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Digitalization or the wide implementation of digital technologies in our energy systems are believed to make our systems smarter, more efficient and reliable. Furthermore, a much higher integration of renewable energy sources into the systems is expected, as well as new business possibilities are generated by the use of innovative digital technologies and processes. In this context, the IEA DHC Annex TS4 project is aiming at promoting the opportunities of the integration of digital processes into DHC schemes. This implies the clarification of the role of digitalization for different parts within the operation and maintenance of the district heating and cooling system. Furthermore, the implementation of these technologies is going to be demonstrated in a close cooperation with a number of industry partners. Moreover, the challenges such as data security and privacy as well as questions about data ownership are also addressed. Traditionally, district heating and cooling (DHC) networks are operated with a limited number of controls (as the control of the supply temperatures or the network pressure) to secure the required supply task and to optimize economics and ecologic performance. Detailed information of the supply and utilization structures (e.g. heat plant characteristics, power demand or time profiles) is not provided in classical network operation. An optimized heat generation and overall network operation is possible with more information on the demand and flexibility options (storages) resulting in e.g. peak shaving and the reduction of expensive peak boiler use. In these systems a wider integration of fluctuating heat sources, such as solar thermal energy and power-to-heat applications operating on the electricity markets, can be shown in already realized projects. Wider implementation of information and communication technologies, as in many other industries, unlocks potentials for better network management based on real-time measurement data and the integration of new business models. A growing number of companies are offering products and services, as e.g. digital analyses platforms or smart meters, in this frame. The current changes and developments in the operating environment are presenting both opportunities and threats for district heating providers. The main impact of the integration of digital technologies and methods for district heating providers is expected to be in the changing business environment. Via these new technologies the ways of working and using already established business models will change, new services and products will enter the market. On the other hand, existing business models are affected by the increased energy efficiency of the building stock caused by reduced heat sales and by the customer's demand for alternative heating solutions. Here digitalization will bring new methods to meet changing customer needs and to communicate with the different groups of customers. The special importance of digitalization in district heating systems is that digitalization is a prerequisite in innovative low temperature, so-called 4th generation, heat networks to integrate renewable and fluctuating heat sources. So, digitalization has the potential to make heat networks more sustainable, more reliable, has the potential to integrate more renewable energy, more excess heat, better suitable for the integration of lower temperature levels e.g. via an optimal usage of heat pumps or CHP units, more profitable e.g. via the reduction of expensive fossil fuel consumption or via the reduction of transmission losses. The presentation, the abstract presents and discusses the first results from the research work within the IEA DHC Annex TS4 on "Digitalisation of District Heating Systems-Optimised Operation and Maintenance of District Heating and Cooling Systems via Digital Process Management".

The advent of DNA sequencing revolutionized the field of microbiome research. Many organisms, by virtue of their codependence and/or growth rate, are either impossible or extremely challenging to get into pure culture. Sequencing allows important taxonomic and phylogenetic information to be obtained independent of culturing. Development of the sequencing technology itself has allowed for high throughput workflow that has allowed low cost and extensive sampling of microbiomes across environments. The co-development of reference datasets for taxonomy and functional assignments, along with open-source bioinformatics pipelines has further empowered scientists to explore microbiomes in many environments. However, there are limitations to sequence data that have constrained the ecological inferences in microbiome research. One such limitation, the compositional nature of sequence data, has impeded our ability to make accurate inferences about the environmental drivers of taxon abundance and covariance across conditions. In this dissertation I explore the use of quantitative PCR in combination with sequencing techniques to generate “Quantitative Sequencing” data (QSeq) that mitigates the limitations of compositionality on inferences relating to taxon abundance and covariance across environmental gradients. In chapter 1, I reviewed key characteristics of the soil environment and sequencing as a mechanism for sampling. In chapter 2, I leveraged modeling, synthesis, and literature review methods to establish the questions and data characteristics that demand QSeq methodology. I show that even small amounts of variation in total abundance make determining the effects of environment (biotic and abiotic factors) on any given taxon unreliable without QSeq. In Chapter 3, I extend the logic of quantitative sequencing to improve metagenome prediction from PICRUSt2. Using data synthesis methods, accounting for 16S gene abundance consistently improved the accuracy of predicted functional genes. This was confirmed by high correlations between predicted and measured gene abundance (QPCR). There was however a large variation in prediction accuracy, likely due in part to database biases and in part to decoupling of bacterial function from taxonomy. In Chapter 4, I applied QSeq in the context of an experimental, long-term farming system that has large gradients in total abundance with depth, and I used QSeq to identify taxa that changed in abundance due to different farming system management and soil depth. Finally in Chapter 5, I used QSeq to identify putative N-fixing taxa that responded to glyphosate in four experimental farming systems. I show that the abundance of these taxa were decoupled from other effects of glyphosate on N-fixation in soybean across farming systems.

