Das städtische Mikroklima: Analyse für die Stadt‐ und Gebäudeplanung

In the face of global warming, human thermal comfort has become an increasing important aspect in applied urban planning. As the urban heat island is not a homogenous factor the microclimate conditions play an important role also for single buildings and the situation inside. For a better consideration of this aspect in the planning process, qualitative and especially quantitative assessment tools are required. To get a better knowledge about the quantitative dimension of urban climates investigations on thermal comfort in outdoor and indoor spaces are carried out in selected city quarters in the city of Kassel in Germany. These studies consist of experimental investigations including field interviews about usage of urban open spaces and thermal sensation and numerical simulations on thermal comfort under recent as well as future regional climate conditions. The added‐value of the interdisciplinary research project is based on the correlation of findings from human‐biometeorology with the outcomes from sociologic questionnaires and building physics, which will be used to plan and design structures in a high spatial resolution. The thermal conditions outside continue inside the building, a combination of internal and external climate considerations must be made. The aim of a research at the University of Kassel is the examination and presentation of different microclimate and its influence on the thermal behavior of buildings.     

Entwicklung und Validierung einer hygrothermischen Raumklima‐Simulationssoftware WUFI®‐Plus

Development and validation of the hygrothermal indoor climate simulation software WUFI®‐Plus. Well‐balanced conditions of thermal, moisture and air quality are very important in buildings because an imbalance of these factors could have significant influences on the construction and the inhabitants. The focus of this paper is the influence of different materials on the fluctuation of relative humidity specifically humidity peaks. In lieu of complicated and expensive laboratory testing several different software tools have been developed to estimate the indoor environmental conditions of buildings. The Fraunhofer‐Institute for Building Physics (IBP) developed a hygrothermal simulation tool. With this software the temperature and moisture conditions of the walls, ceiling and floor constructions, of the indoor air and the energy consumption for the building can be calculated. In the context of the IEA‐Annex 41 project “Moist‐Eng“ a common exercise has been carried out for the validation of such software tools. For the common exercise at the free field investigation area in Holzkirchen (Germany) two identical rooms were used to measure the moisture buffering capacity of several interior finish systems. To address the questions of buffering capacity the IBP developed a hygrothermal simulation tool, WUFI®‐Plus [1]. Using the measurement data from the common exercise calculations were carried out with several software tools for the validation of it. In this paper the results of the laboratory tests and simulation results are described.     

Coupling the multizone airflow and contaminant transport software CONTAM with EnergyPlus using co-simulation

Building modelers need simulation tools capable of simultaneously considering building energy use, airflow and indoor air quality (IAQ) to design and evaluate the ability of buildings and their systems to meet today’s demanding energy efficiency and IAQ performance requirements. CONTAM is a widely-used multizone building airflow and contaminant transport simulation tool that requires indoor temperatures as input values. EnergyPlus is a prominent whole-building energy simulation program capable of performing heat transfer calculations that require interzone and infiltration airflows as input values. On their own, each tool is limited in its ability to account for thermal processes upon which building airflow may be significantly dependent and vice versa. This paper describes the initial phase of coupling of CONTAM with EnergyPlus to capture the interdependencies between airflow and heat transfer using co-simulation that allows for sharing of data between independently executing simulation tools. The coupling is accomplished based on the Functional Mock-up Interface (FMI) for Co-simulation specification that provides for integration between independently developed tools. A three-zone combined heat transfer/airflow analytical BESTEST case was simulated to verify the co-simulation is functioning as expected, and an investigation of a two-zone, natural ventilation case designed to challenge the coupled thermal/airflow solution methods was performed.     

Impact of airflow profile on indoor air quality—a tropical study

The validation of the concentration levels of indoor contaminants and the measurement of ventilation parameters with CFD simulation results often poses considerable difficulty due to the effect of several confounding factors. Whilst a building in dynamic operation with varying operating characteristics in terms of the air-conditioning system and the activities of the occupants renders the possibility of a continuous measurement of IAQ and ventilation data, it is almost impossible to simulate such dynamic changes in the CFD environment. It then becomes imperative that steady-state measurements in buildings be used as representative data for the purposes of CFD simulation. This paper reports the findings of a study, in which the simulation of airflow pattern in an office building in Singapore is based on the indoor environmental conditions and the corresponding ventilation parameters measured on a typical day. Boundary conditions are obtained through hood measurements to determine the airflow rate from each diffuser. The findings of this study clearly support the critical impact of airflow on pollutant pathways in the building as a result of air supply volume, arrangement of air inlet and outlet devices, space design and the presence of heat sources.     

