40 results on '"Felsmann, Clemens"'
Search Results
2. Experimental demonstration of grid-supportive scheduling of a polygeneration system using economic-MPC
- Author
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Sawant, Parantapa, Bürger, Adrian, Felsmann, Clemens, and Pfafferott, Jens
- Published
- 2022
- Full Text
- View/download PDF
3. National methods fail to calculate standardized deep renovation concepts for dwellings: Benchmarking in three EU climates
- Author
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Võsa Karl-Villem, Kurnitski Jarek, Felsmann Clemens, Meinsenbach Andrea, Carli Michele De, Tonon Massimo, and Iivonen Mikko
- Subjects
Environmental sciences ,GE1-350 - Abstract
Renovation of existing buildings has been highlighted as an essential action in the European Green Deal and in the latest revision of the EPBD to achieve energy efficiency targets. Renovation Wave strategy aims to double the deep energy renovation rate in EU by 2030, while specifically targeting the worst-performing segment of the existing building stock. The objective of this study was to assess the energy performance of deep renovation concepts on single and multi-family houses in three different geographical settings – Germany, Italy and Estonia. Typical German 1970s buildings were used as a baseline reference, and it was shown that very similar renovation concepts can be successfully applied across Europe that provides good bases to develop standardized solutions. Energy performance of two common renovation concepts was assessed both with national calculation methodologies and dynamic simulation with harmonized inputs and detailed heat pump plant models. The renovation concepts included improved envelope insulation and airtightness, switched to heat pump systems and heat recovery ventilation as well as incorporated on-site PV while complying with nearly zero-energy requirements for major renovations in all three countries. National energy calculation methodologies showed good accuracy for before the renovation situation but failed in many cases to calculate adequately NZEB renovation concepts with heat pumps and PV, indicating the development needs towards hourly calculation and more detailed treatment of heat pumps.
- Published
- 2023
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- View/download PDF
4. Field Trial Evaluation of a Hybrid Heat Pump in an Existing Multi-Family House before and after Renovation.
- Author
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Neubert, Daniel, Glück, Christian, Wapler, Jeannette, Marko, Armin, Bongs, Constanze, and Felsmann, Clemens
- Subjects
HEAT pumps ,GREENHOUSE gas mitigation ,APARTMENT buildings ,FIELD research ,BUILDING repair ,HEATING - Abstract
Renovation of existing buildings is fundamental to reduce greenhouse gas emissions of the building sector and to ensure the efficient operation of renewable heating systems. In multi-family houses, the suitability of heat pumps is limited by high required temperatures for the hot water preparation, which can be mitigated by hybrid heat pump systems. In this study, the energetic performance of a hybrid heat pump in a multi-family house, built in 1964, is investigated based on field data before and after a renovation. Multiple months are measured and mapped to a full year period. The combination of different renovation measures in the heating system and building envelope is rated w.r.t. their ecological and economical impact by taking into account the actual investment costs. The evaluation shows that the installation of a hybrid heat pump can achieve an accumulated greenhouse gas emissions reduction of 45%, which is similar to a building renovation to a new-build standard, which reduces the space heating demand by up to 62%. Nevertheless, only a combination of both measures can substantially reduce the emissions, which in this case are 81% lower compared to a gas boiler in 1990, which is still below the German climate target for 2040. Due to the low investment costs of a hybrid heat pump system, tenants are more likely to profit from a renting costs reduction, while a building renovation is especially economically beneficial at high energy prices. The results therefore emphasize that the insulation level should be selected carefully, as heat pumps already prepare space heating efficiently and that the heat pump must be able to support the hot water preparation to reach high emission reduction targets. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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5. Development of a rat capnoperitoneum phantom to study drug aerosol deposition in the context of anticancer research on peritoneal carcinomatosis
- Author
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Göhler, Daniel, Geldner, Antje, Gritzki, Ralf, Lohse, Franz, Große, Stephan, Sobilo, Julien, Felsmann, Clemens, Buggisch, Jonathan R., Le Pape, Alain, Rudolph, Andreas, Stintz, Michael, and Giger-Pabst, Urs
- Published
- 2021
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6. Quasi-First-Principle Based Grey-Box Modelling of Microscale Trigeneration Systems for Application in Automatic Control
- Author
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Sawant, Parantapa, Pfafferott, Jens, and Felsmann, Clemens
- Published
- 2018
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- View/download PDF
7. Creating common exercises for modelling building and district energy systems: lessons learnt from the IBPSA Project 1 - DESTEST
- Author
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Johra Hicham, Jafarinejad Tohid, Beyzaee Arash Erfani, Hirsch Hauke, Felsmann Clemens, and Saelens Dirk
- Subjects
Environmental sciences ,GE1-350 - Abstract
The District Energy Simulation Test (DESTEST) is a series of common exercises about modelling building stocks and district heating networks aiming at testing, benchmarking and verifying different urban-scale energy system simulation tools. For each common exercise, participants are modelling a case with well-defined characteristics, grid topology and boundary conditions. The DESTEST allows participants to discuss common mistakes and pitfalls and define guidelines from the experience and feedback. These common exercises can also be used for training purposes. This article discusses the development process of these common modelling exercises and presents the main lessons learnt during the creation of the DESTEST.
