Comparison between two genetic algorithms minimizing carbon footprint of energy and materials in a residential building

The emergence of building performance optimization is recognized as a way to achieve sustainable building designs. In this paper, the problem consists in minimizing simultaneously the emissions of greenhouse gases (GHG) related to building energy consumption and those related to building materials. This multi-objective optimization problem involves variables with different hierarchical levels, i.e. variables that can become obsolete depending on the value of the other variables. To solve it, NSGA-II is compared with an algorithm designed specifically to deal with hierarchical variables, namely sNSGA. Evaluation metrics such as convergence, diversity and hypervolume show that both algorithms handle hierarchical variables, but the analysis of the Pareto front confirms that in the present case, NSGA-II is better to identify optimal solutions than sNSGA. All the optimal solutions are made of buildings with wooden envelopes and relied either on heat pumps or on electrical heaters for proving heating

Determination of requirements on occupant behavior models for the use in building performance simulations

The following article illuminates existing challenges and restrictions when implementing available stochastic user behavior models in building performance simulation (BPS). 24 occupancy behavior models from the literature containing a clear mathematical description are attempted to be coupled with a BPS model in a case study. Different methods, amongst others co-simulation approaches benefitting from the Functional Mock-up Interface (FMI) standard, were investigated to realize the implementation. The majority of OB models were coupled successfully with the BPS; however, some were not. The reason for the failed coupling is rather based on the restriction of OB models for BPS use than the coupling methods. Generally, OB models are based on stochastic modeling, while BPS requires a clear decision, a trigger for further interaction. Some OB models do not provide an output in such a binary form. Therefore, it is difficult to use these models in BPS without any assumption from the modeler. Furthermore, the majority of OB models lead to a state change depending on a comparison between its computed probability and a random number, which conflicts with the reproducibility of BPS results. In addition, some OB models result in an improper behavior without a reversal function or hysteresis. Based on the case study, these issues and requirements for OB models for the use in BPS as well as the advantages and disadvantages of various coupling approaches with BPS are discussed

Thermische Behaglichkeit bei Temperaturübergängen: Literaturstudie und ‐analyse von Probandenexperimenten

In recent decades, the possibilities for the targeted control of climatic parameters in interiors have changed significantly due to high-performance HVAC-systems. Even though most of the rooms are naturally ventilated, there are no technically limits for regulation of the indoor climate. At the same time, the world of work has dramatically changed, offices and other rooms are often used only temporarily and also shared. However, the desired indoor conditions are based still on steady-state temperature set-points for whole operation duration. For concepts for the dynamic control and regulation of the indoor climate, there is a lack of scientific evidence for the evaluation of thermal comfort under transient conditions. In the context of this work a literature study on subject studies in transient climatic conditions was carried out. A descriptive description and a comparison of these subject studies was made to gain new insights into the thermal comfort after temperature transitions from the totality of these studies

Effiziente Strahlungssimulation für ein thermisches Behaglichkeitsmodell

The presented work analyses the local effects of asymmetric shortwave and longwave radiation in complex 3D building models. The new simulation tool provides thermal loads caused by non-uniform radiant temperatures and solar irradiation in indoor environments. The method implements efficient raytracing and viewfactor calculation on programmable graphic processing units. Therefor temperature based longwave radiation exchange and heat gains from direct and diffuse solar radiation are computed. Models of globe-thermometers are placed in selected room positions, in order to investigate local radiation impacts. Accurate analysis of local thermal conditions is enabled by detailed virtual manikin models. Radiant temperatures are evaluated by means of directional quantities, since asymmetric radiation is known to effect thermal comfort

Concepts for comfortable air-conditioning - simulation using a zonal cabin model and a metrological evaluation based on equivalent temperature

