Low energy buildings

which treated the first 3 years measurements. The report begins with a brief description of the low-energy house and the reference simulation used for evaluation / comparison of the estimated annual heat consumption. The report also presents measured results from the house. It should be noted that only one half of the house is inhabited (2-3 adults, South-western apartment), so detailed analysis of low-energy house performance cannot be directly compared with the previous year's polls. The other part of house (North-eastern apartment) is used occasionally as a guest house. This report is based on previous three annual reports made by Jesper Kragh. The report language is English.

Tout d'abord, je tiens à remercier l'ensemble des membres du jury et en particulier messieurs Alain BASTIDE et Benoit DELINCHANT qui ont bien accepté de rapporter ce mémoire afin de lui apporter l'accréditation de la communauté scientifique. Je tiens à adresser ma très vive gratitude à mon encadrant de thèse, Monsieur Laurent MORA, pour la confiance et le soutien qu'il m'a accordé tout au long de ce travail. Son aide et ses précieux conseils ont contribué fortement à la bonne réalisation de ce travail. J'adresse également mes plus vifs remerciements à ma directrice de thèse Mme Elena PALOMO DEL BARRIO pour ses remarques intéressantes qui ont contribué à faire avancer et améliorer ce travail. Milles merci à mes amis et mes collègues du labo qui m'ont partagé mes moments toujours conviviaux durant cette thèse. Sans que la liste soit exhaustive, je remercie Léa SAMARJI, Mathieu DHAYBI, Vladimir CANSECO, Nisrine SEFRIOUI, Audrey DUPHIL, Cécile Gaborieau et Stéphanie BONTEMPS. Un grand merci à mon cher mari Ayman pour son soutien et sa confiance en moi. Pour finir, je tiens à remercier ma mère, qui grâce à elle je suis Docteur aujourd'hui, mon père et mes soeurs qui m'ont apporté et m'apporteront le soutien de tout genre. Il s'en passe des choses pendant trois ans avec un bon nombre de personnes diverses et variées. Pour ne pas commettre d'impaire, je vais me permettre d'esquiver la difficulté en remerciant toutes les personnes qui ont contribuées de près ou de loin à mes travaux. J'espère qu'elles se reconnaitront. i Résumé La conception des bâtiments à faible consommation d'énergie est devenue un enjeu très important dans le but de réduire la consommation d'énergie et les émissions de gaz à effet de serre associées. Pour y parvenir, il est indispensable de connaître les sources potentielles de biais et d'incertitude dans le domaine de la modélisation thermique des bâtiments d'une part, et de les caractériser et les évaluer d'autre part. Pour répondre aux exigences courantes en termes de fiabilité des prévisions du comportement thermique des bâtiments, nous avons essayé dans le cadre de cette thèse de quantifier les incertitudes liés à des paramètres influents, de proposer une technique de diagnostic de l'enveloppe, de propager les incertitudes via une méthode ensembliste sur un modèle simplifié et enfin de proposer une démarche permettant d'identifier les paramètres de modélisation les plus influents et d'évaluer leur effet sur les performances énergétiques avec le moindre coût en termes de simulations.

This editorial in Renewable and Sustainable Energy Reviews (RSER) is a virtual special issue (VSI) dedicated to the three conferences on Sustainable Development of Energy, Water and Environment Systems (SDEWES) held in 2018. These included the 13th SDEWES Conference (30 September to the 4 October in Palermo, Italy), the 3rd

Actions Towards Sustainable Outcomes Environmental Issues/Principal Impacts • Energy used for space heating and cooling in homes creates high levels of greenhouse gases. • The cost of this energy creates a financial burden for home occupants. • In a dry temperate climate such as that in Perth, both of these negative impacts can be greatly reduced with negligible impost on building cost or lifestyle through the use of simple climatically sensitive and user friendly designs. • Passive designed buildings exemplify the importance of occupant involvement in maintaining indoor thermal comfort. • Town planning decisions can have an important impact on energy efficient design, particularly solar access to windows, and solar collectors.

The paper presents a novel demand-responsive control strategy to be equipped centrally at the district level for district heating systems. The demand-responsive feature was maintained as to both the direct and the indirect substation configurations (by basing on their rating measures) in order to achieve lowest possible return temperature degrees from the end-user substations. Different than the traditional weather-compensation based supply temperature resetting, the new control strategy was formulated to adjust the supply temperature at the district level as to the cooling performance at the end-user substations. Two different simulations were carried out in order to quantify the benefits of the novel control strategy as compared to the traditional weather-compensation, equipped both at the substation level and the district level. The results obtained showed that the new control strategy, when considering the electricity loss at the heat production plant, shows superiority when compared to other control strategies.

