References of "Scholzen, Frank 50003040"
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See detailDynamic Thermal Simulations for Developing Early-Stage Assessments for Office Buildings
Degens, Anja; Scholzen, Frank UL; Odenbreit, Christoph UL

in EPFL scientific publications (2015)

Office buildings account for a large portion of the total energy consumption in Europe because due to increased comfort requirements almost all recent buildings are air-conditioned. This project is ... [more ▼]

Office buildings account for a large portion of the total energy consumption in Europe because due to increased comfort requirements almost all recent buildings are air-conditioned. This project is focused on the influence of thermal storage capacity of commonly used structure types of office buildings and different technical strategies on energy efficiency and thermal comfort. The technical parameter ventilation strategy is essential compared to the parameters structure type or window-to-wall ratio. Additionally a lighting control system based on solar radiation shows a high influence on the internal gains and in consequence on the overheating hours. The slab type respectively the accessibiltiy of the thermal mass has a significantly higher influence than the differences of “massivity” between solid and light weight structures. [less ▲]

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See detailA semi-centralized, valveless and demand controlled ventilation system in comparison to other concepts in field tests
Merzkirch, Alexander UL; Maas, Stefan UL; Scholzen, Frank UL et al

in Building & Environment (2015), 93(21-26),

The idea of adapting the air supply rate to the actual demand in a building is not a new one. In commercial buildings it is already state-of-the-art to establish a demand controlled ventilation, where the ... [more ▼]

The idea of adapting the air supply rate to the actual demand in a building is not a new one. In commercial buildings it is already state-of-the-art to establish a demand controlled ventilation, where the level of air ow is based on sensors or time control. In residential buildings however, mechanical ventilation systems, whether centralized or decentralized, are in most cases operated in a constant modus, providing fresh air regardless if the fresh air is needed or not, even though the technology and the components needed for demand controlled ventilation exist and can be purchased at reasonable prices. In this article, results of eld tests with a semi-centralized demand feedback-controlled ventilation system are shown and compared to outcomes with other demand controlled systems. The semi-centralized prototype includes decentralized fans per ventilation zone, making a room-wise ventilation possible and valves to balance the system hydraulically unnecessary. It is shown that each presented concept of demand controlled ventilation can save energy by decreasing the operational time or the mean airflow rate without compromising air quality. Concepts which make a zone- or even a room-wise control of air ow possible, showed the highest energy saving potential of up to two-thirds compared to a system operating at constant flow rates. In addition to the energy savings due to decreased operational time, the maintenance and lter costs are decreased while the user comfort is increased, as natural ventilation in spring, summer and autumn may easily be added when delta T between inside and outside is small. [less ▲]

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See detailWie genau sind unsere Energiepässe?
Merzkirch, Alexander UL; Hoos, Thorsten UL; Maas, Stefan UL et al

in Bauphysik (2014), 1(2014), 40-43

Member States of the European Union are obliged to present a calculation method and certificate for the energy performance for buildings according to the guidelines 2002/91/EG und 2010/31/EU. In ... [more ▼]

Member States of the European Union are obliged to present a calculation method and certificate for the energy performance for buildings according to the guidelines 2002/91/EG und 2010/31/EU. In Luxembourg it is obligatory to add the real final energy consumption to the certificate after 3 years. The measured real final energy consumptions and the calculated ones were compared for 125 single-family homes and 105 multi-family homes with 870 dwellings in total. The mean calculated values for single-family homes were 74 % higher, the mean calculated values for multi-family homes 103 % higher than the actual measured data. The older the buildings, the higher the deviations, as the input parameters, which were partly assumed and partly predefined, diverge between calculations and reality. Sensitive parameters of interest are the indoor room temperature, the U-values, the used assessment for thermal bridges and the air exchange rate. [less ▲]

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See detailField Study on the Energy Consumption of School Buildings in Luxembourg
Thewes, Andreas UL; Maas, Stefan UL; Scholzen, Frank UL et al

in Energy & Buildings (2014)

