5]. A well-functioning neighborhood also promotes social integration of all residents but mostly of minorities and marginalized groups like migrants, income-poor, or single-parent households. In addition, local communities can serve as a source for local social and political engagement. Even though all these social functions cannot be reduced to the neighborhood alone, it remains an essential promoter to residents being embedded into social networks and able to generate social capital. The next section will refer to this topic in more detail.
Social integration and inclusion do not rest upon a general and external natural law. Still, they are the temporary results of negotiation processes within and between social collectives whose participants are equipped with different amounts of social power, which, in turn, result in uneven social relations, local knowledge and social positions. Housing and neighborhood functions are therefore linked to issues of social inequality social (in)justice, which must be raised in the context of the prevailing economic model of neoliberal capitalism. This model places an individual's liberty and autonomy and self-reliance at the core of economic and societal action. All types of equal opportunities, which, among other things, affects access to housing, are to be valued and criticized against a neoliberal understanding of the equal opportunity. An alternative approach to the concepts of equal opportunity is given with Rosanvallon's [6] equity of relationships, delineated in the next section.
Housing space is geographically not evenly distributed nor available but depends on market regimes influenced by numerous factors, such as economic development, local and regional labor markets, infrastructure, return expectation of real estate markets, and local and regional planning. Housing preferences reflect these factors with spatio-temporal variations. Urban agglomerations are characterized by periods of urbanization, suburbanization and re-urbanization, while rural regions are affected by out-and in-migration, depending on location and infrastructural facilities. The last three or so decades represent periods of novel forms of residential segregation such as gentrification or gated communities [7]. They represent a growing social fragmentation whose spatial mechanisms of exclusion reveal different aspirations of housing [8].
Transnational and seasonal labor migration, forced migration due to civil war or changing climate conditions, lifestyles of multi-locality or long-distance commuting are some manifestations of globally mobile societies which affect the individual and social assessment of housing functions too. An example of the highly dynamic residential mobility processes at the local scale is given with statistical data of the twenty largest cities in Germany, illustrating residential movement of households: on average, 8.5 percent of households move each year, with a range of six to eleven percent [9]. Mobile households compete with the needs of the long-established population with regard to needed shops and infrastructures, cultural and sports facilities or the availability of outsourcing housing services (cleaning, food provision).
Individual and social functions of housing and neighborhood compete with economic functions of the home in several ways. With the advent of neoliberal market principles in the 1980s, the commodification of the house became an essential strategy of capital accumulation [10]. In fact, housing commodification has turned out to be the predominant investment strategy to date since many alternative investments yield lower rates of profit. Besides expectations on return of capital investment, it represents additional income during one's old age (because pensions are expected to decline). In this case, the residence is not always intended to be used by the buyer but serves as a second or touristic home (Airbnb) for others. These housing units are then divested of the regular housing market. Social housing strategies -represented by public housing, housing associations, or private housing assemblies -are seen as an attempt to mitigate sky-rocketing housing prices due to housing commodification. Housing policies dedicated to all types of settlements (urban, suburban, rural) are confronted with a fundamental dilemma. On the one hand, (attractive) new construction is meant to be a measure to grow demographically (and by tax revenues). On the other hand, competing with other cities or municipalities on residents is prone to risks of vacant housing stocks, which, in turn, impacts ecological sustainability and endamages a city's image.
Three overall domains can be extracted from the discussion of a multi-layered, interdependent and competitive amalgamation of housing functions, which are inevitably relevant to sustainable housing and correspond with the three dimensions of sustainability. The first domain represents the home as part of the social infrastructure, which is one precondition for residents being embedded into social networks (social sustainability). The second domain emphasizes the preservation of the building. Investment of capital is seen as a strategy to maintain the building substance without pursuing the goal of maximizing profit (economic sustainability). The third domain accounts for the fact that land and construction materials are finite resources. New building is neither excluded nor ranked first (ecological sustainability). The next section delineates theories of social capital and equity of relationships to make a plea for the social sustainability of housing, followed by a critical discussion of the capitalistic commodification of housing to shed some light on the problems of economic sustainability. Both sections result in reflections on measures taken to ultimately strengthen local political power in order to promote ecological, social, and economic sustainability as a function of political-and social-ecological transformation [11]. This kind of promotion aims to take a particular perspective on the social sustainability of housing that carries further the idea of transformation as a bottom-up process. Figure 1 illustrates the functional interdependencies of housing (arrows do not represent exclusive relations, as there are many more relationships between the mentioned objectives; all the other connections are excluded deliberately to keep the illustration clear).

