A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland)

Energy xxx (xxxx) xxx

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A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland) Luca Pampuri a, Marco Belliardi a, Albedo Bettini a, Nerio Cereghetti a, Ivan Curto a, Paola Caputo b, * a b

ISAAC, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Switzerland Department of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Italy

a r t i c l e i n f o

a b s t r a c t

Article history: Received 10 April 2019 Received in revised form 1 October 2019 Accepted 4 October 2019 Available online xxx

The technical literature underlines the strategic role of district heating systems (DHS) in the decarbonization process in the European context. The main scope of this work is to develop a method for identifying areas potentially suitable for DHS, taking heat need density as the main metric. The method is tested for the case study of Canton Ticino (Switzerland) and allows analysis of the total and public building stock. This implies the collection and elaboration of energy data about public buildings, providing a dataset formerly unavailable. Because these buildings are managed by a few owners who are generally asked to be exemplary in terms of sustainability, they could have a pivotal role for the development of DHS. By using a multi-criteria and GIS- supported method, the study ensures the mapping of areas potentially suitable for DHS and renewable sources available for thermal purposes toward low carbon targets. Based on the results of the research, it is estimated that potentially 17% of the global heat needs in Canton Ticino could be satisfied by DHS, by also exploiting thermal renewable energy sources locally available. The consistency of the method was tested through a validation on the existing DHS. © 2019 Elsevier Ltd. All rights reserved.

1. Introduction The path to carbon-neutral communities presents long-lasting and urgent challenges for all governments. For example, in Switzerland, Energy Strategy 2050 is in force, defining the main targets for energy policy until 2050 [1]. Energy statistics highlight the role of buildings' operation in energy consumption, at least in developed countries. For example, Swiss buildings are responsible for more than 40% of the total final energy consumption [2]. More in detail, statistics show that buildings space heating accounts for 71% of the end-use energy consumption in Switzerland, while lighting and electrical appliances account for 15%, water heating for 12% and cooking for 4% [2]. This information highlights the importance of defining steps for reducing heating needs and for improving the performance of the heating systems. Also [3] underlines that space heating in Switzerland is reliant on oil (42%) and natural gas (26%) and that

* Corresponding author. E-mail address: [email protected] (P. Caputo).

decarbonizing the Swiss heating supply is key to meeting its environmental targets. In this context, the role of district heating systems (DHS) could be very effective, especially if local renewable sources are utilised, in addition to energy retrofit measures. More in general, DHS and thermal district systems are compatible with the path towards smart local energy systems, which are able to manage combined heat and power (CHP) generation, as well as different uses of heat at district level, as stated also in Refs. [4e7]. Furthermore, district thermal systems could be equipped to satisfy cooling purposes, as reported in Refs. [8e10], which emphasise the challenging path toward future 4th or 5th generation DHS. About 6000 different systems can be found all over Europe today. In total, these systems have a distribution network trench length of almost 200,000 km [5]. These systems are more common in northern Europe, while other areas have not fully exploited this potential. According to Ref. [3], in Switzerland, DHS represents only 5% of the heat supply while Europe's share is 13% and, e.g., Denmark's is 63%. DHS have undergone a profound evolution and technological maturation [11]. Several review studies carried out in relation to the European context, such as [9,12and13], provide an effective attempt in the definition and classification of DHS and in describing their

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Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297

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evolution and development. The design of a DHS represents an important project of local energy planning, a promising investment for the territory and implies cooperation among different stakeholders [14]. The feasibility, characteristics and dimensions of DHS depend mainly on local characteristics of heat needs [3], proper local sources availability and relative market, climatic, morphologic and orographic conditions and regulative framework in force. Where feasible, several benefits can be achieved, such as a proper use of available renewable sources, otherwise not exploited; a significant contribution to renewable energy targets for thermal purposes; a driver for the realization of underground infrastructures (e.g. broadband connection). However, the presence of favourable conditions such as heat needs and local renewable sources does not guarantee the feasibility of these systems that mainly depend on cost effectiveness conditions and on the possibility to connect a minimum number of users. Reasonably, users are prone to DHS if market and operational conditions are favourable. Feasibility indicators and criteria are cited in the technical literature for the selection of areas theoretically suitable for new DHS. According to Ref. [14] and enclosed references, the absence of competitive carriers and a high-density heat need are probably the most pivotal conditions. In Canton Ticino, a region in southern Switzerland, in the last few years some high-temperature DHS have been realized and studies for developing small high temperature and lowtemperature DHS, depending on local conditions, have been carried out. These actions are in line with the need to decarbonize space heating and domestic hot water supply in Switzerland, according to Ref. [3]. In parallel, a process of increasing the energy efficiency of the built environment is in progress, making more cost effective systems that are based on low-grade thermal energy sources. In the last decade, Canton Ticino has been prone to promote DHS. In fact, after the elaboration of the Cantonal Energy Plan in 2010 [15], an Action Energy Plan was developed in 2013 [16], where low carbon energy targets and measures of support were defined. In addition, the cantonal authority economically supports predesign studies, realizations and new connections regarding DHS1 and a tool for municipalities, able to support a proper analysis of their territory toward promoting DHS, has been defined as fundamental.2 These local incentives can certainly improve the economic feasibility of DHS. Based on the experience of the authors, among the great difficulties for the realization of a DHS, there is the scouting of the users who could be actually connected to the network, in particular during the early stages of study. Although a connection to the DH network may be interesting and effective in long term scenarios, often, private users seem reticent when they are asked to answer if they agree to abandon their actual heating system in favor of DHS. The uncertainty on the number of users that could be connected makes it difficult to assess the real economic and energy convenience of a district heating project in a specific district or part of the territory. The approach of this paper allows not only mapping of the local structure of heat needs but also individuating areas with favourable conditions in terms of potential users and local suitable energy sources. Public and para-public owned buildings could represent interesting DHS users, since they are often a considerable part of

