
Dirk MuellerRWTH Aachen University · Institute for Energy Efficient Buildings and Indoor Climate
Dirk Mueller
Univ.-Prof. Dr.-Ing.
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966
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Introduction
Skills and Expertise
Publications
Publications (966)
This paper provides a comprehensive comparative analysis of smart building solution providers within Europe, emphasizing the technological advancements and market strategies employed by companies selected for the study. As energy efficiency becomes a critical focus due to rising global energy demands and climate change concerns, smart building tech...
Citation: Nabilou, F.; Derwein, D.; Kirmas, A.; Dhake, A.; Vogt, R.; Eckstein, L.; Rewitz, K.; Müller, D. A Manikin-Based Study of Particle Dispersion in a Vehicle Cabin. Atmosphere 2025, 16, 116. https:// Abstract: Recently, there has been a growing interest in understanding how respiratory particles spread within passenger cars, especially in lig...
Zusammenfassung
Die Effizienz von Wärmepumpen wird maßgeblich durch das verwendete Kältemittel bestimmt. Dabei haben sich Kohlenwasserstoffe wie Propan (R290) in vielen Anwendungen etabliert. Neben Reinstoffen bieten zeotrope Gemische das Potenzial, die Effizienz zu steigern, indem aufgrund des resultierenden Temperaturgleits die Verluste während d...
Building control architectures are strongly limited by the systematic lack of measurements at user-relevant locations. This paper proposes a digital twin architecture grounded in Correlated Gaussian Processes (Corr-GP) that provide information in the form of pseudo-measurements. Tested with thermal and CO
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In dem öffentlichen Forschungsprojekt „AkuPerat“ wurde das aeroakustische Verhalten von handelsüblichen Decken-Luftdurchlässen untersucht. Hierzu kamen neben strömungstechnischen Experimenten und akustischen Messungen auch psychoakustische Auswertungen zum Einsatz. In Hörversuchen konnte festgestellt werden, dass die Präferenz der untersuchten Durc...
District heating (DH) systems play a pivotal role in decarbonizing the building sector's heat supply. While innovative low-exergy DH and cooling systems are increasingly adopted in new developments, the transformation of existing DH systems remains critical, as many still depend on fossil-based heating plants. Achieving a sustainable heat supply ne...
Heat pumps are one of the key technologies to reduce CO2-emissions and reach a net zero building stock. However, heat pumps still induce CO2-emissions, which split up into direct and indirect emissions. Direct emissions result from leakages on site and indirect emissions mainly relate to the power consumption. In particular, the refrigerant choice...
Ground-source heat pumps (GSHPs) coupled with borehole heat exchangers (BHEs) are energy-efficient technologies for heating and cooling buildings. However, these systems often fail to operate at their full potential due to discrepancies between the assumptions made during the design phase and the actual conditions during operation. To enhance overa...
Im IBPSA Project 1 wurde neben der Kernbibliothek Modelica‐IBPSA auch die Bibliothek AixLib zur quelloffenen Modellierung von Gebäudeenergiesystemen mit Modelica entwickelt. Verglichen mit dem speziell für die energetische Gebäudesimulation entwickelten quelloffenen Programm EnergyPlus ermöglichen die Modelica‐Bibliotheken eine physikalisch realist...
Vorstellung einer Methode zur frühen Kältemittelleckagedetektion basierend auf Vibrationssensoren
Results of an experimental investigation including low-GWP refrigerants and zeotropic mixtures for the use in residential heat pumps.
In addition to the experimental results, a simulation-based optimization is conducted to investigate the maximum improvement potential for the residential area with zeotropic mixtures based on natural refrigerants.
Hydrofluorocarbons (HFCs) and so-called hydrofluoroolefins (HFOs) are used as refrigerants in air conditioning, refrigeration, chillers, heat pumps and devices for dehumidification and drying. However, many HFCs, including R-134a and R-125, have a high global warming potential and some of the HFCs and HFOs degrade atmospherically and form trifluoro...
The increasing utilisation of demand-controlled ventilation strategies leads to the frequent operation of fans under part-load conditions. To accurately predict the energy demand of a ventilation system with a fan array in the early design stages, models that calculate reliable results across the whole operating range are required. We present the c...
This paper investigates thermostat interventions and window openings across 77 offices during the heating and transition seasons of 2023. A cloud-based heating controller, that takes user preferences and anticipated presence schedules,was evaluated in two buildings of the Living Lab Energy Campus (LLEC) at Forschungszentrum Jülich, Germany. Occupan...
Model predictive control is a promising approach to robustly control complex energy systems, such as hybrid battery-hydrogen energy storage systems that enable seasonal storage of renewable energies. However, deriving a mathematical model of the energy system suitable for model predictive control is difficult due to the unique characteristics of ea...
In heat pumps, the use of refrigerants with a low global warming potential (GWP) gains importance due to increasingly strict regulations regarding their ecological impact. In this regard, hydrocarbons (HCs), hydrofluoroolefins (HFOs), and their mixtures are the most promising options due to their thermodynamic properties. Besides the impact of the...
