Affordability is defined as the state of being cheap enough for people to be able to buy (Combley, 2011). Applied to housing, affordability, housing unaffordability and the mounting housing affordability crisis, are concepts that have come to the fore, especially in the contexts of free-market economies and housing systems led by private initiatives, due to the spiralling house prices that residents of major urban agglomerations across the world have experienced in recent years (Galster & Ok Lee, 2021). Notwithstanding, the seeming simplicity of the concept, the definition of housing affordability can vary depending on the context and approach to the issue, rendering its applicability in practice difficult. Likewise, its measurement implies a multidimensional and multi-disciplinary lens (Haffner & Hulse, 2021). One definition widely referred to of housing affordability is the one provided by Maclennan and Williams (1990, p.9): “‘Affordability’ is concerned with securing some given standard of housing (or different standards) at a price or a rent which does not impose, in the eyes of some third party (usually government) an unreasonable burden on household incomes”. Hence, the maximum expenditure a household should pay for housing is no more than 30% of its income (Paris, 2006). Otherwise, housing is deemed unaffordable. This measure of affordability reduces a complex issue to a simple calculation of the rent-to-income ratio or house-price-to-income ratio. In reality, a plethora of variables can affect affordability and should be considered when assessing it holistically, especially when judging what is acceptable or not in the context of specific individual and societal norms (see Haffner & Hulse, 2021; Hancock, 1993). Other approaches to measure housing affordability consider how much ‘non-housing’ expenditures are unattended after paying for housing. Whether this residual income is not sufficient to adequately cover other household’s needs, then there is an affordability problem (Stone, 2006). These approaches also distinguish between “purchase affordability” (the ability to borrow funds to purchase a house) and “repayment affordability” (the ability to afford housing finance repayments) (Bieri, 2014). Furthermore, housing production and, ultimately affordability, rely upon demand and supply factors that affect both the developers and home buyers. On the supply side, aspects such as the cost of land, high construction costs, stiff land-use regulations, and zoning codes have a crucial role in determining the ultimate price of housing (Paris, 2006). Likewise, on the policy side, insufficient government subsidies and lengthy approval processes may deter smaller developers from embarking on new projects. On the other hand, the demand for affordable housing keeps increasing alongside the prices, which remain high, as a consequence of the, sometimes deliberate incapacity of the construction sector to meet the consumers' needs (Halligan, 2021). Similarly, the difficulty of decreasing household expenditures while increasing incomes exacerbates the unaffordability of housing (Anacker, 2019). In the end, as more recent scholarship has pointed out (see Haffner & Hulse, 2021; Mulliner & Maliene, 2014), the issue of housing affordability has complex implications that go beyond the purely economic or financial ones. The authors argue that it has a direct impact on the quality of life and well-being of the affected and their relationship with the city, and thus, it requires a multidimensional assessment. Urban and spatial inequalities in the access to city services and resources, gentrification, segregation, fuel and commuting poverty, and suburbanisation are amongst its most notorious consequences. Brysch and Czischke, for example, found through a comparative analysis of 16 collaborative housing projects in Europe that affordability was increased by “strategic design decisions and self-organised activities aiming to reduce building costs” (2021, p.18). This demonstrates that there is a great potential for design and urban planning tools and mechanisms to contribute to the generation of innovative solutions to enable housing affordability considering all the dimensions involved, i.e., spatial, urban, social and economic. Examples range from public-private partnerships, new materials and building techniques, alternative housing schemes and tenure models (e.g., cohousing, housing cooperatives, Community Land Trusts, ‘Baugruppen’), to efficient interior design, (e.g., flexible design, design by layers[1]). Considering affordability from a design point of view can activate different levers to catalyse and bring forward housing solutions for cities; and stakeholders such as socially engaged real estate developers, policymakers, and municipal authorities have a decisive stake in creating an adequate environment for fostering, producing and delivering sustainable and affordable housing.   [1] (see Brand, 1995; Schneider & Till, 2007)

Housing is usually deemed unaffordable when it consumes more than a set percentage of a household's monthly income. The Eurostat (2022) and the OECD (Chung et al., 2018) follow this threshold approach and define households overburdened with housing costs as those that spend more than 40% of their disposable income on housing. However, this indicator fails to capture financial hardship, particularly among lower-income households. In fact, lower-income households may be spending less than 40% of their income on housing and yet failing to meet adequate consumption levels for other goods. As a response, the residual income approach ascertains housing (un)affordability by defining a minimum level of consumption for a set of goods according to particular household types. The residual income approach builds on consumption data to define the minimum level of income necessary for a household to survive after housing costs. The main shortcoming of this approach is that relies on subjective measures of what constitutes the necessary minimal expenses for a household. These two definitions of affordability navigate two tensions 1) between housing and other types of consumption and 2) between the individual conceptions of what is affordable and what the government considers to be affordable (Haffner & Hulse, 2021). More recently, scholars have emphasized the multi-faceted nature of affordability to include commuting and transport costs together with energy costs (Haffner & Boumeester, 2010). Other approaches focus on supply-side measures, for instance on the share of the housing stock that a household can afford (Chung et al., 2018). Evolutions in the measurement of affordability bear witness to the complexity of housing systems. Affordability is not only dependent on housing consumption but also on housing supply, particularly in inelastic markets where providers have considerable power, see for example Kunovac & Zilic (2021). At the same time, displacement pressures and rising energy costs in an older and inefficient stock add pressure on households to access affordable housing.