This paper illustrates how the choice of indicators changes the design of a waste heat recovery system in district heating. A prospective system in Grenoble (France) aims to valorize waste heat from the French National Laboratory of Intense Magnetic Fields (LNCMI) by injecting it at 85 °C to the nearby district heating network. We optimize its design for three possible waste heat temperatures: 35 °C (current), 50 °C (viable) and 85 °C (innovative). As major components, the system includes a thermal storage (ranging from 10 MWh to 40 MWh) and may include a heat pump depending on the waste heat's temperature. Different optimizations are guided by two energetic indicators (one source-oriented, the other demand-oriented) and by the overall exergy efficiency. The system's annual performance is assessed through the Sankey and Grassman diagrams and compared between optimal designs. Yearly simulation included optimal management of the thermal storage, through mixedinteger linear programming. The demand-oriented optimal design suggests recovering waste heat at 35 °C with a heat pump and a 40-MWh storage, granting the highest coverage of residential needs (49 %). On the other hand, the source-oriented optimal design suggests recovering waste heat at 85 °C without heat pump and with a 40-MWh storage, reaching the highest recovery of waste heat (55 %). Exergy analysis supports the source-oriented design, as it reaches the highest global exergy efficiency (27 %). Our prospective techno-economic and exergoeconomic analyses should complement these results and may change some conclusions, especially regarding the storage capacity.

This report is one of the outcomes of the work within CoNZEBs. CoNZEBs is an EU Horizon 2020 project on the topic 'Cost reduction of new Nearly Zero-Energy Buildings' (call H2020-EE-2016-CSA, topic EE-13-2016). As such it receives co-funding by the European Union under the Grant Agreement No. 750046. The project period is from 01/06/17 to 30/11/19. The planned work can be summarised as follows: CoNZEBs identifies and assesses technology solution sets that lead to significant cost reductions of new Nearly Zero-Energy Buildings. The focus of the project is on multi-family houses. Close cooperation with housing associations allows for an intensive interaction with stakeholders and tenants. The project starts by setting baseline costs for conventional new buildings, currently available NZEBs and buildings that go beyond the NZEB level based on the experience of the consortium. It analyses planning and construction processes to identify possible cost reductions. An investigation of end-users' experiences and expectations together with a guide on co-benefits of NZEBs promotes living in these buildings and enhances the energy performance by conducive user behaviour. The technology solution sets include approaches that can reduce costs for installations or generation systems, pre-fabrication and construction acceleration, local low temperature district heating including RES, and many more. All solution sets are assessed regarding cost savings, energy performance and applicability in multi-family houses. A life cycle assessment of different building levels and NZEBs using the solution sets provides a longer term perspective. Communication to stakeholders and dissemination of the project results includes events and discussions with the national housing associations. EU H2020 754046 CoNZEBs D2.1: Overview of Cost Baselines for three Building Levels 6 EU H2020 754046 CoNZEBs D2.1: Overview of Cost Baselines for three Building Levels 7

The paper presents the findings on end-users' experiences and expectations about living in multi-family Nearly Zero-Energy Buildings (NZEBs). The survey in four European countries (Slovenia, Italy, Denmark and Germany) was part of EU Horizon 2020 project CoNZEBs (2017-2019) and addressed end-users living or thinking about living in multi-family NZEBs. Targeted end-users were living (as tenants or owners) in either ordinary buildings or in high performance buildings such as NZEBs (mandatory after 2020 according to Directive 2010/31/EU). In the survey, the following topics were addressed: the level of end-user's understanding of the NZEB concept, the source and quality of information on NZEB from the end-users' perspective, the importance of various apartment features for the end-users, perception of NZEB characterizing technologies, and decision triggers for living in NZEB. Concerns, doubts and eventual fears about living in NZEBs were studied to enable a tailored information for future end-users, to increase the demand for NZEB and beyond NZEB buildings and to improve their acceptability. To facilitate the living in NZEBs a guide for end-users was developed, explaining the "Myths" about NZEBs as well as presenting testimonials of current NZEB users in four participating countries.