- Published
- 2022
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- View/download PDF
8. Load shifting using the heating and cooling system of an office building: Quantitative potential evaluation for different flexibility and storage options
- Author
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Klein, Konstantin, Herkel, Sebastian, Henning, Hans-Martin, and Felsmann, Clemens
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- 2017
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9. Integration of Solar Thermal Systems into District Heating – DH System Simulation
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Heymann, Martin, Rühling, Karin, and Felsmann, Clemens
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- 2017
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10. Creating common exercises for modelling building and district energy systems:lessons learnt from the IBPSA Project 1 - DESTEST
- Author
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Johra, Hicham, Jafarinejad, Tohid, Beyzaee, Arash Erfani, Hirsch, Hauke, Felsmann, Clemens, Saelens, Dirk, Hviid, C. A., Khanie, M. S., and Petersen, S.
- Subjects
Lessons learnt ,DESTEST ,IBPSA ,SDG 11 - Sustainable Cities and Communities ,District energy systems ,Common exercise ,BSN ,Building simulation ,District heating ,Numerical modelling ,SDG 13 - Climate Action ,Common modelling exercise ,SDG 7 - Affordable and Clean Energy ,SDG 9 - Industry, Innovation, and Infrastructure ,SDG 12 - Responsible Consumption and Production ,SDG 4 - Quality Education - Abstract
The District Energy Simulation Test (DESTEST) is a series of common exercises about modelling building stocks and district heating networks aiming at testing, benchmarking and verifying different urban-scale energy system simulation tools. For each common exercise, participants are modelling a case with well-defined characteristics, grid topology and boundary conditions. The DESTEST allows participants to discuss common mistakes and pitfalls and define guidelines from the experience and feedback. These common exercises can also be used for training purposes. This article discusses the development process of these common modelling exercises and presents the main lessons learnt during the creation of the DESTEST.
- Published
- 2022
11. Numerical simulation of radiative heat transfer in indoor environments on programmable graphics hardware
- Author
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Kramer, Stephan, Gritzki, Ralf, Perschk, Alf, Rösler, Markus, and Felsmann, Clemens
- Published
- 2015
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12. Nearly zero energy renovation concepts for apartment buildings
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Kuusk Kalle, Naumann Jens, Gritzki Annina, Felsmann Clemens, De Carli Michele, Tonon Massimo, and Kurnitski Jarek
- Subjects
Environmental sciences ,GE1-350 - Abstract
Revised EPBD directive has set ambitious targets for renovation. It is stated that Member States shall establish a long-term strategy facilitating the cost-effective transformation of existing buildings into nearly-zero energy buildings. The long-term strategy should set out a roadmap with a view to the long-term 2050 goal of reducing greenhouse gas emissions in the European Union. This creates the need for cost-efficient renovation solutions which can be implemented in large scale. The impact assessment shows that roughly a doubled renovation rate of 3 % would be needed to accomplish the energy efficiency ambitions in a cost-effective manner. The objective of this study is to specify renovation concepts with adequate heating and ventilation, based on Estonian and German apartment buildings and corresponding local solutions. Energy performance and sizing analyses were conducted for selected multifamily apartment buildings typical for 1960-70es with three different renovation concepts. Energy calculations were conducted with national energy calculation methods and national energy requirements for major renovation. In the renovation, the building envelope insulation, air tightness, and heating and ventilation systems were improved so that the renovated building complies with national nearly zero-energy requirement for major renovation.
- Published
- 2020
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13. Solubility Coefficients for Solar Liquids, a New Method to Quantify Undissolved Gases and Practical Recommendations
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Heymann, Martin, Panitz, Felix, Rühling, Karin, and Felsmann, Clemens
- Published
- 2014
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14. Model-predictive control of mixed-mode buildings with rule extraction
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May-Ostendorp, Peter, Henze, Gregor P., Corbin, Charles D., Rajagopalan, Balaji, and Felsmann, Clemens
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- 2011
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15. Identification of urban cellular structures for flexible heat and temperature distribution in district heating networks
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Felsmann, Clemens, Mann, Luise, and Boß, Vera
- Published
- 2021
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16. Analysis of the Operation Characteristics of a Hybrid Heat Pump in an Existing Multifamily House Based on Field Test Data and Simulation.