A universal definition of social housing is difficult, as it is a country-specific and locally contextualised topic (Braga & Palvarini, 2013). This review of the concept focuses on social housing in the context of the UK from the late 1980s, which Malpass (2005) refers to as the phase of ‘restructuring the housing and welfare state’, to the early 2000s, known as the phase of the ‘new organisation of social housing’. In response to previous demands for housing, such as those arising during the Industrial Revolution, and recognising the persistent need to address the substandard quality of housing provided by private landlords in the UK (Scanlon et al., 2015), the primary objective of social housing has historically been to enhance the overall health conditions of workers and low-income populations (Malpass, 2014; Scanlon et al., 2015). However, this philanthropic approach to social housing changed after the Second World War when it became a key instrument to address the housing demand crisis. Private initiatives, housing associations, cooperatives and local governments then became responsible for providing social housing (Carswell, 2012; Scanlon et al., 2015). Social housing in the UK can be viewed from two perspectives: the legal and the academic (Granath Hansson & Lundgren, 2019). Along these two perspectives, social housing is often analysed based on four main criteria: the legal status of the landlord or provider, the tenancy system or tenure, the funding mechanism or subsidies, and the target group or beneficiaries (Braga & Palvarini, 2013; Carswell, 2012; Granath Hansson & Lundgren, 2019). From a legal perspective, social housing maintained its original goals of affordability and accessibility during the restructuring period in the late 1980s. However, citing the economic crisis, the responsibility for developing social housing shifted from local authorities to non-municipal providers with highly regulated practices aligned with the managerialist approach of the welfare state (Granath Hansson & Lundgren, 2019; Malpass, 2005; Malpass & Victory, 2010). Despite the several housing policy reviews and government changes, current definitions of social housing have maintained the same approach as during the restructuring period. Section 68 of the Housing and Regeneration Act 2008, updated in 2017, defines social housing as low-cost accommodation provided to people whose rental or ownership needs are not met by the commercial market (HoC, 2008; 2017, pp. 50-51). The Regulator of Social Housing, formerly the Homes and Communities Agency, has adopted the earlier definition of social housing and clarified which organisations provide it across the UK. These organisations include local authorities, not-for-profit housing associations, cooperatives, and for-profit organisations (RSH, 2021). In contrast, the National Housing Federation emphasises the affordability of social housing regardless of the type of tenure or provider (NHF, 2021). From an academic perspective, Malpass (2005) explains that during the restructuring phase, social housing was defined as a welfare-supported service – although it did have limitations, which meant that funding principles shifted from general subsidy to means-tested support for housing costs only, which later formed the basis for the Right to Buy Act introduced by the Thatcher government in the early 1980s (Malpass, 2005, 2008). The restructuring phase, however, came as a response to the housing 'bifurcation' process that began in the mid-1970s and accelerated sharply from the 1980s to 1990s (Kleinman et al., 1998; Malpass, 2005). During this phase, the role of social housing in the housing system was predominantly residual, with greater emphasis placed on market-based solutions, and social housing ownership concerned both local authorities and housing associations (Malpass & Victory, 2010). This mix has influenced the perception of social housing in the 'new organisation' phase as a framework that regulates public housing intervention for specific groups and focuses on enabling non-municipal providers (Malpass, 2005, 2008; Malpass & Victory, 2010). Currently, as Carswell (2012) explains, social housing plays an important role in nurturing a variety of initiatives aimed at providing ‘good-quality’ and ‘affordable’ housing for vulnerable and low-income groups (Carswell, 2012). Oyebanji (2014) sees social housing as any form of government-regulated housing provided by public institutions, including non-profit organisations (Oyebanji, 2014). Additionally, Bengtsson (2017) describes social housing as a system that aims to provide households with limited means, but only after their need has been confirmed through testing (Bengtsson, B, 2017 as cited in Granath Hansson & Lundgren, 2019). To a great extent, social housing in the UK can be seen as a service system that is intricately linked to the welfare state and influenced by political, economic, and social components. Despite being somehow determined by common factors and actors,  the relationship between social housing and the welfare state can sometimes be complex and subject to fluctuations (Malpass, 2008). In this context, the government plays a vital role in shaping and implementing the mechanisms and practices of social housing. While the pre-restructuring phase focused on meeting the needs of the people by increasing subsidies and introducing the right to buy (Stamsø, 2010), the aim of the restructuring phase was to meet the needs of the market by promoting economic growth (privatisation, market-oriented policies and reducing the role of local authorities) (Stamsø, 2010; Malpass, 2005) . The new organisational phase, on the other hand, works to meet and balance the needs of all, with people, politics and the economy becoming more intertwined. Welfare reform legislation passed in 2010 aims to enable people to meet their needs, but through 'responsible' subsidies, leading to a new policy stance that has been described as 'neoliberal' thinking (Hickman et al., 2018). However, there are still no strict legal requirements for the organisation and development of social housing as an independent service system, and most of the barriers to development are closely related to the political orientation of the government, rapid changes in housing policy and challenges arising from providers' perceptions of existing housing policy structures (Stasiak et al., 2021).

Measuring housing affordability refers to assessing the extent to which households can secure suitable housing in relation to their financial resources and other relevant factors. To date there is no global agreement on measuring housing affordability, nor is there a single metric which comprehensively encompasses all the considerations regarding households' ability to access suitable housing in a convenient location at an affordable cost (Ezennia & Hoskara, 2019; OECD, 2021b). Several approaches exist to measure housing affordability, with two popular approaches, namely the Income Ratio Method (IRM), and the Residual Income Method (RIM) (Ezennia & Hoskara, 2019; Stone et al., 2011). Both are recommended to be accompanied by housing quality standards to evaluate what a household is paying for and a measure of housing satisfaction (Haffner & Heylen, 2011; OECD, 2021b). However, the perception of what constitutes satisfactory, quality, or affordable housing is subjective. This perception can be influenced by economic and social circumstances that policymakers may not perceive as directly relevant to housing policy (OECD, 2021b). The Income Ratio Method (IRM) is the most commonly used in policy and housing market-relevant statistics, as it is easy to measure and compare among different countries. It is based on the housing costs to income ratio defined by national authorities not to exceed a certain proportion (Haidar & Bahammam, 2021; Smith, 2007; Stone, 2006). The official EU indicator for IRM is the "Housing Cost Overburden" index. It considers households suffering from affordability issues if more than 40% of their net income is spent on housing costs (AHC, 2019; Hick et al., 2022; OECD, 2020). However, IRM has been widely criticised as it does not reflect if the household could afford non-housing costs and for how long. The focus on housing costs neglects non-housing costs of utility bills, schools, health, transportation, and so on (AHC, 2019). In this sense, Ezennia & Hoskara, (2019) investigation of the weaknesses of measuring housing affordability emphasised the need to reflect a household's capability to balance current and future costs to attain a house – "access to a house at a certain period" while maintaining other basic expenses without experiencing any financial hardship. The Residual Income Method (RIM) is the second dominant approach. It recognises that after paying the housing costs, a household might be unable to satisfy its non-housing requirements. Thus, the RIM is the remaining income after subtracting housing costs, based on the idea that Housing Affordability is the households' ability to cover their housing costs while still being able to pay their non-housing expenditures (Stone et al., 2011; Stone, 2006). The residual income method took a step closer to resonating with non-housing costs. However, both Haffner & Heylen (2011) and Bramley (2012) advised that the IRM and RIM approaches "are not interchangeable" and need to be combined to provide a comprehensive perception of housing affordability. This combination becomes apparent when comparing both for different household compositions, health, or work conditions. For instance, a house might be affordable when measured using the IRM from the housing costs standpoint, but it might not be affordable utilising the RIM, which is connected with non-housing costs. This combination is referred to as the Composite Method from which several advanced economic modelling approaches to measure housing affordability were developed (Ezennia & Hoskara, 2019). However, relying solely on economic criteria to assess affordability and thus overlooking quality and sustainability may not prove sufficient. A poor-quality house can impose hardships on its residents, and an unsustainable dwelling can strain the environment. Mitigating this issue may involve complementing affordability measurements with indicators reflecting housing quality and sustainability to expand the purely economic view (Ezennia & Hoskara, 2019; Haffner & Heylen, 2011; Mulliner et al., 2013; Salama, 2011). Various indicators can be used to assess housing quality beyond just its cost. These indicators could be seen as serving three primary purposes: (1) to measure the quality of a housing scheme and compare it to others within a country (Homes and