In the design of future electric vehicles, the air conditioning of the passenger compartment is considered as the largest auxiliary consumer. To test new climate control concepts and quantify their effectiveness in terms of user acceptance, energy efficiency and driving range, corresponding methods and tools are needed. This includes the numerical, experimental and subject-supported study regarding human thermal comfort. New developed zonal models simulate air flow and temperature, surface temperature, pressure and also humidity in a closed environment. Predicting indoor environmental conditions in vehicle cabin is achieved in transient inhomogeneous load cases. With the combination of a radiation model, the long-wave radiation exchange between human and cabin is included in the heat balance equation with a high level of detail. In order to improve the assessment of the local thermal conditions near the passenger, a climate measurement system (DressMAN 2.0) was developed by the Fraunhofer Institute for Building Physics (IBP). Using dedicated controllers and sensor devices the DressMAN is able to measure equivalent temperature on local segments for evaluation according to DIN EN ISO 14505-2. Based on these methods novel and existing concepts for heating have been tested with subjects in a cabin mock-up. The experiments used simulation-based methods and local climate measurement devices to compare and evaluate different climate control concepts

Methodological approach for calibration of building energy performance simulation models applied to a common "measurement and verification" process

Eine große Herausforderung bei Energiespar-Contracting-Projekten ist die transparente und zuverlässige Bestimmung der Energieeinsparung vor und nach der Sanierung. Der sogenannte „Measurement & Verification“ (M&V)-Prozess kann mittels der Kalibrierung von Simulationsmodellen mit gemessenen Daten, z.B. den Berechnungsdaten von Energieversorgern, durchgeführt werden. Es gibt mehrere Leitfäden für die Vorgehensweise bei solchen M&V-Prozessen, Projektberichten von Fallstudien zufolge wird die Kalibrierung der Gebäudesimulationsmodelle jedoch mit recht unterschiedlichen Ansätzen bewerkstelligt. Ziel dieser Arbeit ist es, einen einheitlichen, praxistauglichen methodischen Ansatz für den M&V-Prozess zu entwickeln. In dem hier vorgestellten neuen Ansatz können sowohl Methoden der visuellen Untersuchung, parametrische Studien als auch Optimierungsverfahren angewendet werden. Die Methoden der visuellen UntersuchungUntersuchung können in erster Linie dazu beitragen, Eigenschaften eines bestimmten Gebäudes zu verstehen. Der große Nachteil dabei ist, dass sie auf einer „Trial and Error“-Vorgehensweise beruht. Somit ist sie mit hohem Zeitaufwand verbunden und die Qualität des Ergebnisses hängt stark von der durchführenden Person ab. Automatisierte parametrische Studien werden bislang in erster Linie für Sensitivitätsanalysen durchgeführt. Eine Übertragung dieser Methode auf die Modellkalibrierung erscheint jedoch im genannten Kontext vielversprechend. Die große Herausforderung für eine praktische Anwendung ist hierbei, einen hohen Automatisierungsgrad zu erreichen, da eine sehr große Anzahl von Simulationsfällen ausgewertet werden muss. Darüber hinaus erfordert sie vom Anwender vertiefte Fachkompetenzen im Bereich Statistik. Optimierungsverfahren erlauben es, schnell zu quantitativ besseren Lösungen zu gelangen. Deren Nachteil ist jedoch, dass sie keine Analyse des Systems vornehmen und dadurch kaum zu einem besseren Systemverständnis beitragen. Zudem sollten die Ergebnisse eines Optimierungsprozesses sorgfältig geprüft werden, da daraus zwar mathematisch korrekte, aber unter Umständen physikalisch bedeutungslose Systemvarianten resultieren können. Aufgrund der bekannten Vor- und Nachteile dieser Methoden wäre ein Kalibrierungswerkzeug wünschenswert, welches alle drei Verfahren in der Praxis nutzbar macht, um die Wirkung energieeffizienter Sanierungsprojekte besser vorhersagen zu können

ECO-SEE Deliverable D4.4: IEQ Assessment Tool: ECO-innovative, Safe and Energy Efficient wall panels and materials for a healthier indoor environment