1 This is described at https://www3.ti.ch/CAN/RLeggi/public/raccolta-leggi/legge/ numero/9.1.7.1.8, in Italian. 2 See in particular the form related to DHS in the Action Plan of the Cantonal Energy Plan.

the real estate. Furthermore, assuming that public authorities are asked to be exemplary in terms of environmental and energy sustainability, public buildings can be considered particularly suitable for connection to efficient DH networks. This is an interesting driver for DHS, since few entities, involved also in the definition of precise and long lasting contracts for energy services, are responsible for the management of such large building stocks. The identification of public and para-public buildings by Geographic Information Systems (GIS) and the definition of their thermal power and heat need, together with the estimation of the total heat need in buildings in the same territory, allows mapping by GIS of the heat need density. In addition, the definition of criteria able to define the level of appropriateness of a territory concerning the development of a DHS ensures mapping of the most suitable areas. Finally, this result can be overlapped onto the analysis of the potential thermal sources locally available in order to define, again by GIS, the most suitable areas in terms of matching energy needs and supply carriers. Following this approach, a method was developed and tested for the case of Canton Ticino in order to represent the theoretical potential of DHS and to evidence the areas that more deserve to be further studied in order to accomplish a proper feasibility analysis. 2. DHS sources, technologies and costs According to Ref. [17], DHS have historically consisted of largescale conventional production units owned by energy companies and generally fueled by fossil carriers. The technical literature (e.g. Refs. [18,19]) defines that DHS can use a number of different heat sources such as: combustion-based heat generation plants using biomass or fossil fuels; combined heat and power (CHP) plants; renewable geothermal heat; solar heat; industrial waste heat; heat from municipal solid waste (MSW) incinerators; and large scale heat pumps. As the knowledge and awareness of environmental problems grows, the approach to DHS has been changed resulting in a higher integration of renewable energy in heat supply and in a higher global efficiency. This is the reason why our work focuses on the matching of thermal needs and local proper renewable sources potential. As mentioned in section 1, especially in connection with buildings that only require low supply temperatures for space heating, low-temperature district heating offers new possibilities for greater energy efficiency and utilization of renewable energy sources, which lead to reduced consumption of fossil fuel-based energy. However, in integrating decentralized heat sources, many issues have to be addressed and a proper use of regulation of the grid becomes more important [17]. In this framework, an important challenge is making DHS in operation capable of evolving together with the built environment and increasingly supplied by local renewables. Schematically, DHS can be divided into three subsystems, namely the heat sources or heat production plants, the heat distribution system, and the customer interfaces [17]. DHS initially involves high investment cost. However, in case of high heat densities, the overall economic effectiveness of the project could be sustainable. According to Ref. [20], the estimation of costs related to DH is very complex. In general, the cost of a DH system includes the heat generation cost (or collection cost, if heat is derived from an existing source) and the heat distribution cost. Both these costs consist of capital cost and operation and maintenance costs. Investment costs, the network losses and the auxiliary energy consumption are mainly affected by the following parameters: the pipe diameter (and thus the dimensioning of the network); the type of pipe (material, design); and the thermal insulation

Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297

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thickness. According to Ref. [19] that collected data referred to European countries, investments costs range from 405 V/kW to 1115 V/kW of thermal power. The price of DH for final users often involves three components: connection fee for the construction and connection by the heat company; basic price per kW of connected thermal power, in order to cover the fixed costs; and operation price per kWh of delivered heat. The resulting combination leads to different costs for the final users, depending on the conditions of the context. According to Ref. [21], which regards the calculation of the cost-optimal combination of heat savings with either district heating or individual supply technologies for different building groups located in different areas according to the availability of a current district heating network, a range of 50e100 V/MWh (more likely 80e90 V/MWh) of sold heat can be found for different scenarios. Based on the experience of the authors involved in the research here presented, the cost of heat supplied by the district heating networks in Ticino is in the range of 80e120 V/MWh (including capital cost, operational and maintenance costs). Therefore, in some contexts DHScan be cost effective if the supporting measures described in section 1 are taken into account. 3. Case study and datasets The context of application is the territory of Canton Ticino in southern Switzerland. The study explores the built environment in terms of heating needs and existing heating systems. In order to define the potential users to be connected, our research includes an interesting focus on public and para-public buildings, their distribution and features, since, according to section 1, this particular building stock could represent a massive and easier to manage energy user in DHS development. In section 5.2, Canton Ticino is analyzed also in terms of renewable sources available for DH purpose with particular regard to future 4th and 5th generation systems. 3.1. Case study Canton Ticino is a region of about 2800 km2 and 350,000 people in southern Switzerland (Fig. 1). It is a florid and environmentally conscious area, with economic resources that can be activated in the energy field. Due to its geographic position, in Canton Ticino various landscapes, morphologic and climatic conditions are present. The conditions found are similar to those present in other neighboring European regions belonging to northern Italy, southern Germany, Austria and France. Referring to winter conditions, the standard Degree-Days (DD) in Ticino range from 2438 in Lugano station to 3994 in the mountain station of Piotta [22], underlining the compatibility to DHS. Low elevation areas like Lugano have a temperate/continental climate, similar to the urban contexts in adjacent northern Italy, while high elevation zones have alpine climatic conditions. Moreover, the building stock of Canton Ticino presents architectural technologies, types of envelope and ages similar to those averagely present in Europe. For example, Canton Ticino has an average population density of 125 inhabitants per km,2 little more than the EU average (113 inhabitants per km2) and a little less than the Italian average (200 inhabitants per km2). In the few important urban areas of Ticino (i.e. Lugano, Locarno, Bellinzona), all the building sectors are present: residential, commercial and industrial. However, in general, most of the buildings are homes and dwellings. Public statistics related to residential buildings such as [23,24] indicate that more than half of them (54.7%) were built before 1961, which suggests the need for