This paper presents grey-box modeling of the heat dynamics of an apartment in a highly insulated test building located in the Arctic. Data from a 16-day-long experiment is analyzed and used to fit lumped parameter models formulated as coupled stochastic differential equations. The output of the models is the measured indoor air temperature, and the models are fitted using maximum likelihood techniques with the software CTSM-R. Models are compared using likelihood-ratio tests and validated considering autocorrelation and periodograms of residuals. The fitted models facilitate description of both the fast responses to mechanical ventilation and solar radiation through a large window facade, and the slow responses to floor heating and outdoor temperature. To successfully describe the dynamics of the system, solar radiation is given special attention in modeling of both the physical system and the observational noise. The estimated physical parameters which include UA-value, total heat capacity, and time constants for the apartment are discussed. Simulations are performed to illustrate step and impulse responses of inputs.

The paper deals with the control of low-temperature heating systems and their responses to changes in indoor environment with the main focus on indoor environmental quality and real energy savings reflecting low-energy buildings energy needs. In relation to energy savings, utilization of low-temperature heating systems is increasing today, in connection with lowtemperature heat sources, such as heat pumps. Lower temperature difference between the heating unit and the environment, along with the heat capacity, however, requires better control to be able to make effective response to potential changes in the indoor environment.

Animalistic metaphors have been used since the dawn of time to dehumanise members of outgroups and thereby deny them their rights. This paper examines the causes and symptoms of animalistic dehumanisation through the analysis of connotations of several terms used to conceptualise undesirable individuals and groups across various cultures, focusing on four source domains: rat, cattle, wolf, and dog.

Animalistic metaphors have been used since the dawn of time to dehumanise members of outgroups and thereby deny them their rights. This paper examines the causes and symptoms of animalistic dehumanisation through the analysis of connotations of several terms used to conceptualise undesirable individuals and groups across various cultures, focusing on four source domains: rat, cattle, wolf, and dog.

Background-Low-energy and net-zero energy buildings ▪ Onsite renewable energy, such as solar power, supports building consumption and sends excess power to electricity grid ▪ Net-zero buildings provide all their own energy on average over a full year ▪ Multidisciplinary challenges: Improved construction materials, lighting systems, air conditioning, and thermal insulation ▪ Low-energy buildings are integrated systems of renewable energy generation, advanced space conditioning, EV charging, and storage Research Support Facility at the National Renewable Energy Laboratory (source: nrel.gov) Upcoming Apple headquarters (source: news.sky.com

A district heating (DH) system is one of the most important components of infrastructures in cold areas. Proper DH network design should balance the initial investment and the heat distribution cost of the DH network. Currently, this design is often based on a recommended value for specific pressure loss (R = ∆P/L) in the main lines. This will result in a feasible network design, but probably not be optimal in most cases. The paper develops a novel optimization model to facilitate the design by considering the initial investment in the pipes and the heat distribution costs. The model will generate all possible network scenarios consisting of different series of diameters for each pipe in the flow direction of the network. Then, the annuity on the initial investment, the heat distribution cost, and the total annual cost will be calculated for each network scenario, taking into account the uncertainties of the material prices and the yearly operating time levels. The model is applied to a sample DH network and the results indicate that the model works quite well, clearly identifying the optimal network design and demonstrating that the heat distribution cost is more important than the initial investment in DH network design.

The efficiency of a District Heating (DH) network depends among other things on the quality of its design and more precisely on the sizing of the distribution network pipes. Providing DH designers with relevant methodology to select appropriate pipes is crucial to maximize the utility of those systems. This paper presents a methodology focusing on the optimal sizing of pipe diameters in DH networks: the methodology uses a genetic algorithm to generate a set of Pareto-optimal sizing choices. An implementation of the methodology is presented, and is validated on three test cases, each of them corresponding to an elementary configuration, which can be encountered in real-world DH network. As a result, the performance of the results provided by the optimization for each test case are as good or better than the best reference solutions we could provide. The last part of this paper addresses the scalability of the proposed sizing methodology. The interest of the presented methodology is lies in the typology of optimal solutions provided for the test cases that could not be devised with traditional sizing methods and by the scalability of the method that makes it suitable for optimal sizing at city scale.

• DHC thermal mass and heat losses in energy supply are studied. • An Energy Management System is proposed to provide optimal supply strategies. • DHC thermal mass is used as energy storage increasing power plant benefits. • Heat losses are reduced by the use of an optimal supply temperature.