Communities Agency, 2011), (2) to measure the quality of housing in one country and compare it to other countries (OECD, 2021b), and (3) to measure housing satisfaction across groups (OECD, 2021a; Riazi & Emami, 2018). An example of the first purpose is England's Housing Quality Indicators (HQIs) system (Homes and Communities Agency, 2011), which is currently withdrawn. HQIs served  as “ measurement and assessment tool to evaluate housing schemes on the basis of quality rather than just cost” design standards mandated for affordable housing providers funded through the National Affordable Housing Programme from 2008 to 2011 and the Affordable Homes Programme from 2011 to 2015. The system comprised ten indicators, which can be categorized into four groups. The first category focused on the location and proximity to amenities and services. The second dealt with site-related aspects such as landscaping, open spaces, and pathways. The third pertained to the housing unit itself, encompassing factors like noise, lighting, accessibility, and sustainability. Lastly, the fourth category addressed the external environment (Homes and Communities Agency, 2011). To enable meaningful cross-country comparisons, it is crucial that the data used for measuring and assessing these indicators are both available and up-to-date. However, it is important to acknowledge that this may not be the case in all countries, as pointed out by the OECD in 2021 (OECD, 2021b). Consequently, to accurately determine what residents are paying for in terms of quality and to facilitate meaningful comparisons, the OECD 2021 Policy Brief on Affordable Housing has emphasized the necessity of two additional housing quality indicators to complement affordability measurements. The first proposed indicator is the "Overcrowding Rate," which evaluates whether a dwelling provides sufficient space for household members based on their composition. This metric assesses whether residents have adequate living space according to the size and structure of their household. The second indicator is the "Housing Deprivation Rates," which gauge inadequate housing conditions. This encompasses issues related to maintenance, such as roofs, walls, floors, foundations, and deteriorating window frames. Moreover, these rates consider the absence of essential amenities, including sanitary facilities. By taking all these factors into account, this indicator offers a comprehensive perspective on the overall quality and habitability of housing in a specific area. Considering subjective measures of housing affordability can be advantageous when assessing housing affordability and quality based on household perceptions. These measures aim to capture housing satisfaction, reflecting the quality of the dwelling as accommodation (OECD, 2021a). In a broader context, housing satisfaction might be termed residential satisfaction, encompassing not just the dwelling but also its surroundings, including places and people. Residential satisfaction assesses how well the current residence and surrounding environment align with the household's desired living conditions (Riazi & Emami, 2018). Therefore, incorporating subjective measures is valuable in assessing housing affordability, helping to identify the determinants of housing satisfaction. Indicators such as satisfaction with the availability of good and affordable housing are crucial aspects to consider in this context (OECD, 2021a). When it comes to sustainability indicators, incorporating them into the measurement of housing affordability remains a wicked  problem. Finding a single comprehensive measure that encompasses the multifaceted aspects of sustainability related to housing affordability is challenging. The technical complexity stems from the necessity to integrate assessments of household characteristics, environmental impacts, financing, and financial aspects, along with housing stress factors. This challenge is exacerbated by the persistent fluctuations in housing prices and recurring expenses like water and energy bills (AHC, 2019). Hence, easily calculable methods such as the Income-to-Rent Ratio (IRM) and Residual Income Model (RIM) continue to be widely used for assessing housing affordability from a top-down perspective at a macro level. Although imperfect, these methods still provide valuable support for policy decision-making to a certain extent (AHC, 2019; Haffner & Heylen, 2011; OECD, 2021a).   

Housing allowance is a financial housing policy measure, mostly aimed at making rental housing more affordable for both individuals and households (Bengtsson, 2006; Bežovan, 2010; Haffner & Boelhouwer, 2006; Ytrehus, 2015). It is often means-tested and forms part of the welfare scheme. While the primary beneficiaries are renters, there are cases where homeowners may also be eligible for housing allowances. The primary goal is to ensure that majority of the population can access housing at prices within their means (Kemp, 2000). In the realm of housing subsidies, two primary categories exist: demand-side and supply-side subsidies. Housing allowances are categorized as demand-side subsidies, which means they benefit the receivers of housing services, such as renters, who have some control over the subsidy and the right to choose their housing units (King, 2016). On the other hand, supply-side subsidies target land developers and construction companies, and recipients have no control over the subsidy. Over time, there has been a shift from supply-side to demand-side subsidies, particularly during the 1970s and 1980s, resulting in means-tested subsidies that were "person-based" rather than "object-based" (Haffner & Boelhouwer, 2006; King, 2016) These changes contributed to reducing housing prices, especially rents. However, concerns arose in the 1990s, with critics contending that means-tested subsidies introduced work disincentives (Bozio et al. 2017), discouraging people from entering the labour market and potentially leading to increased poverty. Another identified risk was the potential for housing over-consumption due to mass subsidies. Despite these criticisms, housing allowances play a crucial role in providing income support during both transitory and long-term periods of poverty. They help to mitigate risks associated with housing expenditure during income interruptions caused by factors such as unemployment or illness (Griggs & Kemp, 2012). The impact of housing allowances on households’ disposable incomes is significant and serves an important income support function. It distinguishes between ensuring the affordability of adequate accommodation and having enough budget left for non-housing expenses. The growing need for income support through housing allowances arises from emerging social risks, including factors such as lone parenthood, precarious work, long-term unemployment, mental health, and working poverty (Griggs & Kemp, 2012). The relationship between housing allowances and the impact on rising rent levels is a central debate in the literature (Eerola & Lyytikäinen, 2021; Eriksen & Ross, 2015; Hyslop & Rea, 2019; Susin, 2002). Some of these studies suggest that the introduction of housing allowances can lead to an increase in rents within the private rental market, while others do not provide conclusive results. However, the influence of housing allowances on housing prices appears to be intricate, exhibiting variations across countries and time periods, making it a complex and multi-faceted issue (Eerola & Lyytikäinen, 2021; Hyslop & Rea, 2019). Housing allowances come in various forms, including means-tested, income-related, and quota-based, with payments made directly to tenants or landlords (Hyslop & Rea, 2019). The same authors note that there was a slight increase in rents when housing allowance was introduced. However, it is not clear whether this was due to increased demand for rental housing, to which landlords responded by raising prices, or whether recipients spent more on better quality (or quantity) housing. The authors state that two-thirds of recipients benefited from higher disposable income after deducting housing costs in that study. From a theoretical standpoint, the neoclassical market model serves as a valuable framework for predicting a possible uptick in rental prices through the introduction of housing allowances. These grants make recipients less sensitive to rent increases, and if the supply is not perfectly inelastic (i.e. the quantity supplied of the good remains the same regardless of price changes), the increased demand will shift the demand curve upward (D > D0 > D1). Consequently, the new price equilibrium will rise (P* > P0 > P1), accompanied by only a small increase in the quantity of housing supplied (Q* > Q0 > Q1). This change is shown in Figure 1.   Figure 1. Theoretical representation of the rent price increase due to housing allowance introduction. Source: Hyslop & Rea (2019) According to Hyslop & Rea (2019) “a major concern with an increase in housing subsidy is that the intended welfare gains for recipients will be eroded by an increase in rents, with landlords capturing a substantial fraction of the benefits of the subsidy.” Despite this concern, the provision of housing allowances for the lowest-income households could enable them to escape from substandard housing, offering a pathway to potentially alleviate issues related to homelessness and overcrowding (Hyslop & Rea, 2019). In post-socialist countries, housing allowances gained prominence after regime changes and the transition from rent regulation regimes. However, their role was relatively minor compared to other policies, such as the right-to-buy policy (Bežovan, 2010; Hegedüs, 2013; Lux & Puzanov, 2013). The distribution of housing allowances varied significantly among these countries, with Russia and Hungary having higher percentages of households receiving allowances (Lux & Puzanov, 2013). The finances for these programmes typically come from state or municipal budgets. An issue with housing allowance programmes in these countries is that they do not consider national differences in living costs, leading to unequal assistance for households in less expensive areas compared to those in more costly regions. Another issue lies in the grey economy; renting without a contract between the landlord and the tenant prevents the application and eligibility for receiving allowances. Housing allowances play a pivotal role in both welfare and housing policy, with a dual aim of enhancing housing affordability and offering income support to individuals and households. Nonetheless, their impact on rent levels remains a subject of debate, and their effectiveness exhibits variations across different countries and contexts.