Social capital and equity of relationships
Theories of social capital contribute significantly to assess the relevance of housing as being a part of the social infrastructure, even though the idea of capitalizing on social relations is questionable [12]. Definitions of social capital are different in scale and incorporated values, but they all emphasize its meaning in social network relations. Bourdieu [13, p. 248] defines social capital as "[…] the aggregate of the actual or potential resources which are linked to possession of a durable network of more or less institutionalized relationships of mutual acquaintance and recognition". Since resources are incorporated into actors, his utilitarian perspective primarily focuses on the nodes of the networks. The values are given by solidarity, reciprocity, and trust expressed as network connections.
Coleman [14, p. 302], in contrast, accounts for assigning value to the edges, thus relations, of a social network: "Social capital is defined by its function. It is not a single entity, but a variety of different entities having two characteristics in common: They all consist of some aspect of a social structure, and they facilitate certain actions of individuals who are within the structure". Though different in their focus on social networks, both definitions share a common understanding of the preconditions -resources and social structure -necessary to trade social capital and of the selective mechanisms of exclusion and inclusion that emerge with the quantity and quality of social capital recognized and appreciated in particular social networks. In order to explicate those different forces within and between social networks that are responsible for social inequalities, it is worth referring to Woolcock's [15, p. 10] distinction of "bonding", "bridging", and "linking" social capital [16].
Even though we take into consideration that the value units of social capital derive from societal sources that lay outside social networks -"trust, reciprocity, moral, or attitudes will be reproduced and modified in social networks, but not exclusively produced" [12, p. 11] -we are able to recognize the relevance of social capital in community building and participation, notwithstanding. The home serves as one, albeit not a single spatial node of their residents' social networks. The Sustainable Housing 6 home functions as the material source for creating and exchanging the ingredients social capital is made of, irrespective of the intensity of its use and the social status, ethnic background, or any other discrimination of its inhabitants. Any social interaction needs to be embedded into a local context to be recognized and accumulated as a potentially valuable contribution of belongingness and inclusion. Social capital is, therefore, one core concept to strengthen the social housing function against other concurrent functions.
A second core concept is given with the equity or justice of relationships [6]. The requirement for equal relationships arises from the insufficient applicability of equal opportunities in capitalistic societies. The relational equity principle does not claim to represent a utopian counter-program against the free-market liberal paradigm but to propose a realistic attempt of prioritizing social prosperity over individual justice of achievement. None of the concepts of equal opportunities -be it legal, institutional, instrumental or radical -aim for a comprehensive reduction of social inequality, nor do they fairly value individual success (or failure) against societal achievements. Furthermore, they largely fail to offer satisfactory suggestions to the range of legitimate inequality, a just redistribution of wealth or a commonly accepted poverty level [6, p. 286ff., 17].
According to Rosanvallon, social inequality rests, at least, upon three causes: (i) the privilege of social origin, that correlates with unevenly distributed capabilities among people; (ii) the growing commodification of life, that jeopardizes social and ecological well-being; (iii) the social-spatial segregation, that threatens social cohesion due to limited possibilities of mutual recognition and communication across these segregated areas.
Individual and social functions of housing suffer from economically preferred individual justice of achievement and social inequalities. Against these problems, Rosanvallon proposes a relational justice that satisfies three conditions: firstly, 'singularity' appreciates the mutual recognition of human beings. It does not qualify individual autonomy and liberty as a state but as a relational property. Social rights derive from unconditional access to societal institutions, including housing markets. Mutual recognition is particularly committed to less privileged and/or less affluent people struggling to articulate their rights in economic relationships. Secondly, it claims equal participatory rights of co-produced goods and services, as well as commonly shared values, referred to as 'reciprocity' . This relates to commons, not to trade and exchange. Needs are anticipated and shared democratically. In our context of housing functions, reciprocity accounts for the globally claimed human 'right to housing' and the targets addressed by the Sustainable Development Goals, such as affordability, basic protection of tenants against disproportionately rising rents or displacement. The third condition of relational justice refers to 'communality' , which avoids the creation and maintenance of communities to be realized by socio-cultural ascriptions. These discriminations imply a commodification of the person, with which inclusion and exclusion -and asymmetrical power relations that derive from these processes -are established. Residential segregation is one of the results, reproduced and seemingly legitimated by those discriminations. Communality urges all people to strengthen local democratic relationships and local social spaces [6]. It can be understood as a synthesis of singularity and reciprocity criticizes contemporary processes of gentrification because they discriminate against humans socially and reward economic Darwinism.