District Heating Systems (DHS) connected to distrib u ed solar collectors may contribute in reaching, especially in areas with hi gh population density, the target of 50% of the heat demand for domestic hot water, spac e heating and cooling provided by renewable sources, which will be mandatory in It aly, from January 1, 2017, for new and deeply renovated buildings. By means of a s tware platform, developed by the Energy Efficiency Department of ENEA, a small-s ca e district heating system located in a suburb in the Municipality of Bologna (Italy) and including residential buildings, schools, public buildings and a commerci al building and heated by gas boilers was simulated. The introduction, in the sim ulated DHS, of one or more solar thermal fields integrated on the roofs of the build ings was studied, and sensitivity analysis on the effect of the number and the size o f the solar fields on the energy and economic performance of the DHS was carried out. Th e energy performance of...

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning dis...

The implementation of renewable energy sources and heat pumps with natural refrigerants in the existing 3rd-generation district heating (DH) systems is a promising technology for the conversion to a 4th-generation DH system. This paper aims to investigate this transition through a case study for the existing DH system in Croatia. The district of Rijeka, which is considered in the case study, has an existing 3rd-generation DH system with a capacity of 9.2 MW, which was originally designed for a temperature regime of 130/70 °C and produces thermal energy from natural gas. In order to use heat pumps efficiently in such a system, the temperature of the distribution system and the energy consumption should be reduced. Trnsys software was used to perform complete dynamic simulations of the DH system. Used baseline models were validated according to the actual energy consumption reported by the heat supplier. The application of heat pumps with natural refrigerants in combination with on-si...

Apartment position and operation within buildings play a significant role on energy consumption and also on perceived thermal comfort. Dwellings with favorable positions can have significant benefit, also when heated for a limited number of hours, if compared to apartments located in disadvantaged positions (i.e., upper or lower floors or north-oriented). This may be the cause of debates, especially in buildings with central heating, when heat costs are shared among tenants by means of sub-metering systems. In this paper, authors address this issue by studying the “heat thefts” phenomenon in dynamic conditions in a low-insulated building, when the heating system is used unevenly by the tenants (i.e., with different temperatures and/or use). To this end, a social housing building located in Mediterranean climate, where daily temperature excursions and solar heat gains enhance the dynamics of the heat flows, has been chosen as the case-study. The real operation of the building has bee...

The main purpose of the current study is to investigate the im- pact associated with a wider introduction of very low energy buildings in Europe, especially for EU Member States (MS) which have elaborated plans for the future towards very low energy buildings. In the study, the resulting energy savings and CO 2 emission reduction from buildings constructed as very low energy buildings will be dealt with, taking into account the national energy-mix as well as national interpretation of very low energy buildings. In addition, the study seeks to obtain information on relevant national studies on very low energy buildings, including measures and programmes to promote such buildings and to remove barriers to their future develop- ment. In this context, education, training, and the public sector are areas of special interest. In a recent study (1) we gathered a picture of the planned strategies in European countries regarding the implementation of requirements towards very low energy buil...

The Directives 2002/91/CE and 2010/31/UE greatly evolved the building and real-estate sector towards low energy building, both in the case of building retrofitting and new buildings. Thanks to the Energy Performance Certificate influence on the real estate market, or thanks to the economic crisis, as it is some new buildings-the best-were built with Energy Class A or Nearly Zero classification. The Energy Building Performance standards, e.g. CEN Umbrella and their transposition, will be improved in the future, in spite of this these should be considered solid, and designers, architects and engineers must apply technical strategies (e.g. high insulation, reduction of air leakage, use of renewable systems) in order to reduce building energy consumption. The new challenge will be to improve relations between Building Energy Performance and Indoor Environmental Quality (IEQ). As regards these relations, the CEN Umbrella provides to implement the Standard 15251. In the present paper we describe the results of IEQ monitoring in a low energy performance building (Class A+ less than 25 kWh/m 2 year). The results show that low energy performance building do not always guarantee a better category of IEQ, especially during the summer.

PLEA 2008 – 25th Conference on Passive and Low Energy Architecture, Dublin, 22nd to 24th October 2008 ... 122: Intelligent facades in hot climates: energy and comfort strategies for successful application ... Carlos Ernesto Ochoa 1*, Isaac Guedi Capeluto 1 ... 1Climate and Energy ...

