Too big to succeed? Institutional inertia in low-carbon district heating experiment

The energy transitions are in an acceleration phase, where less carbon intensive technologies emerge, but their applicability is uncertain creating a need for real-life experimentation. Cities have become a focal context, where novel constellations of technologies and practices are introduced to reconfigure patterns of production and consumption. One area of urban energy governance gaining increasing attention especially in a Northern context is the low carbon transition in district heating systems that provide the majority of heating in the residential sector and has been primarily built around combustion technologies relying on fossil energy reserves. This article analyses a bidirectional low heat experiment in district heat in Finland by examining what are the dimensions of institutional inertia and how it impacts the reconfiguration of an urban energy system. Institutional inertia emerges from the technical innovation itself, land-use planning practices, the absence of formal regulations and via organisational inertia in the implementation of the experiment. We find that visions about the innovation can become constraints of the experiment, which limit learning and reshaping of innovation, thus preventing radical transformation of the district heating system and watering down the initial target of the experiment. We contribute to the conceptualisation of institutional inertia within the energy transition.


Introduction
The energy transitions are currently in an acceleration phase, where shifts towards less carbon intensive technologies emerge faster than anticipated (Sovacool, 2016).The urban energy governance has become central in reconfiguring the existing material energy systems and related actor roles and practices (Bulkeley et al., 2014;Reinekoski et al., 2023) and experimenting with the technologies, capacities and actor-networks to speed-up and scale-up the transitions in the embedded contexts (e.g.Bulkeley and Castán Broto, 2013;Wolfram, 2017).Sustainability transition scholars have called for future research on the role of cities in experimentation and how experiments proceed and scale up (Köhler et al., 2019) as they require constant reconfiguration of existing material and institutional arrangements (Geels and Turnheim, 2022;Ryghaug and Skjølsvold, 2021).
The governance of district heating (DH) networks has gained increasing attention especially in the Northern context.Urban DH landscape has become an arena for energy transitions as the demand for third-party heat production is rising.Novel district heating systems, which have low water temperature and bidirectional flow of heat from decentralised heating sources to the users, are seen as a solution to cut heating related emissions (IEA, 2023;Volkova et al., 2022;Wirtz et al., 2022).The deregulation of the DH market and the mistrust towards the DH companies (e.g.perceptions of the fairness of pricing) has made some customers invest in their own heat production technology (Lygnerud, 2018).A study from Denmark shows that most DH systems in the rural areas are owned by citizen cooperatives.The different ownership structure, where users of heat are also system owners, enables more easily to try alternative institutional arrangements, such as incentives, to ease entrance of new energy technologies in DH systems which can lead to economic benefits (Gorroño-Albizu et al., 2019;Gorroño-Albizu and De Godoy, 2021).In Sweden, some companies have initiated open dialogue between their major customers due to increased customer activism (Lygnerud, 2018).Krog et al. (2020) point out that much of the literature on DH focuses on technical aspects (e.g.how much lower temperature can decrease it causes no concern over comfort or use of consumer applications) and that consumer supply of heat is less discussed in comparison to demand for heat by consumers.Previous research on DH examines rather how to use industrial scale excess or waste heats in DH systems (e.g.Fritz et al., 2022;Lumbreras et al., 2022) but not residential sources of energy.However, engaging residents in the bidirectional, low-carbon and a low heat DH system can improve the sustainability of the energy system by improving the energy efficiency and enabling decentralised heat production.
In Finland, DH provides the majority of heating in the residential sector as well as urban office buildings (Patronen et al., 2017).Approximately 46% of the heating energy of residential and service buildings was produced by DH in 2018 (Motiva, 2022).Urban heatingand also coolingservices are generally provided by combined heat-and-power (CHP) production in the centralised production plants.The heat production is largely governed by publicly owned utilities and the production is still mainly relying on combustion technologies utilising fossil energy sources and biomass.Yet, the more ambitious decarbonisation targets on national and urban scales as well as coal phase-out policies are challenging the status-quo.Building sector needs massive emission cuts by 2030 to reach climate targets (Nijs et al., 2021), and DH has a central role in the Baltic and Nordic context (European Environment Agency, 2023) in particular.However, there are no readily available low-carbon solutions for DH, yet the alternative socio-technical constellations of energy production and consumption are being experimented in the urban areas (e.g.Miller and Mössner, 2020;Reda et al., 2021).Beyond the embedded contexts, experimentation is connected to broader reconfiguration of infrastructures, governance institutions and user norms to enable new socio-technical assemblages (Creasy et al., 2021;Davidson et al., 2023).