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retrofitting envelopes and plants. About 10,000 buildings were built in each decade in the sixties, seventies and eighties. The real estate park built in the nineties and two-thousands was more modest, respectively with 6646 and 7185 buildings. Between the years 2011 and 2017 a total of 4406 buildings were built. Among various information available, we did not find data to quantify and characterize buildings of public property. The only information available concerns the official estimate of the real estate assets based on the type of owner, from which it can be deduced that the public buildings represented an asset of 3.7 billion CHF at the end of 2017. The present study is also aimed at supplying this lack of information; therefore, the first step is the identification of public buildings. 3.2. Available datasets According to similar research aimed at defining a method for developing district thermal systems, such as [3,21] and, referring to the analyzed territory [2,6], available databases were examined. Information about the existing buildings and related heating systems have been collected based on the available datasets: 1. Federal Register of Buildings and Dwellings (FRBD) [25]; 2. Register of Companies and Establishments (RCE) [26]; 3. Official measurement database and maps, a service to achieve a precise and official measurement of the surface of buildings [27]; 4. Norm SIA 380/1, Thermal energy in construction (2009) [28]; 5. Cadaster of large-scale combustion plants (i.e. plants greater then 1 MW)3; 6. Cadaster of small combustion plants (i.e. plants lower then 1 MW); 7. Heat pump database (HPDB)4; 8. District heating database (DHDB)5; 9. Land Register of Swiss Real Estate [29]; 10. Database of the Logistics Section - Department of Finance and Economy, Internal Logistic Section Database6; 11. Database of the Platform for Energetic and Technological Retrofit in Architecture (Petra) [30,31]; 12. Database of the Cantonal Hospital Entity7; 13. Energo Database, about energy efficiency in buildings [32]. It is clear that all mentioned databases serve different aims and they are not homogeneous; they refer to different building stocks and they can hardly be linked together. The first eight databases of the list were used to map and characterize main building features and energy carriers in buildings, while the other five focus on public and para-public buildings (Fig. 2). The latter provide important information: building category, age, reference heated surface and actual heating consumptions. The FRBD includes all buildings in Switzerland used for

3 The Cadaster of combustion plants, both large scale and small, is required by the Regulation for Applying the Decree against Atmospheric Pollution. The decree is available in Italian at https://m3.ti.ch/CAN/RLeggi/public/index.php/index/ nuovafinestra/atto/537/volume//numLegge/834.350, last access March 2019. 4 Provided by the University of Applied Sciences and Arts of Southern Switzerland (SUPSI) and supported by AIL, the Association of the Industrial Companies of Lugano. 5 Provided by the Institute of Sustainability Applied to the Built Environment (ISAAC) of the University of Applied Sciences and Arts of Southern Switzerland (SUPSI). 6 Internal database provided by the Cantonal Department of Finance and Economics (https://www4.ti.ch/dfe, in Italian, last access March 2019). 7 Internal database provided by the Cantonal Hospital Entity (https://www.eoc. ch, in Italian, last access March 2019).

Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297

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Fig. 1. Map of the case study in the European and Swiss context.

residential purposes and the dwellings therein. Due to unambiguous and nationwide-unique building and dwelling identification codes, the most important basic data, such as address, location details, year of construction, number of floors, type of heating for the buildings are recorded, and also for the dwellings, number of rooms, size (floor area), etc. Unfortunately, this information is not

always available and reliable; in fact, about 7% of the buildings were discarded due to data incompleteness. Through the RCE it is possible to have the code aimed at identifying the main economic activity of each company among 21 available classes and further specific subclasses. Thermal needs for domestic hot water (DHW) and space heating

Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297

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Fig. 2. Scheme of the method adopted, available datasets and data extraction and representation.

were estimated accordingly to SIA 380/1 [28]. This comprehensive norm includes not only the method for the calculation of the buildings energy balance, but also typical standards of space heating and DHW needs for several categories of buildings depending on their use. This source was adopted also in a previous research supported by an analogous method [2]. It is interesting to underline that, on the basis of the Cadaster of combustion plants, most of the heating systems are fueled by oil. In fact, oil boilers have a total power of 2.2 GW, while natural gas boilers have a total power of 0.7 GW. About 3% of the heating systems registered in the Cadaster are biomass boilers or heat pumps (HP), i.e. systems without combustion. Indeed, HP belong to buildings recently refurbished (previously equipped with combustion systems), according to the fact that the penetration of HP has been increasing. Data reported in the HPDB refers only to a portion of the territory analyzed (about the half of the total municipalities of Canton Ticino), supplied by the same electric company. They are updated to 2015 and describe a presence of 4292 HP, 3455 electric boilers for DHW and 42 electric boilers for space heating, for a total power of 32 MW and about 5 kW as average power per system. Interestingly 45% of these systems adopt inefficient technologies since heating purposes are satisfied by electric resistances. The DHDB reports the presence of 19 networks for a total amount of 244 connected buildings, representing less than the 0.2% of the total building stock in Ticino. These plants are fueled by: biomass (14 plants and 172 buildings); natural gas (3 plants and 16 buildings); waste to energy (1 plant and 49 buildings) and waste heat (1 plant and 7 buildings). The overview underlines an interesting panorama for exploiting renewable energies and waste heat by DH technologies. About 82% of these buildings are described also in the FRBD database [25]; therefore, 201 buildings connected to DHS will be included in the following elaborations. The Land Register of Swiss Real Estate [29] allows the identification of the public and para-public buildings, and reports general information and further details about current and previous owners. Ownership is a key piece of information because it allows an immediate dialogue with public building owners (authorities, entities

