Electricity and district heating are the most important energy carriers for the residential and service sector in Sweden. Today, district heating supplies about half of the total heating requirement of residential and commercial premises in Sweden. The aim of this paper is the analysis of the heating system of a school, placed in Gävle, Sweden. The heat is delivered to the school by a district heating network. First of all, the Heat Balance must be done, with the purpose of obtain the best knowledge of the present situation in the school. The calculations about the transmission and ventilation losses and the internal heating generated have been showed. After this, the point of view has been focused on the district heating system itself. It is means, the distribution pipe system inside the school. The efficiency and accuracy of the net will be analysed and discussed. Three possible ways to improve the net will be showed. The first of all is the most simple: just take the pipe system and try to reduce the waste heat, the heat losses; the second choice is to make a new connection to the district heating network, joining all the buildings with one connection for each building –five more- instead of only the connection that exists at the moment when this paper was written; the third option seems as a different model of the second, it is means to divide all the school in two bigger parts and make another connection to the district heating network with the purpose of dividing the heating system in two equal parts. Thanks to the heat balance done in the school and in the district heating system, it is possible to know the waste of heat. Mainly, these losses are found in the district heating net. The amount of waste is around 17%, a really high amount of energy wasted, which must be reduced. According to the data of the company Gävle Energy, the waste in old buildings like the school which is under study in this paper, usually is between 15% and 20% of the supplied energy. So, this showed the accuracy of the method used to make this paper. According to the possibilities of improvement, it will depend on the ultimate decision of the Gävle Fastigheter, company which owns the school, to choose the way that could be better for their own interest. However, in this paper the prices and possible pay-back times are showed, in order to provide better information. Although the best solution has a total cost of 1750000 Swedish crowns (186289 €) and a pay-back time of 21 years –talking about making five new connections-, another cheaper possibility is also commented: improving the isolation of the pipe system, with a cost of 549000 SEK (58441 €) and a pay-back time near 7 years.

A city’s characteristics of mixed-use zoning, diverse built form, high-density development, and residual heat generation by urban processes, present potential for optimizing the thermal energy end-use of certain waste streams. A method was developed to identify sources of waste thermal energy and heat demand clusters in a mixed-use jurisdiction and design a preliminary primary network of a district heating system based on these waste heat sources. The method applies systems analysis, energy potential mapping (GIS spatial analysis) and network optimization (linear programming) techniques. The method is implemented using a case study of data for peninsular Halifax. Finally, the method and implementation’s influence on climate change (i.e. a reduction in GHG emissions) and energy security, two central themes of this research, are discussed.

The demand for environmental assessments on buildings and energy consumption is increasing as well as the energy performance requirements for buildings. At the same time it is increasingly common with self-producers of heat and electricity generation. The main purpose with this master thesis is to investigate how time resolution affects the environmental assessment of energy consumption in office buildings connected to district heating (DH). Environmental assessments were done with both attributional LCA and consequential LCA with system expansion. Fortum´s DH system in Stockholm was analyzed and district heating production was simulated in a Matlab-model. Greenhouse gas (GHG) emissions for the production were calculated. The heat demand of the office Gångaren 16 in Stockholm was simulated in IDA ICE. Thereafter the environmental impact in terms of GHG emissions was calculated with data from the assessment of the DH production. The results show that the highest time resolution that should be used for environmental assessment of energy consumption in buildings connected to DH is daily average values, regardless of LCA perspective. Moreover, sufficient results are achieved with yearly average values with attributional LCA. The results for consequential LCA with system expansion show that daily and yearly average values are not sufficient. Since peak production is temperature dependent rather than time dependent it is recommended that DH peak production is environmental assessed by temperature in future work.