Dem Himmel entgegen – Klimadesign für den Federation Tower Moskau

Skywards – climate design for the Moscow Federation Tower. Advanced simulation tools were used in developing the climate design for the roof covering the taller of the two blocks at Moscow's Federation Tower. The all‐glass roof space at a height of 365 m is designed to accommodate the finest and most exclusive hotel areas. Several restaurants, bars and lounges and a Sky Dance Club will offer entertainment and fabulous views across the whole city. Simulations were used to develop and verify a design that ensures thermal comfort taking into account architectural, climate and utilisation requirements. The structure and the building services were simulated based on a 3D model, and simulations were carried out for summer and winter scenarios. This paper describes the design process including load calculations and the development and assessment of the climate design by means of simulation.     

建筑环境设计模拟分析软件DeST第8讲自然通风与机械通风系统的联合模拟分析

建筑通风对建筑环境的影响是直接而迅速的,因此对建筑热环境的模拟必须解决建筑通风的模拟问题。建筑的通风包括自然通风和机械通风,二者本质相同并且经常是同时发生的,计算时应该一起考虑,而不是分离开来。详细介绍了建筑热环境模拟软件DeST中根据多区域网络模型和管道流体网络模型发展出来的建筑通风的统一的网络模型,介绍其求解方法,并给出了建筑中常见的通风支路阻力模型,实现了建筑热环境和自然通风真正的耦合模拟。通过介绍几个利用通风模拟来分析解决设计中问题的实例,指出了建筑通风模拟的应用范围和实际意义。     

Flughafen München Terminal 2 – Optimierung der Glas‐Doppelfassade und des Glasdaches

Munich Airport Terminal 2 – Computerized simulation as a part of integrated planing. Dynamic computer simulations were used to optimize the architectural concept of the Munich Airport Terminal 2. With these simulations, the various requirements on architecture, building science issues, indoor climate conditions and energy demand could be fine‐tuned. Among others, comparing the design of different double wall facades has enabled the selection of optimal controls for the double wall facades ventilation louver and shading devices. Daylight simulations allowed the determination of a roof type that meets the demands on natural illumination without the negative detraction of glare.     

Fast and self-learning indoor airflow simulation based on in situ adaptive tabulation

Fast simulation for stratified indoor airflow distributions is desired for various applications, such as design of advanced indoor environments, emergency management, and coupled annual energy simulation for buildings with stratified air distributions. Reduced order models trained by pre-computed computational fluid dynamics results are fast, but their prediction may be inaccurate when applied for conditions outside the training domain. To overcome this limitation, we propose a fast and self-learning model based on an in situ adaptive tabulation (ISAT) algorithm, which is trained by a fast fluid dynamics (FFD) model as an example. The idea is that the ISAT will retrieve the solutions from an existing data set if the estimated prediction error is within a pre-defined tolerance. Otherwise, the ISAT will execute the FFD simulation, which is accelerated by running in parallel on a graphics processing unit, for a full-scale simulation. This paper systematically investigates the feasibility of the ISAT for indoor airflow simulations by presenting the ISAT-FFD implementation alongside results related to its overall performance. Using a stratified indoor airflow as an example, we evaluated how the training time of ISAT was impacted by four factors (training methods, error tolerances, number of inputs, and number of outputs). Then we demonstrated that a trained ISAT model can predict the key information for inputs both inside and outside the training domain. The ISAT was able to answer query points both inside and close to training domain using retrieve actions within a time less than 0.001?s for each query. Finally, we provided suggestions for using the ISAT for building applications.     

Erweiterung des Hitzewarnsystems um die Vorhersage der Wärmebelastung in Innenräumen

Extending the existing heat/health warning system with indoor heat load predictions. A heat/health warning system (HHWS) was established in Germany as a climate change adaptation measure and as a direct consequence of the heat wave in 2003. The system used by the German weather service currently only provides information about outdoor conditions, i.e. no data on indoor climate – which may differ significantly from ambient conditions – are provided. This article describes an extension of the existing heat/health warning system based on a thermal building simulation model. It enables internal heat loads to be estimated based on predicted meteorological conditions. While the prediction model is limited to a worst‐case scenario for practicability reasons, the information derived from the load values can nevertheless be very useful. The technique was used during summer 2007 in parallel with the conventional system, illustrating the added value.     