The paper deals with the control of low-temperature heating systems and their responses to changes in indoor environment with the main focus on indoor environmental quality and real energy savings reflecting low-energy buildings energy needs. In relation to energy savings, utilization of low-temperature heating systems is increasing today, in connection with lowtemperature heat sources, such as heat pumps. Lower temperature difference between the heating unit and the environment, along with the heat capacity, however, requires better control to be able to make effective response to potential changes in the indoor environment.

Integrated thermal-daylighting simulations on a low energy building are performed. Optimal WWR of the façade that minimize the total energy demand is searched. Optimal WWR were found in the range 35-45%, regardless the orientation. If state-of-the-art technologies are used, WWR play a crucial role (maximum influence: 11%). The optimal configurations are tested against different building geometries and HVAC efficiencies.

In this paper, the behaviour of a special roofing system is investigated. It is a passive building component that consists of a ventilated roof with a maintained wet lower surface of the cavity over which flows the external air. The authors have carried out numerical simulations of the thermal field, flow field and water vapour concentration of air within the duct for thermal performance evaluation purposes. In order to obtain an estimate of the thermal cooling flux on the wet surface, suitable procedures were coded and linked to a commercial program for computational fluid dynamics (CFX 4.4). An original approach to solve a coupled heat and mass transfer problem is presented. Results of numerical simulations of the temperature field and the values of the mean specific heat and mass fluxes of the wet lower surface are shown. Numerical problems that have been dealt with, due to particular physical phenomena such as boundary coupled fields and radiation between cavity surfaces, are highlighted.

Projected population growth and urbanization rates will create a huge demand for new buildings and put an unprecedented pressure on the natural environment and its limited resources. Architectural design has often focused on passive or low-energy approaches to reduce the energy consumption of buildings but it is evident that a more holistic, whole-life based mindset is imperative. On another scale, the movement for, and global initiatives around, low carbon cities promise to deliver the built environment of tomorrow, in harmony with the natural boundary of our planet, the societal needs of its human habitants, and the required growth for economic prosperity. However, cities are made up of individual buildings and this intimate relationship is often poorly understood and under-researched. This multi-scale problem (materials, buildings, and cities) requires plural, trans-disciplinary, and creative ways to develop a range of viable solutions. The unknown about our built environment is ...

The necessity for transition in the energy sector is beyond dispute and high on the political agendas. Climate change, the depletion of fossil fuels and the vulnerability of economies to resource speculation and unreliable political systems in the producing countries lay path for a broad implementation of smart alternative solutions. This means the integration of more sustainable renewable energy sources in the existing supply structures or the displacement of existing systems by new ones. Cities and communities are central players in the energy transition process. Energy demand is determined by the built environment. Renewable energy production needs space. The conflicts between different interest groups often break out in the context of local implementation measures that affect urban planning and the appearance of landscapes. Small- and medium-sized communities might prove to be game-changers in the overall energy transition because many problems have to be solved within their amb...

District heating networks (DHN) are becoming an energy-saving and cost-effective alternative to conventional conversion systems (boilers, chillers, combined heating and power systems) and appear as a vector of the energy transition because of the diversity of the energy sources that can be used for their operation. They are increasingly used in cogeneration and more efficiently when operating at lower temperature levels. Indeed, many previous works were able to simulate thermal and hydraulic losses of different structures of networks. These works have been carried out in several European countries, notably in Switzerland, Great Britain but also in countries such as Denmark and Sweden. The approach for representing the networks and the simulation models could be complex to use for a general optimization purpose. This paper presents a new approach and methodology to represent the structure of the network in order to simplify models while performing accurate calculations for the therma...

The Directives 2002/91/CE and 2010/31/UE greatly evolved the building and real-estate sector towards low energy building, both in the case of building retrofitting and new buildings. Thanks to the Energy Performance Certificate influence on the real estate market, or thanks to the economic crisis, as it is some new buildings-the best-were built with Energy Class A or Nearly Zero classification. The Energy Building Performance standards, e.g. CEN Umbrella and their transposition, will be improved in the future, in spite of this these should be considered solid, and designers, architects and engineers must apply technical strategies (e.g. high insulation, reduction of air leakage, use of renewable systems) in order to reduce building energy consumption. The new challenge will be to improve relations between Building Energy Performance and Indoor Environmental Quality (IEQ). As regards these relations, the CEN Umbrella provides to implement the Standard 15251. In the present paper we describe the results of IEQ monitoring in a low energy performance building (Class A+ less than 25 kWh/m 2 year). The results show that low energy performance building do not always guarantee a better category of IEQ, especially during the summer.