As a part of Fortum's vision of a future Solar Economy, a feasibility study of a Solar District Heating facility was conducted. The focus of this study was to determine the technical, economic and environmental potential of a Solar District Heating facility, combined with a seasonal thermal storage, in the district heating network in Stockholm. Three different cases have been studied. The cases differ on the size of the available land area, on what type of storage technology utilized and if excess heat from different production facilities in the network is included or not. The results indicate that it is technically possible to implement a Solar District Heating facility in Stockholm, no obvious limitations in the network has been identified. The thermal storage should preferably be charged throughout the year and be discharged during December to March. The economic results indicate that none of the studied cases are economically feasible without any subsidies, increased revenues or other reductions of initial investment costs. The most economically beneficial system configuration was to utilize a smaller land area for solar collector installations, include excess heat from local production facilities and to utilize existing rock caverns and infrastructure in the area. The Solar District Heating facility could decrease the climate impact and the net primary energy use compared to the production of a biofuel production facility, but a further study is needed.

With development within district heating leading to more incorporation of decentralized production, lowered temperature levels are required to enable these possibilities. Therefore, this study was conducted in collaboration with Fortum with the purpose of investigating and quantifying the effects of lowered delivery temperatures on mass flow and return temperatures. When these effects had been determined, the limiting factors were identified as well as the adjustments needed to enable the lowering delivery temperatures. This study is divided into two sections: a modeling of four type buildings and two case studies of specific areas of the Stockholm district-heating grid. The two sections of the study both use an Excel constructed model to examine the effects of the new proposed delivery temperature levels. The first section uses four type buildings with varying internal temperature levels to display how different secondary systems react to the changes in delivery temperature. The second section contains two case studies of outer parts of the grid where actual buildings are modeled. In the case studies the pipes speeds and secondary systems are analyzed to determine limiting factors for the lowering of the delivery temperatures. Overall this study contributes with quantified results of the effects of four lowered delivery temperature profiles on different customer systems. Analysis of the delivery temperatures showed that the largest change was shifting from the actual delivery temperatures of 2011 to the delivery profile that Fortum currently promised to deliver. The pipes of the studied areas were found not to be a limiting factor even in cases where the when mass flows increased three fold. The greatest limiting factor was determined to be the internal temperatures of the buildings, which set a strict limit and cannot be altered by Fortum without the customers’ cooperation. In conclusion a range of limiting factors were identified that proved to be potential limitations depending on the circumstances of a specific case. Depending on the investment needs in a specific case the economic viability was deemed to most likely be positive. When implementing lowered delivery temperatures in reality it is vital to acquiring data on secondary systems in order to identify the specific limitations of the proposed area. In addition an area of more research on the effects of lowered temperatures on the entirety of the grid as this study only investigates isolated sections.

Thermal energy storage (TES) systems are technologies with the potential to enhance the efficiency and the flexibility of the coming 4th generation low temperature district heating (LTDH). Their integration would enable the creation of smarter, more efficient networks, benefiting both the utilities and the end consumers. This study aims at developing a comparative assessment of TES systems, both latent and sensible heat based. First, a techno-economic analysis of several TES systems is conducted to evaluate their suitability to be integrated into LTDH. Then, potential scenarios of TES integration are proposed and analysed in a case study of an active LTDH network. This is complemented with a review of current DH legislation focused on the Swedish case, with the aim of taking into consideration the present situation, and changes that may support some technologies over others. The results of the analysis show that sensible heat storage is still preferred to latent heat when coupled with LTDH: the cost per kWh stored is still 15% higher, at least, for latent heat in systems below 5MWh of storage size; though, they require just half of the volume. However, it is expected that the cost of latent heat storage systems will decline in the future, making them more competitive. From a system perspective, the introduction of TES systems into the