In a nutshell
Theories of social capital and relational equity/justice are two approaches that delineate common principles of establishing and preserving social communities. Other approaches not explicitly considered in this contribution are sociological and social geographical theories, such as actor-network theory [18], system theory [19], theory of structuration [20], and theory of action [21], as well as social-and political-philosophical theories like, for example, the theory of justice [22]. Social capital and relational equity theories take a relational perspective on communities and highlight the functions of relational structures. In so doing, they enable a critique of current housing policies from a sustainability's perspective. Social capital theories exhibit the principles of social relationships, the mechanisms on which social networks of different size, quality, and hierarchy develop and differentiate, and the roles, positions and power relations that emerge due to capital allocation. Theories of relational justice set out alternative norms of collective participation and engagement. Priority is entitled to an equitable status of community members against individually justifiable inequalities.

The capitalistic exploitation of dwellings
Industrialization implicated a comprehensive division of labor and, consequently, the functional and spatial division of living and working. While productive activities had been relocated to firm sites, the home mainly served for tasks of reproduction. Further outsourcing of housing functions followed through with the proliferation of health, education, and cultural institutions. With the growing availability of leisure time, recreational and sports activities were outsourced increasingly as well. This intense spatial differentiation of functions has changed with the development of modern information and communications technologies over the last 20 or so years, as both productive and reproductive tasks can now be relocated to the home. This development, however, happens to take place selectively, voluntarily, and involuntarily. The measures to combat the COVID-19 pandemic are currently the most obvious signifier of a complex mix of functions at home. All these processes will influence -and partly even determine -the economic meaning of the dwelling as a commodity.
With the implementation of the neoliberal regime in market societies since the 1980s, economical housing functions have also altered. Globalization and deregulation of financial markets led to significant demand for properties as capital investment. Commercial and housing real estates are valued profitably, primarily in large urban agglomerations such as global cities, not least due to other capital investments are assessed less attractive because of low interests. Also, the privatization of public commodities like social housing complexes increased the revenue expectations of investors. For example, Germany's number of social housing units declined from almost 4.0 million (1987, only West Germany) to 1.2 in 2020 [23]. The economic and financial crises of 2008 further boosted housing commodification and reinforced housing market structures -with private interests outperforming social needs. Accumulating capital clearly prevails [24], though personal risk management is increasing likewise [25].
Land and real estates are finite and scarce commodities whose utilization depends on diverse interests and needs -agriculture, commerce, housing, transportation, recreation or natural livelihoods' preservation. Scarcity and competition ask for high demand, which also varies due to locational parameters. Globalization, deregulation, and privatization of commodity and financial markets made numerous and flexible possibilities of capital reinvestment available simultaneously. Overproduction of commodities and falling prices thereof produce a surplus of capital in the "primary circuit of capital" [26]. This capital seeks valorization in the "second circuit of capital", to which real estate markets belong too. Urban and suburban housing markets are predominantly affected by increased exploitation of capital [27].
The influence of economic geographical parameters manifests, among other places, in processes of gentrification. Gentrification, defined as a process of economic, architectural, cultural and social upgrading of mostly attractive urban areas (concerning location), often accompanied by a displacement of less affluent households which have lived in these areas for long [28][29][30][31], is theoretically analyzed by different approaches. Rent gap and value gap theories focus on the investment behavior of financial companies (real estate agencies, insurances, mortgage lenders, private housing companies, etc.) and government agencies. Driven by suburbanization processes with rising land prices in these regions, "[…] the relative price of inner-city land falls. Smaller and smaller quantities of capital are funneled into the maintenance and repair of the inner-city building stock. This results in what we have called a rent gap in the inner city between the actual ground rent capitalized from the present (depressed) land use and the potential rent that could be capitalized from the "highest and best" use […], given the central location" [30, p. 133]. Figure 2 illustrates the rent gap theorem. Though similar in its principle explanatory objective, value gap theories consider rent-housing markets of European cities mainly [32].