Financialization, as a broad concept, denotes the growing prominence and impact of financial institutions and markets. Within the realm of housing, financialization refers to how finance plays a pivotal role in rendering housing as a highly liquid asset, thus erasing distinctions between income and wealth distribution (Aalbers, 2016; Stephens & Hick, 2022). Moreover, financialization encompasses the rising dominance of institutional investors as primary participants in the housing market, effectively elevating housing to the status of a distinct asset class. Aalbers (2016) defines financialization as “the increasing dominance of financial actors, markets, practices, measurements and narratives, at various scales, resulting in a structural transformation of economies, firms (including financial institutions), states and households” facilitated by the combination of “economic circumstances, conscious government decisions, unforeseen consequences (“negative externalities” in economist speak) of government decisions, and financial-technical possibilities” (p. 118). In the housing sector, financialization encompasses a diverse array of activities and strategies pursued by both institutional and private investors. These include practices such as debt management, securitization, and the establishment of real estate investment trusts (Holm et al. 2023). Central to this phenomenon is the treatment of housing as a commodity. Commodification, broadly defined as the process by which the economic value of a thing dominates over its other uses, means that housing's function as real estate supersedes its role as a place to live (Madden & Marcuse, 2016).                  The evolution of global investment and financial markets has led to a structural shift in housing, culminating in its commodification. As a result, housing is primarily seen as a commodity rather than as a place of residence (Farha & Porter, 2017), and it is turned into a commodity that accumulates wealth which can be bought or sold on global markets. Consequently, housing has increasingly become a means of wealth accumulation for a privileged few, exacerbating its affordability crisis for the broader population. Therefore, the financialization of housing poses a significant threat to human rights by disconnecting housing from its essential social function as a place to live. Financialization has sparked significant interest in housing studies, emerging as a novel process shaping housing institutions (Hick & Stephens, 2022). This interest surged notably in the aftermath of the global financial crisis (GFC) of 2007-08, underscoring the heightened attention paid to financialization in research circles (Holm et al., 2023). Moreover, scholars argue that the financialization of housing is not only pertinent to housing researchers but also to welfare and poverty researchers. Adopting a theoretical lens rooted in the “varieties of capitalism” approach to the welfare state, the extent of financialization within housing markets is viewed as a determinant of national growth levels and is regarded as a driver of growth (Hick & Stephens, 2022) The financialization of housing has led to significant changes in European housing systems, manifested in various effects and forms including rising house prices, declining rates of home ownership, an increase in the private rented sector, deteriorating housing markets, and decreased affordability of housing (Stephens & Hick, 2022). The trend towards financialization is changing the housing market and increasing income inequality in a society, while fuelling housing price instability by encouraging speculation (Dewilde & de Decker, 2016; Fields, 2016). Financialization is thus an obstacle to the affordability and stability of housing supply. The best example of this is the GFC, which has its origins in speculative mortgage derivatives. Stephens et al (2015) state that “the nature of tenure and its relationship with finance reflect the role of the state and the market as sources of (housing) welfare.” The responses of different governments and housing markets to the GFC varied across Europe (Whitehead, 2014). This was confirmed by Holm et al. (2023) and their comparative analysis of financialization in seven European cities, who found that each city filtered global processes differently due to “place-specific historical and socio-political arrangements” (p. 159). Financialization thus introduced a new logic of economic conditions for the provision and distribution of housing, facilitated by innovative financing practices that promoted housing as a safe, low-risk, high-return investment opportunity (Holm et al., 2023). The continued financialization of housing is anticipated to exacerbate affordability challenges for both mortgage homebuyers and renters, with renters experiencing a greater and more immediate impact (Hick & Stephens, 2022). As Aalbers (2016) asserts, if financialization is the root problem in the housing market, then de-financialization is the solution. De-commodification measures are essential, particularly for tenants and low-income families lacking secure housing. However, tackling the issue necessitates more than just examining the role of financial institutions and markets. It requires to increase the provision of social housing, reforms in housing governance, labour markets, and banking and taxation regulations, which collectively influence the nature and extent of financialization in housing.

Defining deliberative democracy  Deliberative democracy is a form of democracy that emphasizes the role of discussion and deliberation in the decision-making process. Unlike traditional democratic models that prioritize voting and the aggregation of preferences, deliberative democracy focuses on the quality and process of debate among citizens. The core idea is that through reasoned argument, dialogue, and the exchange of ideas, participants can reach more informed, reflective, and legitimate decisions. In a deliberative democracy, participants are encouraged to engage in discussions that are open, equal, and inclusive. This means that all participants have an equal opportunity to speak, be heard, and influence the outcome. The deliberative process typically involves several key components. Key components of deliberative democracy Inclusiveness: Ensures that all those affected by a decision have the opportunity to participate in the deliberation, including marginalized and minority voices (Rasmussen, 1994). Reason-giving: Expects participants to provide reasons for their positions and engage with the reasons provided by others, fostering understanding, social learning, and respect. Respect and civility: Essential requirements for a respectful and civil exchange of ideas, listening to each other, and refraining from personal attacks. Informed and rational discourse: Encourages participants to have access to relevant information and engage in critical thinking to evaluate different arguments. Consensus-orientation: Despite possible conflicting and plurality of views and values on the issue under scrutiny it is crucial to reach decisions that reconcile and are acceptable to all participants, or at least to the majority, while respecting minority opinions. It therefore has transformative potential. Deliberative democracy aims to harness the "forceless force of the better argument" (Habermas, 1975, 108) in an environment that is tolerant of dissent. It can take various forms, including citizens' assemblies, deliberative polls, and participatory budgeting, designed to facilitate structured and meaningful dialogue among diverse groups of people. This approach helps form a “we-perspective” (Rostbøll, 2008). Positioning deliberative democracy If we were to position deliberative democracy within the spectrum of existing democratic models (see image 1), it would likely fall between direct democracy and representative democracy. Direct democracy aims to include an impractically large number of participants, while representative democracy often creates significant distances between representatives and those they represent. For Habermas, the essence of democracy lies in discourse (Habermas, 1996), rejecting the utilitarian approach. A deliberative approach does not need to ignore the practicalities of representative democracy but can address the “imbalance between the vertical and the horizontal dimensions of democracy” (Hansen et al., 2016). The guiding principles of deliberative democracy Deliberative democracy finds its guiding principles in discursive ethics as it prioritizes reasoned dialogue and inclusive discourse to achieve collective decision-making that respects the inherent worth and equality of all participants. Both Habermas and Dryzek emphasize that ethical discourse and rational deliberation are essential for achieving mutual understanding and consensus in democratic processes. Habermas is a central figure in developing the theory of discourse ethics, which forms the philosophical foundation for his concept of deliberative democracy. One key