network results in an increase in flexibility leading to lower heat production costs by load shifting. It is achieved by running the production units with lower marginal heat production costs for longer periods and with higher efficiency, and thus reducing the operating hours of the other more expensive operating units during peak load conditions. In the case study, savings in the magnitude of 0.5k EUR/year are achieved through this operational strategy, with an investment cost of 2k EUR to purchase a water tank. These results may also be extended to the case when heat generation is replaced by renewable, intermittent energy sources; thus increasing profits, reducing fuel consumption, and consequently emissions. This study represents a step forward in the development of a more efficient DH system through the integration of TES, which will play a crucial role in future smart energy system. / Thermal energy storage (TES) eller Termisk energilagring är en teknologi med potentialen att öka effektivitet och flexibilitet i den kommande fjärde generationens fjärrvärme (LTDH). Studien har som mål att kartlägga en komparativ uppskattning av TES systemen, baserad både på latent och sensibel värme. Resultaten visar att lagring av sensibel värme är att föredra före latent värme när den kopplas med LTDH: pris per lagrade kWh kvarstår som 15% högre än för latent värme i system under 5 MWh av lagringsutrymme; dock fordrar de endast hälften av volymen. Utifrån systemperspektiv innebär introduktionen av TES system i nätverket en ökning av flexibilitet vilket leder till reducerade värmeproduktionskostnaderna i mindre belastning. I fallstudien nås en sparnivå av femhundra euro per år genom denna operativa strategi, med en investering av 2000 euro för inköp av vattentank. Resultaten kan också vidgas till en situation där värmeproduktionen ersätts av förnybara, intermittenta energikällor; till detta medföljer högre vinster, lägre bruk av bränsle vilket skulle innebära lägre utsläpp. Studien kan ses som ett steg framåt mot skapandet av en mer effektiv DH system genom integrationen av TES, vilket kommer att spela en betydande roll i framtida smarta energisystem.

District heating is the most common source of heating in Sweden and has played a crucial part in the country’s substantial reductions of carbon dioxide emissions. This recycling technology is ideal in order to use thermal energy as efficiently as possible and makes the goals set for a sustainable future more achievable. The future potential of this technology is therefore huge. Today, a lot of the district heating systems have installed heat storages in order to improve the systems reliability and performance. These heat storages have the potential to be utilized even further in the future by acting as a balancing power for the power grid. However, there is currently no data available regarding the storage capacity available in the district heating systems. This thesis therefore seeks to quantify the installed storage capacity in Swedish district heating systems. The data gathered regarding this can then be utilized in research regarding potential future applications of heat storages, such as balancing the power grid. All collected data regarding heat storage capacity has also been analyzed in an effort to find any correlations between the relative storage capacity and the size, energy sources, customer prices and operational costs of each investigated system. This analysis has concluded that most of the district heating systems in Sweden have installed storage capacity and that it is more commonly used in larger systems. It is also concluded that most of the installed storage capacity is used to counteract daily heat load variations. The heat storages influence district heating systems by reducing their operational costs as well. / Den vanligaste formen av uppvärmning i Sverige är fjärrvärme. Sverige har minskat landets utsläpp av koldioxid kraftigt det senaste årtiondet och fjärrvärmen har bidragit stort till denna bedrift. Denna teknologi är ideal när det gäller att återvinna samt använda värme så effektivt som möjligt. Potentialen för den teknik i framtiden är därför stor. Många fjärrvärmesystem har idag värmelager i systemet för att öka dess effektivitet och pålitlighet. Dessa värmelager kan potentiellt utnyttjas ännu mer i framtiden genom att aggera som balanskraft för elnätet. Det finns dock ingen data tillgänglig gällande lagerkapaciteten som finns tillgänglig i fjärrvärmesystemen i dagsläget. Syftet med detta examensarbete är därför att kvantifiera och analysera den installerade lagerkapaciteten i Sveriges fjärrvärmesystem. Den insamlade datan kan sedan användas i studier för framtida applikationer för värmelager, så som att agera som balanskraft för elnätet. All insamlad informationen om värmelagernas kapacitet har även analyserats för att hitta samband mellan den relativa lagerkapaciteten för varje fjärrvärmesystem och dess storlek, energikällor, kundpriser samt driftkostnader. Slutsatser som har dragits från denna analys är att de flesta fjärrvämesystemen i Sverige har värmelager installerade, samt att värmelager är vanligare i större fjärrvärmesystem. De flesta värmelagren används till att balansera daliga variationer i värmelasten och värmelager sänker även driftkostnaderna för fjärrvärmesystemen.