In this paper, the behaviour of a special roofing system is investigated. It is a passive building component that consists of a ventilated roof with a maintained wet lower surface of the cavity over which flows the external air. The authors have carried out numerical simulations of the thermal field, flow field and water vapour concentration of air within the duct for thermal performance evaluation purposes. In order to obtain an estimate of the thermal cooling flux on the wet surface, suitable procedures were coded and linked to a commercial program for computational fluid dynamics (CFX 4.4). An original approach to solve a coupled heat and mass transfer problem is presented. Results of numerical simulations of the temperature field and the values of the mean specific heat and mass fluxes of the wet lower surface are shown. Numerical problems that have been dealt with, due to particular physical phenomena such as boundary coupled fields and radiation between cavity surfaces, are highlighted.

Jakarta is a metropolitan city that continues to strive to develop the capacity of its mass transport as other large cities in the world, primarily the development of the rail-based transportation. Indonesia Railway Company (PT Kereta Api (Persero)) had forecasted that there will be 1.2 million passengers per day on Jakarta in 2019. To meet these targets, it is necessary to adequate the infrastructure planning, especially the capacity of the DC substations which supply the electric power to the trains. This paper will demonstrate the strategy used to determine the point of placement of new DC substation and/or existing DC substation upgrades throughout the Jakarta area from 2013 to 2019. The current railway timetable and the future pattern of railway operation plan are used to predict the possibilities of peak load spots along the track.

A novel CHP configuration is presented, which is fueled by low-temperature geothermal energy and delivers heat to a district heating (DH) system.This so-called ''Preheat-parallel" configuration has a higher net electrical power output (_ W net) and a higher exergetic plant efficiency (g ex) than the convenient series and parallel configurations for the connection to a state-of-the-art 75/50 DH system.For the considered cases, _ W net and g ex are 1.3-6.4% and 0.4-1.9%-pts higher than for the parallel configuration, respectively.The highest values correspond to the highest heat demand.With respect to the series configuration _ W net and g ex are 2.1-9.9% and 0.7-3.0%-pts higher, respectively, where the highest values correspond to the lowest heat demand.Furthermore, the optimal CHP configuration-series, parallel or ''Preheatparallel"-is discussed.The optimal configuration depends on the DH system requirements.Supply and return temperatures in the range of T supply ¼ 40-110 C and T return ¼ 30-70 C are considered.We conclude that the series and parallel configurations have the best performance for the connection to low-temperature and high-temperature DH systems, respectively.However, for a wide range of T supply and T return , the ''Preheat-parallel" configuration is the most appropriate.The preheating-effect is the main feature of the ''Preheat-parallel" configuration, and is more useful for a large temperature difference T supply À T return and for low values of T return .Furthermore, we found that for high heat demands and small temperature differencesT supply À T return , the ''Preheat-parallel" or series configurations might perform better than the parallel configuration for the connection to a high-temperature DH system.

The development of sustainable and innovative solutions for the production and supply of energy at district level is nowadays one of the main technical challenges. In the past, district heating and cooling networks aimed to achieve greater energy efficiency through the centralization of the energy production process but with relevant losses related to heat transport. Moving towards a higher share of renewables and lower demand of primary energy requires redesign of the energy district networks. The novel concept of cold district heating networks aims to combine the advantages of a centralized energy distribution system with low heat losses in energy supply. This combined effect is achieved through the centralized supply of water at relatively low temperatures (in the range 10-25 • C), which is then heated up by decentralized heat pumps. Moreover, cold district heating networks are also very suitable for cooling delivery, since cold water supplying can be directly used for cooling purposes (i.e., free cooling) or to feed decentralized chillers with very high energy efficiency ratio. This paper provides a preliminary literature review of existing cold district heating networks and then qualitatively analyses benefits and drawbacks in comparison with the alternatives currently used to produce heat and cold at district level, including the evaluation of major barriers to its further development.