etc.) regarding a possible connection to DHS. The Database of the Logistics Section includes information about maintenance and operation of buildings owned by Canton Ticino. The Petra Platform includes about 300 buildings, most of which are public and para-public. This platform allows the calculation of the building's energy balance following the SIA 380/1 method and therefore the estimation of space heating and DHW needs. The Database of the Cantonal Hospital Entity was adopted in order to study energy needs in hospitals and buildings for elderly people. 4. Method of analysis In the current energy framework, an analytic method able to find areas that are compatible with the development of DHS is necessary; not only for investors, aimed at verifying the technoeconomic feasibility of their investments, but also for planners, public administrators and for communities involved in decision mechanisms about the development of the territory, with important roles also in the approval or disapproval of big projects. Based on the available dataset, the research starts with a procedure to estimate the heating need of the overall buildings stock and to focus on buildings of public and para-public property. For the latter, a list and a graphic representation is given, estimating also their energy needs. 4.1. Analysis of the building stock and focus on public and parapublic buildings The first step of the study regards the elaboration of information about space heating and DHW needs and thermal power in buildings. Therefore, a method capable of characterizing and mapping with GIS the energy performance of the built environment at territorial scale was developed. It follows a simplified procedure that takes into account collection, a long lasting phase of updating of data available in the FRBD and a geo-referencing of the collected data on a territorial map of Canton Ticino by GIS. The case study is reported in Fig. 1 with the indication of the number of

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Table 1 Canton Ticino, buildings and surfaces grouped by building's categories. SIA 380/1 Categories

Types of buildings

Number of buildings

Surface, m2

Surface on total, %

I II III IV V VI VII VIII IX X XI XII XIII

multi-family buildings single-family buildings administrative buildings schools shops restaurants a public spaces hospitals industrial buildings warehouses sports buildings swimming pool buildings special buildings b Total

33,356 75,600 4614 402 580 0 941 145 634 111 59 0 858 117,300

17,894,273 14,452,323 3,605,541 731,334 1,125,592 0 437,236 464,789 1,347,439 217,370 63,796 0 801,155 41,140,848

43.50 35.13 8.76 1.78 2.74 0 1.06 1.13 3.28 0.53 0.16 0 1.95 100.00

a b

a

It was not possible to individuate these buildings by overlapping the available databases; however, their role toward DHS promotion is negligible. Category not available in SIA 380/1, but created for this investigation: car parks, open sheds, cabins etc.

existing buildings in each territorial ambit (district) of Canton Ticino. By analyzing all the above-mentioned databases, selecting the reliable information and collecting it together for each building thanks to the merging between the different databases, it was possible to define the number of buildings with available data, their typologies according to SIA 380/1 classification, the different fuels and systems adopted for heating and the related heated surfaces. Due to the lack of a unique identifier in all databases, this operation has often required the use of crossover methods using spatial analysis tools (GIS) or mailing address with confirmation on a caseby-case basis. A summary, referring to the entire territory of Canton Ticino, is reported in Table 1 and Table 2. It is interesting to observe that: 1. Data were available and accurate for 117,300 buildings (the 99% of buildings included in the FRBD dataset); 2. Residential buildings represent 79% of the total heated surface analyzed; 3. Even not considering electric systems, 2/3 of the surfaces are heated by fossil fuels and mostly by oil. This figure evidences a clear need to shift the heating supply in Canton Ticino towards low carbon scenarios, underlining the great potential of efficient DH technologies. Following the analysis of the entire building stock, in order to select public owned buildings, the database from the Land Register of the Swiss real estate was used. At the end, 73,301 real estate objects8 were identified, as described in Table 3, and a lot of interesting available information was collected. More in detail, almost half of public real estate is owned by municipal entities. Moreover, through a more detailed consultation of the available datasets, it was possible also to extract information about the parapublic real estate, 2758 objects in total, mainly owned by transport and energy companies. As a result, in total, the public and parapublic real estate objects analyzed in detail were 76,059. However, most of the real estate classified in Table 3 is not represented by buildings, but by unbuilt areas and other surfaces, like sports fields or technical rooms owned by Municipalities or Canton Ticino (code 41 and 42), religious monuments owned by the Parish or Dioceses (code 47 and 48). Therefore, after a further analysis and selection, 21,977 public buildings and 1077 para-public

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The objects includes buildings, land, cabins, fountains, garages, accessory buildings, etc.

buildings were conclusively identified. These buildings are mainly owned by municipal entities, Canton Ticino, Swiss Railways, parishes and dioceses. The information previously described were overlapped with that included in the Land Register of the Swiss real estate due to the presence of the unique codes available for each building and a territorial map of public and para-public buildings (i.e. with public and para-public owners) was developed following the procedure described in Fig. 2. Also taking into account information provided by FRBD database, the result was a set of 3454 buildings available in all the considered datasets. Results are reported in Table 4, where buildings are classified according to SIA 380/1 [28] in order to satisfy the aim of representing all the available information useful for determining heating needs. Most of the public and para-public buildings are located in the most urbanized districts of the region; in particular, 80% of the sample belong to the districts of Lugano, Bellinzona, Mendrisio and Locarno. 4.2. Estimation of heating needs and focus on public and parapublic buildings In this research, the evaluation of the thermal needs was carried out in three steps. The first step regards the estimation of the needs for space heating and DHW in residential buildings (categories I and II of Tables 1 and 4). According to Ref. [2] the needs for space heating (in kWh/y) were calculated as the multiplication of the yearly heating needs index (in [kWh]/[m2y] for the energy reference surface (i.e. the heated surface in m,2 available for each building). As yearly heating needs index, the average value available for the age span in which the building lies was considered. These values were then aggregated by age, providing the total heating demand for each age and, as sum, the global residential building stock. Needs for DHW were calculated as the multiplication of the DHW limit values reported in SIA 380/1 [28] 9 and the energy reference surface. In the second step, the heating needs for non-residential buildings (categories V, VI, VII, IX, X and XII of Tables 1 and 4) were defined according to SIA 380/1 and to Ref. [2]. Needs for DHW were estimated as described for residential buildings. A summary of the adopted values is reported in the following

9 SIA 380/1 (2009) is a comprehensive norm and includes not only the method for the calculation of the buildings energy flows, but also typical standards of space heating and DHW needs for several categories of buildings depending on their use.

Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297

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Table 2 Canton Ticino, Buildings heated by different fuels and the related heated surfaces. Type of heating supply

Number of buildings

Surface, m2

Surface on total, %

None Oil Coal Natural gas Electricity Wood biomass HP Solar collectors DH Others Unknown Total

1156 51,454 8 11,453 21,953 11,919 13,045 149 201 206 5756 117,300

235,068 21,234,259 1427 6,859,912 4,423,783 1,837,459 5,088,934 37,591 63,902 170,575 1,187,938 41,140,848

0.57 51.61 0.00 16.67 10.75 4.47 12.37 0.09 0.16 0.41 2.89 100.00

Table 3 Canton Ticino, public objects selected by the Land Register of the Swiss real estate by typologies. Code

Owner

Number of real estate objects

41 42 43 44 45 46 47 48 49

Municipal entity State of Canton Ticino Swiss Confederation Swiss Confederation e State Railways Patricians Consortium Parish Diocese Other institutions and entities Total

35,771 8435 1998 1351 14,228 2311 6837 235 2135 73,301

Types of buildings

Category in SIA 380/1

Types

DHW, kWh/ m2y

Space heating, kWh/ m2y

I

multi-family buildings single-family buildings administrative buildings schools shops restaurants public spaces hospitals industrial buildings warehouses sports buildings swimming pool buildings special buildings

21

-

a

14

-

a

7

37

7 7 56 14 28 7 1 83 83

43 32 58 51 40 52 56 68 82

0

0

II III

Table 4 Selection of public and para-public buildings, grouped by categories according to SIA 380/1. SIA 380/1 Categories

Table 5 Thermal needs provided by SIA 380/1.

Number of buildings

IV V VI VII VIII IX X XI XII XIII

b

a

I II III IV V VI VII VIII IX X XI XII XIII

multi-family buildings single-family buildings administrative buildings schools shops restaurants public spaces hospitals industrial buildings warehouses sports buildings swimming pool buildings special buildings Total

1909 734 277 268 30 29 69 41 17 25 54 0 0 3454

Table 5. The third step regards the estimation of heating needs in public buildings (categories III, IV, VIII and XI of Tables 1 and 4) and derives from the need to identify, based on real documented data, the consumption of these particular categories of public or para-public property (focus of this study). Therefore, some of the mentioned indexes have been updated by available real data collected in the various databases as follows. Datasets 10 to 13 (section 3.2) were taken into account and overlapped. In this comparison, some errors found in databases (like the false attribution of the type of building) were corrected and, at the end, 297 public and para-public buildings belonging to different typologies were selected, underlining the representativeness of the sample. Since for some categories the number of available buildings was too small, an estimation of the energy demand was not possible using these databases. The final sample is

These values were estimated, therefore those provided by SIA 380/1 were not taken into account. b Created for this project (it includes garages, cabins etc.).

composed of 248 buildings: 102 administrative buildings; 126 schools, 13 hospitals and 7 sports buildings. The datasets available for these buildings allow to estimate the space heating needs more accurately, through the analysis of thermal balances and fuels consumption. Also in this case, needs for DHW were estimated as the multiplication of the DHW limit values reported in SIA 380/1 and the energy reference surface. This innovative procedure, which, for the first time, takes into consideration all the information reported in different and nonuniform databases, has provided a snapshot of the public building stock in Canton Ticino. A summary of the results of the third step is reported in the following Table 6, for non-residential buildings and by representative values grouped by age. It is possible to observe that space heating indexes reported in this table are higher than those reported in Table 5 for the same categories. This difference is due to the comparison between real data and theoretical data, which therefore can barely reflect the consumption of old buildings. Indeed, data reported in SIA 380/1 could well represent thermal needs of recent buildings. Conversely, the thermal needs of old buildings are in general underestimated. Finally, taking into account the results obtained in the three steps described above, a map of the heating need density in Canton Ticino was elaborated (section 5 and sub-sections). Buildings were geo-referred and the territory was divided into equal parcels using grid squares with a side length of 200 m (4 ha). In the maps, two heating need densities (MWh/ha per year) were reported: one

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Table 6 Thermal needs, results obtained for public and para-public buildings. Category in SIA 380/1

Types

Age of construction

III

administrative buildings

IV

Schools

VIII

hospitals

XI

sports buildings

1900e1945 1946e1990 1991e2000 2001e2016 1900e1945 1946e1990 1991e2000 2001e2016 1900e2000 2001e2016 1900e2000 2001e2016

a b c

a

DHW, kWh/m2y 7 7 7 7 7 7 7 7 28 28 83 83

b

Space heating, kWh/m2y

c

157 128 87 64 131 123 109 51 107 48 117 81

Ages defined according to Ref. [2]. According to SIA 380/1 [28]. Average values.