Low temperature district heating is a heat supply technology for efficient, environmental friendly and cost effective community supply. Moreover, it is recognized as a key technology for transforming and decarbonating heat energy systems by efficient integration of renewable energy sources as solar thermal, geothermal and other waste heat sources. The results from the international cooperation activity IEA DHC Annex TS2 on "Implementation of Low-Temperature District Heating Systems" provide advice and recipes for obtaining lower network temperatures as well as information on other features to include in existing and new district heating systems (Averfalk et al. 2021). Accomplished by summarizing the economic benefits of low-temperature district heating and gained experiences from early adopters in various urban areas throughout Europe. Lessons learned can be applied in new and expanding district heating systems and are presented in this paper. We discuss economic benefits, temperature levels in buildings, temperature levels in district heating systems, an applied case, competitiveness of low temperature district heating and transition strategies for cities with existing district heating systems.

Denkmalpflege in Baden-Württemberg – Nachrichtenblatt der Landesdenkmalpflege, Bd. 47, Nr. 3 (2017)

By introducing better interfaces between the demand and supply, district heating and cooling (DHC) systems can be transformed into a smart grid energy system on a district level. In the IEA DHC Annex TS1 project, the Subtask C collects and identifies promising models, concepts, and technologies to meet the goals of future renewable based community energy systems. The problem of the improved interfaces in DHC may be explained via hard and soft issues. The hard issues cover the following: DHC network structures, requirements for consumer substations and buildings, and connection principles for distributed energy sources. The soft issues cover the following: technical and economical modelling of the distribution system, optimization between demand and generation side, innovative control concepts and energy measurement, transition of the existing DHC grid to the LTDH grid, and new pricing and business models. The article aims to provide an overview on the necessary measures to enable transition to the LTDH. Several examples with successful utilization of waste and solar heat for the district heating purpose are shown. Connection principles and strategies to decrease the return temperature are shown. To enable continuously a desired level of the return temperature, fault detection and diagnosis are necessary in both DHC network and consumer substations. Good fault detection and diagnosis require advanced monitoring system and smarter heat grids, especially in substation interfaces. Developing new pricing models is essential to promote sustainable development of LTDH systems. Necessary measures to enable higher market share for waste and solar heat are suggested. Published by Aalborg University Aalborg

This report titled “Case studies and demonstrations” is the subtask D report of the IEA DHC|CHP Annex TS1 project “Low Temperature District Heating for Future Energy Systems” carried out between 2013 and 2016. The project was led by Fraunhofer Institute for Building Physics (IBP) with the other participants being VTT Technical Research Centre of Finland (VTT), Technical University of Denmark (DTU), Norwegian University of Science and Technology (NTNU), Stuttgart Technology University of Applied Sciences (HFT) and SSE Enterprise in United Kingdom. The demonstration cases described in the report include examples on low temperature district heating systems, solar heating in a district heating system, heat pump based heat supply and energy storages for both peak load management and for seasonal heat storage. Some demonstrations have been implemented while others are at planning phase. The implemented cases have provided measurement data for the verification of different calculation tools and analysis while the projects in planning phase have benefited on simulation results on operation of a realised system. The collaboration group would like to thank the partners for the cooperation making the presentation of the case studies possible in this report.

The fossil fuel dependent energy landscape is changing from demand led to cultivating renewables. As a major energy consumer, the buildings sector must adapt. And while good cross-sectoral integration can aid this transition, the boundary with the transportation sector is blurring.

It is important to demonstrate the potential of low exergy thinking at the community level for realising energy and cost efficient solutions with low temperature resources.

There is an obvious and indisputable need for an increase in the efficiency of energy utilisation in buildings. Heating, cooling and lighting appliances in buildings account for more than one third of the world’s primary energy demand. In turn, building stock is a major contributor to energy related environmental problems. There are great potentials, which can be obtained through a more efficient use of energy in buildings. An optimisation of the exergy flows in buildings and the related supply structures, similar to other thermodynamic systems such as power stations, can help in identifying the potential of increased efficiency in energy utilisation. Through analyses, it can be shown that calculations based on the energy conservation and primary energy concept alone are inadequate for gaining a full understanding of all important aspects of energy utilisation processes. The high potential for a further increase in the efficiency of; for example, boilers, can not be quantified by energy analysis - the energy efficiency is close to 100%; however, this potential can be showed by using exergy analysis, the exergy efficiency of a common gas boiler is about 8%. The Low Exergy (LowEx) approach entails matching the quality levels of exergy supply and demand, in order to streamline the utilisation of high-value energy resources and minimise the irreversible dissipation of low-value energy into the environment. This approach is the key concept for the work of Annex 49 on energy use and supply structures in the built environment. Using a typical case, the advantages of the analyses and the difference between energy and exergy analyses are demonstrated. In conclusion, based on an analysis of a real and existing building suggestions for a benchmarking system for so-called LowEx buildings are presented. In order to achieve an exergy optimised building design, loads on the building service system have to be reduced as much as possible. The suggested benchmarking method gives an engineering approach to archive those building system configurations. The presented research work is related to the ongoing international cooperation work in the IEA ECBCS Annex 49 “Low Exergy Systems for High-Performance Buildings and Communities”, the established Network for “Low Exergy Systems in Buildings - LowExNet” and the ongoing German activities in the collaboration project in the exergy field from industry partners and research institutes.

