1,721,004 research outputs found
New computational workflow based on genetic algorithm for robust multi-objective optimization for the NZEB target.
No full textNet Zero Energy Buildings (NZEBs) play an important role in energy decentralization by using new strategies to save and harvest energy. However, uncertainties concerning stability of energy production from renewables and unpredictable scenarios that may occur during building life frequently cause measured performance of the building-plants system to differ from predictions. For the achievement of NZEB target, it is crucial to investigate, early in the project, the best design alternatives, also considering uncertain circumstances. The scope of this work is to provide a new workflow based on multi-objective optimization that sets the robustness of the building-HVAC system configurations as an optimization Key Performance Indicator, along with financial aspects, also verifying optimal design solutions for NZEB target. An integrated technique that combines open-source coding language Python with dynamic energy simulation engine EnergyPlus is proposed. First obtained results on the attainment of robust energy self-sufficiency of NZEBs favour designs with lower energy demand that use ground source heat pumps GSHP and variable refrigerating flow systems VRF for air conditioning and medium-high size of photovoltaic panels, although with high investment costs
Fixed and tracking PV system for Net Zero Energy Buildings: comparison between annual and monthly energy balance
No full textThe energy needs of a Net Zero Energy Building (NZEB) are fully met by renewable energy sources. These strongly depend on their characteristics and on meteorological-geographical factors, but also on different kinds of energy balance.
The aim of this paper is to investigate the comparison between two different photovoltaic systems (fixed and tracking) and two kinds of energy balance (yearly and monthly), to evaluate which system better achieves the definition of NZEB for an existing residential building, so limiting exchanges with the national electricity grid. A dynamic energy simulation software (DesignBuilder) is used.
The results show that the photovoltaic surface which attains the NZEB target on yearly basis not always achieves the same objective when the energy balance is performed on monthly basis. Furthermore, considering a monthly balance, the size of the photovoltaic system with biaxial solar tracking is 45% minor compared to the fixed photovoltaic system, thanks to a steadier energy production
HVAC SYSTEMS, COVID-19 INFECTION RISK MITIGATION AND ENERGY-COST ANALYSIS
No full textIt is well known that in March 2020 a state of emergency was declared, due to the worldwide spread of the new SARS-CoV2 virus. Since that time, all nations have put containment measures in place to avoid a health and social collapse. The main ways of spreading the Covid-19 infection are close contact with an infected person, inhalation of respiratory droplets produced by an infected person and contact with infected surfaces. Part of the droplets produced by an infected person are so small that they are not affected by the force of gravity, so they remain in suspension forming the bio-aerosol. The method of transmission via bio-aerosol is a mechanism recognized by the World Health Organization (WHO), which in that case highlights the important role of mechanical ventilation of building rooms to reduce the risk of contagion. Starting from this assumption, the aim of the paper is to analyse various HVAC systems, evaluating which of these is more efficient to reduce the contagion from Covid-19, and to carry out an energy-cost analysis of the different proposals. To date, there are no legal obligations for the correct design of an air conditioning system capable of countering the spread of the infection from Covid-19. In this paper, the Walles-Riley model was used to derive the number of external air changes per hour needed to reduce contagion. This model can be used for diseases that spread by air. The analyses were conducted on an existing building of the public administration for office use in Southern Italy. The model was dynamically simulated and validated through energy bills. The HVAC systems analysed were fan-coils with primary air and radiant panels with primary air. The energy analysis was first conducted under standard conditions and then in conditions that counter the spread of the virus. An analysis of energy costs was also carried out to assess the increase in expenditure compared to standard conditions. The results show that the number of external air changes per hour necessary to drastically reduce the probability of Covid-19 infection is equal to 5 vol/h. Acting on the air conditioning system is useful to counter the spread from Covid-19 but requires very high energy consumption. A solution to this problem could be to couple the intervention on the air conditioning system with one or more interventions on the building envelope
Indoor Environment and Energy Efficiency in Educational Buildings - Indoor Environment and Energy Efficiency in Educational Buildings - Part 1 Principles
No full text“Indoor Environment and Energy Efficiency in Educational Buildings – Part 1 Principles”. Authors: REHVA Working Group [Francesca Romana d'Ambrosio Alfano (chair), Laura Bellia, Atze Boestra, Manuel Carlos Gameiro da Silva, Elvira Ianniello, Jarek Kurnitski, Gino Lopardo, Francesco Minichiello, Jari Palonen, Piercarlo Romagnoni, Dennis Shuiling, Froukje van Dijken]. REHVA (Federation of European Heating, Ventilation and Air Conditioning Associations) – ISHRAE (The Indian Society of Heating, Refrigerating and Air Conditioning Engineers) Guidebook, REHVA Guidebook n° 13, REHVA Edition, 2021, ISBN 978-2-930521-30-5, 169 pagine – Libro a diffusione internazionale, con revisori
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Energy saving strategies in air-conditioning for museums
No full textABSTRACT: In the museum environment a strict thermal-hygrometric control is necessary primarily for the correct
artwork conservation and then for the visitor thermal comfort. Considering that the air-conditioning system
has to operate constantly, suitable techniques permit to obtain useful energy savings, allowing, however,
a good dynamic microclimatic control.
In this paper a case study is presented about various strategies used to reduce energy requirements for
HVAC systems in an exhibition room of a modern museum. Using the dynamic simulation code DOE 2.2
and typical climatic hourly data sets, the annual energy use for an all-air system has been calculated, as
well as the savings obtainable using different techniques, such as dehumidi???cation by adsorption (desiccant
wheel ??? saving equal to 15% with respect to a base con???guration), total energy recovery from
the relief air (passive desiccant ??? 15%), outdoor air???ow rate variation (demand control ventilation ???
45%). Moreover, the correspondence has been analyzed between the energy request and the admitted
variation of indoor temperature and relative humidity: changing the admitted indoor RH range from
50 ± 2% to 50 ± 10%, energy savings around 40% have been obtained. As regards the thermal-hygrometric
performance, an optimal control of temperature has been guaranteed with all the con???gurations, while
the best performance in RH control has been obtained with the desiccant system.
Considering a simple payback analysis, if the artworks preserved in a museum are particularly sensitive
to indoor humidity variation, a desiccant system should be properly used; on the contrary, when the
indoor humidity control is not strongly needed, the use of a HVAC system with demand control ventilation
is advisable, because of the lowest payback value. The system with total energy recovery presents
intermediate features
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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