- Author
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Neubert, Daniel, Glück, Christian, Schnitzius, Julian, Marko, Armin, Wapler, Jeannette, Bongs, Constanze, and Felsmann, Clemens
- Subjects
HEAT pumps ,APARTMENT buildings ,ELECTRIC power distribution grids ,GREENHOUSE gas mitigation - Abstract
Unrenovated multifamily houses in Germany are mostly heated by fossil heat generators; therefore, measures are required for CO
2 emission reduction. The use of air–water heat pumps is restricted by high required flow temperatures and heat output but can be mitigated by hybrid heat pumps. To limit additional operation costs by the heat pump, a new operation strategy is introduced in this study, which allows to maintain a target CO2 emission. The operation strategy is applied in a field trial in a small unrenovated multifamily house built in 1964. A thermohydraulic simulation model is verified and is used in full-year simulations to apply improvement measures and compare the new control strategy with existing optimizing strategies. The results show that the control onto target emissions is possible and limits additional costs but can also result in higher CO2 mitigation costs, making it less favorable. The hybrid heat pump reduces the direct fossil CO2 emissions by 61% (in total by 22%); thus, it is a relevant solution for multifamily houses, especially within a further decarbonized electrical grid. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
17. Primary energy and comfort performance of ventilation assisted thermo-active building systems in continental climates
- Author
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Henze, Gregor P., Felsmann, Clemens, Kalz, Doreen E., and Herkel, Sebastian
- Published
- 2008
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18. Advances in near-optimal control of passive building thermal storage
- Author
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Henze, Gregor P., Florita, Anthony R., Brandemuehl, Michael J., Felsmann, Clemens, and Cheng, Hwakong
- Subjects
Heat storage devices -- Properties ,Buildings -- Equipment and supplies ,Engineering and manufacturing industries ,Environmental issues - Abstract
Using a simulation and optimization environment, this paper presents advances toward near-optimal building thermal mass control derived from full factorial analyses of the important parameters influencing the passive thermal storage process for a range of buildings and climate/utility rate structure combinations. Guidelines for the application of, and expected savings from, building thermal mass control strategies that can be easily implemented and result in a significant reduction in building operating costs and peak electrical demand are sought. In response to the actual utility rates imposed in the investigated cities, fundamental insights and control simplifications are derived from those buildings deemed suitable candidates. The near-optimal strategies are derived from the optimal control trajectory, consisting of four variables, and then tested for effectiveness and validated with respect to uncertainty regarding building parameters and climate variations. Due to the overriding impact of the utility rate structure on both savings and control strategy, combined with the overwhelming diversity of utility rates offered to commercial building customers, this study cannot offer universally valid control guidelines. Nevertheless, a significant number of cases, i.e., combinations of buildings, weather, and utility rate structure, have been investigated, which offer both insights and recommendations for simplified control strategies. These guidelines represent a good starting point for experimentation with building thermal mass control for a substantial range of building types, equipments, climates, and utility rates. [DOI: 10.1115/1.4001466]
- Published
- 2010
19. Sensitivity analysis of optimal building thermal mass control
- Author
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Henze, Gregor P., Le, Thoi H., Florita, Anthony R., and Felsmann, Clemens
- Subjects
Buildings -- Heating, cooling and ventilation ,Cost control -- Methods ,Energy consumption ,Engineering and manufacturing industries ,Environmental issues - Abstract
In order to avoid high utility demand charges from cooling during the summer and to level a building's electrical demand profile, precooling of the building's massive structure can be applied to shift cooling-related thermal loads in response to utility pricing signals. Several previous simulation and experimental studies have shown that proper precooling can attain considerable reduction of operating cost in buildings. This paper systematically evaluates the merits of the passive building thermal capacitance to minimize energy cost for a design day using optimal control. The evaluation is conducted by means of a sensitivity analysis utilizing a dynamic building energy simulation program coupled to a popular technical computing environment. The optimal controller predicts the required extent of precooling (zone temperature set-point depression), depending on the utility rate structure, occupancy and on-peak period duration and onset, internal gains, building mass, occupancy period temperature set-point range, and weather as characterized by diurnal temperature and relative humidity swings. In addition to quantifying the building response, energy consumption, and utility cost, this paper extracts the dominant features of the optimal precooling strategies for each of the investigated cases so that guidelines for near-optimal building thermal mass savings may be developed in the future. [DOI: 10.1115/1.2770755]
- Published
- 2007
20. Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control
- Author
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Henze, Gregor P., Pfafferott, Jens, Herkel, Sebastian, and Felsmann, Clemens
- Published
- 2007
- Full Text
- View/download PDF
21. Development and Experimental Evaluation of Grey-Box Models for Application in Model Predictive Control of a Microscale Polygeneration System
- Author
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Sawant, Parantapa, B��rger, Adrian, Doan, Minh Dang, Felsmann, Clemens, and Pfafferott, Jens
- Subjects
FOS: Electrical engineering, electronic engineering, information engineering ,Systems and Control (eess.SY) ,Electrical Engineering and Systems Science - Systems and Control - Abstract
With the need for optimisation based supervisory controllers for complex energy systems, comes the need for reduced order system models representing not only the non-linear characteristics of the components, but also certain unknown process dynamics like their internal control logic. We present in this paper an extensive literature study of existing methods and a rational modelling procedure based on the grey-box methodology that satisfies the necessary characteristics for models to be applied in an economic-MPC of a real-world polygeneration system at the Offenburg University of Applied Sciences. The engineering application of the models and their fitting coefficients are shared in this paper. Finally, the models are evaluated against experimental data and the efficacy of the methodology is discussed based on quantitative and qualitative arguments.
- Published
- 2019
22. Evaluation of optimal control for active and passive building thermal storage
- Author
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Henze, Gregor P., Felsmann, Clemens, and Knabe, Gottfried