Transforming existing district heating (DH) systems to provide efficient and climate-neutral heat supply to buildings is a huge challenge. Large DH systems in densely populated cities are particularly complicated to transform, as the building stock in such cities is very heterogeneous. The rapid evaluation of transformation measures or the identifi...
FIWARE, an open-source initiative providing open-source software platform components and a set of standardized APIs (Application Programming Interfaces), has been instrumental in driving digitalization across various domains and research fields (Araujo et al., 2019). The use of FIWARE enables faster, easier, and cheaper developments of a wide range...
This study introduces a scalable, cloud-based approach to occupancy monitoring designed to optimize HVAC operations in office buildings. It addresses the challenges of developing and implementing a multi-parameter IoT-based occupancy monitoring system by integrating various off-the-shelf sensors—CO2, infrared (IR), motion (PIR), and door status det...
The increasing demand for heat pumps reveals bottlenecks in installation and maintenance processes. Concurrently, the number of service requests increases due to the growing number of heat pumps in operation that are subject to wear. To avoid shifting bottlenecks from installation to maintenance to services, there is an urgent need to minimize the...
In heat pumps, the use of hydrocarbons and their mixtures becomes increasingly important due to their low global warming potential and thermodynamic potential. The overall potential and the corresponding overall efficiency depend on the refrigerants, mixture composition, and cycle configuration (e.g., basic cycle and internal heat exchanger cycle)....
Enthalpy exchangers recovering sensible and latent heat have an increasing share of use in residential ventilation. In this study, we introduce an optimization approach for membrane-based enthalpy exchanger (MEE). Therefore, we develop a system model, combine it with a genetic optimization algorithm and optimize the design regarding energy demand a...
Hydrofluorocarbons (HFCs) and so-called hydrofluoroolefins (HFOs) are used as refrigerants in air conditioning, refrigeration, chillers, heat pumps and devices for dehumidification and drying. However, many HFCs, including R-134a and R-125, have a high global warming potential and some of the HFCs and HFOs degrade atmospherically and form persisten...
In heat pumps, the use of refrigerants with a low global warming potential (GWP) gains improtance due the increasingly strict regulations regarding their ecologic impact. In this regard, hydrocarbons (HCs), hydrofluoroolefins (HFOs), and their mixtures are the most promising options due to their thermodynamic properties. Besides the impact of the r...
Model predictive control (MPC) is a promising approach for optimizing the performance of borehole heat exchangers (BHEs) in ground-source heat pump systems. The central element of MPC is the forward model that predicts the thermal dynamics in the ground. In this work, we validate the prediction accuracy of four BHE modeling approaches against real-...
Introduction
Studies support the association of core body temperature with the circadian rhythm and cognitive performance aspects, including alertness. Additionally, evidence shows that lower ambient temperatures improve cognitive performance. However, less is known on the dynamic effect of ambient temperature on alertness, which could also follow...
The transformation process in the building sector towards future city concepts requires changes in our society that aim for significant emission reduction until 2045. Currently, buildings in Germany are constructed and operated in such a way that no changes need to be made to them for decades. Therefore, any upcoming changes that do not achieve the...
Heat pumps are a key technology in the transition to a carbon-neutral residential building stock. This study examines the barriers to their adoption in existing multi-family houses, in particular the technical challenges posed by high system temperature requirements. Existing literature mainly focuses on temperature reduction measures in single-fam...
Air-source heat pumps (ASHPs) are essential in driving Europe's transition towards decarbonized residential heating. Key aspects to enhance the market reach of ASHPs include increasing their energy efficiency and reducing their noise emissions. Both the efficiency of the heat pump and its sound emissions are closely linked to the rotational speeds...
Development of an ontology for expert-based fault detection and diagnosis in air handling units.
This paper presents a Fault Detection and Diagnosis methodology for district heating substations, leveraging Machine Learning and Internet of Things technologies. By employing a two-stage approach that combines multiple regression models with a knowledge-based diagnosis system, our work addresses the challenge of fault detection in the absence of l...
The COVID-19 pandemic has led to a significant increase in working from home worldwide, making the work-from-home (WFH) setting a crucial context for studying the influence of indoor environmental quality (IEQ) on workers’ well-being and productivity. A narrative and visual synthesis of 41 research articles on IEQ in WFH settings was conducted to i...
Integrating sustainable heat sources into district heating systems is crucial to reduce the mainly fossil-based heat supply in the building sector. However, integrating a heat source into an existing district heating system can be challenging due to non-matching temperature levels or unfavourable availability of the heat source intended for utilisa...
Für die Energiewende stellt die Wärmepumpe eine entscheidende Lösungsmöglichkeit dar. Fast 80 % aller bis heute verbauten Wärmepumpen sind Luft-Wasser-Wärmepumpen (LWWP), die Umgebungsluft als Wärmequelle verwenden und einem Wasserkreislauf zur Verfügung stellen. Diese Ausführungsform benötigt neben einem Verdichter einen oder mehrere Ventilatoren...