We contribute to the conceptualisation of institutions within the energy transition in an urban context.Previous studies on sociotechnical transitions have found that there are characteristics of systems that cause hindrance to change such as path dependencies and carbon lock-in (e.g.Garud et al., 2010;Khalil, 2013;Lovio et al., 2011), and institutional inertia (e.g.Pierson, 2004;Stål, 2015;Unruh, 2000).How socio-technical transitions emerge beyond technological experimentation and niche protection and connect with institutions and governance have been identified as research gaps in the field (Foxon et al., 2013;Köhler et al., 2019, p. 9;Turnheim et al., 2015).We focus on how institutional inertia of the energy regime (Unruh, 2000) hinders the advancement of the systemic low-carbon DH experiment.Previous DH experiments have largely focused on technological capabilities (e.g.Bünning et al., 2018;Yazdani et al., 2022), although there are specific socio-technical features in DH networks that impact their governance and cause lock-in (Nciri and Levenda, 2020;Reda et al., 2021).DH operates on an intermediate scale somewhere between individual consumers and the universal grid (Karvonen and Guy, 2018).The heating service is materially embedded to large investments of utility pipelines that require wide coordination and input of energy, which makes the owners of production units and pipelines, the local energy companies, central actors in system coordination.Heating networks are located at the intersection of energy and housing regimes (Lazarevic et al., 2019).However, empirical case studies on reconfiguring urban heating systems remain scarce and often focused on purely techno-economic aspects.
In our empirical case study, we examine an experiment of lowcarbon bidirectional DH in an urban residential area in Finland through the lens of institutional inertia.The case represents dynamics of how a systemic socio-technical innovation developed in protected piloting is brought into real-world testing in the spatial planning context.The analysis shows how the initial ambitiousness of the experiment was watered down and the initial framing of the experimentation slowly transformed due to inertia in the system that constrained the implementation.Our focus is analytically to break down how institutional inertia emerges in socio-technical instances, and therefore draw lessons for broader reconfiguration of urban energy systems.We have formulated the following research questions: i) What are the dimensions of institutional inertia in an urban energy experiment in a residential heating context?ii) How does institutional inertia impact the reconfiguration of an urban energy system?
We next discuss institutionalisation, institutional inertia and energy experimentation, and examine institutional reconfiguration of the urban DH systems.The third section describes the case context and methodology.The fourth section analyses dimensions of institutional inertia of the urban DH experiment.Finally, we discuss the role of institutional inertia for urban energy transitions through experimentation and draw conclusions for research and policy.

Institutions, actors and reconfiguration of urban energy systems
Institutions can be defined as widely diffused and shared structures that influence the cognition and behaviour of actors as well as the broader diffusion of practices, regulations, norms, values and culture (Fuenfschilling and Truffer, 2016).Within any system, institutions govern actions (Lawrence and Suddaby, 2006) as institutions set the context and guidelines within which actors shape their activities.However, because institutions are socially shared and legitimised, their constraining nature steers action towards habitualisation, which limits the potential for change (DiMaggio and Powell, 1983).Therefore, institutional approach becomes useful in examining processes within the DH experiment and the constraining conditions of its socio-technical environment.
Existing institutions tend to resist change unless they become 'problematic' (Berger and Luckmann, 1966, p. 135), and in cases even long after that (such as the institutionalised use of coal for energy production).Institutional inertia refers to such change resistance and stagnation of institutions (Pierson, 2004).Here, we use inertia as a tool to analyse the 'stickiness' in the socio-technical system that maintains its stability.While there is ample literature on systemic lock-in (e.g.Foxon, 2002;Khalil, 2013;Lovio et al., 2011;Unruh, 2000), literature on institutional inertia related to energy domain remains limited.Mitchell (2014) has examined governance and inertia in the energy system and Lockwood et al. (2017) touch on inertia from the point of view of historical institutionalism and politics of energy transition.In their empirical research, Fünfschilling (2014) has studied institutional logics and inertia in the water sector and Stål (2015) has focused on inertia at industrial sustainability.In each of these cases, institutional inertia has been found to hamper the systemic transition toward sustainability.
A mean to overcome institutional inertia is a concept of institutional work that connects actors to institutions (Fünfschilling, 2014;Heiskanen et al., 2019;Kainiemi et al., 2020;Lawrence et al., 2011;Lukkarinen et al., 2023).Institutional work has been defined by Lawrence and Suddaby (2006, p. 215) as "the purposive action of individuals and organizations aimed at creating, maintaining and disrupting institutions".According to socio-technical transitions research, old-established institutions restrain the habitualisation of new technologies and practices, thus preventing the diffusion of sustainable alternatives (e.g.Foxon, 2002).However, scholars such as Duygan et al. (2019) argue that institutional work to disrupt institutions may succeed, if actors are provided with decent amounts of discourses, networks and resources, such as power and knowledge.Since institutions are maintained in social action (Berger and Luckmann, 1966), institutional work provides a useful conceptualisation for the analysis of actors' interpretations of the hindrances in DH experiment and means to overcome them.