- Published
- 2004
- Full Text
- View/download PDF
23. Nearly zero energy renovation concepts for apartment buildings.
- Author
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Kurnitski, J., Kalamees, T., Kuusk, Kalle, Naumann, Jens, Gritzki, Annina, Felsmann, Clemens, De Carli, Michele, Tonon, Massimo, and Kurnitski, Jarek
- Published
- 2020
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- View/download PDF
24. Prediction of Inhalation Exposure on the Base of Nanomaterial Release Data and Propagation Modelling
- Author
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Göhler, Daniel, Gritzki, Ralf, Rösler, Markus, Felsmann, Clemens, R. R. Retamal Marín, and Stintz, Michael
- Published
- 2018
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25. Transformation Roadmap from High to Low Temperature District Heating Systems:Annex XI final report
- Author
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Averfalk, Helge, Werner, Sven, Felsmann, Clemens, Rühling, Karin, Wiltshire, Robin, and Svendsen, Svend
- Published
- 2017
26. Transformation Roadmap from High to Low Temperature District Heating Systems
- Author
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Averfalk, Helge, Werner, Sven, Felsmann, Clemens, Rühling, Karin, Wiltshire, Robin, Svendsen, Svend, Li, Hongwei, Faessler, Jérôme, Mermoud, Floriane, and Quiquerez, Loic
- Subjects
Energy efficiency ,Energy ,ddc:550 ,Temperature ,District Heating - Abstract
The condensed Transformation Roadmap can be expressed as: 1. Eliminate temperature errors in existing distribution networks and substations in order to make existing systems more efficient. This will reduce existing temperature levels. 2. Avoid these temperature errors in new network parts and in new substations. 3. Use heat exchangers with longer thermal lengths in substations for indirect connection of customer heating systems and closed hot water preparation. This will reduce the temperature differences between the warmer distribution waters and the colder fluids to be heated. 4. Reduce existing customer temperature demands by elimination of local temperature errors, reduction of heat demands by means of energy efficiency measures, and by installation of larger heating surfaces in radiator and ventilation systems. 5. New low temperature network parts in conjunction with existing systems can be connected by concurrent operation of these parts as secondary networks. 6. The long-term vision is to deliver heat to substations with a supply temperature of 50°C, while obtaining a return temperature of 20°C as annual average. However, the technical solutions for obtaining this low return temperature have yet not been defined.
- Published
- 2017
27. Experimentelle und numerische Untersuchung des Einflusses der Strahlungsasymmetrie auf die thermische Behaglichkeit am Beispiel temperierter Halbräume.
- Author
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Gritzki, Ralf, Schinke, Lars, Beyer, Maximilian, Seifert, Joachim, and Felsmann, Clemens
- Subjects
THERMAL comfort ,FLOW simulations ,HEAT radiation & absorption ,ATMOSPHERIC temperature - Abstract
Copyright of Bauphysik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
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28. IEA DHC Annex X report:Toward 4th Generation District Heating:Experience and Potential of Low-Temperature District Heating
- Author
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Dalla Rosa, Alessandro, Li, Hongwei, Svendsen, Svend, Werner, Sveb, Persson, Urban, Ruehling, Karin, Felsmann, Clemens, Crane, Martin, Burzynski, Robert, and Bevilacqua, Ciro
- Published
- 2014
29. Fully parallel, OpenGL-based computation of obstructed area-to-area view factors.
- Author
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Kramer, Stephan C., Gritzki, Ralf, Perschk, Alf, Rösler, Markus, and Felsmann, Clemens
- Subjects
HEAT radiation & absorption ,GAUSSIAN quadrature formulas ,COMPUTATIONAL complexity ,RADIATORS ,BIT rate - Abstract
We present a fully parallelized, high-performance, OpenGL-based approach to compute obstructed area-to-area (A2A) view factors for radiative heat transfer. The A2A view factors are computed from the defining surface integral by Gaussian quadrature. The values of the integrand, i.e. the point-to-area view factors, are computed using an OpenGL-based hemicube (HC) method to efficiently solve the obstruction problem by exploiting the hardware-accelerated visibility testing on modern graphics cards. The final steps to maximize hardware usage are rendering the HC and performing the numerical quadrature in parallel such that data transfer times are completely shadowed by computations. To demonstrate the power of our approach we compute the A2A view factor matrices for a warehouse equipped with ceramic infrared heaters and a test cabin conforming to EN 442 containing a section of a panel radiator. To judge the quality of the results we measure the deviation from unity of the area-weighted column sums of the view factor matrix and the error in radiant flux balance. Compared to a previous, ray-tracing-based implementation, we gain three orders of magnitude in speed in the view factor computation. Conservation of radiant flux is also substantially improved. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
30. Sensor-Based Machine Learning Approach for Indoor Air Quality Monitoring in an Automobile Manufacturing.
- Author
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Wandy, Yose, Vogt, Marcus, Kansara, Rushit, Felsmann, Clemens, and Herrmann, Christoph
- Subjects
AUTOMOBILE manufacturing ,AIR quality monitoring ,MACHINE learning ,ENERGY consumption ,AIR filters ,ELECTRIC power consumption ,INDOOR air quality ,MATHEMATICAL optimization - Abstract
The alternative control concept using emission from the machine has the potential to reduce energy consumption in HVAC systems. This paper reports on a study of alternative inputs for a control system of HVAC using machine learning algorithms, based on data that are gathered in a welding area of an automotive factory. A data set of CO 2 , fine dust, temperatures and air velocity was logged using continuous and gravimetric measurements during two typical production weeks. The HVAC system was reduced gradually each day to trigger fluctuations of emission. The data were used to train and test various machine learning models using different statistical indices, consequently to choose a best fit model. Different models were tested and the Long Short-Term Memory model showed the best result, with 0.821 discrepancy on R 2 . The gravimetric samples proved that the reduction of air exchange rate does not correlate to escalation of fine dust linearly, which means one cannot rely on just gravimetric samples for HVAC system optimization. Furthermore, by using machine learning algorithms, this study shows that by using commonly available low cost sensors in a production hall, it is possible to correlate fine dust data cost effectively and reduce electricity consumption of the HVAC. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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31. An investigation of optimal control of passive building thermal storage with real time pricing.