Analyses of the exergy flows are common for the optimization of many thermodynamic systems since half of last century. Several international ongoing research projects try to extend this approach to the building sector, in order to develop more efficient buildings and supply structures by reducing the exergy losses in each step of the buildings´ energy supply chain. Most of the energy in the building sector is used for heating and cooling purposes, i.e. to maintain constant room temperatures of around 20°C. Because of the low temperature level, the actual demand for exergy in space heating and cooling applications is low. In turn, solar radiation is undisputedly a high quality source, and thus high exergy losses arise when solar energy based technologies are used to cover a low exergy demand. Following, solar energy based technologies seem to be unsuitable to cover these demands from an exergy perspective. This evaluation schema however, is physically inconsistent with the one used for the assessment of any other energy sources. In the paper a new assessment framework for technologies making a direct use of solar radiation is presented. Several solar-based technologies for heating and cooling of buildings are analysed using the proposed framework, and compared to the results obtained using the conventional assessment approach. From the results of the analysis the suitability of these technologies is shown, and first estimations on the contribution of these technologies for increasing the energy and exergy performance of buildings are derived.

There is still an obvious and indisputable need for an increase in the efficiency of energy utilisation in buildings. Heating, cooling and lighting appliances in buildings account for more than one third of the world’s primary energy demand and there are great potentials, which can be obtained through better applications of the energy use in buildings. This thesis focuses on the development of methods and models for heat and mass transfer processes in buildings, which have a vital impact on the energy utilisation. These models can be used in optimisation procedures aiming at increasing efficiency in the energy use, i.e. at minimising consumption of the necessarily supplied high quality energy, i.e. exergy, in buildings. Through the use of the method of analysing exergy flows in buildings, similar to the analysis applied on other thermodynamic systems, such as power stations, it is possible to identify the potential of increased efficiency in energy utilisation. It has been shown that calculations based on the energy conservation and primary energy concept alone are inadequate for gaining a full understanding of all important aspects of energy utilisation processes. Thus, a method for exergy analyses, based on a combination of the first and second laws of thermodynamics, is presented and an assessment tool has been developed for a better understanding and design of energy flows in buildings. Ventilation heat losses account for a significant fraction of the overall heating energy use in buildings. The implementation of natural ventilation strategies allows for the possibility of supplying indoor space with the required fresh air volume, without any fan power. Because of the ability to create high air flows, the use of natural ventilation can be beneficial to for night cooling processes. All in all, it is important to estimate the expected air flow rates during the design and planning stage of a building. That is why a model, based on earlier published works on single sided natural ventilation on tilting windows, has been developed for natural cross ventilation conditions with tilting windows. There are also building service system solutions which can help to reduce exergy consumption caused by the heating and cooling of rooms. The thermally activated building components are examples of these systems; they use very low temperature differences between the heat carrier medium and the room to be tempered. Earlier derived models of such systems are not always satisfactory for the design of all system configuration or new regulation strategies. The developed macro element modelling (MEM) approach is based on research conducted on the modelling of dynamic heat flows in solid constructions with discrete resistances and capacitances. In this work, it has been expanded by the simultaneous modelling of heat carrier flows and used on the thermally activated components. A methodology for modelling thermally activated components has been developed and verified. Optimised resistance-capacitance (RC) networks combined to so-called macro elements are used to model the solid parts of the system, the fluid temperatures are calculated under the precondition of a linear variation of mass node temperature between the calculation nodes. It has been demonstrated and verified that the MEM method is generally suitable for modelling the dynamic behaviour of combined systems with a heat carrier flow and solid construction parts with substantial heat storage capacity.

QC 20110616

Inhalt: Kimpel, Dieter: Vorwort; Markelin, Antero: Richard Döcker - Kollege; Posener, Julius: Grußwort; Gutbrod, Rolf: Erinnerungen an Richard Döcker; Kimpel, Dieter: Das kulturelle Klima in Stuttgart seit der Jahrhundertwende; Worbs, Dietrich: Richard Döckers Architektur in den 20er und 30er Jahren; Joedicke, Jürgen: Die Neugründung der Stuttgarter Schule nach 1945; Schmidt, Dietrich W.: Vom pathetischen Aufbruch in die Moderne zur Stagnation im Dogma. Theoretische Anmerkungen zum Wandel von humanen Architekturvisionen; Ostertag, Roland: Als Student Richard Döckers in den fünfziger Jahren; Durth, Werner: Die Botschaft Richard Döckers; Schmidt, Dietrich W.: Biographische Hinweise - Werkübersicht