Another theoretical strand related to socio-technical change that has F. Moilanen et al. conceptualised the purposive actions aimed at creating novel technologies or practices and disrupting the old socio-technical systems (including institutions within) is Strategic Niche Management (SNM) (Kemp et al., 1998;Nill and Kemp, 2009;Schot and Geels, 2008).In SNM literature, the focus has been especially in experimentation with novel technologies, vision building and learning of the novelty, whereas the concept of institutional work focuses on the concrete doings of the actors in a change process.The SNM approach is based on the idea that technological novelties emerge in protected spaces, niches, that allow for the nurturing and experimentation of innovations which can be governed in order to guide transitions towards sustainability (e.g.Kemp et al., 1998;Schot andGeels, 2007, 2008).SNM relies on the understanding that technological and social change are interrelated and that a process of niche development can lead to change by the replacement of the dominant technologies (ibid).SNM connects to institutional theory through the conceptualisation that the dominant socio-technical system, the regime, stands for the paradigmatic core of a sector, which emerges from the co-evolution of technologies and institutions (rules, regulations, values) over time (Fuenfschilling and Truffer, 2014).Thus, the regimes are achievements of past institutionalisation which are challenged by niche interventions in the form of experiments.We combine these analytical approaches to examine the dynamics of change in an experimental urban context.We analyse inertia in the socio-technical system emerging in the experimental context by examining actors' interpretations and experiences related to practical challenges of the experiment as well as actors' attempts to overcome them.Following Bulkeley et al. (2014), we understand socio-technical experimentation as co-evolution of social organisation, i.e. institutions, with technological artefacts, such as heating technologies.Previous conceptualisations of socio-technical experimentations in niches focusing on the role of actors, visioning and expectations agree that social views on the new technology play a key role in processes of technology development (e.g.Bos and Grin, 2008;Farla et al., 2012;Kemp et al., 1998;Matschoss and Repo, 2020;Schot and Geels, 2008;Sengers et al., 2019).In addition, in the context of transition governance actor roles to reach certain ends are negotiated over a period of time (Wittmayer et al., 2017) and understanding the roles of different actors and the power relations between them is considered important for research on transition governance (Avelino and Wittmayer, 2016).In experimentation, differences between actors' roles, visions and motivations can thus impact how participating actors are able to reflect their institutional positions in a specific context.
Transformative visions often follow alternative institutional logics, engaging the advocating group in institutional work to make a case for specific socio-technical constellations (Fuenfschilling and Truffer, 2016).Such visions consist of engineering ideas, management beliefs and expectations about the market potential on the technology developers and experimenters' side as well as perceptions of the technology on the user side (Kemp et al., 1998).In practice, visions that require adjustments in the accustomed practices of multiple stakeholders can seem less feasible than visions based on technical transitions that can be readily plugged-in the existing system.Traditionally, the research focus has been on the technological end of innovations, while diverse multi-regime interactions and changing of multiple user-practices have received less attention (Konrad et al., 2008).The DH experiment of Skanssi provides an interesting case to investigate technology expectations, since scaling up the innovation does not limit to energy systems only, but requires changes in the housing, construction, and administrative regimes as well.Therefore, the institutional context extends the experiments beyond its original technical boundaries -possibly making it too big to succeed.
Finally, the process of institutionalisation within the experimental space has received little attention in the previous SNM and institutional literature.For institutionalisation to take place, the process does not necessarily require the involvement of a large number of individuals, but it is a feature of social interactions that can also take place on a small scale (Berger and Luckmann, 1966).Thus, alternative visions may begin to institutionalise among various actors, which directs experimentation towards less radical directions at the same time as generation of knowledge of the innovation increases during experimentation.In other words, in addition to the general view that socio-technical innovations tend to fail due to their misalignment with regime institutions (Kemp et al., 1998), institutionalisation may also take place within niche experiments which produce institutional inertia.This institutionalisation within the experiment may prevent it in reaching its goal and lead the development towards incremental transitions.The existing DH technologies and practices offer an interesting case in point to experiment, being historically constructed to accommodate large-scale and centralised fossil fuel combustion, while materially connecting diverse actors in building and energy regimes.