- Author
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Greensfelder, Erik M., Henze, Gregor P., and Felsmann, Clemens
- Subjects
HEAT storage devices ,BUILDINGS -- Equipment & supplies ,OFFICE building air conditioning ,COOLING - Abstract
The cost savings potential of optimal passive thermal storage control were examined for day-ahead real time electricity rate structures. The operational strategies of three office building models were optimized in four US cities (Chicago, New York, Houston and Los Angeles) using price and weather data for the summer of 2008. Optimization of building thermal mass was conducted using a predictive optimal controller to define supervisory strategies in terms of building global cooling temperature setpoints. A global minimization algorithm determined optimal setpoint trajectories for each day divided into four distinct time periods. Cost savings were found to range from 0 to 14% depending on the building, climate, and characteristics of the rate signal. The best cost savings occurred for price spikes or cool nighttime temperatures. Moreover, it was found that low internal gains favoured a more flexible precooling strategy, while high internal gains coupled with low thermal mass resulted in poor precooling performance. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
32. DIN V 18599 und die Bewertung von thermisch aktivierten Bauteilen.
- Author
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Schalk, Katrin and Felsmann, Clemens
- Published
- 2009
- Full Text
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33. An Empirical Validation of Modeling Solar Gains Through a Glazing Unit Using Building Energy Simulation Programs.
- Author
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Loutzenhiser, Peter G., Manz, Heinrich, Strachan, Paul A., Felsmann, Clemens, Frank, Thomas, Maxwell, Gregory M., and Oelhafen, Peter
- Subjects
COOLING ,THERMOPHYSICAL properties ,HEAT transfer ,ENERGY transfer ,THERMODYNAMICS - Abstract
Empirical validation of building energy simulation tools is an important component in assessing the reliability of the simulation software. An experiment performed in conjunction with the International Energy Agency's Task 34/Annex 43 was used to assess the performance of four building energy simulation codes used to model an outdoor test cell with a glazing unit. The experiment was run for a 20-day period during October 2004, and experimental cooling powers were compared with predictions from (1) EnergyPlus, (2) DOE-2.1E, (3) TRNSYS-TUD, and (4) ESP-r. Detailed code inputs for optical and thermophysical properties as well as the impact of thermal bridges were quantified through experiments and simulations; numerous statistical parameters and sensitivity analyses were implemented to facilitate a thorough comparison of predicted and experimental cooling powers. The mean percentage differences for all four codes were: 1.9% for EnergyPlus, -3.6% for DOE-2.1E, -6.2% for TRNSYS-TUD, and 3.1% for ESP-r. The implications of various modeling procedures as well as a detailed discussion of the results are provided, specifically concerning the sensitivity of the code cooling power predictions to the selection of convective heat transfer coefficients and algorithms. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
34. Experimental Analysis of Model-Based Predictive Optimal Control for Active and Passive Building Thermal Storage Inventory.
- Author
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Henze, Gregor P., Kalz, Doreen E., Simeng Liu, and Felsmann, Clemens
- Subjects
CONTROL theory (Engineering) ,HEATING ,HEAT engineering ,VENTILATION ,AIR conditioning ,ENVIRONMENTAL engineering of buildings ,HEATING & ventilation industry ,REFRIGERATION & refrigerating machinery - Abstract
This paper demonstrates model-based predictive optimal control of active and passive building thermal storage inventory in a test facility in real time using time-of-use differentiated electricity prices without demand charges. A novel supervisory controller successfully executed a three-step procedure consisting of (1) short-term weather prediction, (2) optimization of control strategy over the next planning horizon using a calibrated building model, and (3) post-processing of the optimal strategy to yield a control command for the current time step that can be executed in the test facility. All primary and secondary building mechanical systems were effectively orchestrated by the model-based predictive optimal controller in real time while observing comfort and operational constraints. It was determined that even when the optimal controller is given imperfect weather forecasts and when the building model used for planning control strategies does not match the actual building perfectly, measured utility cost savings relative to conventional building operation can be substantial. Central requirements are a facility that lends itself to passive storage utilization and a building model that includes a realistic plant representation. Savings associated with passive building thermal storage inventory proved to be small in this case because the test facility is not an ideal candidate for the investigated control technology. Moreover, the facility's central plant revealed the idiosyncratic behavior that the chiller operation in the ice-making mode was more energy efficient than in the chilled-water mode. Field experimentation is now required in a suitable commercial building with sufficient thermal mass, an active TES system, and a climate conducive to passive storage utilization over a longer testing period to support the laboratory findings presented in this study. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