Unlike top-down approaches of capital accumulation, theories such as the invasion-succession-cycle theory primarily take the investment behavior of households into account. According to this theory, gentrification is distinguished into phases of invasion (firstly of pioneers who are engaged in activities of cultural upgrading, followed by gentrifiers whose primary interest lies in profit-making) and succession (an increase of firstly pioneers and then gentrifiers lead to a transformation of the residential population due to rising rent and property prices, referred to as 'social' upgrading). Despite these analytical differences, both approaches highlight the function of housing as a commodity.  Furthermore, the strong position of the economic functions of housing can be explained by the heavy meaning of the competition law and private property within the European Union. One conclusion of this meaning is that social housing policies must not distort competition. In other words, social housing is exclusively restricted to low-income households unable to afford homes offered on the private market [33, p. 20]. Private property is explicitly legally protected as a basic liberal right, while social housing needs are not. The human right to housing is interpreted as a right to "housing assistance" that obliges the state to issue adequate political conditions and not accomplish an individual right to housing. The consequences of this politics are far-reaching: Sweden, for example, had to adapt its previous praxis of fixing rents when it joined the EU in 1995. The "reasonable rent" was related to the dwellings of the public housing companies; private rent prices were not allowed to exceed five percent. Today, rents of public housing companies have to comply with freemarket conditions. In addition, Sweden has reduced public funds in housing to zero [33, p. 24].
It is not only private companies but also cities and municipalities which share a common interest in responsibly taking care of the economic functions of housing. In contrast to the private housing economy, public institutions are required to gauge economic, social and ecological concerns against each other, for which they have to adjust their local programs and plans to regional and national ones. Given their sovereign right to designate land to be utilized for construction, they govern the settlement development of their territory mostly independently, however. Income and commercial tax revenues force cities and municipalities to promote the economic development within their territory selfishly and independently, under which a trans-locally coordinated settlement development suffers. Planning rules (e.g., building density and height) as hard facts and cultural aspirations (e.g., preference of detached houses in suburban and rural regions) determine the housing forms sustainably. Middle-and high-income residents are supposed to be most attractive since they pay more taxes and spend more money which, in turn, increases municipalities' scope of freedom for future local development -a self-enforcing process has been initiated, which ultimately is economically risky and ecologically unstainable.
Even a balanced local housing market development is prompted to take the private interests of landlords into account, even though it affects low-income households adversely. Social housing associations increasingly struggle to supply affordable housing for all income groups (income that relates to the regional labor market with its salary structure). For example, the income and living expenses of Salzburg's residents grew by 22 percent, while rent prices did so by 30 percent and property prices by 70-100 percent [34]. Current rent prices for tenants of social housing are almost 11 Euro per m 2 , compared to private rent prices of 15 Euro per m 2 on average [35]. Although a significant difference is given, for a growing number of low-income households, it gets more and more difficult to afford these rent prices.
A related problem is that housing markets are spatially and temporarily volatile due to socio-demographically varying attitudes of housing preferences. Suburbanization, reurbanization, counter-urbanization or living in the countryside are all trends of changing popularity that affects the supply and demand of housing. While vacancy in demographically shrinking regions is accompanied by a dereliction of buildings and a decay of prices, it is a signifier of speculation in regions of growth. Economic sustainability of such processes is at least questionable, since individual profit-seeking is local and costs of housing conservation are socially outsourced. Ecological and social sustainability are disastrous because the emigration of people is followed by the emigration of businesses and services.

In a nutshell
The growing dominance of housing market functions against their personal and social functions jeopardizes the social sustainability of housing. It neglects the justifiable needs of those persons, being unable to rent or purchase dwellings offered to private (and increasingly social) market conditions. Solidarity across social strata is threatened, and novel mechanisms of exclusion provoke intersectional fragmentation and marginalization, introducing room for encapsulation and resistance. Contemporary capitalistic housing functions are, furthermore, in sharp contrast to challenges of ecological sustainability (land and resources consumption, housing forms, housing locations). Economic sustainability is challenged by short-term profit-seeking versus long-term income security (rent revenue). Housing markets are socially and ecologically blind [36].

Strengthening social functions of housing sustainably
The increased evidence of economic housing functions is, to a large degree, the result of global developments, particularly the financial economy. Although housing commodification manifests locally and regionally differently, a dominance of global interests versus local needs is empirically evident [37]. Therefore, local countermeasures are required, aiming to strengthen the social objectives of sustainable housing. The following suggestions are subdivided into three domains, have been discussed in the literature with different intensity, and are anything but complete. The first domain refers to measures meant to directly strengthen individual and social functions of housing, while the second domain is seen as a framing condition that helps promote personal and social housing functions by forcing back economic housing functions of capital accumulation. The third domain appreciates the local level of political activism by its regional counterpart.

