•District heating consumption analysis for buildings grouped into types.•Automatic separation methodology for heating and DHW consumption.•Domestic hot water heat loss evaluation based on the summer ...period.•Examination of the impact of buildings characteristics on the energy consumption.•Detailed energy signature analysis for the different building types.
The present study focuses on analysing the heat consumption of multifamily buildings. The study evaluates measured district heating consumption data in Budapest, Hungary. The examined 218 buildings were grouped into 11 building types based on their architectural characteristics and analysed separately. The study aims to answer the question: how the buildings' characteristics influence the energy demand of the buildings. In the buildings only the total energy consumption is measured, thus the domestic hot water energy demand was examined in the summer months, when there is no heating in the building. The domestic hot water heat loss was 37–54% of total heat consumption in the summer period. The specific total district heating consumption data kWh/m3/day has higher deviation in colder months. The length of heating period is 183 days in Hungary, however the average length of heating period was longer in the examined buildings and it was even longer in case of the uninsulated buildings. From the measured consumption data the energy signature curves were developed for each building type for both the insulated and uninsulated buildings separately and the results were compared and analysed in detail. The energy signature diagrams showed a significant gap between the insulated and uninsulated buildings’ total district heating consumption data in the heating period. Lines were fitted to the data and the slope of the lines fitted to uninsulated buildings’ data indicate higher decline for every building type. A separation method was also suggested to divide the data of heating and non-heating period if its term is unknown. The difference between the average slope values of the fitted lines were analysed compared to buildings’ characteristics. It aimed to examine if the consumption reduction is influenced by the buildings’ physical parameters. In conclusion, the buildings’ characteristics did not always influence the final results (e.g. domestic hot water heat loss). But uninsulated buildings tend to have longer heating periods and buildings with smaller cooling surface area per heated volume had a predominantly lower energy consumption reduction rate.
•The paper has a focus on energy consumption habits and trends using statistical methods.•Occupants’ behavior is monitored using smart metering system and awareness surveys.•The impact of a serious ...game on occupant's behavior is evaluated.
The paper has a focus on energy consumption habits, trends and intervention strategies in residential buildings, mainly through the serious game approach with a combination of direct consumer feedback through smart metering. More than 150 homes in France and Spain have been involved in the research experiment and the consumption habits of approximately 50 homes were deeply analyzed. The applied methods, processes, results and findings of the monitoring data analysis are presented in the paper with two aims. First, consumption profiles and trends were determined for apartment homes with regard to heating, domestic hot water and electric consumption. Second, the impact of a serious game experiment was assessed comparing energy consumption, indoor air temperature and users’ habits (based on questionnaires) before and after launching the experiment.
•Classical load matching indicators are incapable of advising photovoltaic capacity.•Novel indicators with technical optima are introduced for PV sizing.•Self-production can be a useful metric for ...maximizing renewable share on-site.•Grid-liability indicator is practical when planning off-grid sites.
Integration of renewable energy sources in energy systems is crucial in achieving climate goals. Transformation of the power system – decentralization and prosumerism has led to the spread of domestic power plants taking part in the process. Mismatch problem of these predominantly grid-connected systems are typically described with load matching indicators. Most commonly used self-consumption and self-sufficiency metrics, though come with limits. One of the greatest is that they are monotone as the function of the capacity of photovoltaics implemented, making them uncapable of suggesting a technical optimum for system size. The scope of this study is to introduce two novel indicators with technical optima those can serve as a sizing principle for domestic photovoltaic plants for different approaches. First, self-production metric is introduced which allocates photovoltaic capacity that delivers maximum renewable utilization on-site and second, grid-liability reveals an optimum from the perspective of minimizing grid usage.
A reference building is studied with two control approaches to observe both the existing and indicators. As a base scenario, a water heater with classical control is simulated, while in the second case, demand side management is achieved via improved rule-based control, aiming to store surplus photovoltaic power production. Simulations reveal that the optimum capacity of the photovoltaics from the perspective of both self-production and grid-liability is much lower than the capacity (of 6.57kWp) that would cover the annual electricity demands of the observed household. In case of the traditional control, self-production leads to an optimal photovoltaic capacity of 4.38kWp, while grid-liability to a 0.73kWp. With improved control, optimal capacities are much closer, 2.92and 2.19kWp respectively.
The response of chiral fermions to time and space dependent axial imbalance and constant magnetic field is analyzed. The axial-vector–vector–vector (AVV) three-point function is studied using a ...real-time approach at finite temperature in the weak external field approximation. The chiral magnetic conductivity is given analytically for noninteracting fermions. It is pointed out that local charge conservation plays an important role when the axial imbalance is inhomogeneous. Proper regularization is needed which makes the constant axial imbalance limit delicate: for static but spatially oscillating chiral charge the chiral magnetic effect (CME) current vanishes. In the homogeneous (but possible time-dependent) limit of the axial imbalance the CME current is determined solely by the chiral anomaly. As a phenomenological consequence, the observability of the charge asymmetry caused by the CME turns out to be a matter of interplay between various scales of the system. Possible plasma instabilities resulting from the gradient corrections to the CME current are also pointed out.
•Mathematical modeling of nocturnal cooling with transpired solar collectors.•Method developed for the choice of equivalent sky temperature model.•Field study for nocturnal radiative cooling with ...transpired solar collectors.•New Nusselt correlation for heat transfer between airflow and transpired plate.•Maximum cooling performance of transpired solar collector 66.5 W/m2.