related to heating needs of all the buildings with available information and another related to heating needs of public and parapublic buildings. 4.3. Criteria for selecting areas suitable for DH This phase of the research aims to identify suitable areas in Ticino for the construction of DH networks. According to other works such as [21], once the energy needs have been determined, thanks to a multi-criteria analysis based on the estimated heat need density and theoretical and empirical feasibility indexes, it will be possible to identify the areas potentially suitable for DHS integration. Then, these areas will be classified in order of suitability and afterwards matched with local renewable sources availability. This is a preliminary result that allows a territorial representation of the theoretical potential for DHS; the actual technical and economic feasibility will then be verified through further investigations. Methodologically, criteria, parameters, thresholds and weights described subsequently were selected according to the objectives of the research and to the expertise and common sense of the involved stakeholders (authors; working groups in which the authors are involved; Ticino's Cantonal Authorities for energy efficiency and local energy companies that demonstrated interest in DHS). Based on their expertise regarding the Cantonal energy system, the authors elaborated a list of metrics, parameters and weights defined as fundamental for supporting decisions about the identification of areas that, being suitable, deserve to be further studied in order to accomplish a proper feasibility analysis. The pertinent technical literature was also checked and metrics, parameters and weights were discussed with the involved stakeholders. During this process, the thresholds indicated in the following were changed according to a trial-and-error process, to obtain results compatible with the validation reported in section 5.1. This selection is based on feasibility indicators and criteria that take into account important features of the built and natural environment. In particular, the following characteristics are considered in order to select suitable areas: heat need density, morphology, presence of public and para-public buildings, age of the heating systems and plants, etc. According to Ref. [3], a common approach for mapping DH potential is to calculate heat need density metrics and apply the respective thresholds on the basis of “rules of thumb”. A real heat need density is probably the most important metric for evaluating the feasibility of DHS, since it is proportional to the heat sold in a year within a defined territory. In addition,

knowledge of the fossil energy sources available and of their market price allows definition of the competitiveness of DHS as heat suppliers. On the other hand, since the use of coal and oil is particularly critical for climate change, the unavailability of natural gas is a promising condition for promoting DH. The age of existing heating systems and plants is another key parameter because, if heating systems and plants are near their end of life, the owners can be more attracted to considering different options for their substitution, including DH. Finally, a strong presence of public buildings is beneficial because it can mean a high number of users easily involved in a district heating project, as explained in section 1. The methodology used is to evaluate exclusion criteria and weighting criteria in order to identify pertinent areas. The aim of the former is to eliminate from the territorial analysis the users not interested in a connection to DHS. E.g. exclusion criteria may regard buildings not heated or already connected to DHS in operation or built after 2005 or equipped with competitive systems such as solar collectors etc. Instead, the weighting criteria, used on the remaining users, allow an evaluation of the suitability of portions of the building stock. The latter criteria therefore have the purpose of establishing, for a given territory, a greater or lesser interest with regard to a possible connection to DHS. For these criteria, experimental results and expertise derived from previous researches were taken into account. Therefore, the final selected criteria are the following:





Presence of public and para-public buildings: weight 33.3%; Energy carrier typology: weight 23.3%; Heating need density: weight 23.3%; Contiguity with other areas with high heating need density: 10%;
Presence of natural gas network: 10%. Taking into account the aims of the work, the percentages defined above result from a careful discussion between the involved experts (authors; working groups in which the authors are involved; Ticino's Cantonal Authorities for energy efficiency and local energy companies that demonstrated interest in DHS). Public buildings carry the highest weight for those who intend to invest in the creation of a DH network as they need to know which users could be connected and the possibility of entering into contracts with the owners of public buildings allows greater guarantees in this regard. Once built, the same network may be of interest also for some initially reticent users. Technical literature such as [3,14] were considered regarding parameters and percentages, e.g. thresholds

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Table 7 Selection criteria: score method for defining suitable areas for DHS. Parameter Energy carrier currently adopted for heating

Heating need density

(Heating needs of public and para-public buildings)/(Total heating needs) Contiguity with other areas with high heating need density

Presence of natural gas grid inside the 4 ha parcel a

Score for DHS suitability Oil Natural gas Electricity (direct electric systems)a Wood Electricity (HP) Others Unknown <150 MWh/ha per year 150 - 300 MWh/ha per year >300 MWh/ha per year 0e0.25 0.25e0.5 0.5e1 No adjacent parcel with heating need density > 300 MWh/ha per year 1 or 2 adjacent parcels with heating need density > 300 MWh/ha per year 3 or more adjacent parcel with heating need density > 300 MWh/ha per year Yes No

10/10 10/10 4/10 4/10 8/10 6/10 6/10 3/10 6/10 10/10 3/10 6/10 10/10 0/10 5/10 10/10 5/10 10/10

Because, since these systems do not have distribution components, it is very difficult that their users could be interested in DHS connection.

Table 8 Procedure followed for each parcel for defining suitable areas for DHS for buildings that remain after the application of criteria of exclusion. Parameter

score range

weight

Energy carrier typology Heating need density Presence of public and para-public buildings Contiguity with other areas with high heating need density Presence of natural gas network Final score

4 3 3 0 5

e e e e e

adopted for the heating need density and for the contiguity (Table 7). For each parameter involved in the multi-criteria evaluation, a system of scores was considered, as described in Table 7. If the final score is at least equal or greater than 5, the parcel is considered suitable for DHS. The overall procedure is schematized in Table 8 and a map was provided by GIS, as described in section 5. Moreover, the reliability of the overall procedure of evaluation has been verified based on the information on the already completed district heating networks, confirming the robustness of the method (section 5.1). 5. Results: GIS representation of the heating need density The procedure of data collection and elaboration aimed at mapping the density of the heating needs, described in Fig. 3, and the application of the criteria aimed at finding the most suitable areas for developing DH networks, described in section 4 and subsections, were concluded providing several GIS maps such as, for example, those reported in Fig. 4 and Fig. 5. Additionally, according to the final score assignation (Table 8), a summary map (Fig. 6) was developed taking into account all the available information, the criteria defined etc. This map, based on the consultation of several databases, offices and entities and through a complex phase of data elaboration and verification, represents an innovative and useful tool for all the stakeholders involved in the decision process related to energy planning aimed at verifying the preliminary conditions to initiate further investigations, in the framework of proper technoeconomic feasibility studies of DSH.

weighted score range 10 10 10 10 10

23.3% 23.3% 33.3% 10% 10%

0.9 0.7 1.0 0 0.5 3

e e e e e

2.3 2.3 3.3 1,0 1,0 10

As main findings, about 17% of the global heat needs in Canton Ticino (i.e. 8185 buildings) could be theoretically satisfied by DHS. Another finding is that about 18% of the urbanized territory presents a good level of suitability to DHS (i.e. including the parcels with weighed scores equal or greater than 7, according to Table 9).