Case study, data and methods
Our case study examines a bidirectional low-heat DH experiment organised in a Finnish city of Turku.Skanssi residential district has been a key place of cooperation for urban climate action and smart city developments through low-carbon experimentation.Spatial development of Skanssi began in 2000 as a typical neighbourhood for anticipated 2500 inhabitants (see, Fig. 1).First apartment buildings and a shopping mall were finished in 2009.The new General Plan of Turku was approved in 2010 staging the development of "smart and sustainable Skanssi" as a city's new flagship project.The sustainability vision declared that Skanssi would inhabit from 5000 to 8000 inhabitantstripling the earlier target.The area was presented as a testbed for a novel smart neighbourhood concept for urban planning.
The city of Turku can be considered a key actor in the experiment with most land ownership, control over the energy company and a role as legal implementer of a land allocation plan of the city.However, the idea of DH system experimentation was introduced by the publicly owned local energy incumbent, Turku Energia.The experiment engaged Business Finland, the largest innovation financer in Finland that organised strategically important smart city programmes.The technology developers, VTT and Sustecon Ltd assembled renewable energy solutions on the basis of previous projects and the construction company YH kodit was among the first companies to construct apartments in the area.Finally, the technological vision was discussed with citizens in meetings and workshops where they had an opportunity to express their opinions on the experiment (Fig. 2).
The bidirectional DH experiment was enticing for Turku Energia, as regulation constrained the profitability of electricity experimentation and the DH system opened pathways for more systemic lessons.The prime vision was to construct the bidirectional DH system to enable trade of excess heat of buildings and heat produced on distributed Fig. 1.Skanssi area on the map of Turku.
F. Moilanen et al. emission-free technologies (e.g., ground-source heat pumps and solar collectors, see Fig. 3).Beyond the technological vision, the experiment challenged planning practices to set standards for low-carbon technologies, market principles for heat trade in the local network and means of engaging the inhabitants with new energy practices.However, no decentralised heat production had emerged by 2022 and the city's development was diverted to other areas.
The primary research data consists of expert interviews with key actors that participated in the planning and implementation of the bidirectional DH experiment in various roles between 2012 and 2022.As researchers, we were not connected to the implementation of the experiment but instead conducted an external evaluation of the process.Eleven interviews were conducted with civil servants of the city, energy company representatives, technology developers and a construction company (see appendix A).The interviews were held face-to-face between February and May 2018.In addition, two follow-up interviews were conducted online in October 2022 to gain insights on the further development of the experiment.The interview data was analysed with content analysis (Neuendorf, 2018) and coded with atlas.ti-software.
The data analysis was an abductive process with four coding categories.The forms of inertia were categorised according to the content whether they related to technology, land-use planning, actors and organizations, or regulations (Appendix B illustrates the inertia codes and their sub-categories in a coding tree).In the results section, we utilise illustrative captions from the interviews to emphasise the main results regarding the different categories of inertia.The interviews were complemented with document analysis on the planning process.The complementary data consisted of city council and board public records on the area development, local energy company reports, articles in the Finnish media and professional journals as well as national energy interest group's publications on DH system transitions.Document data was key in building a coherent case narrative.

Results: Forms of inertia in emerging innovation
This section presents our analysis of the district heat experimentation by focusing on the different aspects of institutional inertia: the mobilisation of technical innovation, practices and continuums in land-use planning, organisational factors and actors, and unclear formal regulation and contractual arrangements.Table 1 summarises the results with illustrative data extracts.

Inertia of the technical innovation
The technological experimentation of the low-carbon heat energy grid was based on an incremental development of a typical DH network that relied on new exchange technology enabling lower water   temperatures in the grid.Lowering the water temperature enables decentralised production of heat, for example by solar heat collectors, and feed-in of excess heat from connected buildings, which would not be economically feasible in conventional grids, where heat temperatures need to be over 100 Celsius.VTT and Sustecon Ltd were involved in planning the technical capabilities of the low-temperature DH system and the innovation funder provided finance.However, the housing actors and means to implement decentralised DH production did not receive funding.Thus, this nurturing of innovation mostly focused on its technological aspects, and behavioural and regulative questions were not investigated simultaneously, although considered important.
Installing heat production equipment into buildings challenged the accustomed designs of centrally heated houses, because the technical system requires coordination and reconfiguration due to several technological components.The novel connection technologies enabling bidirectional exchange between the buildings and heating grid required more space already in the planning of the buildings, which caused confusion among the construction companies and civil servants, as there were uncertainties about the specific functionalities and prices of technology at the early stages of the experimentation.The construction companies involved in the experiment lacked the required capacities to engage in planning and implementation of the experiment.