aspect is communicative rationality. Habermas’s concept of communicative rationality emphasizes the role of reasoned discourse in achieving mutual understanding and consensus. In ´The Theory of Communicative Action´(1984), Habermas argues that democratic legitimacy arises from free and open dialogue where participants justify their claims through rational arguments. This idea is essential for deliberative democracy, which relies on inclusive and reasoned discussion to make collective decisions. It was Habermas who introduced the notion of the ideal speech situation (1983), where communication is free from coercion and participants have equal opportunities to speak and be heard. This ideal situation is crucial for ethical discourse, ensuring that decisions are reached through fair and unbiased deliberation. In his work (Between Facts and Norms, 1996), Habermas connects discourse ethics directly to democratic theory by arguing that legitimate laws and policies must be justified through public deliberation. He contends that the legitimacy of democratic decisions hinges on the quality of the deliberative process, aligning with the core principles of deliberative democracy. John Dryzek extends Habermas's ideas, emphasizing practical and inclusive aspects of deliberative democracy. He argues that legitimate democratic decision-making requires incorporating diverse discourses and perspectives (1990). He builds on Habermas's idea of communicative rationality, advocating for a democracy that is open to multiple forms of communication and expression, thus ensuring a more inclusive and representative deliberative process. Dryzek (2006) argues for the empowerment of marginalized voices in deliberative processes. He stresses that genuine deliberative democracy must engage all affected individuals, reflecting Habermas’s ethical concern for inclusivity and equality in discourse. Additionally, Dryzek (2010) focuses on the practical aspects of implementing deliberative democracy. He discusses real-world applications and challenges, drawing from Habermas’s theoretical framework but adapting it to diverse political contexts. Dryzek emphasizes the importance of creating institutional arrangements that facilitate effective and fair deliberation. Both Habermas and Dryzek see discourse ethics as integral to the functioning of deliberative democracy. Habermas provides the theoretical and ethical groundwork, while Dryzek offers practical insights and adaptations for real-world democratic practices. Together, they underscore the importance of rational, inclusive, and ethical deliberation in achieving democratic legitimacy. The relevance of deliberative democracy in affordable and sustainable housing  Deliberative democracy is particularly relevant to the development of affordable and sustainable housing policies. Housing issues are complex and multifaceted, involving economic, social, environmental, and political dimensions. A deliberative approach to housing policy can address these complexities in several ways. By including a wide range of stakeholders—residents, developers, policymakers, and community organizations—deliberative processes ensure that the voices of those most affected by housing decisions are heard. This inclusivity can lead to more equitable and just outcomes. Deliberative democracy emphasizes the importance of reasoned debate and evidence-based decision-making, which is crucial in housing policy where decisions need to balance affordability with sustainability, and economic feasibility with social equity. Achieving consensus can help build broad-based support and legitimacy for the resulting policies, particularly important in contentious areas such as land use planning, zoning regulations, and the allocation of resources for housing development. The deliberative process encourages creative problem-solving by bringing together diverse perspectives, leading to innovative solutions that might not emerge from more traditional, top-down decision-making processes. Especially when it comes to issues that have a direct and significant impact on everyone's lives, such as housing policy. Decision-making should not just fall into the remit of technocrats and politicians. The housing question should be opened up to public deliberation, as has happened in other spheres of urban planning and governance with experiences like participatory budgeting in Belo Horizonte or Porto Alegre (Baiocchi, 2005; Cabannes, 2004; Melo & Baiocchi, 2006). Deliberative democracy and public reasoning can be used as a means for more representative and equitable housing-led regeneration processes to ensure that projects are in the best interests of those directly affected and maximise social value. The democratisation of housing management can also be attained by incorporating the principles of deliberative democracy. Giving tenants more control over decision-making can have a transformative impact on the long-term sustainability of housing schemes. Sustainable housing requires long-term thinking, and deliberative democracy fosters a more holistic approach to policy-making, planning and building, taking into account the long-term consequences of decisions and the need for sustainable development. Possible implementation in the housing landscape Clapham & Foye (2019) identify three levels in which deliberative democracy can be a powerful tool to facilitate housing-related decision-making processes and evaluate housing outcomes: Dwelling scale: Standards developed to set minimum qualities of the housing stock should incorporate a component informed by bottom-up consultation that incorporates residents’ views on what constitutes a decent home. In this way, publicly discussed aspirations and needs are brought together with more quantitative and technical considerations. One example of this is the Living Home Standard, developed by Shelter (2016) following a broad consultation process in which hundreds of members of the public were convened in focus groups and workshops to define what a home means and to identify its key and most valuable elements. In doing so, the process provided the elements necessary for a meaningful exchange, public discussion and debate between participants, in which diverse viewpoints were included. Neighbourhood scale: In his reflections on the ideal size of a city, Aristotle determined a roughly appropriate size based on various characteristics that would ensure its self-sufficiency. Just as important as having access to resources, in his view, was the successful administration of a city, which had to be linked to democratic processes and wellbeing considerations (Lianos, 2016). In such an arrangement, the debate is direct, open and face-to-face. In modern-day terms, at the neighbourhood level, the local context enables a type of relationship between citizens and the city in which they recognise themselves and have a tangible interest in the issues under discussion because it is at the local scale where consequences of ill-considered decisions can have a greater impact. Sennett (2018) identifies similar characteristics in Jane Jacobs’ understanding of a well-functioning neighbourhood as the generative unit of a vibrant and thriving city. In this case, direct democracy practised at the neighbourhood level would constitute, by addition of the parts, a more democratic city. At this level, the relevant stakeholders are expected to play an active role in the participation process because of their attachment to the place. Examples include neighbourhood renewal processes, urban planning and development projects, refurbishment of housing estates or the creation of a local plan. National scale: Although often seen as terrain for more vertical forms of democratic arrangements such as representative democracy, Clapham & Foye (2019) propose deliberative democratic forums held at a national level to discuss highly political issues around housing, such as property tax relief, lad value tax abatements, house price inflation, rent reform, etc. This view aligns with that of Marcuse & Madden (2016), who call for the democratisation of the housing system as a necessary step in devising transformative solutions to the housing crisis worldwide. In order to rebalance the existing power relations, decision-making control should be handed over to those who are “the true experts on their own housing” (p.212), i.e. to those who are oppressed by the current system. A process that relies on a truly democratised housing system, i.e. a system that is open and inclusive enough to allow for broader democratic scrutiny and ensure that the input of non-experts and historically disempowered communities is accounted for. In summary, deliberative democracy provides a framework for developing a housing system that is not only affordable and sustainable but also inclusive, equitable, and widely supported by the community. By fostering open, informed, and respectful dialogue, deliberative processes can lead to more effective and legitimate housing solutions that meet the diverse needs of society.  

