1,721,049 research outputs found
A review on optimization and cost-optimal methodologies in low-energy buildings design and environmental considerations
Full text linkThe topic of low-energy buildings received a widespread and growing interest in last years, thanks to energy saving policies of developed countries. The design of a low-energy building is addressed with energy saving measures and renewable energy generation, but the correct assessment of phenomena occurring in a building usually requires to perform dynamic simulations and to analyze multiple scenarios to attain the optimal solution. The optimality of a technical solution may be subject to contrasting constraints and objectives. For this reason, designers may employ mathematical optimization techniques, a non-familiar topic to most of building designers. In this paper, a review on optimization of low-energy buildings design is provided, in order to collect the results of previous works and to guide new designers. The topic received an increasing interest in last years, with multi-objective optimization and genetic algorithms being the most popular. The most common objective functions are the costs and the operating energy consumption, while the environmental aspects are often neglected. As low-energy buildings should reduce the global energy demand, their design may benefit enormously from the assessment of energy consumption and environmental impacts in the whole life cycle, even in a simplified way
Energy-related GHG emissions balances: IPCC versus LCA
No full textAddressing climate change is one of the greatest environmental challenges. Due to the impact of cities to energy consumption, the involvement of the local authorities in environmental policies is rapidly increasing. The Covenant of Mayors (CoM), launched by the European Commission, is an urban initiative aimed at reducing CO2 emissions. The signatories have to compile the greenhouse gas emissions (GHG) balance of their territory and, to do so, they can use the Intergovernmental Panel on Climate Change (IPCC) or the Life Cycle Assessment (LCA). Moreover, the signatories have to define strategies to reduce the GHG emissions.
In this context, authors estimate the GHG balance of an Italian municipality using both methodologies in order to compare the results. In detail, the first application is the IPCC, the second one is the LCA approach for which two cases are analysed: i) LCA with fossil fuels and electricity GHG emission factors based on the European Reference Life Cycle Database, LCA (I); and ii) LCA with a site – specific GHG emissions for electricity generation, LCA (II).
They propose energy strategies in order to quantify the achievable GHG emissions reduction by the exploitation of the renewable energy resources. The study shows that the GHG emissions results obtained with the LCA approach are higher by 20% than those calculated with the IPCC approach. This difference is relevant and it could be significant in identifying effective climate strategies. The LCA methodology ensures a systemic accounting of emissions, then, it can be more effective in order to achieve GHG emissions reduction at global level. The examined energy strategies allow for reducing the GHG emissions of about 7% of the total reduction required by the CoM. This confirms that a preliminary evaluation of the strategies is useful for the allocation of the financial resources to the environmental policies
LCA comparativa di una Power Supply Unit: funzionamento in corrente alternata o in corrente continua
No full textIn un contesto in cui gli apparecchi elettronici in corrente continua sono sempre più diffusi, è necessario indagare sulla sostenibilità ambientale di tali dispositivi, rispetto a quelli che hanno un funzionamento in corrente alternata. Il presente lavoro applica la metodologia LCA per stimare gli impatti energetico-ambientali di una Power Supply Unit, esaminando due scenari: 1) un’unità alimentata in corrente alternata, 2) un’unità alimentata in corrente continua. L’analisi mostra che il secondo scenario determina miglioramenti su tutti gli indicatori ambientali, con percentuali variabili dal 15% (tossicità umana-cancerogena) al 45% (radiazioni ionizzanti)
CLCA for Assessing Environmental Impacts of Power Sector in the GHG Policy Context
Full text linkPurpose: Current greenhouse gas (GHG) policy aims at reducing emissions from power sector. However, there are some known trade-offs of GHG emission reductions, in terms of other types of environmental impacts and impacts on other economic sectors. Consequential life cycle assessment (CLCA) has been developed to assess the environmental impacts of the power sector in relation with changes in the policy and its indirect impacts on other economic sectors.
Methods: A systematic review of CLCA method is conducted in the power sector. CLCA studies since 2005 are reviewed in terms of obtained results and methodology to identify whether CLCA is a more suitable approach for assessing environmental impacts of power sector in the context of GHG policy intervention, compared to attributional life cycle assessment (ALCA).
Results and discussion: With CLCA the total environmental impacts/benefits of power system change when indirect impacts are accounted. The variations between the total environmental impacts quantified with CLCA and ALCA range widely from inconsiderable difference (less than 5%) to 200%, depending on the investigated product system. These variations originate from CLCA’s modelling principles of expanding the system boundary and the inclusion of socio-economic interactions. With the expansion of system boundary, CLCA covers affected products and accounts for their relevant environmental impacts, which makes the obtained results comprehensively quantified. At the same time, the inclusion of socio-economic interactions in CLCA improves its capability of identifying the connections between environmental impacts and social-economic changes such as economic growth and consumer behaviours
Life Cycle Environmental Assessment of Energy Valorization of the Residual Agro-Food Industry
Full text linkThis study assesses the potential environmental impacts related to the energy valorization of agro-food industry waste thought the Life Cycle Assessment methodology (ISO 14040). The system examined consists of a real anaerobic digester coupled with a combined anaerobic digester and heat and power plant (AD-CHP) operating in Sicily. The analysis accounts for all the impacts occurring from the delivery of the biomass to the AD-CHP plant up to the electricity generation in the CHP. The main outcomes of the study include the eco-profile of the energy system providing electricity and the assessment of the contribution of each life cycle phase aimed at identifying the potential improvement area. The obtained results highlight that the direct emissions associated with the biogas combustion process in the CHP account for 66% of the impact on climate change, and feedstock transport contributes 64% to the impact on mineral, fossil fuels, and renewable depletion. The contribution to
the impacts caused by the electricity consumption is relevant in many of the environmental categories examined. It ranges from a minimum of about 22% for climate change up to 82% for freshwater ecotoxicity. Then actions aimed at reducing electricity consumption can significantly improve the environmental performances of the energy system examined
Ottimizzazione Multi-Obiettivo delle Prestazioni Energetiche e Ambientali di un Edificio Residenziale
No full textIl presente lavoro, svolto nell’ambito dell’Annex 72 dell’International Energy Agency, descrive un approccio metodologico volto all’identificazione di interventi ottimali di ristrutturazione da effettuare sull’involucro di un edificio residenziale, permettendo di minimizzare contemporaneamente quattro funzioni obiettivo: i consumi energetici in fase d’uso, i costi d’investimento e gli impatti energetici e ambientali di ciclo di vita. L’ottimizzazione, eseguita tramite un algoritmo multi-obiettivo, ha permesso di identificare gli spessori di materiale isolante e di materiali massivi da aggiungere sul tetto e sulle pareti perimetrali dell’involucro edilizio per minimizzare le quattro funzioni obiettivo. La domanda energetica in fase d’uso è stata valutata tramite un simulatore termofisico, mentre per stimare i costi e gli impatti di ciclo di vita sono stati utilizzati dati di letteratura
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
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
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