In practice, these challenges meant that civil servants engaged with the experiment needed to acquire technological knowledge in the planning process.The generated technological understanding was later transported in the application of the municipal zoning policy tool, the land use stipulations.
The people who discuss land transfers with us may not know the connections that well, because it is quite detailed as to which type of connections must be used to connect to the district heating or which connections must be in the building.-Land use specialist Furthermore, the heat demand patterns of the buildings created another source of technological inertia.All of the buildings except a kindergarten zoned in the Skanssi area were planned to be apartment buildings with less heat demand during the daytime.Furthermore, at the time of the experiment, there were no readily available heat storage technologies -although one apartment building decided to experiment on heat storages in its piling structures.There were also little incentives for the municipal energy company to purchase the excess heat.The mismatch in heat production and consumption remains to be an unsolved issue that highlights how the narrow technological framing opens up systemic inertia in the implementation of an experiment.
… we don't need that heat when the property doesn't need it either and all the other properties are the same, and in the same way our consumption is going down so it's not right that the property condenses that heat into our network because it doesn't fit anywhere … and at least we can't pay anything for it.-DH specialist 1 The focus of experimentation moved from direct technological demonstration towards technological readiness of the buildings, as the technological uncertainties and systemic functioning became challenged in implementation.However, four years into construction, no apartment building had invested into the production technologies to engage in local heat exchange although they had installed a heat exchange technology enabling supply of domestically produced heat into the local DH grid.The first buildings were creating the demand for the future heat market.

Inertia in practices and continuums of land-use planning
With the introduction of plot assignment stipulations, Skanssi experimentation moved from technological framing to the land-use realm.Local authorities utilised plot assignment stipulations in guiding construction companies to use land according to landowners' expectations.Most land area in Skanssi was owned by the city of Turku that had chosen climate neutrality as a central strategic goal, which motivated a more active role in land-use planning.Although the plot assignment stipulations were supporting the experiment by providing more concrete guidelines, the way they were introduced produced inertia in the execution of the experiment.
There were several experimental features in the revised plot assignment stipulations: The construction companies were obliged to make instalments to the structures of buildings that deviated from the old established practices in the housing sector.These included reserving space for heat exchange facilities and installing IoT housing technology.However, the stipulations did not include specific guidance for the practical realisation of heat production and exchange, as no rules for local heat markets had been defined.
The local construction companies perceived the stipulations complicated as the stipulations guided the construction into atypical directions compared to traditional construction projects.According to city and energy company representatives, the challenges were not anticipated before the practical application of the stipulations in the actual planning of buildings.For the participating construction companies the situation appeared as a drift between targets and implementation: We didn't have a complete picture of what the end result is, when we joined that project … if we were to go join it now and all the conditions were known, we would examine and interpret the project in a slightly different way than back then … -Construction company The process of defining and publishing the plot assignment stipulations was also considered counterproductive for the experiment.Drafting of the stipulations was done in close collaboration between the civil servants, the energy company, and the intermediaries.Yet, due to temporal mismatch in bureaucratic preparation, the plot assignment stipulations were published only after the general area development had begun and the first construction company operating in the area had already started the planning on the basis of regular development practices, which were put under pressure to change after introducing the stipulations.
However, the land-use stipulations were not the core challenge of the land-use planning practice.Rather, the communication of the broader development vision was not translated to the planning realm, and thus the incremental aspect of complex stipulations gained a much stronger role than anticipated.From the energy company's point of view, the challenges were rooted in a lack of general development vision that would connect the different aspects of the system being experimented.
After the early challenges, the civil servants revised the plot assignment stipulations.The standards were clarified and streamlined to better meet the requirements of the construction companies.As of writing in 2023, the stipulations had not been replicated to any other context in the city or considered as an important innovation emerging from the Skanssi experiment.

Inertia in organisational factors and the roles of actors
The incomplete energy vision of the Skanssi experiment was connected to the roles of the city, energy company and construction companies in the administration of the experiment -each joining with their own expectations, offerings and organisational cultures.The city was the responsible party for the overall development as well as negotiating with the construction companies and making land use agreements.The energy company, meanwhile, was responsible for the management of the technical aspects of the DH network, such as construction of the grid and making agreements with the housing units.However, the roles in and the legitimacy of the experiment became challenged as the project failed to take off.