We present an approach for holistic indoor environmental quality (IEQ) assessment incorporating dynamic heat and moisture transport effects, indoor air flow and pollutant distribution. A common tool infrastructure provides interfaces to multidisciplinary models that are using product and material specific data stored in Building Information Models (BIM) for early design assessment. Hence, we present the results of a prototype tool development utilising integrated dynamic simulation models on the basis of the Modelica language. The sub-domain models for airflow and hygrothermal simulations are cross validated with state-of-the-art tools and experimental results. The properties of innovative multi-functional eco-materials and components are provided in a structured database as basis for high quality predictions of IEQ under a defined range of boundary conditions. The procedures for simulations and results evaluation are automated and comparable figures for overall IEQ ratings are provided by a user friendly interface. The main components of the IEQ Assessment Tool are the 3-D graphical user interface, the dynamic multi-physics simulation model, and the tabular and graphical interpretation of the simulation results in terms of hygrothermal, acoustic and air quality performance

Bauphysikalische und ökologische Potenziale von adaptiven Leichtbaukonstruktionen

The increasing use of resources and the associated environmental effects are becoming more and more important in architecture and construction. Currently, the two disciplines are responsible for about 60 % of resource consumption and about 35 % of energy consumption [1, 2]. This percentage may rise, if all men demand conventional buildings since the world population continues to increase. Forecasts predict an increase in the world population by 2100 from currently just under 7.5 billion to around 11.2 billion people [3]. Innovative, resource‐saving lightweight constructions are indispensable in order to meet the growing world population and the large demand for resources. Latest research work extends the spectrum to adaptive lightweight constructions, which make it possible to manipulate building physical properties in a targeted manner. They are attributed with great potential in terms of their slimness, low mass and heat storage capacity, sustainability and the associated ecobalance. In order to be able to verify and quantify these potentials, the influences of the adaptivity of lightweight constructions on their structural‐physical behaviour and their ecological balance were simulated and described for the first time

Bauphysikalische Untersuchung von Sandwichelementen

Sandwich constructions are used in lightweight construction, especially in aerospace, transport, civil engineering and furniture. They consist of two facesheets, which are joined by a light core and provide high specific strength and stiffnesses. Currently used cores are foams, woods, or honeycombs. New sandwich constructions using cellular foldcores offer great versatility and potential for civil engineering applications. They can be used as light dividing wall or ceilings, and at the same time as actively conditioned elements. This enables multifunctional constructions, which can help to save mass and energy while at the same time providing a comfortable environment

Uniform segment-wise body parametric convection heat transfer coefficient model for sitting posture in vehicles

In many industrial multi-physics engineering applications, models need to capture the heat transfer effects of spatial and temporal changes in conditions around the human body. For thermal comfort assessment, convection heat transfer coefficients (hc) form part of the heat balance equation of the human body. In many non-uniform flow conditions, due to the turbulently mixed or stratified environment, convection heat transfer varies significantly on the human body. Parametric, segment-wise applicable convection heat transfer correlations are seen as an alternative in order to bridge these scales and levels in space and time. Therefore, robust reduced-order convective heat transfer models are needed for predicting heat transfer between the human body and its surroundings. The main goal of this research is to develop a reduced order model database that provides the segment-wise convective heat transfer coefficients (hc) for typical indoor flow responses in multiple applicat ions. In this article, a new parametric approach was detailed for estimating segment-wise body convection heat transfer coefficients for sitting posture in vehicles. The methodology follows a new strategy, i.e., in this application domain, here a car cabin, primarily relevant parameters are identified which affect the convective heat exchange. Following the sensitivity analysis of numerous computational fluid dynamics simulations with varying conditions, we identify relevant primary variables and heat transfer coefficients correlations and test the model robustness accordingly. A database-driven approach is developed in order to make correlations accessible during simulations, for example addressing energy performance. Finally, the experimentally investigated heat transfer analysis around the human body is presented and later compared with numerically reproduced data