35. Impact of Forecasting Accuracy on Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory.
- Author
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Henze, Gregor P., Felsmann, Clemens, Kalz, Doreen E., and Knabe, Gottfried
- Subjects
- *
ENVIRONMENTAL engineering of buildings , *WEATHER forecasting , *HEAT storage , *ENVIRONMENTAL engineering , *CONTROL theory (Engineering) , *FORECASTING - Abstract
This paper evaluates the benefits of combined optimal control of both passive building thermal capacitance and active thermal energy storage systems to minimize total utility cost in the presence of forecasting uncertainty in the required short-term weather forecasts. Selected short-term weather forecasting models are introduced and investigated with respect to their forecasting accuracy as measured by root mean square error, mean bias error, and the coefficient of variation. The most complex model, a seasonal autoregressive integrated moving average (SARIMA), shows the worst performance, followed by a static predictor model that references standard weather archives. The best prediction accuracy is found for bin models that develop a characteristic daily profile from observations collected over the past 30 or 60 days. The model that projects yesterday's patterns one day into the future proved to be a surprisingly poor predictor. We test the predictor models in the context of a predictive optimal control task that optimizes building global temperature setpoints and active thermal energy storage charge/discharge rates in a closed-loop mode. For the four locations investigated in this article—Chicago, IL, Denver, CO, Omaha, NE, and Phoenix, AZ—it was determined that the 30-day and 60-day bin predictor models lead to utility cost savings that are only marginally inferior compared to a hypothetical perfect predictor that perfectly anticipates the weather during the next planning horizon. In summary, the predictive optimal control of active and passive building thermal storage inventory using time-of-use electrical utility rates with significant on-peak to off-peak rate differentials and demand charges is a highly promising control strategy when perfect weather forecasts are available. The primary finding of this paper is that it takes only very simple short-term prediction models to realize almost all of the theoretical potential of this technology. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
36. Optimization of Building Thermal Mass Control in the Presence of Energy and Demand Charges.
- Author
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Henze, Gregor P., Brandemuehl, Michael J., Felsmann, Clemens, Hwakong Cheng, Florita, Anthony R., and Waters, Clarence E.
- Subjects
- *
ENVIRONMENTAL engineering of buildings , *HEAT storage , *AIR conditioning , *VENTILATION , *ENERGY conservation , *COST control - Abstract
Thermal load shifting in commercial buildings has previously been employed, in anticipation of costly time-of-use (TOU) and peak electrical-demand utility charges, by precooling a building's massive structure to take advantage of its inherent thermal capacitance. In both theoretical and experimental studies, supervisory control has mostly been evaluated heuristically to determine cost reduction from a typical night- time setup strategy However, the applicability of these results are limited. This paper describes the development of an optimal passive thermal-mass control simulation environment, in which a dynamic building simulation program is coupled to a popular technical computing environment for total utility cost minimization, including both energy and demands charges. The relative alignment of utility and occupancy schedules defines how the optimal control trajectory is calculated, and is characterized by: (1) a precooling duration and temperature setpoint during the unoccupied and off-peak period, (2) an occupied period temperature setpoint before on-peak, (3) an occupied, on-peak postcooling duration and temperature setpoint, and finally (4) an exponential controlled release of storage to the upper comfort limit described by a time constant. With demand commonly charged over a monthly billing period, the environment features an outer loop, where a target demand limit is enforced in the underlying energy cost optimization. The underlying monthly optimization is a closed-loop certainty-equivalent model predictive control optimization, with a 48-hour planning and a 24-hour execution-time horizon, and the Nelder-Mead Simplex method as the solver. The environment was formulated to evaluate factors that drive the cost savings potential in building thermal mass control and to allow for model-based predictive control in future work. [ABSTRACT FROM AUTHOR]
- Published
- 2008
37. Investigation on the heat extraction performance of deep closed-loop borehole heat exchanger system for building heating
- Author
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Chen, Chaofan, Kolditz, Olaf, Shao, Haibing, Felsmann, Clemens, Wang, Fenghao, and Technische Universität Dresden
- Subjects
ddc:690 ,Tiefengeothermie, Erdwärmesonde im geschlossenen Kreislauf, Gebäudeheizung, Langzeitverhalten, Geothermiekraftwerk, OpenGeoSys ,Deep geothermal energy, Closed-loop borehole heat exchanger, Building heating, Long-term performance, Geothermal power plant, OpenGeoSys - Abstract
In recent years, deep geothermal energy has been widely exploited through closed-loop borehole heat exchanger system for building heating. In order to precisely evaluate the sustainable heat extraction capacity and the impact of different designs and operating parameters, two heat transfer models are implemented in the open-source scientific software OpenGeoSys (OGS), with respect to the Deep Borehole Heat Exchanger (DBHE) and Enhanced U-tube Borehole Heat Exchanger (EUBHE) system. Besides, three types of boundary conditions are implemented, including the constant inflow temperature, the constant heat extraction rate, and constant building thermal power that integrates the ground source heat pump (GSHP) module. By applying the two BHE models, the influence of different designs and operating parameters on the GSHP system is evaluated. The sustainable heat extraction capacity and efficiency of a deep EUBHE system are predicted. Moreover, its performance and efficiency are further compared against the 2-DBHE array system that has the same total borehole length. It is found that the soil thermal conductivity is the most important parameter in the design of DBHE and EUBHE systems. The sustainable specific heat extraction rate of the EUBHE system is 86.5 W/m higher than an array with 2 DBHEs. Under the building thermal load of 1.225 MW, the total electricity consumed by the EUBHE system is approximately 27 % less than the 2-DBHE array over 10 years. The average Coefficient of System Performance (CSP) value of the EUBHE system is 1.66 higher over 10 heating seasons. The two numerical models implemented in the OpenGeoSys software can be used to predict and optimize the thermal characteristics of the closed-loop DBHE and EUBHE systems in real projects.