Buildings account for 40 % of total energy consumption and 35 % of the total CO2 emitted in the EU. In consequence, there is an enormous energy saving potential and the European Union requires from all EU ... [more ▼]

Buildings account for 40 % of total energy consumption and 35 % of the total CO2 emitted in the EU. In consequence, there is an enormous energy saving potential and the European Union requires from all EU member states to save energy in this sector. Hence, reducing the energy consumption of buildings represents an essential component of environmental protection efforts. Furthermore, the new European directive 2010/31/EU requires that the member states tighten national standards and draw up national plans to increase the number of “nearly zero-energy buildings”. Well-planned energy-saving strategies presume knowledge of specific characteristics of the current national building stock. Therefore, the implementation of a process to support systematic data collection, classification and analysis of the energy consumption of buildings will become increasingly important during the coming years. In the field study described below we analyzed the energy consumption of 68 school buildings in Luxembourg. A separate collation of electricity and heat energy consumptions allowed to make a detailed analysis of specific energy parameters. Clustered according to energy sources, the new buildings were analyzed from a statistical point of view. We defined the energy relevant parameters such as energy standards, the purpose of use of the buildings or whether they had canteens. [less ▲]

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See detailDevelopment of a constitutive hyperelastic material law for numerical simulations of adhesive steel–glass connections using structural silicone
Dias, Vincent UL; Odenbreit, Christoph UL; Scholzen, Frank UL et al

in International Journal of Adhesion & Adhesives (2014), 48

Silicone elastomers are amongst others employed in glass façades as structural connection materials. They are known to be durable adhesives, able to transfer forces under variable loading and atmospheric ... [more ▼]

Silicone elastomers are amongst others employed in glass façades as structural connection materials. They are known to be durable adhesives, able to transfer forces under variable loading and atmospheric conditions during their design life. For the dimensioning of adhesive joints, numerical simulations are often used, especially for joints which exhibit large deformations and/or for complex geometries. However, silicones have strong non-linear material behaviour already at small strain deformations, are slightly compressible and show a time-depending behaviour. The current existing material laws do not allow for considering these effects properly in simulation, particularly for combined loading. Therefore a hyperelastic material law for silicones has been developed and validated, based on a strain energy function. For this purpose, test series have been carried out to determine all relevant material parameters needed to describe the strain energy potential, namely tension, compression, shear and multi-axial oedometric test series on non-aged and artificially aged specimens. Furthermore, the softening due to low cyclic loading (Mullins’ effect) has been considered and quantified by comparison to quasi-static loading for all test series. The developed hyperelastic model has been implemented into the finite element software Abaqus® for validation and the results of numerical simulations have been compared to experimental results and existing laws. The comparison showed that the proposed model better matched the real behaviour of silicone elastomers and led to an increase in exactness of the numerical simulations of adhesive joints. [less ▲]

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See detailVOLUME FLOW UNBALANCES AND SHORTCUTS IN DECENTRALIZED AND CENTRALIZED VENTILATION UNITS – FIELD TESTS IN RESIDENTIAL BUILDINGS
Merzkirch, Alexander UL; Maas, Stefan UL; Scholzen, Frank UL et al

Scientific Conference (2014)

Centralized and decentralized mechanical ventilation have become state-of-the-art in modern energy-efficient residential buildings. Calculations for the energy demand of buildings are done with nominal ... [more ▼]

Centralized and decentralized mechanical ventilation have become state-of-the-art in modern energy-efficient residential buildings. Calculations for the energy demand of buildings are done with nominal values of the ventilation units, assuming a proper function of the devices. The used ventilation concepts may be divided into two main categories- centralized and decentralized units and both come with advantages and disadvantages in terms of energy efficiency. In Luxembourg, a comprehensive field test has been performed in order to evaluate and compare their performance in practice. It could be shown that ventilation systems often do not meet the expectations. High unbalances in volume flows, high sensitivity to pressure differences and recirculation were measured in several cases. Only a proper installation and balancing of the systems can ensure an energy efficient function. [less ▲]