Zur Aussagekraft von Simulationsergebnissen auf Basis der Testreferenzjahre (TRY) über die Häufigkeit sommerlicher Überhitzung

Frequency of overheating during the summer – How meaningful are simulation results based on test reference years? Thermal comfort during the summer is becoming an increasingly important quality characteristic of modern office buildings. With attention increasingly also focusing on sustainability considerations, designs for such buildings are often based on passive ventilation without air‐conditioning or mechanical ventilation. The design and assessment of such energy‐saving indoor climate concepts is based on peak room temperatures and the frequency of overheating during the summer, usually involving (zonal) thermal simulation software. The calculation of overheating frequencies requires meteorological data for a whole year, in Germany usually in the form of original test reference years (TRYs) provided by Deutscher Wetterdienst (DWD), Germany's National Meteorological Service. However, these TRYs were developed for other purposes and tend to represent hot spells during the summer inadequately. In addition, TRYs do not take into account urban heat islands or the effects of climate change observed since the 1990 (with increasing tendency). Frequencies of high room temperatures during the summer determined using the original TRYs are therefore unrealistically low and unsuitable as a basis for decisions relating to climate concepts. For more realistic overheating frequency calculations it is advisable to use TRYs incorporating extreme summers and perhaps weather data for future years, which will shortly be made available by meteorologists.     

Auswirkungen der Baurestfeuchte auf Innenklima und Holzfeuchte bei Holz‐Mischbauweisen

Effects of the build‐in‐moisture on indoor climate and wood moisture of timber mixed construction Within the scope of the competence center “wood technology” the Holzforschung Austria deals with the combination of prefabricated timber elements in the building shell with concrete construction parts for high rise buildings. In addition to the design of construction details a one‐zone model has been created – in close collaboration with the Technical University of Vienna – to analyze the effects of residual humidity on the internal climate and on the moisture content of the timber elements. The simulated drying properties of the concrete elements are consistent with the results of the analysis of the Verein der Österreichischen Zementfabrikanten in matters of drying time and change of moisture content. In addition to the variation of the beginning and progress of construction work and the behavior of air conditioning three different exterior wall constructions – one timber frame construction with OSB and one with PE as vapour barrier and a construction with solid timber boards without vapour barrier have been analysed.     

Using results from field surveys to predict the effect of open windows on thermal comfort and energy use in buildings

Windows are one of the major means by which building occupants control the indoor environment. This research uses results from field surveys to formulate a method for simulation of office buildings to include the effects of window opening behaviour on comfort and energy use. The paper focuses on: (1) what is general window opening behaviour? (2) how can we frame an “adaptive algorithm” to predict whether windows are open? (3) how can the algorithm be used within a simulation to allow the effects of window opening on comfort and energy use to be quantified? We have found that: (1) the proportion of windows open depends on indoor and outdoor conditions, (2) logistic regression analysis can be used to formulate an adaptive algorithm to predict the likelihood that windows are open, (3) the algorithm when embedded in simulation software provides insights not available using more usual simulation methods and allows the quantification of the effect of building design on window opening behaviour, occupant comfort and building energy use.     

Multi-zone simulation of outdoor particle penetration and transport in a multi-story building

In areas with poor ambient air quality, indoor particle concentrations can be significantly affected by particulate matter originating outdoors. The indoor environments of multi-zone and multi-story buildings are affected differently by outdoor particles compared with single-family houses, because of the buildings’ more complicated airflow characteristics. The objective of this study is to analyze outdoor particle penetration and transport, and their impact on indoor air, in a multi-zone and multi-story building using a CONTAMW simulation. For the airflow and particle transport analysis, the building leakage, penetration coefficients, and deposition rates were determined by on-site experiments. The results of airflow simulations for cold winters show that outdoor air infiltrates through the lower part of building and exfiltrates from the upper part. The results of the particle simulation also indicated that the airflow characteristics, combined with deposition rates, cause the lower floors of a multi-story building to be exposed to higher fine particle concentrations compared with the upper floors of the building. The study demonstrated that the CONTAMW simulation can be useful in analyzing the impact of outdoor particles on indoor environments through the identification of key particle transport parameters and validated airflow simulations.     