There is currently an ongoing urban transformation in a small Swedish town named Kiruna, it is located in the very north of Sweden well above the Arctic Circle in a sub-arctic climate. Large part of the town will be relocated due to the ground deformation that is caused by the progressing iron ore mining activity and it is affecting all infrastructures of the town. This thesis aims to accomplish a holistic analysis on the district heating (DH) system for the town of Kiruna and its future challenges. Energy companies with a DH system recognize the importance in having a good understanding about the network characteristics, for obtaining an efficient and stabile heat delivery to the end-users. In this thesis, a method for modeling and simulation of meshed DH networks is described, that makes it possible to study and analyze the flow pattern in order to locate non-obvious paths, bottlenecks and overloaded pipes. For carrying out the DH simulations a fundamental input is to set the thermal losses for each pipe segment in the model, a fictitious series with all pipe diameters is created which corresponds to the annual losses in the real network. In comparison with the pipes series manufactured today the created one is best described by the series with least insulation and highest thermal losses. The studied network has its origin in the 60th and is the sum of the different piping technics that has been valid over time, this mixture is positioning the thermal performance as a close to a worst-case scenario. To the meshed DH network a number of heat production sites are connected for delivering the thermal requested by the end-users, each site consisting of several boilers and using different resources. A hybrid evolutionary-Mixed Integer Linear Programing (MILP) optimization approach is developed and applied for finding the cost-optimal heat production for three scenarios in combination of two heating demand levels. It is stated that no matter the geographically location of the site the cheapest resource should always be favorable as fuel, in the case when the same resource is viable at different sites a differentiated heat production is obtained. The supply temperature from each site is found to be the one lowest possible in order to serve all site-concerned end-users with a temperature level high enough for hot water production. The findings recommend a network temperatures reduction with the consequence in higher cost related to pumping work, but is lower than the savings due to the reduction in thermal losses. In order to provide the relocated part of the town with DH the hybrid evolutionary-MILP optimization routine is reshaped for finding different alternatives for network expansion layouts. The result is presented as a multi objective analysis between the operation cost and installation cost, showing the complete spectra of all optimal possible solutions and how the different cost correlate to each other. In this way, the outcome can be used for support in decision making, helping network owners is their planning and pipe sizing for new areas. For constructing the buildings that will populate the new city-area the Swedish government has stated a number of recommendations for achieving livable thermal indoor climate. An investigation is carried out analyzing the impact from the usage of three different heating system; air/air heat pump, air heating and floor heating in a low energy family house, where the first two system are aimed to use heat from the DH network. The analysis show that only the floor heating system satisfies the recommendations stated, but with carefully planning an air heating system could also fulfill the recommendations. Further, a techno-economical evaluation declares that the cheapest heating cost over 30 years is by using an air/air heat pump. In order to make DH competitive as heating source the needed price reduction is found for the hydronic floor and air heating system. Finally, three different building energy performance scenarios are studied in conjunction with the urban transformation in combination with the suggested energy measures from the Energy Performance certificates (EPC). In order to reach the national target entailing a reduction of 50% until 2050 all re-built buildings have to be built with passive standard and all advised measures in the EPC has to be carried out. Wort noticing is that the scenarios is analyzed as part of a 3-D City Model, which is found to be a worthwhile working tool for staff dealing with energy related issues.