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See detailSimulated and experimental results on heat recovery from hot steel beams in a cooling bed applying modified solar absorbers
Tarrés Font, Joana UL; Maas, Stefan UL; Scholzen, Frank UL et al

in Journal of Cleaner Production (2014), (68), 261-271

In recent years, the steel industry has undertaken efforts to increase energy efficiency by reducing energy consumption and recover otherwise lost heat. About 60% of the energy consumed in a steel plant ... [more ▼]

In recent years, the steel industry has undertaken efforts to increase energy efficiency by reducing energy consumption and recover otherwise lost heat. About 60% of the energy consumed in a steel plant is lost in cooling beds where the hot steel beams are cooled down by natural convection and radiation. In this paper, the potential of heat recovery by radiation in a cooling bed was determined. Firstly, numerical simulations of the heat flux were done and validated with experimental measures. Secondly, a pilot test to recover the heat with modified solar absorbers was installed at the side of the cooling bed. The standard solar panels were painted with high absorption paint in the wavelength range of the hot beams. The results showed that up to 1 kW/m2 could be recovered with a temperature of 70°C at the side of the cooling bed, with a thermal efficiency of approximately 40%. As the experimental results were promising, further research is suggested to find an adequate selective coating and glazing. This would maximize the absorption at the wavelength range of the hot beams and minimize the emissivity at operational temperature of the absorber (100°C). Additionally, it would be of interest to find the optimum position for the absorbers in the cooling bed, which maximizes the heat recovery and does not interfere in the production process. [less ▲]

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See detailEnergy performance assessment of an existing double-skin façade: measurements and simulation
Carton, Julien UL; Scholzen, Frank UL; Thomas, Sébastien et al

in Energy Forum - Solar Building Skins, 06 - 07 December 2012, Italy (2012, December)

An existing office building with an active double skin façade in Luxembourg has been analyzed. In the first step in-situ measurements have been performed. For this purpose outside, inside and cavity ... [more ▼]

An existing office building with an active double skin façade in Luxembourg has been analyzed. In the first step in-situ measurements have been performed. For this purpose outside, inside and cavity conditions have been measured for representative summer and winter conditions. In a second step, a thermal simulation using TRNSYS was performed. The simulation model has been compared to the time limited series of measurements and thus has been validated for some of the annual meteorological conditions. Then the model has been extrapolated to a whole year in order to assess the energy performance of the given façade. Further a parametric study of alternative façades has been carried out based on the validated simulation model to assess their own performances. For the given case study building, the double skin concept energetically performs well compared to other concepts with non outside (non weather exposed) solar protection, but worse than an external solar protection. The thermal comfort level in the rooms has also been determined by simulation - the calculated room averaged comfort level is quite optimal, but further investigations regarding the local comfort close to the glazed façades still have to be achieved. [less ▲]

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See detailDevelopment of material law for silicone to simulate structural adhesive connections
Dias, Vincent UL; Odenbreit, Christoph UL; Hechler, Oliver UL et al

in Jens Schneider, Bernhard Weller (Ed.) Engineered Transparency Handbook (2012, October)

Recently developed adhesive materials enable the transfer of high loads between glass and other materials for structural use. However, for a numerical simulation, the description of the non-linear ... [more ▼]

Recently developed adhesive materials enable the transfer of high loads between glass and other materials for structural use. However, for a numerical simulation, the description of the non-linear behaviour of the adhesives must still be improved. Therefore extensive experimental investigations have been carried out on a structural elastomer and a material constitutive model has been derived based on the experimental results. Via numerical studies, the new constitutive model has been validated and assessed by comparison to test data and existing models. [less ▲]