A dynamic performance of district heating systems was analysed with an emphasis on temperature profile distortion throughout a heating system network. Therefore, a modelling approach (the so-called node method) developed at the Technical University of Denmark was applied. For comparison purposes, commercial TERMIS software was also used in this work. Typical supply conditions were investigated in the considered district heating systems in Denmark. Large and sudden temperature changes in supply temperature were depicted in the district heating system in Madumvej while the pronounced transient supply conditions of temperature wave were exhibited in the district heating system in Naestved. Time-dependent consumer data from the district heating systems were applied to compare the results obtained from modelling approaches. Based on the analysis of temperature wave propagation through the network, it was noted that temperature wave spread unevenly on different locations of the network. S...

It is possible to determine and evaluate the total energy usage of buildings for each independent unit in the central heating system. The total energy spent for heating and hot water supply is different for each independent unit. However, a single bill is generated for the heating device and water consumption and so it is divided equally used per individual unit in the absence of substations. It is known that these stations work primarily in use water. Utilizing solar energy to provide utility hot water is quite advantageous as another application. The adaptation of solar energy systems to these substations will be an advantage for both systems. With this system connected to the station pipelines, the heat exchanger temperature will be kept high. Thus, the additional energy costs will be eliminated or will decrease, depending on the requested water temperature for the usage hot water. In addition, the warm-up time will be reduced and thermal comfort will be ensured.

Low and moderate geothermal resources are found in most areas of the world. In order to decrease air pollution and save conventional energy, geothermal energy as a heat source for district heating system have been used widely in China in recent years due to its cleanness and lower operating cost. This paper describes the geothermal resource and district heating system in Tianjin. Heat load for one sample building was calculated. Based on it, both geothermal heating and a fuel fired system using steady-state model and dynamic model were simulated, influence of radiator size on return temperature and mass flow was analyzed and radiator was selected, A sample district heating system network was set up, pressure and temperature drop of pipeline were calculated, and the system simulated. The results show that radiator size affect the indoor temperature significally, and, dynamic simulation model is an effective way to study the system performance, as the heating system can be controlled ...

District heating systems are almost always located in densely populated urban areas where various heat sources are available, such as cooling and refrigeration systems in supermarkets, shopping malls, and power transformers. These urban sources often have a large share of waste heat, which is usually emitted into the environment. This waste heat could be used to partially cover the thermal load in district heating systems. The biggest challenge for their integration is the spatial distribution of urban heat sources in relation to the existing heat network and the temporal distribution of the availability of waste heat energy throughout the year. In this paper, we have developed an economic assessment model for the integration of urban heat sources into existing district heating systems. By the hourly merit order of waste heat utilization technologies based on pinch analysis, we have defined the most suitable integration of urban heat sources into existing district heating systems. D...

Central Solar Heating Plants with Seasonal Storage (CSHPSS) are systems producing heat from solar radiation for a district heating system. These systems are able to produce thermal energy during all the year providing a significant part (high solar fraction) of the demands required for space heating and Domestic Hot Water (DHW). The design and calculation of the behaviour of these systems during the year is a complex process requiring detailed climatic and demand data in order to properly design/sizing the plant components to reach the desired behaviour (e.g. a specific solar fraction). The location of the plant and the different demands corresponding to different climatic areas affect very significantly the behaviour of these systems. As a consequence, the sizing and design criteria of the pieces of components of these systems are very different in the North and the South of Europe. The utilization of simple methods for the calculation of these systems allows the design of the main components and provides an estimate of the behaviour of the system during the year. In this paper is proposed a simple method for the calculation of CSHPSS using demand data and simple and easy to find available public climatic data. The proposed method is completely described and applied to specific Spanish locations to pre-design the main components of these systems. The model also provides a preliminary economic evaluation of the system and is very useful to perform parametric analysis to evaluate the CSHPSS system performance, as well as to establish optimization and design criteria of CSHPSS.

Although some literature on the benefits of improving the thermal characteristics of Maltese buildings already exists, further research is required in order to quantify the full extent of these benefits. This is particularly relevant when considering that many new buildings are multi-storey complexes whose thermal characteristics differ from floor to floor on a seasonal basis. The research presented in this paper aims to improve the understanding of using insulated compared to non-insulated construction materials in a multi-storey residential building. A building simulation tool was used to simulate the thermal performance of a three-storey building assuming different building fabric scenarios. The scenarios investigated varied between two extremes; a low efficiency and a high efficiency scenario. The various measures which differentiate the two scenarios were individually simulated to assess their specific effect on space heating and cooling energy demand and internal temperatures....