Flygbranschen står idag för 2 % av de globala utsläppen av fossil koldioxid och har som första världsomspännande industri enats om gemensamma globala miljömål för att minska sin klimatpåverkan. Fjärrvärmebranschen står inför tuffa utmaningar då fjärrvärmeunderlaget förutspås minska på sikt. Smart Climate Scandinavian AB:s idé att värma flygplan med fjärrvärme när de står parkerade på backen är världsunik och möter de behov som både fjärrvärme- och flygbranschen har, att hitta nya affärsområden respektive minska sina utsläpp. Syftet med detta examensarbete var att ta fram underlag för utveckling av nästa generations styrsystem för Smart Climates klimataggregat samt undersöka konsekvensen av byte från ett traditionellt aggregat till ett från Smart Climate med hänsyn till energieffektivitet, miljöbelastning och driftkostnad. Mätningar av de termiska egenskaperna hos ett flygplan av typen ATR72-500 genomfördes. Det genomsnittliga U-värdet beräknades till 2,0 W/(m2·K) och värmekapaciteten till 3,421 MJ/kg. Med Excel VBA programmerades en applikation som har använts och kan fortsätta användas som ett verktyg för produktutveckling. Denna applikation beräknar energibehovet för ett flygplan baserat på inställda parametrar, som till exempel utetemperatur och flygplanets termiska egenskaper. Med Excelapplikationen beräknades den potentiella energibesparingen vid införande av nattsänkning, det vill säga tillfälligt sänk temperatur i flygplanet, till ca 30 % av ursprungligt energibehov. En konsekvensanalys av byte från elbaserade aggregat till ett fjärrvärmebaserat aggregat med föreslagen nattsänkning genomfördes. Analysen avgränsar sig till flygplanet som systemgräns och saknar därför en jämförelse av skillnad i förluster som vartdera systemet har. Beräkningarna visar att nattsänkningen innebär en reduktion av det årliga behovet från 25000 kWh till 15500 kWh för en ATR72-500. Traditionella aggregat tillämpar inte denna reglerteknik. Byte av energikälla från el till fjärrvärme innebär en minskning av de globala CO2e-utsläppen med mellan 9000 och 22000 kg per år. Hur stor besparingen i driftkostnad blir beror på rådande energipriser. Vid utveckling av nästa generation styrsystem rekommenderas att nattsänkning införs för Smart Climates aggregat då det visat sig ge stora energibesparingar. Dessutom föreslås styrsystemet vara uppkopplat mot internet för att underlätta framtida reglerjusteringar, datainsamling och produktutveckling. Att styra tillförd effekt på kabintemperaturen har visat sig mer pålitligt än vid styrning med hänsyn endast till utetemperaturen. Framtida studier föreslås fokusera på att utvidga systemgränsen från flygplanet till att ta med energitransportförluster i beräkningarna. Förslagsvis utses en specifik flygplats och systemgränsen sätts vid flygplatsens energimätare för el respektive fjärrvärme. Optimering av glykol/vattenflöde och dimensionering av ledningar, strypventiler och pumpar är intressanta frågeställningar. Frigörande av kapacitet i flygplatsens transformatorstation kan i sig vara en orsak till att välja varmhållning av flygplan med fjärrvärme. Den kanske viktigaste konsekvensen av att ersätta el med fjärrvärme är att högvärdig energi kan användas där den behövs. / The aviation industry today is responsible for 2 % of the fossil carbon dioxide emissions and has, as the first global industry, united around common goals for reducing its effect on climate change. The district heating industry faces tough challenges ahead considering the demand of its primary product is predicted to decrease in the longer run. Smart Climate Scandinavian AB’s idea of heating airplanes parked on ground with district heating unites the needs for both the aviation and district heating industry of reducing emissions and finding new areas of application respectively. The purpose of this thesis is to provide information for development of the next generation Smart Climate air climate unit control system and to study the consequences of changing from a traditional air climate unit to one from Smart Climate, with regard to energy efficiency, environmental impact, and operation cost. The thermal properties of an airplane of the type ATR72-500 where measured. The U-value was calculated to 2,0 W/(m2·K) and the heat capacity to 3,421 MJ/kg. An Excel application was programmed in Excel VBA to be used for product development. The application calculates the energy demand of an airplane based on settings such as outside temperature and the airplane’s thermal properties. The potential energy savings of introducing night time reduction, which is temporarily reducing the temperature in the airplane, is calculated to about 30 % of the initial energy demand. A consequence analysis of changing from a traditional electricity based air climate unit to one based on district heating with the proposed night time reduction was performed. The analysis was limited to the airplane as the system boundary and hence does not include energy losses which both systems have. The night time reduction is not implemented in traditional air climate units and hence the demand in energy is calculated to decrease from 25000 kWh to 15500 kWh per year for an ATR72-500. Changing energy source from electricity to district heating results in a reduced emission of CO2e of somewhere between 9000 and 22000 kg per year. How big the saving in operation cost will be depends on the energy prices for electricity and district heating. An introduction of night time reduction is recommended in the next generation control system of Smart Climate’s air climate unit since it evidently comes with great energy savings. It is also proposed that the next generation is wired up online on the internet. This will facilitate future setting adjustments, data gathering and product development. Also validated during the study is that the technique of regulating the temperature of inlet air by measuring the cabin temperature is more reliable than the traditional technique of using the outside temperature. It is suggested for future studies to include energy transport losses and hence should focus on one airport with well-defined system boundaries. A suggestion is using the same boundary as the energy meters of the airport. Optimizing glycol/water flow and dimensioning of pipes, valves and pumps are interesting issues to investigate. A reduced electricity demand will decrease the needed capacity of the transformer station and could give reason for considering heating airplanes with district heating. Perhaps the most important consequence of replacing electricity with district heating is that primary energy can be used where it is needed.