Zur Verbesserung der Luftqualität in Innenräumen werden in immer mehr Gebäuden Lüftungsgeräte eingebaut, welche eine kontinuierliche Frischluftzufuhr sicherstellen. Jedoch entsteht der unerwünschte Nebeneffekt von Luftüngsgeräuschen. Werden die Systeme bei niedrigen Volumenströmen betrieben, kann dies schon zu Schallleistungspegeln knapp über typis...
The consequences of climate change are already visible, and yet, its effect on psychosocial factors, including the expression of empathy, affect, and social disconnection, is widely unknown. Outdoor conditions are expected to influence indoor conditions. Therefore, the aim of this study was to investigate the effect of indoor air temperature during...
Automated vehicles offer many advantages, but also entail an increased risk of motion sickness. To avoid such an aversive experience, early and reliable detection of individual states of motion sickness is required to initiate appropriate countermeasures. To this end, a study was conducted to investigate different measures of motion sickness while...
With the introduction of novel automated vehicles (AVs), drivers are becoming passengers who could be susceptible to motion sickness symptoms in cars (carsickness). Therefore, it is advisable to adapt driving characteristics like accelerations, braking, lane change behaviors based on the sensitivity of the passengers. Physiological markers play an...
This study provides a detailed exploration of how innovation management and digital entrepreneurship models can help transform technical use cases in smart grid contexts into viable business cases, thereby bridging the gap between technical potential and market application in the field of energy informatics. It focuses on the I-GReta project Use Ca...
By considering forecasts and exploiting storage effects, model predictive control can achieve significant energy and cost savings in the building sector. However, due to the high individual modeling effort, model predictive control lacks practical applicability. For that reason, data-driven process models, approximating the system behavior based on...
To achieve climate goals, the European Union needs to increase building renovation rates. In owner-occupied buildings, energy cost savings provide financial incentives for renovation. However, 30% of all Europeans live in rented property, where conflicting stakeholder interests arise. Landlords are responsible for renovation decisions (building env...
During the SARS-CoV-2 pandemic, the air quality and infection risk in classrooms were the focus of many investigations. Despite general recommendations for sufficient ventilation, quantitative analyses were often lacking due to the large number of combinations of boundary conditions. Hence, in this paper, we describe a computational fluid dynamics...
The increasing adoption of heat pumps presents new challenges for power grids, including the potential overloading of transformers and cables. To address this issue, in this work, a Model Predictive Control (MPC) for a Low-Temperature District Heating (LTDH) network is proposed to prevent the overloading of transformers and cables. A comprehensive...
Energy communities can be created in neighborhoods in a geographically and structural delineated area. Local energy markets in energy communities offer a promising approach to promote local balancing of distributed power generation and consumption. These markets enable direct energy trading between prosumers and consumers, resulting in financial be...
Faulty programming of control functions in Building Automation and Control Systems (BACS) might result in inefficient building operations. To reduce programming errors, an automated implementation process of control functions might be a promising solution. Recently, Building Information Modeling (BIM) contributes to digitizing building construction...
Modelica enables an object-oriented approach to model complex systems in product development and research, and, thus, the development of various model libraries. Library development requires collaborative development in a team of multiple developers. A typical challenge in collaborative development, especially in the area of open source, is to crea...
Domain-overarching system models are crucial to investigate sector coupling concepts. Specifically, the coupling of building and electrical energy systems becomes crucial to integrate renewable energy sources such as photovoltaic power systems (PV). For such interdisciplinary simulation models, Modelica is a suitable language. However, most open-so...
Decarbonizing the heating sector requires the increased use of large-scale heat pumps in district heating. In Germany, these are still very rare due to high investments and operating costs. To reduce the operating costs, a high plant efficiency is required. Science efficiency strongly depends on the temperature lift between the heat source and sink...
Exergieanalyse verschiedener Injektionszustände abhängig von den Betriebsgrenzen eines Scrollverdichters bei Verwendung eines Economizers
The Districtgenerator enables an automated generation of time-resolved load profiles for residential districts. The profiles generated for each building within the district are the demands for electricity, space heating demand, domestic hot water, and the occupancy profiles. Additionally, a heating load calculation is carried out for each building....
Non-residential buildings are equipped with building automation systems (BAS). BAS provide a vast amount of building operation data. However, the analysis of this data is laborious and requires a scalable and automated process. The authors developed the BUDO schema for a standardized, object-oriented description of monitoring metadata. The translat...
Improving control loops in buildings is cost-intensive due to the need of expert time. With well structured data, the development of data-driven algorithms is promising to minimize the required time. But data stream names across buildings do not follow a uniform naming schema.
We developed a method to identify temperature control loops (sensors and...
As energy efficiency demands increase, buildings get smarter, and the amount of data to analyze grows, where each building device may generate multiple data streams. These extensive quantities of monitoring data serve as a great opportunity for detecting anomalies in building automation systems and for optimizing their control. However, each buildi...