Financial wellbeing is an emerging concept with valyrious definitions, many of which focus on the financial capabilities of individuals. A household's financial wellbeing encompasses its capacity to comfortably meet current and ongoing financial responsibilities, fostering a sense of security about future obligations while enjoying the ability to make life choices (Aubrey et al., 2022). Riitsalu et al. (2023) describe it as "feeling good about one's personal financial situation and being able to afford a desirable lifestyle both now and in the future" (p.2). Brüggen et al. (2017:229) frame it as "the perception of being able to sustain current and anticipated desired living standards and financial freedom." This perception highlights the robust link of financial wellbeing influencing human wellbeing, which is a combination of "feeling good and functioning well" (Ruggeri et al., 2020:1). Other terminologies are used interchangeably to describe financial wellbeing, including financial health, financial resilience, and financial freedom (Riitsalu et al., 2023).     In the UK, the public health sector cares to raise awareness of financial wellbeing due to its impact on households' health and populations' productivity. On their official website page on Financial Wellbeing, they used the definition by The Money and Pension Service (Gov.UK, 2022: online) as follows:   "Feeling secure and in control of your finances, both now and in the future. It's knowing that you can pay the bills today, can deal with the unexpected, and are on track for a healthy financial future."   These explanations and the terminology used, including "afford" and "sustain," underscore the interconnections between financial wellbeing and the vital components of household life. These components encompass mental health, productivity, and pursuing economic sustainability in the present and future. Therefore, a household's financial wellbeing is pressured by various housing-related factors, including the costs of renting or buying and non-housing costs like utility bills and repairs, all of which can affect the household's income.   The issue of rising housing costs directly undermines financial wellbeing. This trend can be attributed to several factors, including increased construction costs, labour shortages, and rising material prices (Brysch & Czischke, 2021). Furthermore, there is a notable shortage in affordable and social housing supply (Emekci, 2021; Gov.UK, 2022). This scarcity is partly due to decreased public investment in new dwellings (Housing Europe, 2021; OECD, 2020). This issue further burdens low-income households who face high private rental costs and a gradual reduction in housing benefits (Tinson & Clair, 2020).   This issue also leads many households to cut back on essential needs. For instance, interviews with social housing residents in Scotland with low to modest incomes revealed a tendency to prioritize rent payments over other necessities, such as food and heating (Garnham et al., 2022). Similarly, Adabre and Chan (2019), , citing Salvi del Pero et al. (2016), warned that:   "Households who are overburdened by housing cost may cut back on other important needs such as health care and diet. Besides, in the medium term, households may trade-off costs for lower quality housing such as smaller size of rooms and housing in poorer locations which lack better access to education and other social amenities. The latter has often been cited as the cause of residential segregation."   Another financial burden is non-housing costs involving energy costs for heating (AHC, 2019; Stone et al., 2011). According to Lee et al. (2022), this issue persists, contributing to financial strain and even excess winter deaths in the UK. Poor housing quality raises energy bills (AHC, 2019; Lameira et al., 2022). It presents the risk of considering dwellings as affordable due to local authority support focusing on housing costs alone (Granath Hansson & Lundgren, 2019), regardless of its quality impacting energy bills (OECD, 2020). Social housing residents, particularly the ageing population and those living in poverty are at increased risk of fuel poverty (Tu et al., 2022). Fuel poverty occurs when more than 10% of a household's income goes towards energy consumption for heating (Howden-Chapman et al., 2012).   Looking forward, two factors could continue burdening households’ financial wellbeing. One factor is the fluctuating energy prices that are often increasing, such as the case in the UK (Bolton, 2024). Another factor is the impact of climate change, leading to colder winters and the potential for overheating, increasing energy demand during extreme weather conditions, as warned by the Committee of Climate Change in the UK (Holmes et al., 2019).   Non-housing costs associated with extensive housing repairs can also impact household financial wellbeing, which may arise from several factors. For instance, selecting low-quality construction materials, workforce or equipment to reduce construction costs might lead to increased repair costs over time (Emekci, 2021). Hopkin et al. (2017) highlighted a related issue in England, where new housing defects were believed to be partly attributed to the building industry's prioritization of profitability over customer satisfaction. Another factor could be improper periodic maintenance, potentially accelerating the physical deterioration of the dwelling (Kwon et al., 2020). Additionally, dwellings may fall into disrepair due to unresponsive maintenance services from housing providers, and residents may lack the financial means to cover repair costs themselves (Garnham et al., 2022).     Financial wellbeing is closely tied to household income. Low-income households are particularly vulnerable to being burdened by rising housing costs (Housing Europe, 2021; OECD, 2020), leading to financial insecurity (Hick et al., 2022). In addition, they might suffer housing deprivation due to the increasing housing and non-housing expenses coupled with their declining incomes (Emekci, 2021; Wilson & Barton, 2018). The financial pressure due to low income is further exacerbated if a household member has a disability or severe illness, potentially consuming up to 35% of their income (AHC, 2019). Recently, the COVID-19 pandemic period highlighted households' financial wellbeing vulnerability to housing-related financial challenges (Brandily et al., 2020; Hick et al., 2022; National Housing Federation, 2020). During this period, job losses led to difficulties covering housing and non-housing costs, with a third of low-income social housing residents burdened by housing costs (OECD, 2020).   The issues discussed above on dwellings being of poor quality or unaffordable harm financial wellbeing, leading to residential segregation (Adabre & Chan, 2019; Salvi del Pero et al., 2016) as well as intensifying gaps of social injustice, health injustice, poverty, and fuel poverty (Barker, 2020; Garnham et al., 2022). Without addressing those housing-related issues, many households' financial wellbeing would remain vulnerable to economic insecurity even if they live in housing considered to be "affordable" in terms of rent-to-income ratio.

Housing quality is concerned with the conditions and characteristics ensuring it is safe, healthy, comfortable, and sustainable for its occupants. It considers the physical conditions of a dwelling and the social and physical environment surrounding it (Bonnefoy, 2007; Swope & Hernández, 2019). There is increasing pressure to ensure affordable housing meets quality standards in Europe and the UK. Neglecting quality in assessing affordability could perpetuate poor-quality, unsustainable housing, harming both the planet and households' wellbeing (AHC, 2019; Fraser et al., 2023; Haffner & Heylen, 2011; OECD, 2021). This vocabulary entry focuses on housing quality.   Housing quality directly impacts the wellbeing of households by influencing physical and mental health and financial stability. It has been recognised as a crucial determinant of health and wellbeing, as poor housing conditions are linked to numerous health issues, including respiratory and cardiovascular diseases, injuries, and mental health disorders (WHO, 2018). As such, housing quality not only concerns the physical attributes of a dwelling but also its capacity to support the health and wellbeing of its occupants​ (Rolfe et al., 2020).     Levels of Housing Quality   Housing quality can be recognised through various contextual levels, which include:   Physical structures and features of buildings, such as insulation, ventilation systems, materials used, and essential services such as heating, plumbing, and electrical systems (Keall et al., 2010). Internal environment and living conditions, which refer to the atmosphere within a dwelling. These include air quality, light, noise levels, and thermal comfort, all contributing to indoor environmental quality. They could also encompass factors such as overcrowding and cleanliness (Riva et al., 2022). The living conditions arise from the interaction between the building characteristics and the residents, and how they use or treat the dwelling. (Bonnefoy, 2007; Riva et al., 2022). For example, mould can develop due to a lack of proper ventilation systems suitable for the household and dwelling size. Alternatively, a proper ventilation system might be provided; however, occupants may not use it when cooking, bathing or showering (Keall et al., 2010). Household characteristics refer to the behaviours and lifestyles of residents. According to Keall et al. (2010, p. 767), the household level encompasses "social, cultural and economic aspects such as affordability, suitability, security of tenure,” which impact people's needs for space, energy, water, and transport. Additionally, it acknowledges that demographic, psychological, and biological aspects, such as attitudes towards recycling, maintenance, cleaning routines, and use of space, influence lifestyles. External community and infrastructure involve the neighbourhood, regional policies, and global environmental conditions impacting housing quality. Factors such as urban planning decisions, availability of community resources, and neighbourhood safety play crucial roles (Keall et al., 2010; Swope & Hernández, 2019). Regulatory and policy frameworks pertain to the standards and regulations to ensure housing quality. Compliance with these regulations should promote equity in housing practices (Swope & Hernández, 2019). For example, A new set of Consumer Standards established by the Regulator of Social Housing in England aims to improve the quality of social housing and ensure that landlords fulfill their responsibilities to tenants by providing quality homes, transparent operations, and fair tenancy management (Regulator of Social Housing, 2024).     