Strengthening individual and social functions of housing
Measures that strengthen individual and social functions of housing justify their purpose by the fundamental meaning of housing as being part of the social infrastructure. One of these measures is to prioritize permanent housing function over touristic usage (e.g., Airbnb) or as second homes. In a study of the city of Salzburg, Van-Hametner et al. [38] uncovered 17 percent of housing units being used alienated; political measures like registration, fixing a maximum number of permitted housing units to be used for touristic purposes, or introducing penalty fees, may alleviate this.
Another measure that helps foster social justice in housing politics is seen in a transformation of funding principles. A politics of social housing is doing better if public funds are dedicated to the construction of housing instead of supporting households. Although the latter is tied to income thresholds, political governance restricts itself to the economic strength of households instead of social need.
Because societies and communities are diverse in their lifestyles, cultural attitudes, demographic structure, and capital composition (economic and social capital), housing politics should account for this diversity by expanding the forms of housing. Up to now, the standardized model of the traditional two-generational family has prevailed. Changing household structures (beyond the biological family) call for new co-living forms, such as social co-housing or intergenerational housing, which provide spaces for collective usage [39]. Ideas comprise spaces such DOI: http://dx.doi.org /10.5772/intechopen.99277 as the kitchen or a room for co-working, co-caring or co-recreation. They promote social interaction and safe resources.
A measure to cope with increased biographical mobility of people (due to increased social mobility) and thus residential mobility is to offer more forms of mobile housing, not only as caravans or campers but also as creative forms of tiny houses [40], for which dedicated public spaces are made available by cities and municipalities. 'Mobile' also refers to a growing supply of furnished dwellings, which simplify residential mobility within a city, a region or beyond.
Residential mobility, furthermore, implies an ongoing change of the household composition in urban (as well as rural) neighborhoods. Establishing relational justice among residents and promoting social interaction to accumulate social capital between residents, cannot be expected to be taken for granted under these dynamic conditions. Instead of hoping for an ideal situation of self-organized, bottom-updriven communication spaces, it would be more appropriate to support interaction among residents by introducing facilitators and intermediaries as appreciated nodes in local social networks. This mode of communication, referred to as "organized urbanity" [41], can be realized through particular (elected) residents themselves or through representatives of public social institutions. Urban quarter management thus strives for solving conflicts (not necessarily resolving them) and creating a social environment that enables the reconciliation of interests.
All these measures are dedicated to enhancing the social infrastructure's role of housing against its growing and powerful capital accumulation function.

Framing individual and social functions of housing
The construction of new dwellings is seen as an adequate strategy to mitigate rising housing prices in mainstream social politics, preferably in urban and suburban regions. Increasing the supply of housing units appears to be a strategy that satisfies an urgent demand due to an increasing population. This, however, is only partly true. Besides the quantitative growth of an urban population, habits of housing are changing: single-person households, multi-local forms of living ("living apart together"), and second homes in attractive regions do apparently increase the demand for dwellings. This seems to result in the paradox of growing property prices due to increasing housing supply. In fact, profit-seeking strategies are the true cause for this contradiction.
Countermeasures that help mitigate those developments are temporarily and regionally adapted moratoria of housing construction [42]. These are socially sustainable because they stem the causes of maximizing capital accumulation as commercial exploitation of dwellings becomes less attractive, even though a further increase of housing prices during the initial phase of transformation cannot be strictly prevented. A moratorium enables affected cities and municipalities to think about the potential future utilization of the existing stock of buildings. No further land will be sealed, no further resources to construct and open up building sites will be needed, and no further energy needs for construction and maintenance will be consumed. With this measure, the daily consumption of land -in Germany, it is 190 square kilometers per year, in Austria it is 44 [43,44] -can be reduced considerably. Also, building materials can be saved (for example, cement production contributes to two percent of CO 2 emissions in Germany; it is six to eight percent worldwide [45]).
A large part of the existing building stock that can be incorporated into the regular housing market are vacant housing units. 2.8 percent of all housing units in Germany (2019) are estimated to be vacant, i.e. would be available immediately or within six months after renovation [46]. For the city of Salzburg, a conservative estimation is four percent (3.500 housing units) [47] but goes up to nine percent. Accompanying measures of public administration are needed to reactivate vacant homes. Measurements can be restrictive (e.g., a penalty charge) by expressing the political will to prohibit vacancy as a violation of the human right to housing, though they might likely be less effective because reactivation cannot be guaranteed. Constructive measures, such as private-public-partnerships to offer vacant dwellings of private homeowners, would be another approach that would be beneficial as they involve the local knowledge of public authorities about housing needs of households of different income constraints.