The energy company approached the experimentation from the perspective of developing its DH operation and heating services as a natural monopoly.The company was making the largest capital investment by installing the technical infrastructure of heating pipelines and pumping stations to the area.Therefore, the experiment was approached with an expectation of long-term profitability, which was reflected in the negotiations with the construction companies.This was deemed problematic by several interviewees, especially because not a single pilot had been established to test the bidirectional exchange of heat.In practice, the energy company fulfilled the first part of the pilot by creating technical capabilities for the low-energy DH network but abandoned the second part related to bidirectional heat exchange.
The challenge with the local heat market was that no previous examples existed, and the ideas how to get out from the inert situation deviated among informants.The energy company aimed at making first contracts temporary so that the functioning of the system could be assessed to find the right pricing.The initial piloting phase was envisioned to lead into a longer-term contract when the system operation was understood better.However, if the energy company would regard the contract unprofitable or malfunctioning, the users would have invested into the pilot technologies that become obsolete.This uncertainty of the benefits of the experiment was producing inertia and the energy company had not succeeded in presenting the benefits of the experiment to the potential parties.
Regulation of the ownership and business models in bidirectional heat experiment had gained broader attention.The Finnish energy sector advocacy group, Finnish Energy, had investigated the potential of bidirectional DH systems and business models in collaboration with consultancy company Pöyry (2018).Rather than expanding the existing operations, the informants noted that a jointly created business model could create a common understanding of the experiment.Moreover, the company's employees questioned the vision that the energy company would remain the owner of the local DH network operator of heat trade in it.As a potential solution, the establishment of a separate local heat trade operator was considered.
In Skanssi, the distribution and production should be differentiated, so that the same pricing model is made as in the electricity networks -DH specialist 1 Interviewees also considered that the city as the owner of the energy company should have taken a stronger role in corporate governance and reconfigure the company's targets to establish a more agile role in the experimentation.One informant brought up the question on whether the experiment had become more dynamic if the leader was not a business entity.Indeed, the city and the energy company had different aims for the experimentation: the energy company minding mainly about technological prerequisites, while the city being more invested in the experimentation as a social innovation.
Despite the mixed roles causing inertia in the experiment, the roles of the main actors were maintained to the implementation stages of the project.This was rooted in the rules of public funding that was directed towards design and installation of the technological capabilities of the grid, but did not include the installation of decentralised heat production in the first housing units or demonstration of operations.It was even noted that the city should have become the first actor to install bidirectional DH production to provide extension of the protected experiment, but it had not become an option due to lengthy area development.Essentially, the organisation of the experiment was framed in a way that did not include the user of the technology in buildings and the experiment was designed so that citizens would need to change their everyday life as little as possible.
… the construction party, the one who will eventually take the connection, is probably the most important partner in this, so at the moment we don't have the situation that we would have a bidirectional connection coming or we know of a developer who wants a bidirectional connection … -DH specialist 2 After little progress, the first bi-directional pilot was planned for the upcoming community centre of Skanssi.However, the city council decided to zone the centre for the neighbourhood outside lowtemperature grid due to its opportunity to improve social inclusion in the area.During the early stages of the Skanssi experiment there were no inhabitants living in the area, but as the experiment matured and the area development progressed, the inhabitants moved in.However, as the heat trade has not materialised, there are no means of evaluating social impacts of the heat exchange or the roles of the final users.Thus, multiple interests in the city organisation guided decision making toward resolution that further hindered the experiment.

Inertia in unclear or missing formal regulations
The existing DH regulation was considered patchy especially in terms of governing the nexus with other regulation, organising model of the heat market operations, and defining the price for heat.Thus, the first pilot case was seen as a crucial step to create a replicable model that would help guiding through similar questions also in other contexts.
Overall, the energy sector is strongly regulated to ensure the functioning of networks and interconnected markets with several types of actors.However, the operation of DH is local and relies on contractual arrangements in specific contexts.
The district heating industry is a lot freer and wilder [than the rest of the energy industry] … the development work has been much more in cooperation with the city than with the legislature, and on the one hand, it leaves more opportunities for the development of operations but on the other hand, in these contractual matters, it was like being on top of nothing, that nothing really regulates them … -Planning specialist 2 Unclear issues emerged in the interface of different regulations.The interviewees raised issues on how to consider the property's own heat production in mandatory energy certificates, what are the rules on competition in situations when production of heat would exceed the consumption, and how to organise the taxation on the heat sales.These issues point in different directions, as the energy certification system is organised by the Ministry of the Environment, competition regulation is governed by the Ministry of Economic Affairs and Employment and taxation is regulated by the Ministry of Finance.None of the regulating bodies were involved in the experimentation or consulted in the process.