5.1. Validation based on DHS in operation In order to be more complete and to verify the reliability of the obtained levels of suitability, a validation phase has been carried out by comparing, in the same territory, the obtained results to the DH network in operation.10 Their main thermal power is in the range 0.2e4 MW, while their total thermal power (with back up) is in the range 0.7e8 MW and the length of the network is in the range 0.2e6 km. The areas involved were divided in 4 ha parcels with at least one building connected to a DH network.11 In the comparison, a score defined on the level of suitability to DHS was assigned to each 4 ha parcel belonging to existing DH networks, as reported in Fig. 7. It is possible to observe that 80% of the areas with buildings connected to DHS in operation in Canton Ticino present a proper level of suitability to DHS on the basis of the method here proposed (according to Table 8, weighed scores equal or greater than 5 were

10

A brief description of the District heating database is reported in section 3.2. In this activity, a particular DHS located in the zone of Bellinzona was excluded because of its peculiarity, since it was developed in order to exploit heat available from the local waste thermal treatment plant. 11

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Fig. 3. Scheme of the work aimed at mapping the heat need density.

Fig. 4. Example of GIS map. Heating need density (all the buildings included) with a resolution of 4 ha.

selected for defining the parcels suitable for DHS). Moreover, as reported in Fig. 6, based on the analysis carried out, it is evident that there are far fewer networks in operation than those that are potentially suitable for DHS.

Since this type of validation can support the overall reliability of the method here presented, the level of potential suitability for DHS was elaborated and mapped for the entire territory of Canton Ticino. Again, scores equal or greater than 5 were selected for

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Fig. 5. A focus on the areas around the municipalities of Lugano-Mendrisio (left) and Locarno-Bellinzona (right) considering heating need density for all the buildings (above) and only for public and para-public buildings (below). Resolution by parcels of 4 ha.

defining the parcels suitable for DHS. In addition, a qualitative judgement was associated to the score: fairly good if the level of suitability for DHS of the parcel is from 5 to 7; good if the level of suitability for DHS of the parcel is from 7 to 9; very good if the level of suitability for DHS of the parcel is from 9 to 10. Results of this evaluation are reported in Table 9.

economic evaluations. In fact, the possibility to exploit local and accessible energy sources implies very often the availability of primary energy sources that are less expensive than fossil fuels, resulting in an improvement of the cost effectiveness of the hypothetical DHS. Therefore, the renewable potential of local renewable sources suitable for thermal purposes was elaborated and mapped for the territory of Canton Ticino (Fig. 8). The following sources were considered in detail:

5.2. Availability of proper local renewable energy sources for DHS Based on the technologies description of section 2, results of the application of the method reported in section 4.3 were compared to the estimation of the availability of local renewable sources suitable for thermal purposes. This issue is very important not only for environmental and energy assessments (i.e. sustainable energy planning, optimal matching of local energy demand and supply, achievement of goals in terms of de-carbonization), but also for


Wood biomass (information derived from the Swiss National Forest Inventory [33]);
Organic waste (information derived from the Plan of Waste Management of Canton Ticino [34]);
Heat from water surfaces (information derived from the GIS of Lakes of Canton Ticino [35]);

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Fig. 6. Areas potentially suitable for DHS in Canton Ticino, with a resolution of 4 ha (in green DHS in operation). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Table 9 Distribution of the parcels of Canton Ticino based on level of potential suitability for DHS (scores from 5 to 10). Level of suitability for DH

Judgment of suitability for DH

Surfaces, ha

Percentage on the total suitable surfaces, %

5e7 7e9 9e10

Fairly good Good Very good

11,480 2176 156

83% 16% 1%


Heat from wastewater (information derived from the Plan of Waste Management of Canton Ticino [36]);
Waste heat (with particular regard to the most important industries, information derived from the Energy Directorial Plan of Canton Ticino [37]);
Heat from underground water (information derived from the Database of Wells and Springs of Canton Ticino [38]). The results of this analysis were then overlapped with the 6400 ha of the territory selected as potentially interesting for the realization of DH networks (parcels with value of suitability equal or greater than 5, as reported in Tables 8 and 9). This map, derived from a deep knowledge of the territory achieved by the consultation of several databases, offices and entities and by a complex

phase of data elaboration, represent a further innovative and useful tool for all the stakeholders involved in energy planning. The outcomes of this evaluation are described in Table 10, where the fundamental role of wood biomass is evident in the whole territory. Results show that most of the surfaces identified are located in areas where it could be feasible to consider the renewable heat from wastewater and surface water as energy carriers for DH networks, in addition to wood biomass. 6. Discussion and conclusions In recent years, district heating technology has been diffused in Canton Ticino. However, our estimations demonstrate that there is still an interesting potential of development, involving an

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Fig. 7. Graph of the areas with buildings connected to DHS in operation ordered by level of suitability to DHS on the basis of the method here proposed (score 9 means the most suitable areas and score 1 means the less suitable areas).

Fig. 8. Map of the renewable sources available for thermal purposes in Canton Ticino.