- Published
- 2021
38. Evaluation of the Primary Factors Impacting the Optimal Control of Passive Thermal Storage.
- Author
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Hwakong Cheng, Brandemuehl, Michael J., Henze, Gregor P., Florita, Anthony R., and Felsmann, Clemens
- Subjects
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HEAT storage , *HEAT engineering , *THERMODYNAMICS , *COST control , *ENERGY conservation - Abstract
This paper identifies the primary factors that impact the optimal control of passive thermal storage. Optimal control strategies are determined with the objective of minimizing total energy and demand costs using an integrated optimization and building simulation tool. A fractional factorial analysis is employed to investigate how cost savings are affected by several building and system characteristics, utility rate structures, and climates. Utility rates, internal loads, building mass level, and equipment efficiency are found to have the largest impacts on cost savings, whereas building envelope characteristics do not have a significant impact. Although the magnitude of the savings is affected by climate, the relative impacts of each of these factors are largely independent of weather [ABSTRACT FROM AUTHOR]
- Published
- 2008
39. Development and experimental evaluation of grey-box models of a microscale polygeneration system for application in optimal control.
- Author
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Sawant, Parantapa, Bürger, Adrian, Doan, Minh Dang, Felsmann, Clemens, and Pfafferott, Jens
- Subjects
- *
PREDICTIVE control systems , *HEAT storage , *BANKING laws , *INTELLIGENT buildings , *LITERATURE studies - Abstract
Optimisation based economic despatch of real-world complex energy systems demands reduced order and continuously differentiable component models that can represent their part-load behaviour and dynamic responses. A literature study of existing modelling methods and the necessary characteristics the models should meet for their successful application in model predictive control of a polygeneration system are presented. Deriving from that, a rational modelling procedure using engineering principles and assumptions to develop simplified component models is applied. The models are quantitatively and qualitatively evaluated against experimental data and their efficacy for application in a building automation and control architecture is established. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
40. Developing a Decision Making Approach for District Cooling Systems Design using Multi-objective Optimization
- Author
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Kamali, Aslan, Felsmann, Clemens, Antwan, Nazar, and Technische Universität Dresden
- Subjects
ddc:621.3 ,Fernkälte, Lineare Optimierung, MILP, Stadtplanung, Pareto-Optimierung, Entscheidungsfindung, Erneuerbare-Energie-Integration ,District Cooling, Linear Optimization, MILP, Urban Planning, Multi objective (Pareto) optimization, Decision making, Renewable-energy integration ,ddc:620 - Abstract
Energy consumption rates have been dramatically increasing on a global scale within the last few decades. A significant role in this increase is subjected by the recent high temperature levels especially at summer time which caused a rapid increase in the air conditioning demands. Such phenomena can be clearly observed in developing countries, especially those in hot climate regions, where people depend mainly on conventional air conditioning systems. These systems often show poor performance and thus negatively impact the environment which in turn contributes to global warming phenomena. In recent years, the demand for urban or district cooling technologies and networks has been increasing significantly as an alternative to conventional systems due to their higher efficiency and improved ecological impact. However, to obtain an efficient design for district cooling systems is a complex task that requires considering a wide range of cooling technologies, various network layout configuration possibilities, and several energy resources to be integrated. Thus, critical decisions have to be made regarding a variety of opportunities, options and technologies. The main objective of this thesis is to develop a tool to obtain preliminary design configurations and operation patterns for district cooling energy systems by performing roughly detailed optimizations and further, to introduce a decision-making approach to help decision makers in evaluating the economic aspects and environmental performance of urban cooling systems at an early design stage. Different aspects of the subject have been investigated in the literature by several researchers. A brief survey of the state of the art was carried out and revealed that mathematical programming models were the most common and successful technique for configuring and designing cooling systems for urban areas. As an outcome of the survey, multi objective optimization models were decided to be utilized to support the decision-making process. Hence, a multi objective optimization model has been developed to address the complicated issue of decision-making when designing a cooling system for an urban area or district. The model aims to optimize several elements of a cooling system such as: cooling network, cooling technologies, capacity and location of system equipment. In addition, various energy resources have been taken into consideration as well as different solar technologies such as: trough solar concentrators, vacuum solar collectors and PV panels. The model was developed based on the mixed integer linear programming method (MILP) and implemented using GAMS language. Two case studies were investigated using the developed model. The first case study consists of seven buildings representing a residential