Housing Quality Indicators   Housing quality indicators are vital for assessing the conditions of dwellings. They could address various aspects of housing, such as safety, sustainability, comfort, and suitability for residents. These indicators are essential for understanding the physical state of housing and the living conditions within dwellings. These indicators could serve four purposes:   Measuring housing quality and affordability across countries: Some housing quality indicators could enable meaningful cross-country comparisons to better determine what residents are paying for in terms of quality. The OECD (2021) Policy Brief on Affordable Housing highlighted some housing quality measures to accompany measuring housing affordability, such as the "Overcrowding Rate," "Housing Deprivation Rate," and subjective measures to assess housing affordability and quality based on household perceptions. Elaboration on these measures is available in the Measuring Housing Affordability vocabulary.   Measuring housing quality within a country: Some indicators are used to evaluate the quality of housing schemes to ensure that housing standards are met across different regions. For example, non-decent housing in England is identified with the help of the Housing Health and Safety Rating System (HHSRS) (Department for Communities and Local Government, 2006). HHSRS assesses 29 potential health and safety hazards in residential properties, including structural dangers, toxicity, mould and inadequate heating. Another example is England's Housing Quality Indicators (HQIs) system. Although currently withdrawn, it served as an assessment tool to evaluate housing scheme quality. The HQIs system encompassed four categories: location and proximity to amenities, site-related aspects (landscaping, open spaces, pathways), housing unit features (noise, lighting, accessibility, sustainability), and the external environment (Homes and Communities Agency, 2011).   Measuring housing satisfaction across groups:  Other indicators measure household satisfaction, gauging how well housing meets their expectations and needs. For example, the English Housing Survey (EHS) collects comprehensive data on housing conditions and residents' satisfaction levels across different demographic groups and regions (DLUHC, 2019). It evaluates housing quality, adequacy of amenities, safety measures, and overall satisfaction with the living environment. Thus, it enables identifying targeted improvements needed within the housing sector.   Measuring housing quality of a specific housing scheme: Post-Occupancy Evaluation (POE) could be considered a housing quality indicator in the design and construction context. POE is a process for assessing buildings' performance and functionality after they have been occupied (Hadjri & Crozier, 2009). It could include energy efficiency, indoor environmental quality, and occupant satisfaction (Elsayed et al., 2023). The evaluation involves various methodologies to collect data, which can be objective (measured data) and subjective (occupant feedback), providing insights that could lead to improvements in management practices and future designs. However, in the EU context, this process remains inconsistent (Elsayed et al., 2023). This inconsistency hinders comparing results and gathering insights to improve broader housing quality.   Despite the usefulness of the indicators mentioned above, accurately measuring housing quality is still challenging. The inherent subjectivity of what constitutes "adequate" housing means that perceptions can vary significantly due to influences of cultural, economic, and individual expectations. Furthermore, the technical feasibility of employing comprehensive quality indicators is often limited by outdated or incomplete data on the characteristics of dwellings. These limitations hinder effective housing quality assessment, making it difficult to enforce and update housing standards consistently (OECD, 2021).

Techno-optimism refers to the belief that advances in technology will improve humanity, enhance quality of life, and solve critical problems including climate change, health issues and social inequality (Danaher, 2022). According to Danaher (2022), techno-optimism assumes technology will ensure “the good does or will prevail over the bad” (p.54). Techno-optimists believe that technological innovation is a key driver for economic growth and can provide solutions to many of the pressing challenges faced by contemporary society (Wilson, 2017). Keary (2016) links faith in technological optimism to an unshakable commitment to economic growth. Technological change modelling (TCM), he argues, has shifted the terms of environmental debate, pulling efforts away from ‘green’ ecologism (associated with degrowth movements), and toward techno-optimism; a belief that mitigation pathways should rely on technological advancements. Techno-optimism emerges from enlightenment ideals, whereby reason and scientific progress are seen as pathways to improving human conditions and capabilities by overcoming “existential risk” (Bostrom, 2002) through technological advancements (Wilson, 2017). Hornborg (2024) criticises techno-optimism for its failure to address ecological and social inequalities exacerbated by technology. Further, technological solutions often address symptoms rather than root causes, leading to a superficial treatment of complex problems (Wilson, 2017).  Hornborg, using Marx’s commodity fetishism and World Systems Theory as his guide (Marx, 1990), seeks to unmask modern assumptions about what technology is. Both capitalists and certain left-wing thinkers exalt technology, viewing it as embodying human progress — a promethean mode of thinking. This overlooks, however, the social relations and material, energetic, and metabolic flows needed to maintain technological systems. Technology needs a “sociometabolic reconceptualization” (Hornborg, 2024, p. 28). Historically, technological progress in the world’s industrial core, was dependent on unequal social relations and colonial patterns of extraction from non-industrial peripheries. Shifting to green technologies, in Horrnborg’s view, will involve repeating these inequities: sugar-ethanol, or electric powered cars, for instance, will rely on exploited land in Brazil and the cobalt-rich Congo. “High tech cores versus their exploited peripheries” (Hornborg, 2024, p. 38), recasts the colonial industrial core-periphery dynamic (Wolf et al., 2010), exacerbating ecological and social inequalities. By attributing too much power to technology itself, techno-optimists may neglect the need for conscious and deliberate governance of technological change (Bostrom, 2002, p. 11). Further, it is crucial to maintain a balanced perspective that recognises both the opportunities and the limitations of technological advancements (Wilson, 2017). Social, political, and cultural contexts must shape technological outcomes. Danaher (2022) argues through collective effort, it is possible to create the right institutions and frameworks to guide technological development towards beneficial ends. Technological innovation plays a key role in deep energy retrofit (DER), which relies on three main technical improvements to reach end point performance targets, measured in kWh/m2/year: increased thermal insulation and airtightness; improving the efficiency of systems such as heating, lighting, and electrical appliances; and installation of renewables such as photovoltaics (Institute for Sustainability & UCL Energy Institute, 2012). Techno-optimism in DER has led to the widespread adoption of ground source and air source heat pumps, such as mechanical heat and ventilation systems (MVHR) (Traynor, 2019), to mechanically stabalise indoor air temperatures (Outcault et al., 2022), LED lighting smart systems (Bastian et al., 2022), and upgraded systems for heating and hot water (Roberts, 2008). There are many concerns with techno-optimism in DER: (1) the gap between predicted and actual energy performance can reach as high as five times the prediction (Traynor, 2019), (2) the adoption of techno-optimism does not consider the certainty of technological obsolescence, (3) inoperable windows due to mechanical heating and ventilation increases the risk of future overheating, and cooling costs, and (4) DER disregards architectural vernacular and passive energy strategies, including cross ventilation, thermal mass, and solar gains. In social housing retrofit, non-energy benefits including comfort, modernity, health, and safety, (Amann, 2006; Bergman & Foxon, 2020; Broers et al., 2022)—negated in techno-optimism—are often more important to social housing residents than energy-related benefits. Further, technological innovation in retrofit is often tested on social housing (Morgan et al., 2024), despite housing tenants from marginalised groups, to convince private markets to adopt technologies.

