Analyse und Vergleich energetischer Standards anhand eines exemplarischen Einfamilienhauses bzgl. Energiebedarf und Kosten über den Lebenszyklus

Im Kontext einer nachhaltigen Entwicklung konnten in den letzten Jahren vor allem im Neubaubereich eine Reihe von Fortschritten erzielt werden. Besonders hervorzuheben ist die Weiterentwicklung von Technologien zur Nutzung regenerativer Energien und neuer Baustoffe mit besonders geringer Wärmeleitfähigkeit. Parallel wurden Konzepte für Niedrigheizenergie‐ bis hin zu Passiv‐ und sogar Plusenergiehäuser entwickelt und umgesetzt. Diese Gebäudestandards weisen einen geringen Heizenergiebedarf auf und ermöglichen so erhebliche Energieeinsparungen während der Gebäudenutzungsphase. Es stellt sich die Frage, ob sich durch die Verwendung von neuen Technologien und Baustoffen ein Teil des Gesamtprimärenergiebedarfs von der Nutzungs‐ in die Erstellungs‐ und Instandhaltungsphase verlagert. Fraglich ist dabei auch, welche Mehrinvestitionen den erwarteten Betriebskosteneinsparungen gegenüberstehen. Um dies zu untersuchen, wurden exemplarisch für ein freistehendes Einfamilienhauses mehrere Ausführungsvarianten geplant und eine Lebenszyklusanalyse mit dem Programmwerkzeug LEGEP durchgeführt. Auf dieser Grundlage können für das exemplarische Einfamilienhaus Aussagen hinsichtlich des lebenszyklusübergreifenden Primärenergiebedarfs sowie der Kostenentwicklung getroffen werden. Die Ergebnisse haben jedoch keinen allgemeingültigen Charakter. Sie machen deutlich, dass im Sinne eines nachhaltigen Ressourceneinsatzes für den Einzelfall nur eine ganzheitliche Betrachtung zielführend ist. Analysis and comparison of energy standards based on a typical single‐family house in terms of energy demand and costs over the entire life cycle. Over recent years significant progress has been made with regard to sustainable development, particularly for new buildings. Particularly noteworthy are the advancement of renewable energy technologies and new building materials with very low thermal conductivity. In parallel, solutions for lowenergy, passive and even surplus‐energy homes were developed and implemented. These building standards are characterised by low heating energy consumption and therefore enable significant energy savings during the building utilisation phase. The question is whether the application of new technologies and building materials results in a partial shift of the total primary energy demand from the utilisation phase to the construction and maintenance phase. It is also questionable, however, what additional investments are required to achieve the savings in operating costs. In order to answer this question a number of different design and construction options for a free‐standing single‐family house were examined and subjected to a life cycle analysis using the LEGEP software tool. Based on this analysis a number of statements regarding the primary energy demand over the life cycle of the exexemplary single‐family house and also for the cost trend can be made. However, the results are not universally applicable. They indicate that a holistic analysis is required for each individual case in order to achieve sustainable resource use.     

Three-dimensional atomic imaging of colloidal core-shell nanocrystals

Colloidal core-shell semiconductor nanocrystals form an important class of optoelectronic materials, in which the exciton wave functions can be tailored by the atomic configuration of the core, the interfacial layers, and the shell. Here, we provide a trustful 3D characterization at the atomic scale of a free-standing PbSe(core)-CdSe(shell) nanocrystal by combining electron microscopy and discrete tomography. Our results yield unique insights for understanding the process of cation exchange, which is widely employed in the synthesis of core-shell nanocrystals. The study that we present is generally applicable to the broad range of colloidal heteronanocrystals that currently emerge as a new class of materials with technological importance.     

An alternative method for spectral response measurements of large‐area thin‐film photovoltaic modules

A new method for the spectral response measurement of large‐area single and multi‐junction thin‐film photovoltaic modules is presented, making use of a chopped monochromatic beam produced from a continuous source with band pass filters and lock‐in technique. The beam is projected onto part of the test module and superimposed over continuous bias light of variable colour. The procedure for the determination of the absolute spectral response is presented, and the influence of the intrinsic non‐uniformity of the monochromatic beam is investigated. The results obtained are compared with those from two other methods of spectral response measurement, providing a validation of the proposed experimental setup. Copyright © 2011 John Wiley & Sons, Ltd.     

Fermentative Produktion von Monorhamnolipiden im Pilotmaßstab – Herausforderungen der Maßstabsvergrößerung

The fermentative production of biosurfactants is usually hampered by the excessive formation of stable foam. Using the example of monorhamnolipids, proposals both for stable maintenance of gassed and stirred fermentations as well as for the isolation of these biosurfactants on a larger scale are given, as these are commercially available only in very small quantity. A special focus is on the use of renewable resources.     

Wavelet Based Identification of Substances in Terahertz Tomography Measurements

In comparison to the X-ray computed tomography Terahertz technique significantly enhances the amount of the information acquired during the sample measurement. Not only amplitude, but also phase, time and spectral characteristics can be determined in THz time-domain spectroscopy. Thus, Terahertz tomography allows localization and identification of substances within the objects due to the characteristic fingerprints in this frequency range. Certainly, an appropriate data processing and comparison algorithms are crucial for the accurate identification of the substances in the measured sample. Therefore, we present a new wavelet-based identification method which is suitable even for the substances with broad absorption curves and small or no absorption peaks. The performance of this algorithm was evaluated with the help of a tomographic sample filled with four substances, which were previously characterized for the external database. The continuous wavelet transform was applied to every data cell of the tomographic measurement and compared to the database. Received sinograms were reconstructed into images which depict estimated similarity between the measured and database substances. Furthermore, we suggest a method for the reduction of spectral data after the continuous wavelet transform. This method is based on the extraction of the distinctive features in the form of ridge lines.