A novel use of the commercially available transpired solar collector is presented in the current paper. The reliable solar air heating system loses heat to the night sky if mounted on a building roof so it can be used as a passive cooling system based on thermal radiation. The collector plate cools down below ambient temperature and has the potential to cool the air as it is drawn through the perforations by a fan. A model has been elaborated for the cooling process based on heat transfer between the system components and energy balance equations. A method has been developed in order to choose the most suitable equivalent sky temperature model, as the radiative heat flow to the sky is the driving force of the cooling process and thus its accuracy is of utmost importance. The model has been validated by a series of field measurements carried out using a 5 m2 setup in Edirne, Turkey. It has been found that the collector plate cools down up to 4.3 K below ambient temperature and it has the potential to cool air by up to 4.0 K. The system reached a maximum cooling performance of 66.5 W/m2, while the average cooling performance was 34.6 W/m2. It has been found that the collector plate cools down below ambient temperature an hour before sunset and does not reach ambient until one hour after sunrise under clear sky. A new Nusselt number correlation has been developed for the convection heat transfer between a perforated plate and the transpiring air flow.
•We model solar energy potential of large scale urban areas based on building typology.•Collected energy and system losses (unused energy, delivery and storage) are modeled.•Reduction of primary ...energy compared for PV and solar thermal options.•Significant drop in system efficiency in case of oversizing solar thermal systems.•Building size fundamentally determines the optimal solar energy collecting system.
This paper describes a methodology developed for determining the solar energy potential of large scale urban areas based on building typology. As a result of the method, the solar yield at the roof can be determined, taking into account shading obstructions and assembly distances. In the model the utilized as well as the collected energy is calculated, taking into account the energy losses by unused energy, energy delivery and energy storage.
A main pillar of the method is the building typology that classifies buildings according to roof characteristics and other geometric factors influencing the domestic hot water demand. For each building type the following outputs are calculated: the solar yield, the maximum potential energy that can be produced by roof-integrated photovoltaic panels, the maximum potential energy that can be covered by solar thermal collectors and the realistic energy produced by solar thermal collectors taking into account economical considerations.
Based on the model, urban-level solar potential estimations can be carried out with the use of digital cartography at low costs. Such an estimation is presented in a case study for Debrecen, Hungary, but the model can be adapted to any settlement with different building types or climatic conditions.
This article argues that action learning has been incorporated into the Chinese administrative system because of a functional need for Western learning technology. This finding contrasts with those ...presented in the existing literature, which assert that Western practices have only been partially implemented, if implemented at all, because they were selected to serve certain political objectives. Therefore, this paper presents a different picture of Chinese governance, showing that it is not exclusively driven by political considerations but rather respectfully drawn to Western expertise and open to accommodating foreign ideas in order to update existing administrative knowledge. For practitioners, the findings suggest that, if a Western practice can serve major reform objectives and smoothly function within the constraints of the political ideology of the Chinese Communist Party and if its effectiveness is convincingly demonstrated, the practice can be accepted to improve the functioning of the system, and it can thus have a true impact on Chinese administrative governance.
本文认为，由于中国对西方的学习方法的功能需求，行动学习已被纳入中国的行政体系。这一发现与现有文献中提出的结论形成鲜明对比：现有文献认为，出于某些政治目的，西方实践被有选择性地施行。因此，本文提出了一个关于中国政府实施西方实践的不同的论点，表明中国政府在行政管理方面对西方实践的施行，不是完全由政治考虑所驱动，而是由于中国政府出于谦恭的态度被西方的专业知识所吸引，并愿意接受外国的思想，以更新现有的行政知识。研究结果表明，如果西方实践能够服务于重大的改革目标，并在中国共产党的政治意识形态约束下顺利运作，且其所展示出的价值令人信服，则其价值本身就会被中国政府所认同和接受，并且它因此而影响了中国政府的行政管理。
In the present paper, the performance of the transpired solar collector (TSC) is evaluated for several European cities with different climates. Two primary outputs, the solar air heating, and the ...recapture of transmission heat loss through the walls were analysed. The wall heat loss recapture can be considered as an important factor for energy saving in buildings, which has not been studied before. RETScreen and SWift are two building simulation tools available for the design and evaluation of transpired solar collectors. Another primary aim is to investigate the detailed mathematical approach that describes the heat transfer process of the physical model for each simulation tool. Results of the models were analysed to predict the performance of TSC in delivering heated air for ventilation applications, and the ability of the partial recapture the transmission heat loss from the warm building interior. Solar radiation, heating degree days, wall thermal transmittance, and air flowrate are the key parameters that influence the heat transfer process. The findings indicate a promising result of using TSC as a dynamic insulation solution for energy savings which can reach up to 55 kWh/(m2·year) at high air flowrate 180 m3/(h∙m2) for some climates besides the main duty which is the solar air heating.
We consider the three-dimensional inverse scattering with fixed energy in the spherically symmetrical case. We give a characterization of the sequences of phase shifts for two potentials which can be ...different only in a ball of radius
a. In other words we study how the large distance interaction influences the asymptotical behavior of the phase shifts. We also characterize the tail of the potential by the growth order of the scattering amplitude
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for large
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