A new production facility for a beverage manufacturer has to provide a storage volume for around 5 million bottles as a refrigerated warehouse. The maximum temperatures were not allowed to exceed 14 ...°C due to the quality requirements in the production process. To achieve highest energy efficiency and to avoid year-round heating and cooling, the warehouse is passively conditioned: by explicitly coupling it with adjacent soil, its buffering effect was activated via uninsulated wall and floor components in contact with the ground. The warehouse stock was also integrated into the concept as thermal mass. Furthermore, the remaining building envelope was optimized to reduce heat gains and losses to external air to a minimum.
Thermally activated building systems (TABS) represent a practicable and energy efficient possibility for heating of buildings. Whereas TABS in concrete structures are well-established, wood-based ...materials are barely considered. State-of-the-art simulations were conducted for various ceiling structures based on different wood-based materials and concrete regarding the thermal performance. Steady-state simulations demonstrate that TABS in wooden structures are fundamentally functional and able to achieve an appropriate heat flux of 26 W/m² while meeting the comfort requirement of maximum 4 K temperature difference between room air temperature and surface temperature, although considerably higher fluid temperatures are necessary compared to TABS in concrete. The results of transient simulations show that heat storage capacities of up to 1065 Wh/m² can be achieved within the wooden variants compared to 696 Wh/m² for concrete on condition of an equivalent heat flux underneath the ceiling. Furthermore, a combination of different wooden layers within the structure can contribute to both, a comparatively high energy storage potential and a high heat flux density simultaneously, compromising the fact that a higher heat flux density is often accompanied by a lower thermal storage capacity in the simulated models and vice versa. These findings could be used to develop an element of timber as energy storage system.
•Simulation of thermally activated building systems in wooden structures .•Represents an innovative utilization of wooden structures .•Shows that thermally activated building systems in wood are applicable .•Analysis of achievable heat flux density for different wood-based systems .•Analysis of thermal storage capacity for various wooden variants and concrete .
Heating and cooling of residential buildings is accountable for a significant share of the EU’s final energy consumption. In order to determine the current condition of the building stock and to ...implement appropriate measures and requirements to improve energy efficiency of buildings, a detailed analysis of existing buildings is essential. This paper aims at describing characteristics of the building stock of Salzburg by analysing energy performance certificates. Therefore, the building stock is grouped into archetypes based on the construction period, building condition (not-retrofitted and retrofitted) and building type (single-family house and multi-family house) and then analysed regarding energy need for space heating, energy carrier, heat emission system, share and U-values of building elements and window to wall ratio. The analysis of the data demonstrates that the structure and naming conventions within the EPC-database pose hurdles for a correct investigation of the data. A comprehensible and distinct notation as well as versioning is inevitable for the sake of avoiding a loss of information and enabling international comparability. An analysis of energy carriers of the archetypes reveals, that a significant share of buildings still uses fossil fuels like oil and gas for energy supply, although electricity (heat pumps) and district heating are on the rise for buildings constructed in recent periods as well as for retrofitted buildings, with heat pumps being the most important energy carrier for new single-family houses amounting to a share of 65% and district heating for new multi-family houses amounting to a share of 46%. A detailed observation of the thermal performance of buildings and building elements reveals high potential and practicability not only for energy efficient new buildings, but also retrofitted buildings throughout all construction periods and for both, single-family houses and multi-family houses (e.g. median U-values for retrofitted ceilings/roofs range from 0.17 to 0.26 W/(m2K) compared to a median of 0.14 W/(m2K) for not-retrofitted ceilings/roofs from the most recent construction period). The conducted analysis provides detailed statistical information on the Salzburg building stock and hence a robust basis for further studies regarding the thermal performance of the building stock and future scenarios by means of urban building energy modelling approaches. Furthermore, based on this information, policies for energy efficient buildings can be improved and adapted according to current circumstances.