District heating systems can contribute to reducing the UK's CO2 emissions. This thesis investigates the operational performance of current district heating (DH) systems with the existing and a possible future energy sector. The main contributions to knowledge are:  Operational, financial and exergy performance assessments of three functioning DH systems and one decentralised energy (DE) technology  A methodology to optimise a DH system in a resource efficient and cost effective way The aims of DH systems are to provide heat, reduce CO2 emissions, ensure energy security by operating in a resource efficient way and to tackle fuel poverty. However, the case studies in this project confirm that DH systems operate poorly in the UK. This is largely because of the heat losses from the DH network to the soil being high and the plant operation being suboptimal. Four case studies were analysed. The 785 room Strand Palace hotel has two 250 kWe combined heat and power (CHP) engines set to modulate following the hotel's electricity consumption and providing approximately 90% of this annual demand. It was found that the CHP engines never operate at full load throughout a full day, firstly because the plant cannot export electricity to the grid and secondly the system is not fitted with a thermal store. Financial analysis revealed that the hotel does not reduce its heating cost by operating the CHP engines, but that the energy service company (ESCo) makes £77,000 net operating income per year. Elmswell in Suffolk (UK) is a low heat density DH system that generates heat with a 2008 biomass boiler and pumps it to 26 terraced and semi-detached dwellings. It was found that 39% of its heat is lost to the soil and that the natural gas boiler generates 45% of the heating load and operates with a seasonal efficiency of 65%. The heat losses to the soil for this system were compared to a DH system of higher heat density, Loughborough University, with a lower heat loss of 22% to the soil. In August 2011, Loughborough University installed a 1.6 MWe CHP engine to operate with four 3 MWth natural gas boilers to supply heat to its DH network. A study undertaken demonstrated that by adding a 2 MWe CHP engine with a thermal storage instead of a 1.6 MWe CHP engine on its own could further increase the CO2 emissions savings from 8% to 12.4%. The energy centre at Pimlico District Heating Undertaking (PDHU) includes a gas fired cogeneration plant that supplies heat to 3 schools, 3,256 dwellings and 55 commercial units. It also benefits from a 2,500 m3 thermal store. Every component of PDHU was investigated in detail and its current operation was optimised and compared to a selection of new operating scenarios. It was found that: i) The thermal store operated with 93% thermal efficiency and was not used to reduce the energy consumption or to enable more cogeneration, ii) The CHP engines were undersized and generated only 18% of the required heat in 2012, iii) The boilers modulate and £ 70,000 could be saved per year by setting them to operate at full load by making use of the thermal store, iv) By installing an open-loop heat pump using the river Thames, PDHU could then guarantee to comply with current and likely future policies impacts by setting the energy plant to operate in CHP mode or as an electricity consumer at defined times to benefit from low energy utility costs and to minimise CO2 emissions. A comparison of selected performance metrics was then undertaken and it was found that none of the three DH systems operate in a resource efficient way and that the heating cost could be reduced further by optimising the operation of the systems. To do this, a new optimisation methodology is proposed by maximising their exergy efficiency in addition to maximising their overall energy efficiency and CO2 emissions reduction.