Papers by Gerhard Zweifel
A new set of climatic data for different kinds of calculations has been compiled for various Swis... more A new set of climatic data for different kinds of calculations has been compiled for various Swiss localities. This includes the generation of new design reference year data sets with hourly values for e.g. building simulations. The procedure conforms to a set of new European standards describing the algo- rithms. One key element in this is the processing of solar radiation information, especially for the separation into direct and diffuse components. The most advanced methodology was used. Simulation examples for testing the data showed surprisingly high differences in the energy consumption results compared to the old data sets. Differences as high as +34% in cooling energy resulted for a realistic case. Analysis showed the main reason being the radiation data and especially the direct/diffuse split. This puts into perspective some controversies concerning model details.
Zusammenfassung Für ein transluzentes Fassadenelement der Firma GlassX, welches Phasenwechselmate... more Zusammenfassung Für ein transluzentes Fassadenelement der Firma GlassX, welches Phasenwechselmaterial enthält, wird für dessen thermisches Verhalten ein mathematisches Modell erarbeitet und dazu ein Bibliotheksmodul für die Simulationssoftware IDA-ICE erstellt. Das Modul wird in der Sprache NMF programmiert. Das GLASSX PCM-Fassadenelement ist praxiserprobt und -getestet. Seine Performance in konkreten Anwendungsfällen wird dank des erarbeiteten Simulationsmodells im Voraus verlässlich abgeschätzt werden können. Das bereits erstellte Teilmodell kann alle rein thermischen Aspekte für praktische Anwendungszwecke genügend genau abbilden. Insbesondere zu erwähnen ist hier der Unterkühlungseffekt, welcher eintritt bei einer Abkühlung ausgehend von vollständig geschmolzenem PCM-Material. Diese Unterkühlung spielt eine wichtige Rolle beim betrachteten PCM-Material für die Anwendung in Fassadenelementen. Uns ist kein anderes Simulationsmodell bekannt, welches diesem Aspekt Rechnung trägt. An der EMPA in Dübendorf wurden Messungen an einem Messprototyp in einer Klimakammer durchgeführt. Durch Parametervariation und Vergleich simulierter Temperaturverläufe mit den gemessenen, konnten noch unbekannte Parameter wie Unterkühlungstemperatur und Kristallisationsgeschwindigkeit für das untersuchte System bestimmt werden. Die Simulationsergebnisse stimmten dann gut mit den Messergebnissen überein.
A mathematical model is presented describing the thermal behavior for a translucent facade elemen... more A mathematical model is presented describing the thermal behavior for a translucent facade element, which uses phase change materials to increase building energy efficiency. The model puts the focus on accurately representing sub-cooling effects in the salt hydrate (phase change material) which is used. Based on this model a library module for the simulation software IDA ICE was created, using the programming language NMF. It is furthermore discussed how a change between differently structured systems of equations can be realized in NMF, since the model uses different ones depending on the state of the phase change material.
The International Energy Agency (IEA) was established in 1974 within the framework of the Organis... more The International Energy Agency (IEA) was established in 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. A basic aim of the IEA is to foster co-operation among the twenty-eight IEA participating countries and to increase energy security through energy conservation, development of alternative energy sources and energy research, development and demonstration (RD&D).
Tile coated wood fired appliances are designed to store heat from the intermittently burning fire... more Tile coated wood fired appliances are designed to store heat from the intermittently burning fire in their massive structure and release it slowly to the room. The design of these systems should assure thermal comfort during the whole process and involves dynamic simulation. A customized design tool for these systems was developed. A model of the appliance was created and
Energy and Buildings, 2002
Validation of building energy simulation programs consists of a combination of empirical validati... more Validation of building energy simulation programs consists of a combination of empirical validation, analytical verification, and comparative analysis techniques. An analytical verification and comparative diagnostic procedure was developed to test the ability of whole-building simulation programs to model the performance of unitary space-cooling equipment that is typically modeled using manufacturer design data presented as empirically derived performance maps. This procedure is based on the International Energy Agency (IEA) building energy simulation test (BESTEST) diagnostic method and systematically tests whole-building energy simulation software by comparing results from such software to analytical solutions that were developed for the test cases. Field trials of the new procedure were conducted by researchers from nations participating in the IEA Solar Heating and Cooling (SHC) Programme Task 22, using a number of detailed hourly simulation programs from Europe and the US, including: CA-SIS, CLIM2000, ENERGYPLUS, PROMETHEUS, TRNSYS-TUD, and two versions of DOE-2.1E. This article also includes discussion about simulation validation methodologies. Crown
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Papers by Gerhard Zweifel