All these measures and programs can be easily transferred to vacant office buildings in order to further increase the availability of living spaces. Estimates of 3.5 percent vacancy rate in Germany [48] and 4.7 percent in Vienna [49] (no Austrian data available) likewise illustrate the considerable potential of transformation. Converting office space to living space has primarily to contribute to increase the availability of affordable housing and to restrain strategies of capital accumulation.
Cities and municipalities in Germany and Austria are not only invited to collaborate with private landlords or housing companies more tightly but also to take their general right of pre-emption of housing units more seriously into account. A few cities like Berlin apply this right more intensely in recent years [50]. In order to increase the stock of public housing units by this measure, a more comprehensive financial subsidy and political encouragement of national governments or the European Union is needed. Recalling the above mentioned EU's competition law and property rights illustrates how complex this operation will be, however.

Complementing individual and social functions of housing
Cities and municipalities do have a considerable sway to develop, govern and shape their territories, which implies both numerous policy spaces and risks. To maintain or enhance their attractiveness to residents, businessmen or tourists, they are liable to the growth paradigm. New building programs or the renovation of expensive housing blocks is seen as an indicator of economic prosperity in local settlement development. By generalizing this idea, a selfish competition of potential residents takes place, producing winners and losers even if the national population is growing. In order to oppose this thinking and doing, which is anything but sustainable, mandatory regional planning is necessary, which prioritizes regional needs democratically. Designating land to be built is then not any longer subjected to local individual interests. Strengthening regional planning this way has to cope with a reform of local financial planning that enables cities and municipalities to fulfill their local duties in the future as they do today. Merging municipalities would be an alternative which, however, is less likely realizable though not impossible.
Another measure to account for the social and ecological sustainability of housing without causing severe economic disadvantages for local communities is introducing a fee or a tax to redesignated land (farmland that is designated to be built). With this fee, a comprehensive intervention into private property rights will be avoided, and municipalities' pressure to designate land will be reduced. Revenues can be used ring-fenced for public duties as, for example, health and education infrastructure. This way, compensation between private and public interests is feasible.

Conclusion
The proposed solutions of the previous section entail a prospective movement towards a more substantial commitment of considering social sustainability of DOI: http://dx.doi.org/10.5772/intechopen.99277

Author details
Andreas Koch University of Salzburg, Salzburg, Austria Address all correspondence to: andreas.koch@sbg.ac.at housing a severe issue. Simultaneously, they indicate unfolding the weaknesses of the current circumstances and the obstacles that hinder a progressive socio-ecological transformation of societies. The critical observation that the socio-ecological transformation does not happen [51] results, among other things, in a defensive attitude of liberty, values, and lifestyles of the middle-classes, including the seemingly progressive cultural-left. Ecological behavior in one respect (e.g., buying organic food) serves as to justify a behavior that jeopardizes ecological or social sustainability in another respect (e.g., living in a detached house out in the green).
While the United Nations' Sustainable Development Goals frame the global political requirement of a comprehensive transformation of predominantly neoliberal societies (by leaving the question unanswered whether their goal strategies are good suggestions compared with the problems a global population is facing), a complementing local perspective of strategies' implementation is seen necessary to comply with the requirements of sustainability. Strengthening social functions of housing with the proposed instruments appears to be an essential step in this direction.
Relational equity and justice are not meant to be a "nice to have" ingredient to appreciate social relations but an essential component to reducing social inequality remarkably. Localizing social needs and wants in general and social functions of housing, in particular, argues for a relational understanding of geographical space that takes local relationships of people but also of land, commodities, services and capital circulation primarily into account. The presented competition between social and economic housing functions is only one though highly relevant facet in the political and social arena that determines the wellbeing of the present and future generations. Similar efforts are undertaken that refer to ideas of the commons, degrowth, sharing or circular economies. They all have in common a different understanding of co-habitation -co-habitation that rests upon local and thus trans-local governance and shared responsibility. It eludes comparability for profitseeking accumulation strategies and favors subsistence over global production and consumption. Promoting localizing strategies can help amplify a comprehensive understanding of sustainability.
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