Hygrothermische Wirkungen von Raum‐ und Außenoberflächen

The hygrothermal effect of inside and outside building envelope surfaces. In the past the protection of building constructions under outdoor and indoor climate conditions was one of the most important subjects building physics. Nowadays the energy balance and the hygrothermal performance of building envelopes are current topics. This paper deals with the coupled heat and moisture transfer on the internal and external envelope surfaces. By means of numerical simulation and laboratory investigation the influence of the internal surface of exterior walls on the indoor air humidity is demonstrated. The influence of evaporation cooling on the energy transfer in winter time and during the warm season requires investigations on dewing and driving. It depends on the hygroscopic parameters of the outside wall coating. The effect of infrared reflecting coating is determined. It is shown in which way heat sources integrated in exterior walls could be a possibility to avoid microbiological growth on building envelopes.     

Optimizing energy efficiency and occupant comfort with climate specific design of the building

Designing energy efficient and comfortable buildings requires harmonizing the complex interactions of architecture, construction and building service engineering. The building envelope has a particular importance, since it integrates many functions and has direct influence on indoor climate. Focusing on satisfaction of the user means that the indoor climate is a key for a holistic design approach. Only a satisfied user will not intervene with the designed energy concept or the indoor climate control; dissatisfaction results in multiple system interventions which may cause waste of energy and sometimes even damage to building envelope components. Satisfaction with the indoor environment also increases working productivity or enables effective recreation of residents.The paper deals with international research activities in the field of climate specific building design. Various comfort and energy monitoring surveys of office buildings as well as residential buildings provide substantial information about the occupants' behavior and their needs during specific situations under different outdoor climates. This information allows summarizing basic climate dependent design principles which architects should keep in mind during the early stages of the design process. It also helps to develop strategies aiming at reducing building energy demand and at the same time consider comfort aspects. The second part of this paper demonstrates application of the climate dependent design principles in a housing project in Dubai.     

Außenwandkonstruktionen für Schwimmhallen

Die kontinuierlich steigenden Anforderungen an die allgemeinen Komfortbedingungen in Verbindung mit einer immer weiter wachsenden Nachfrage nach den unterschiedlichsten Wellness‐Angeboten führen sowohl im Hotel‐ und Touristikgewerbe als auch im privaten Bereich zu umfangreichen Neu‐ und Umbaumaßnahmen. Bei öffentlichen Schwimmhallen liegt das Hauptaugenmerk dabei auf geeigneten Maßnahmen zur Steigerung der Energie‐Effizienz bei gleichzeitiger Modernisierung und Attraktivierung der entsprechenden Gebäudeteile. Nun handelt es sich bei diesen Gebäuden oder Gebäudeteilen um bauliche Einrichtungen, deren Nutzung beispielsweise als Schwimmhalle, als Whirlpoolraum oder als Saunavorraum eine gegenüber den konventionellen Randbedingungen von Aufenthaltsräumen deutlich erhöhte Feuchtebelastung bedingt: Es liegen hier nicht nur gegenüber Wohngebäuden deutlich erhöhte Temperaturen und Luftfeuchten – und damit eine völlig andere Größenordnung der Wasserdampfpartialdrücke der Raumluft – sondern auch grundsätzlich andere Nutzungs‐ und Betriebszeiten vor. Damit ergibt sich dann, dass der dauerhaft schaden‐ und mängelfreie Betrieb einer solchen Einrichtung eine entsprechend angepasste Baukonstruktion der umgebenden Bauteile und somit eine spezielle fachliche Betrachtung der bauphysikalischen Randbedingungen erfordert. Während für die konventionelle Wohn‐ oder Büronutzung eines Gebäudes die bauklimatisch anzusetzenden Randbedingungen (sowie die korrespondierenden Nachweisverfahren) normativ geregelt sind und die Auswirkungen auf die entsprechende bauliche Realisierung damit mehr oder weniger geläufig sind, fehlen diese Erkenntnisse im Bereich der Feuchträume im Allgemeinen und der Schwimmhallen im Besonderen weitestgehend. External wall constructions for indoor swimming pools. The continually increasing requirements for general comfort conditions combined with an ever growing demand for the widest range of wellness facilities result in numerous new‐build and extension projects in the hotel and tourist trade as well as in private homes (example see fig. 1). With public swimming pools the focus of attention is on suitable measures to increase the energy efficiency of the relevant parts of buildings and to modernise and make them more attractive at the same time. With these buildings or parts of buildings we are dealing with buildings used as swimming pools, jacuzzis or saunas and much more exposed to the effects of moisture compared to the normal boundary conditions of recreational areas: Not only are the temperatures and humidity content much higher and therefore the partial pressures of the water vapour in the air indoors on a completely different scale, but they are generally open and used at different times. This means that the long‐term operation of such a building free of damage and shortcomings requires a correspondingly suitable construction of the surrounding components and thus a special expert assessment of the building physics boundary conditions. Whereas the boundary conditions relating to the temperature and moisture in the building (and the corresponding methods) to be applied to residential or office buildings are regulated by standards and the effects on the corresponding construction of the building in practice are therefore more or less familiar, there is a general lack of this information for indoor areas with high humidity in general and swimming pools in particular.     