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See detailWIE VIEL ENERGIE VERBRAUCHEN NEUE UNTERRICHTS- UND BÜROGEBÄUDE IN LUXEMBURG?
Maas, Stefan UL; Scholzen, Frank UL; Thewes, Andreas UL et al

in Cahier Scientifique - Revue Technique Luxembourgeoise (2012)

In Luxemburg hat sich in den vergangenen Jahren der nationale Energieverbrauch ebenfalls verstärkt zum Gebäudesektor hin verändert. Während 1990 noch 71 % des gesamten Energieverbrauches auf den ... [more ▼]

In Luxemburg hat sich in den vergangenen Jahren der nationale Energieverbrauch ebenfalls verstärkt zum Gebäudesektor hin verändert. Während 1990 noch 71 % des gesamten Energieverbrauches auf den Industriesektor zurückzuführen waren und nur 20 % auf die Gebäude, hat sich dies bis zum Jahr 2009 deutlich verändert. Demzufolge entfallen nur noch 30 % auf den Industriesektor, 25 % auf Verkehr (nach Abzug der Treibstoffexporte) und 45 % auf den Verbrauch des Tertiären Sektors3, welcher sowohl die privaten und die öffentlichen Haushalte, als auch Dienstleistungsgebäude beinhaltet. Die Direktive 2010/31/EG2 fordert von den Mitgliedstaaten die nationalen Normen weiterhin zu verschärfen und Pläne zu erstellen, um die Anzahl an Niedrigstenergiegebäuden weiter zu erhöhen. Um die Energieströme in Gebäuden besser zu verstehen, Sparmaßnahmen zu erarbeiten und mögliche Bewertungen über das Energieeinsparpotential für Gebäude durchführen zu können, sind jedoch aussagekräftige Verbrauchsdatenanalysen notwendig, die leider oftmals noch nicht in verlässlicher Qualität vorliegen. In der Direktive wird zudem empfohlen für die Berechnung eine Unterteilung aller Gebäude in angemessene Kategorien vorzunehmen, welche von Einfamilienhäusern (EFH), über Bürogebäude und Unterrichtsgebäude bis hin zu Krankenhäuser, Hotels und Sportanlagen reicht. In einer ersten Studie der Universität Luxemburg4 wurden bereits neuere EFH in Luxemburg hinsichtlich ihres realen Energieverbrauches untersucht und ausgewertet. [less ▲]

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See detailIntegrative analysis of the energy flow in a steel plant and a comprehensive approach to increase the energy efficiency
Tarrés Font, Joana UL; Maas, Stefan UL; Scholzen, Frank UL et al

in Proceedings METEC InSteelCON 2011, Düsseldorf Germany, CCD Congress Center, Düsseldorf, 27.06-01.07. (2011, July)

Steel industry is a highly intensive energy consumer. The energy used by the studied electric steelmaking plant could supply 25,000 households with thermal energy and 100,000 households with electrical ... [more ▼]

Steel industry is a highly intensive energy consumer. The energy used by the studied electric steelmaking plant could supply 25,000 households with thermal energy and 100,000 households with electrical energy. Increasing the energy efficiency of a steel plant will not only have impact in the reduction of greenhouse emissions but also in an increase of the competitiveness of the plant. A Luxembourgish steel plant is studied in detail and several options for energy savings are identified. Promising energy efficiency gains can be achieved by the optimization of the electric arc furnace and the reheating furnaces and by the improvement of the logistics between the continuous casting and the reheating furnace. The possibilities of energy recovery for heating purposes and for the generation of electricity with ORC- (Organic Rankine Cycle) or KALINAtechnologies are studied. In addition there is the opportunity to deliver hot water to a near district-heating system using otherwise lost energy and creating regional synergies. Nevertheless there is a need to develop a comprehensive and integrative approach to find a good overall solution instead of treating each step separately. The University of Luxembourg in collaboration with a Luxembourgish steel plant is developing a methodology to assess the technical, economical and environmental aspects of each solution. The objective is to assist in the decision-making in the company’s energy efficiency strategy and to perform a comparative analysis of the different solutions in order to propose an optimized plant, based on its feasibility due to local restrictions and different energy price scenarios. This ideal plant will be composed of individual elements, which proved their effectiveness in different real plants, so that the approach stays applied [less ▲]