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L. Pampuri et al. / Energy xxx (xxxx) xxx Table 10 Presence of thermal renewable energy sources in relation to the parcels of Canton Ticino suitable for DHS. Energy carrier

Surface, ha

Wood biomass Organic waste Heat from water surfaces b Heat from waste-water b Waste heat Heat from ground water b

6400 152 1028 1448 272 180

a

a Wood biomass availability on the 6400 ha is distributed as follows: 8% from 33 to 50 GWh/y of useful heat; 62% from 51 to 100 GWh/y; 16% from 101 to 150 GWh/y; 14% from 151 to 200 GWh/y. b For heat pumps operation.

appreciable part of the whole territory. As a theoretical potential, DHS could supply up to the 17% of heating needs in buildings (for space heating and DHW), against the current supply that is lower than 0.2%. We are aware about the complexity related to the implementation of DH networks because of the great investment needed, because of the evident interventions on the territory and, according to investigations carried out about by the authors and local stakeholders, because of the difficulty in convincing potential users. In order to overcome these barriers, the main purpose of this project was the development of a clear and replicable method to support the identification of areas that, based on the proposed method, result suitable for the development of district heating networks, placing particular focus on the possibility of connecting public and para-public buildings. The developed procedure starts from the data available in different entities and offices and benefits from the long-held expertise and knowledge of the territory by the authors. Results have been verified confirming the reliability of the overall procedure and the hypothesis supporting the multi-criteria approach followed. The possibility of referring to an analytic approach could contribute overcoming some subjective barriers, which affect in particular the social acceptability of DHS, such as those referable to the so-called NYMBY syndrome or other distrusts. Even if the final decision about DHS very often belongs mainly to policy and governance issues, the same analytic approach could help in orienting investments towards cost-effectiveness, giving priority to areas actually suitable for DHS. The method and the achievable results can be of evident interest for public entities, energy companies, consultants and other stakeholders involved in the refurbishment of the built environment and in the realization of important territorial infrastructures. The main innovation is related to the GIS application that allows a useful cartographic support, including the geographic representation of all the involved parameters. However, some weaknesses could be identified and referred to further developments of this work. E.g., in addition to the comparison to the technical literature, to the validation (section 5.1) on existing DHS and to the expertise of the local operators, a detailed sensitivity analysis of criteria and weighting factors (section 4.3) will be added in the next developments of the work. Additionally, the results obtained are to be considered indicative, since a case-specific feasibility study will always remain an indispensable element for assessing the effective suitability of the areas identified. The feasibility studies and in particular the evaluation of the cost effectiveness could make the technical potential (i.e. theoretical potential that is technically feasible on the basis of the local conditions) and economic potential (i.e. technical potential that is economically exploitable) much less than the theoretical 17%. This further analysis should also involve a more systematic determination of the willingness of public entities and privates to be connected to DHS. However, considering the current regulative

and supporting framework in force, the state of the Cantonal built environment and the interest demonstrated by local stakeholders, we would expect that a consistent part of the theoretical potential could be sustainable. Furthermore, the analysis of local renewable sources shows an interesting potential for heating from wastewater and surface water as energy carriers for DH networks in addition to the widespread wood biomass. This result allows the combination of different technologies (e.g. biomass combustion and HP) that can be matched based on buildings’ features and local conditions. However, this analysis provides general information, in a regional perspective, about the various possibilities of exploitation of local renewable energy carriers for district heating networks. When studying a specific case, these general results could lose their validity, leaving space to more in-depth and coherent analysis focusing on the particularities of a smaller scale of operation (i.e. district). In this sense, some municipalities have already started proper analysis of their territory, through the development of the Cantonal Energy Plan. Despite these weaknesses, the method here presented could contribute in promoting interesting investments in the territories for DH, with beneficial synergies and cascade effects: the establishment of innovative funding mechanisms, as discussed also in Ref. [39]; improvements in environmental protection of forests and water; the development of underground networks for ICT (e.g. broadband connections); the de-carbonization of the thermal final uses; the exploitation of local sources otherwise wasted; technological innovations in research and industry sectors toward smart systems, as described also in other research such as [14]. Acknowledgements This research was supported by Ticino's Cantonal Authorities for energy efficiency. We also would like to acknowledge the following institutions for their support and for suppling valuable data and databases: the Cantonal Land Register Office, the Logistic Section of the Department of Finance and Economy of Canton Ticino, the Federal Office of Energy as well as the Energo Association. Special thanks to all the colleagues that have supported us during the whole project. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.energy.2019.116297. References [1] http://www.bfe.admin.ch/energiestrategie2050. available also in English, last access march 2019. [2] Pampuri L, Cereghetti N, Galbani Bianchi P, Caputo P. Evaluation of the space heating need in residential buildings at territorial scale: the case of Canton Ticino (CH). Energy Build 2017;148:218e27. [3] Chambers J, Narula K, Sulzer M, Patel MK. Mapping district heating potential under evolving thermal demand scenarios and technologies: a case study for Switzerland. Energy 2019;176:682e92. € ller B, [4] Mathiesen BV, Lund H, Connolly D, Wenzel H, Østergaard PA, Mo Nielsen S, Ridjan I, Karnøe P, Sperling K, Hvelplund FK. Smart Energy Systems for coherent 100% renewable energy and transport solutions. Appl Energy 2015;145:139e54. € ller B, Persson U, Boermans T, [5] Connolly D, Lund H, Mathiesen BV, Werner S, Mo Trier D, Østergaard & PA, Nielsen S. Heat Roadmap Europe: combining district heating with heat savings to decarbonise the EU energy system. Energy Policy 2014;65:475e89. [6] EU. Commission staff working document on an EU strategy for heating and cooling. 1689e99, ; 2016. [7] International Renewable Energy Agency. IRENA, renewable energy in district heating and cooling: a sector roadmap for REmap. 2017. http://www.irena. org/-/media/Files/IRENA/Agency/Publication/2017/Mar/IRENA_REmap_DHC_ Report_2017.pdf.

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Please cite this article as: Pampuri L et al., A method for mapping areas potentially suitable for district heating systems. An application to Canton Ticino (Switzerland), Energy, https://doi.org/10.1016/j.energy.2019.116297