There were no templates for contractual arrangements related to setting a price for excess heat.The (Pöyry, 2018) publications provided conceptual guidelines on bidirectional DH contracts and business models that had been utilised in the planning of the experiment.The different models rely on locally defining the risk and benefit sharing between the involved actors with different levels of shared operation.However, the energy company concluded that setting a fixed model to Skanssi was not a good option.To overcome this, one informant suggested that an hourly-based tariff for the heat in Skanssi would move the experiment towards a stabilised system.
To this date, the energy company has not published a price for the purchased heat and the experiment of bidirectional heat markets remains dormant.This absence of clear price and policy on the arrangement of bidirectional DH trade caused mistrust on the side of the construction companies, who were reluctant to participate in an ambiguous DH agreement, which included a risk of potential economic losses.Other regulatory challenges were considered to be more practical, and would have been solved over time with the main regulatory bodies.Thus, the uncertainty over bidirectional DH market regulation and pricing was a major cause for inertia.

Discussion
In this article, we have analysed sources of institutional inertia in the urban planning case of establishing a low-carbon DH system in a newbuilt area of Skanssi in Turku, Finland, which presents a case of novel experimentation with bidirectionality and low temperature with residents as anticipated heat producers.Previous experiments have rather F. Moilanen et al. been more technological (Yazdani et al., 2022) and the user/producer interphase has been modelled (e.g.Gorroño-Albizu and De Godoy, 2021) without real world experience of making producers third-party heating system participants.The case study documented the challenges a niche technology faces, when moved from protected development context into wider real-world experimentation as part of an urban planning processthus, putting the criteria of the original technological experiment into question.
The results of the study highlight not only technical hindrances, but also organisational, regulative and land-use planning related challenges that hamper the implementation of a novel, low-temperature, and decentralised DH system.Although the construction of decentralised and low-temperature DH systems is a key to cut heating sector emissions (IEA, 2023;Volkova et al., 2022;Wirtz et al., 2022), there are only a few real-life experiences of how they can be realised.As such, the results presented in Table 1 show the variety of hindrances a niche DH experiment may face, which is a contribution to the previous literature on DH experiments where most focus has been on technology.As noted in the SNM literature, the niches that do not 'work' are also informative regarding experimenting for sustainability transitions (Seyfang and Smith, 2007).In the discussion we want to focus on how the inert institutions require a more careful consideration beyond 'success' and 'failure' of niche innovations.We do this by focusing on multi-regime interactions, role of visions and expectations, and centrality of actors in institutional change.
Despite being mobilised deliberately as a technological niche experiment in the energy system, the experiment as means for urban energy governance involved multiple regimesand embedded regime actors (Bulkeley et al., 2014).It has been noted that some niches do not align with the established sector boundaries but influence and interact with multiple regimes while they take off (Konrad et al., 2008).In the Skanssi experiment, the focus was initially on experimenting with the technical aspects of the energy regime to better understand how the novel DH network could lead to reconfiguration of regime rules in the post-combustion energy system.However, the framing missed the building and housing regime perspectives on both planning and operating the network, which led to changing and expanding the initial experiment to cover these "clients" of systemic reconfiguration (see also, Lazarevic et al., 2019).As a consequence, the implementation of the experiment required changes also in land-use planning and organisational practices and inclusion of the reluctant housing sector actors.The multi-regime view also questions when is the experiment successful: When the heating network is constructed?When clear rules have been established?Essentially, the reconfiguration of the regime rules creates a state of flux, where experimentation becomes institutionalised as a persistent state of affairs.
Moreover, the shifting baseline of the experiment points towards the essentiality of the visions and expectations in the niche development.The technology expectations and visions begin to institutionalise among the involved actors (Berger and Luckmann, 1966).Since institutions develop in relation to their material structures, the old-established technologies steer regime change to path-dependency, which prevents radical transitions (Fuenfschilling and Truffer, 2016).In the Skanssi experiment, technology visions framed the development of the DH innovation toward incremental options, and their ambiguity led to misalignment of actor views (see also Kemp et al., 1998).This led to the centrality of spatial planners to emerge as key intermediaries to interpret the vague expectations in terms of concrete rules.In addition, the expectations relied on citizens' final consumer roles in the DH network despite there being no inhabitants in the area at the time of the experimentation.The material requirements, behavioural aspects and market mechanisms were not included in the initial vision of the experiment but they were presented as implementation obstacles that were not open for transformation or experimentation.Therefore, the shared visions and expectations that should provide the pathway for experimenting can become hindrances to its implementation if there is no reflexivity in terms of the changing context (Kemp et al., 1998).