district while the second case study was a university campus district dominated by non-residential buildings. The study was carried out for several groups of scenarios investigating certain design parameters and operation conditions such as: Available area, production plant location, cold storage location constraints, piping prices, investment cost, constant and variable electricity tariffs, solar energy integration policy, waste heat availability, load shifting strategies, and the effect of outdoor temperature in hot regions on the district cooling system performance. The investigation consisted of three stages, with total annual cost and CO2 emissions being the first and second single objective optimization stages. The third stage was a multi objective optimization combining the earlier two single objectives. Later on, non-dominated solutions, i.e. Pareto solutions, were generated by obtaining several multi objective optimization scenarios based on the decision-makers’ preferences. Eventually, a decision-making approach was developed to help decision-makers in selecting a specific solution that best fits the designers’ or decision makers’ desires, based on the difference between the Utopia and Nadir values, i.e. total annual cost and CO2 emissions obtained at the single optimization stages. Die Energieverbrauchsraten haben in den letzten Jahrzehnten auf globaler Ebene dramatisch zugenommen. Diese Erhöhung ist zu einem großen Teil in den jüngst hohen Temperaturniveaus, vor allem in der Sommerzeit, begründet, die einen starken Anstieg der Nachfrage nach Klimaanlagen verursachen. Solche Ereignisse sind deutlich in Entwicklungsländern zu beobachten, vor allem in heißen Klimaregionen, wo Menschen vor allem konventionelle Klimaanlagensysteme benutzen. Diese Systeme verfügen meist über eine ineffiziente Leistungsfähigkeit und wirken sich somit negativ auf die Umwelt aus, was wiederum zur globalen Erwärmung beiträgt. In den letzten Jahren ist die Nachfrage nach Stadt- oder Fernkältetechnologien und -Netzwerken als Alternative zu konventionellen Systemen aufgrund ihrer höheren Effizienz und besseren ökologischen Verträglichkeit satrk gestiegen. Ein effizientes Design für Fernkühlsysteme zu erhalten, ist allerdings eine komplexe Aufgabe, die die Integration einer breite Palette von Kühltechnologien, verschiedener Konfigurationsmöglichkeiten von Netzwerk-Layouts und unterschiedlicher Energiequellen erfordert. Hierfür ist das Treffen kritischer Entscheidungen hinsichtlich einer Vielzahl von Möglichkeiten, Optionen und Technologien unabdingbar. Das Hauptziel dieser Arbeit ist es, ein Werkzeug zu entwickeln, das vorläufige Design-Konfigurationen und Betriebsmuster für Fernkälteenergiesysteme liefert, indem aureichend detaillierte Optimierungen durchgeführt werden. Zudem soll auch ein Ansatz zur Entscheidungsfindung vorgestellt werden, der Entscheidungsträger in einem frühen Planungsstadium bei der Bewertung städtischer Kühlungssysteme hinsichtlich der wirtschaftlichen Aspekte und Umweltleistung unterstützen soll. Unterschiedliche Aspekte dieser Problemstellung wurden in der Literatur von verschiedenen Forschern untersucht. Eine kurze Analyse des derzeitigen Stands der Technik ergab, dass mathematische Programmiermodelle die am weitesten verbreitete und erfolgreichste Methode für die Konfiguration und Gestaltung von Kühlsystemen für städtische Gebiete sind. Ein weiteres Ergebnis der Analyse war die Festlegung von Mehrzieloptimierungs-Modelles für die Unterstützung des Entscheidungsprozesses. Darauf basierend wurde im Rahmen der vorliegenden Arbeit ein Mehrzieloptimierungs-Modell für die Lösung des komplexen Entscheidungsfindungsprozesses bei der Gestaltung eines Kühlsystems für ein Stadtgebiet oder einen Bezirk entwickelt. Das Modell zielt darauf ab, mehrere Elemente des Kühlsystems zu optimieren, wie beispielsweise Kühlnetzwerke, Kühltechnologien sowie Kapazität und Lage der Systemtechnik. Zusätzlich werden verschiedene Energiequellen, auch solare wie Solarkonzentratoren, Vakuum-Solarkollektoren und PV-Module, berücksichtigt. Das Modell wurde auf Basis der gemischt-ganzzahlig linearen Optimierung (MILP) entwickelt und in GAMS Sprache implementiert. Zwei Fallstudien wurden mit dem entwickelten Modell untersucht. Die erste Fallstudie besteht aus sieben Gebäuden, die ein Wohnviertel darstellen, während die zweite Fallstudie einen Universitätscampus dominiert von Nichtwohngebäuden repräsentiert. Die Untersuchung wurde für mehrere Gruppen von Szenarien durchgeführt, wobei bestimmte Designparameter und Betriebsbedingungen überprüft werden, wie zum Beispiel die zur Verfügung stehende Fläche, Lage der Kühlanlage, örtliche Restriktionen der Kältespeicherung, Rohrpreise, Investitionskosten, konstante und variable Stromtarife, Strategie zur Einbindung der Solarenergie, Verfügbarkeit von Abwärme, Strategien der Lastenverschiebung, und die Wirkung der Außentemperatur in heißen Regionen auf die Leistung des Kühlsystems. Die Untersuchung bestand aus drei Stufen, wobei die jährlichen Gesamtkosten und die CO2-Emissionen die erste und zweite Einzelzieloptimierungsstufe darstellen. Die dritte Stufe war ein Pareto-Optimierung, die die beiden ersten Ziele kombiniert. Im Anschluss wurden nicht-dominante Lösungen, also Pareto-Lösungen, erzeugt, indem mehrere Pareto-Optimierungs-Szenarien basierend auf den Präferenzen der Entscheidungsträger abgebildet wurden. Schließlich wurde ein Ansatz zur Entscheidungsfindung entwickelt, um Entscheidungsträger bei der Auswahl einer bestimmten Lösung zu unterstützen, die am besten den Präferenzen des Planers oder des Entscheidungsträgers enstpricht, basierend auf der Differenz der Utopia und Nadir Werte, d.h. der jährlichen Gesamtkosten und CO2-Emissionen, die Ergebnis der einzelnen Optimierungsstufen sind.
- Published
- 2016
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