1,721,044 research outputs found
Feasibility of periodic thermosyphons for environmentally friendly ground source cooling applications
No full textThis paper presents a feasibility study of a low-energy consumption ground source cooling system based on a periodic two-phase thermosyphon (PTPT) device in which a condensate is periodically transferred back to the evaporator. Operation of the PTPT is passive with the ground condenser positioned 1–11 m below the evaporator. The ground condenser may be at the condensing temperatures of 12–20°C depending on the ground depth. A semi-analytical approach is used to simulate the transient behaviour of the PTPT device. The simulation aims to study the effect of several parameters on the cooling rate of the device, including the length of condensing coil, the ground depth, the temperatures of the soil and the indoor air. The preliminary simulation results indicate that the PTPT device may be promising for ground source cooling applications
Periodic thermosyphons for environmentally friendly ground source cooling applications
No full textThis paper presents a feasibility study of a low-energy consumption ground source cooling systems based on a Periodic Two-Phase Thermosyphon (PTPT) device in which the condensate is periodically transferred back to the evaporator. Operation of this PTPT is passive with the ground condenser positioned 1-11 m below the evaporator. The ground condenser may at the condensing temperatures of 12-20 °C depending on the ground depth. A semi-analytical approach has been used to simulate the behaviour of the PTPT device over time. The model has been used to study the effect of several parameters on the cooling rate of the device, including the length of condensing coil, the ground depth, the temperatures of the soil and the indoor air. The preliminary results looks promising
The case study of a precast aerogel-incorporated mortar panel
Get PDFThe aim of many current studies regarding building envelopes is the improvement of their thermal resistance. Many attempts have been taken to develop highly insulating materials for advanced building envelopes. The present research investigates the possibility to include aerogel granules in mortar products. Several samples of Aerogel-Incorporated Mortar were prepared by adding granules of aerogel to different mixtures of mortar. The thermal conductivity and the mechanical strength of each mixture were measured by means of a heat flow meter apparatus and a compressive machine, respectively. The results showed that the thermal conductivity and the mechanical strength linearly decreased by increasing the quantity of aerogel added to the mixes. The best performing mix was found to be the mortar with an addition of 30 vol.% of aerogel granules, which had a density of 1530 kg/m3, a thermal conductivity of 0.24 W/mK, and a compressive strength of 11 MPa. Finally, a Precast Aerogel-Incorporated Mortar Panel was designed and the hygrothermal analysis of the panel was carried out using the software tool WUFI. Results of the study showed that the thermal transmittance of the panel was reduced by 18% compared to traditional precast panels, which suggested that useful energy savings during the lifetime of the building could be achieved
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Data analysis methods for decarbonisation of built environment - A multi-scale perspective
No full textBuilding sector is one of the most resource consuming sectors at the EU level. If we consider the whole life cycle
impact of a building, from materials extracted, manufacturing processes of construction products, construction,
operation and maintenance, we can clearly understand how design and operation choices for the built
environment have profound implications in terms of sustainability from the environmental, economic and social
standpoint. The definition of feasible decarbonisation paths and sustainability transitions for the built environment
is a priority today and building renovation strategies can act in synergy with new economic and technological
development paradigms to achieve both short-term goals (i.e. economic growth and employment) and long-term
goals (i.e. decarbonisation, resource efficiency and sustainability). The research presented concentrates on the
identification of the most relevant data analysis processes and techniques to respond to practical technical
questions and to support decision-making in the built environment, at multiple scales. The research aims to
highlight the possibility to join the micro-scale view of technological and behavioural problems in buildings and
the macro-scale view of the building stock in order to solve strategic problems at market and policy levels,
through system thinking
Composite Technology for an innovative students’ pavilion: energy, daylight analysis and a new concept of sustainability
Get PDFThe present research investigates an innovative use of fibre-reinforced composite materials (FRP) in the building industry and develops a construction system that has the potential to fuse structural, energy and architectural performances in one single shell, which is light, load bearing and efficient, with systems integrated inside it. This gives the opportunity to deal with the concept of sustainability in a broader sense, changing the approach from assessment protocols based on checklists to the idea of integration and inter-dependence of different aspects. The aforementioned concepts are applied to the design of a University students’ pavilion: its energy and daylight performances are analysed through simulations, while a 1:2 scale prototype of a pavilion portion has been fabricated to test the material characteristics. The construction system consists of a double curvature, load bearing, sandwich shell composed of two external FRP layers and a polyurethane core where systems are included. Potentialities and limitations connected to these materials are discussed, including a critical discussion of the building construction, transportation, energy consumption, environmental impact and overall efficiency and cost. The pavilion design aims to maximize daylight autonomy and solar gains in winter, while avoiding glare and minimizing cooling loads in summer. A ventilation system capable of refrigerating during the night is developed in parallel to a VRF system with heat pump, which is completely autonomous from the existing building. Operative temperature and comfort are evaluated for different periods of the year and results are displayed on maps. Software integration is a key factor in this process of extreme integration of different functions: opportunities and limitations related to the use of software are also discussed
Parametric performance analysis of a Passive House building
No full textPassive House standard is a rigorous voluntary scheme for high energy efficiency buildings. Passive behaviour implies that solar heat gains and internal heat gains due to people, lighting and appliances are able to nearly balance the heat losses due to transmission and ventilation in heating mode. This standard is mostly applied in Northern European countries, where heating represents, in most of the cases, the predominant part of energy consumption. However, the adoption of these strategies in the Mediterranean area has to be carefully evaluated to prevent overheating in intermediate seasons an increase of cooling loads in summer. In other words, the use of this standard in the Mediterranean area, characterized by a mild climate, can be debatable. Further, optimistic assumptions are often considered in the design phase and semi-stationary calculation methodologies are still commonly used. Additionally, occupants’ comfort preferences and behavior can determine a high variability in terms of energy performance, in particular with respect to the cost of energy services and the interaction with infrastructures. The research presented concentrates on the analysis of the potential performance variability due to occupants’ behaviour and envelope quality, starting from a real case study building constructed following Passive House standard in Italy. The research compares the initial design hypothesis, obtained with a semi-stationary calculation tool, with a larger spectrum of data generated by means of a parametric simulation, following a Design of Experiment (DOE) approach. The approach aims to detect potentially critical assumptions already from the preliminary design phase, making a proper use of available simulation methodologies to ensure the robustness of energy performance evaluation in the design phase and the possibility to monitor performance transparently and easily in the operation phase
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