Actors' visions of the experiment lead to changing actor-roles and capacities in the niche experimentation, as it moved from laboratory context through policy visions and land-use planning to implementation.In SNM literature, the key of involving diverse actors with different backgrounds (Schot and Geels, 2008) and the potential tensions between different actors (Avelino and Wittmayer, 2016) is well documented.The actors participating in institutional work to reconfigure the energy system (Duygan et al., 2019) ranged from the city administration and political leadership to the energy company, technology developers and construction companies.As noted by Kainiemi et al. (2020), energy companies are increasingly active in institutional work to reconfigure regime rules of a changing system.However, in the Skanssi experiment the position of the energy company as grid owner, centralised energy producer and potential energy trade operator hindered the full implementation of the vision of bidirectional heat trade.Thus, the energy company was unwilling to alter its role to potentially unprofitable experimentation despite the insufficiency of the current means to experiment.However, institutional work also took less obvious forms, as the urban planners needed to develop new capacities to steer the emergence of low-carbon DH networks.Moreover, the role of the city in setting the sustainability targets and defining regime direction in challenging governance settings became amplified.Thus, the experiment brought up unanticipated skills requirements for the actors in city administration which they were not prepared to embrace.
Even though climate neutrality is part of the strategy of the city of Turku, the vested interests and the realism in policy making have watered down the expectations of Skanssi experimentation in different junctures.This is partially due to the competitive interests between the cities' different administrative branches that undermine the strategic orientation of climate action (Reinekoski et al., 2023).Moving beyond the "stickiness" of the sectoral interestsor the institutional inertiarequires more careful focus in the strategic realm in terms of more longitudinal policy strategies, more explicit focus on actors, capabilities and their institutional work and connecting the implementation of planning more explicitly to the visions (e.g.Lukkarinen et al., 2023;Reinekoski et al., 2023).One implication for future research needs can be provided by the publicly owned utility companies on energy, heat, waste and water, and their actions' potential contradictions with owners' sustainability strategies, which could provide more information on the vested interests and institutional inertia in sustainability transitions.
In sustainability research, institutional inertia provides a useful middle-level concept for analysing the points of friction in sociotechnical systems.Its strengths are in connecting specific analytical insights into broader systemic change dynamics.The sustainability transition literature often refers to the concept of barriers to point out institutional-material hindrances of adopting specific innovations or alternatives.However, inertia complements the conceptual horizon by providing a more nuanced and evolutionary view on how actors actively participate in reconfiguring obstacles and adjusting established regimes and habitualised practices to meet changing expectations.This also entails a more nuanced and dynamic relation between regimes and niches, as the niches are also actively creating and reproducing their own inertia that hinders the linear transition visions in ways that are not captured by the metaphor of 'barrier'.

Conclusions
This article has contributed to the ongoing discussion on institutions in sustainability transitions by showing that institutions in sociotechnical transitions of the energy system refer not only to regime level institutions, but institutions are constructed also in the envisioning of niche expectations.The results show how visions of niche institutions do not necessarily align with the regime, which was the major source of institutional inertia causing the experiment not to advance.The major F. Moilanen et al. obstacles of this energy niche were related to institutions and practices of involved actors engaged with the experiment.The results highlight the need to increasingly pay attention to the collaboration and joint vision building among the actors of transition experiments (see also Bos and Grin, 2008;Schot and Geels, 2008).
There are limitations to our study.First, we could not interview inhabitants in the area, so the views of residents are missing.Hence, future research could investigate the experiences and expectations of the residents living in the area related to the potential of utilising the bidirectional low-heat DH technology.Second, we may have not captured all aspects of various kinds of inertia experienced by all actors involved in the experiment.For instance, a deeper understanding of the sociotechnical systems of construction and housing would have provided a more nuanced picture of the inertia emerging from those systems, but that was out of scope of this article that focused on the experiment.Nevertheless, we think that interviewing various actors has provided a comprehensive enough picture of the forms of inertia in the experimentation.Finally, we did not have direct access to techno-economic data from the experiment.Future research could, however, deepen the understanding by examining more closely the elements of various kinds of inertia in urban energy experiments and connect actor perceptions to technical evaluations.

Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Fig. 3 .
Fig. 3. Illustration of the technological elements of the Skanssi vision on the master plan of the area.

Table 1
Summary of results with data extracts.
The role of Turku city here has been that they have left all responsibility to Turku Energy to think about the economic feasibility, that what are the tariffs and so, and the city has not taken a stand Inertia in unclear or missing formal regulations Apartment building is much more complex environment to operate, who is the payer and who is the beneficiary, the threshold [to experiment] rises quite a much F.Moilanen et al.