A new methodology for the design of low energy buildings

The Kyoto protocol binded the developed countries to reduce the greenhouse gas emissions at least by 5% by 2008-2012 in order to tackle global warming and climate change. Some of the measures of the governments to achieve this goal are to promote new buildings construction and to retrofit existing buildings while satisfying low energy criteria. This means improving energy efficiency of buildings and energy systems, developing sustainable building concepts and promoting renewable energy sources.The design of a low energy building requires parametric studies via simulation tools in order to optimize the design of the building envelope and HVAC systems. These studies are often complex and time consuming due to a large number of parameters to consider. Hence, this paper aims to set up a methodology that simplifies parametrical studies during the design process of a low energy building. The methodology is based on the Design of Experiments (DOE) method which is a statistical method widely used in industry to perform parametric studies that reduces the required number of experiments.     

Crossflex: Concept and early development of a true building integrated wind turbine

This paper describes the concept development and work to date, of an innovative ‘true’ building integrated wind turbine. The context for this is the role of small-scale renewable energy in addressing climate change. In the UK a number of small wind turbines have reached the market, however, in almost all cases, these are existing HAWT or VAWT tower mounted systems. Due to their inherent design qualities, and issues such as planning requirements, these have much reduced output due to their form and siting and are unable to take advantage of augmented airflow around buildings.The Crossflex proposal is a radical new development of a Darrieus turbine form. As well as having a technically innovative flexible blade system, it also utilises a lightweight cowling system that can provide both augmented airflow and improved visual integration into new and existing building forms. It is a modular form that can be sited on ridges and corners of buildings to provide useful levels of generation.     

Großelement‐Dämmtechnik (GeDt) zur energetischen Fassadensanierung

Technology of large‐sized heat‐insulating elements for energetic redevelopment of facades. Sustainable reduction of heating energy – required for our buildings – can be reached by additional insulation of existing old building facades. Sometimes homeowners interest about the heat‐insulating redevelopment of their building facades seemed to be quite small, because of longer construction times and restrictions by scaffolding, noise and pollution often concerned with conventional technologies. New impulses for the realization of additional redevelopment measures can be given by innovative, timesaving and less disturbing redevelopment technologies – like the following described. So the federal ministry for economy and technology and 4 industry partners promoted the research project “Energetic redevelopment of facades with industrial prefabrication technologies” [1], [2] at the University of Bochum (Institute of constructional civil engineering). In the context of this research project all essentials of the technology of large‐sized heat‐insulating elements for sustainable heating energy saving redevelopment of facades were developped. This technology is based on large‐sized heat‐insulating elements (height of about 2,80 m and length up to 8 m) considering aspects of structural analysis, physics relating to construction and assembling elements. For the application of the large‐sized elements at building facades two fixing systems were created and tested – one based on dot‐shaped fixings, the other on bar‐shaped fixings. To ensure the prefabrication of those large‐sized redevelopment elements and their exact assembling the development of a contactless surveying and marking out system was necessary – separately realized at the University of Bochum (area of geodetics). Large size and system‐specific implementation details of the redevelopment elements mentioned above caused the development of suitable tools for assembling and transporting elements.