Urban building energy modelling (UBEM) for analysing buildings in their spatial and functional context is an arising method. Only a few UBEM procedures use detailed building simulation tools, which ...are essential for high temporal and spatial resolution. This paper aims at developing a detailed automated physical bottom-up UBEM framework based on archetypes using Energy Performance Certificate data for predicting hourly heat load profiles of residential buildings. Simulation results are compared to and validated with measurements of two district heating networks and values from the TABULA typology. A comparison of the simulated hourly heat load profile for space heating and domestic hot water with measurement data results in a CV(RMSE) of 0.3, NMBE of 0.085, R2 of 0.85 and r of 0.94 for a sample size of 66 residential buildings, solely based on an estimation of the 3 classification criteria of the archetypes (building period, building condition and building type) and an estimation of the conditioned gross floor area for each measured building. Hence, the model can be declared as calibrated according to acceptance criteria in literature.
•Novel approach for predicting hourly heat load profiles of districts.•Using Energy Performance Certificate data for district modelling.•Including model calibration with measurement data for residential buildings.•Implementing meteorological grid data for considering local weather conditions.•Presenting a bottom-up, physical, detailed urban building energy modelling method.
This paper describes the development of a building technology system for a residential building complex built in 1985 in the city of Salzburg, Austria. The settlement consists of 75 apartments and is ...in great need of renovation. In the context of this survey, an extensive refurbishment and densification is conducted. Due to high costs caused by the construction and maintenance of a ventilation system, it is state of the art in Austria to install a simple exhaust ventilation system without implementing a heat recovery system. One of the main goals is targeting CO.sub.2 reduction by developing a system which combines the benefits of an exhaust ventilation system without heat recovery and a monitored mechanical ventilation system including a central heat recovery system. The required ventilation for each room is provided by overflow openings in the facade, with its benefits to avoid air filter change in comparison to a ventilation system. The novelty is obtained by the exhaust air heat recovery system via an air to brine heat exchanger in combination with a drain water heat recovery system as a heat sources for the conducted heat pumps. The renovation concept is a holistic approach combining the fields of energy, mobility, social structure and the economics of social housing. A monitoring system, which is implemented during the construction phase, is gathering measurement data concerning the performance of the refurbished buildings and should provide information of possible factors to increase efficiency of the system. The developed refurbishment concept will be documented and transferred for an implementation into other residential complexes which are in need of renovation. Performance of the building and its combination with different heating and ventilation systems will be evaluated within the simulation environment IDA ICE Version 4.8, in order to identify possible benefits of the innovative heating system including an exhaust heat recovery system and a drain water heat recovery system. As a result of the simulation, a comprehensive comparison between the systems in terms of CO.sub.2 emissions and energy efficiency is conducted.
Polycomb complexes establish chromatin modifications for maintaining gene repression and are essential for embryonic development in mice. Here we use pluripotent embryonic stem (ES) cells to ...demonstrate an unexpected redundancy between Polycomb-repressive complex 1 (PRC1) and PRC2 during the formation of differentiated cells. ES cells lacking the function of either PRC1 or PRC2 can differentiate into cells of the three germ layers, whereas simultaneous loss of PRC1 and PRC2 abrogates differentiation. On the molecular level, the differentiation defect is caused by the derepression of a set of genes that is redundantly repressed by PRC1 and PRC2 in ES cells. Furthermore, we find that genomic repeats are Polycomb targets and show that, in the absence of Polycomb complexes, endogenous murine leukemia virus elements can mobilize. This indicates a contribution of the Polycomb group system to the defense against parasitic DNA, and a potential role of genomic repeats in Polycomb-mediated gene regulation.
Optical Communications for High-Altitude Platforms Fidler, Franz; Knapek, Markus; Horwath, Joachim ...
IEEE journal of selected topics in quantum electronics,
2010-Sept.-Oct., 2010-09-00, 20100901, Letnik:
16, Številka:
5
Journal Article
Recenzirano
This paper contains a review of technologies, theoretical studies, and experimental field trials for optical communications from and to high-altitude platforms (HAPs). We discuss the pointing, ...acquisition, and tracking of laser terminals and describe how laser beams with low divergence can be used to transmit data at multi-Gigabits per second. Investigating the influence of the atmosphere, background light, and flight qualification requirements on system design, we explain why the data rates in free-space optical communications are still significantly below those possible in today's terrestrial fiber-based systems. Techniques like forward-error correction, adaptive optics, and diversity reception are discussed. Such measures help to increase the data rate or link distance while keeping the bit error ratio and outage probability of the optical HAP communication system low.
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