Throughout history, many different terms have been used to refer to people living on the streets[1], and since the 1980s “homeless” has been the most commonly used expression. The exact number of homeless people is usually difficult to determine due to different typologies and definitions applied across the countries. Homelessness is a “manifestation of extreme poverty and social exclusion, it reduces a person’s dignity as well as their productive potential and is a waste of human capital” (Baptista & Marlier, 2019). It is a symptom of globalisation and systemic changes in the world economy (Ferenčuhová & Vašát, 2022). In 1995, Brian Cooper distinguished between absolute and relative homelessness, absolute being people with no access to shelter or the roof over their heads, while relative homelessness he divided into three degrees. Primary homelessness is “people moving between various forms of temporary or medium-term shelter”, secondary are “people constrained to live permanently in single rooms in private boarding houses” and third degree are “housed but with no condition of a “home”, e.g., security, safety, or inadequate standards” (Bilinović Rajačić & Čikić, 2021; Cooper, 1995; Tipple & Speak, 2005 ). Ferenčuhova & Vašat (2022) frame homelessness as a "structurally determined phenomenon linked to the functioning of economic and political regimes and their diversity", and that one of the causes of growing homelessness is the rapid modernisation of society. The United Nations (UN) (2009) used to distinguish between two categories of homeless people, primary (living on the street) and secondary (frequent moves, long-term sheltering, people with no fixed abode), and today the UN and most EU countries adopt a definition developed by the European Federation of Organisations Working on Homelessness (FEANTSA), which recognises different forms of homelessness and living situations within the framework of the European Typology of Homelessness and Housing Market Exclusion (ETHOS) developed in 2005. According to the typology ETHOS, there are four categories of homelessness: roofless, houseless, insecure housing and inadequate living conditions. These categories are each subdivided into housing categories, which in turn are subdivided into types of living situations (FEANTSA, 2017). “ETHOS light” typology is a simplified version of ETHOS typology with fewer categories, and is mainly used for statistical purposes and comparisons across EU countries. According to the ETHOS typology, there are many forms and manifestations of homelessness, and homelessness is more than just not having a place to sleep. There are some criticisms of the ETHOS typology, for example, that there is no clear distinction between homelessness and housing exclusion (Bilinović Rajačić & Čikić, 2021). A typology based on the risk of homelessness could be acute, immediate or potential, while a typology based on frequency and duration could be temporary, episodic or chronic (Bilinović Rajačić & Čikić, 2021). Many other typologies and definitions of homelessness are found in literature, including various theoretical streams on the causes of homelessness. Some of the main causes of homelessness in the EU are the lack of affordable housing supply and changes in the labour market, i.e., short-term and precarious employment, low wages, unemployment and long-term unemployment (Baptista & Marlier, 2019). No matter what typology or definition is applied, the homeless represent the population of absolute poverty that includes the inability to meet basic human needs, including housing (Kostelić & Peruško, 2021). The Lisbon Declaration of 2021 is a document that builds on the European Pillar of Social Rights and was signed by the relevant European institutions and Member States to work together to end homelessness. It addresses many aspects to address homelessness by recognising where homelessness is most prevalent, and who is most affected by it. The Declaration also states that existing institutions in EU Member States currently lack adequate responses and capacity (Lisbon Declaration, 2021). When it comes to ending homelessness and developing homeless reintegration programmes, there are two main approaches: the “Staircase” programme (treatment-oriented) which has an established history of application, and the innovative “Housing First” programme, which is less represented in practice but increasingly represented (housing-oriented). According to Pleace et al. (2018), services for the homeless across EU countries could be divided into typologies (Figure 1). According to this figure, Croatian service providers would mostly fit into the third quadrant: non-housing focused and low intensity support, but according to Pleace et al. (2018), other Eastern (and Southern) European countries are likely to have the same type of support and this type of service is the most common in Europe, which means overnight shelters, food distribution daycentres etc. In post socialist countries, homelessness is also understood as an emerging new social risk due to increasing mortgage default rate, which was evident in the aftermath of the Global financial crisis of 2008 (Horvat & Bežovan, 2024).   [1] vagabonds, tramps, beggars, itinerant people, homeless people    

Increasing the thermal properties of the building envelope is a passive strategy to reduce energy loss and ensure significant reductions in energy demand (Grecchi, 2022). Van den Brom et al (2019) define thermal renovation as “renovation measures that are taken to reduce energy consumption used for thermal comfort”, and group thermal insulation, airtightness and efficient electrical system into a single category. Accordingly, deep ‘thermal’ renovation occurs when significant improvement in at least three building components bring thermal performance to a level equal to or higher than the current building regulation standards (van den Brom et al., 2019). These building components include roof insulation, floor insulation, façade insulation, window improvements, heating system, domestic hot water system, and ventilation system (van den Brom et al., 2019). Other authors (Institute for Sustainability & UCL Energy Institute, 2012; Sojkova et al., 2019; Traynor, 2019) divide electrical systems into a further category for clearer practical application. The concept of airtightness is revered for saving energy, avoiding structural damage, contributing to thermal comfort (Bastian et al., 2022), and is key to reducing heat loss through ventilation (Roberts, 2008). Draught proofing involves draught-stripping, replacing leaky windows and closing off unused chimneys (Roberts, 2008). The location of an airtight layer should be identified, and all penetrations through it minimised, sealed, and recorded (Traynor, 2019). This airtight layer can be airtight board, a plastered wall, or a membrane with appropriate tape at all junctions such as window openings (Traynor, 2019). Triple-glazed windows in combination with any frame material are the most efficient glazing system at reducing primary energy cost and CO₂ emissions (Sojkova et al., 2019). All air pockets should be sealed to prevent draughts and thermal bridging. Thermal bridging should be eliminated wherever possible, although a comprehensive thermal reduction with low internal surface temperatures can prevent physical problems such as moisture and mould (Bastian et al., 2022). There are many forms of insulation to consider during retrofit that considerably contribute to a reduction in heat loss. Filling external cavity walls with insulation can reduce heat loss through walls by up to 40% (Roberts, 2008). Ground floor insulation and roof insulation are also necessary steps in DER (Grecchi, 2022; Roberts, 2008; Traynor, 2019). Ground floor insulation can occur in suspended timber floors between joists or above solid concrete floors (Traynor, 2019). Roof insulation can be added between structural elements, or using a ‘cold’ roof solution, with insulation laid or sprayed over the existing ceiling (Traynor, 2019). Alternatively, green roofs can reduce the amount of heat penetration through roofs, playing a similar role to roof insulation. This is done by absorbing heat into their thermal mass alongside the evaporation of moisture but will require structural upgrades to manage the new load (Roberts, 2008). External wall insulation (EWI) protects the building fabric, improves airtightness and is relatively quick and easy to install (Roberts, 2008). EWI can also help mitigate overheating by absorbing less heat than the original material, while allowing existing thermal mass from solid masonry walls and concrete to be retained within the insulated envelope (Bastian et al., 2022). The two main external insulation systems are ventilated rainscreen systems and rendered insulation systems (Roberts, 2008). EWI is inappropriate for historical building use because it will cover the historical architectural character. Gupta & Gregg’s (2015) preserved the original exterior façade by using internal wall insulation inside the front façade and EWI on all other façades. However, drawbacks to this solution can include the loss of internal floor area, and reduced energy efficiency as notable heat loss can occur where the internal insulated wall meets the external insulated wall (Gupta & Gregg, 2015).