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See detailThermal comfort of a new university building in Luxembourg with passive cooling
Thewes, Andreas UL; Maas, Stefan UL; Scholzen, Frank UL et al

in Thermal comfort of a new university building in Luxembourg with passive cooling (2010)

The new Luxembourgish university buildings should comply with a low energy standard, which was defined for typical offices and smaller lecture rooms by a thermal end-energy lower than 14 kWh/m3a and an ... [more ▼]

The new Luxembourgish university buildings should comply with a low energy standard, which was defined for typical offices and smaller lecture rooms by a thermal end-energy lower than 14 kWh/m3a and an electricity use for HVAC and lighting of max. 6 kWh/m3a. Consequently it was necessary to find ways to avoid the need for mechanical ventilation and air-conditioning. The heat consumption was minimized by an air-tight and well insulated building envelope. A difficulty was posed by special outside façade elements which were set-up as a grid over the complete outer surface as an architectural element. To prevent the risk of overheating during summer, it is necessary to reduce the solar gains by optimizing the window sizes and the glazing types, as well as through the installation of movable indoor shading elements. Nevertheless enough daylight should enter the rooms to limit the consumption of electricity for artificial lighting. Hence detailed dynamic simulations were performed using TRNSYS and TRNFLOW to ensure thermal comfort without active cooling. The effective electricity consumption of a newly installed state-of-the-art lighting system, including presence detectors and daylight controllers for dimming, was measured in a test installation to determine the internal loads by lighting. Radiation and illuminance measurements were performed on sample elements of the façade grid. The results were used to verify the daylight simulations and to analyze the benefits of daylight controllers. Several iterative steps were taken to gradually improve the building by introducing different modifications, e.g. reduction of the window sizes, installation of a lighting control system, improving the night ventilation and effective use of the thermal inertia of the building. [less ▲]

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See detailDynamic simulations to develop a natural ventilation concept for an office building
Thewes, Andreas UL; Maas, Stefan UL; Scholzen, Frank UL et al

in 8th International Conference on System Simulation in Buildings (2010)

The Sustainability Group of the University of Luxembourg defined for their new buildings a maximum thermal end-energy of 14 kWh/(m3a) and an electricity consumption for HVAC and lighting below 6 kWh/(m3a ... [more ▼]

The Sustainability Group of the University of Luxembourg defined for their new buildings a maximum thermal end-energy of 14 kWh/(m3a) and an electricity consumption for HVAC and lighting below 6 kWh/(m3a). Therefore it was necessary to avoid active cooling loads and mechanical ventilation in the offices and small lecture rooms. The well insulated and air-tight façade, including special outside shading elements which were designed as a grid over the complete building envelope, was an essential given architectural element of the building. Therefore further external shading devices were not applicable. The only possibility to have an influence on solar gains was to optimize the window size, the glazing type and potentially an internal shading device. Furthermore, to prevent the risk of overheating during the summer period, it was necessary to reduce the internal gains from lighting and IT-equipment. Hence detailed dynamic simulations using TRNSYS and TRNFLOW were done to evaluate the thermal comfort without air-conditioning and mechanical ventilation. The effects of optimizations like a state-of-the-art lighting control system or a window-based night ventilation, as well as the influence of the effective thermal inertia of the building were analyzed. The assumed natural ventilation rates were calculated by combining TRNFLOW and TRNSYS simulations and by the software LESOCOOL. [less ▲]

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See detailEnergieaudit Schul -und Sportkomplex Roodt/Syre
Scheuren, Jean-Jacques UL; Scholzen, Frank UL

in Revue Technique Luxembourgeoise (2008), Heft 2-2008

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