1,721,094 research outputs found
Contabilizzazione dell'energia termica: un mercato da regolare
No full textPer ottenere risultati concreti in termini di efficienza energetica e ambientale è necessario uno sforzo sia a livello di ricerca sia di standardizzazione normativ
Proposal of a new method for the characterization and operational air leakages assessment in HVAC systems
Full text linkReducing air leakages in HVAC systems is potentially one of the actions with the best potential for energy savings in the residential sector. The assessing of air leakages in HVAC systems is currently addressed in two ways: i) the traditional DALT (Ducts Air Leakage Tests) to characterize and compare ductwork and ii) the ASHRAE 215:2018 standard method to measure leakage at nominal working conditions. In this paper an innovative experimental method for assessing air leakages in HVAC systems at operative conditions is proposed. The method is based on flow rate measurements at different pressures and performed with closed terminal dampers. The so called “Shut-Off Method” has been then experimentally validated in a real plant showing good agreement with the ASHRAE 215 procedure. Finally, on the basis of the Shut-Off model application, the leakage coefficient used by the standard DALT classification procedure was calculated, showing leakage performance 2,3 times worse than the Eurovent Class A requirements
L’utilizzazione zootecnica delle paglie trattate con soda. La produzione dell’agnello di 100 giorni
No full textSocial and economic risk analysis of natural gas distribution networks
No full textThe continuity of service as well as with its safety and security represent a crucial issue for natural gas transmission and distribution networks and a detailed analysis of the associated risks is essential to increase their reliability. In particular, natural gas distribution networks are characterised by a high number of users and present a very complex structure (with nodes and stretches and presenting mixed typologies, e.g., point to point, star, meshed) which make often difficult to forecast the effects of localised failure events, especially by a social and economic point of view. In this work, the authors develop a methodology for the analysis of the economic and social risk associated with natural gas distribution network failures and for the quantification of the related consequences on residential, commercial and/or industrial users. To this aim, the authors present and discuss the case study represented by a city distribution network located in southern Italy. The results demonstrate the developed method is effective in identifying the structural criticalities of the network, allowing the quick detection of the most critical areas affected by significant risk of service disruption
A novel model to detect abnormal thermal energy consumption in existing buildings with limited metering infrastructure
No full textIn EU, excessive energy waste occurs in existing buildings due to multiple reasons, such as inadequate building design, frequent operation of the technical building systems far from the design and reference conditions, lack of proper maintenance, lack of building automation and control systems, unexpected or exceptional weather conditions and inappropriate end-user behaviours. In this context, the detection of “abnormal” energy consumption is crucial both to increase end-users’ awareness and to help energy managers and technicians in the energy diagnosis. In this paper, the authors present a novel model to detect abnormal thermal energy consumption in existing buildings equipped with limited metering infrastructure. Four heating seasons of daily thermal energy consumption and indoor environmental data of a case study building located in Central Italy were analysed to develop, train and test the model for data processing, benchmarking, abnormal energy consumption identification and diagnosis. The results of the test phase show the ability of the model to detect behavioural faults, such as the low consumption and indoor air temperature in two dwellings and the high ones in one other. Also, the poor thermal insulation properties of the building were clearly highlighted by the proposed model
Dynamic evaluation of heat thefts due to different thermal performances and operations between adjacent dwellings
Full text linkApartment position and operation within buildings play a significant role on energy consumption and also on perceived thermal comfort. Dwellings with favorable positions can have significant benefit, also when heated for a limited number of hours, if compared to apartments located in disadvantaged positions (i.e., upper or lower floors or north-oriented). This may be the cause of debates, especially in buildings with central heating, when heat costs are shared among tenants by means of sub-metering systems. In this paper, authors address this issue by studying the "heat thefts" phenomenon in dynamic conditions in a low-insulated building, when the heating system is used unevenly by the tenants (i.e., with different temperatures and/or use). To this end, a social housing building located in Mediterranean climate, where daily temperature excursions and solar heat gains enhance the dynamics of the heat flows, has been chosen as the case-study. The real operation of the building has been simulated in different operational scenarios and the model has been validated against energy consumption data collected experimentally. Results confirm that special allocation and or/compensation strategies should be taken in heat costs allocation in order to avoid accentuating situations of inequalities, especially in low-insulated and/or occasionally heated buildings
La contabilizzazione accurata e trasparente dell’energia
No full textL’introduzione di sistemi di misurazione e fatturazione del consumo individuale degli appartamenti e degli edifici multi-purpose può generare una sensibile riduzione della domanda di riscaldamento/ raffreddamento. Esiste però una significativa differenza tra sistemi di misura diretta ed indiretta, sia in termini di prestazioni che di tutela del consumator
Analysis of Delta In-Out of natural gas distribution networks
No full textIn recent years, the estimation of Unaccounted for Gas in natural gas networks has been a very debated topic in the scientific literature and within regulatory authorities. In fact, this issue has broad implications since it can affect the cost of supplying gas, the safety of the service and the environmental impact. Unfortunately, although this issue has been widely focused in transmission networks, large and generalized literature studies for the distribution sector are still lacking. In this paper, a theoretical study of the causes of Delta In-Out in natural gas distribution networks, of the related applied analysis methodologies have been presented, together with an indepth analysis of the Delta In-Out in Italian distribution networks. To this aim, Delta In-Out of 2904 natural
gas distribution networks in Italy in the period 2013–2017 have been analyzed aimed at focusing the relevant aspects of the phenomenon and at identifying appropriate reduction strategies. A national average value of Delta In-Out approximately equal to +1% was found, whereas the standard deviation significantly varies depending on the size of the network (i.e. from about 2% for large networks to 10% in small networks) and on the climatic zone (i.e. from about 3% for networks in center-north Italy to 11% in the southern ones)
Uncertainty analysis of energy measurements in natural gas transmission networks
No full textThe value of natural gas depends on the energy obtainable from its combustion. Despite this, natural gas
measurement and billing are normally performed using volume measurements subsequently converted
into base conditions.Thus, to correctly achieve network balancing and accurate billings, both civil and
industrial natural gas consumptions should be measured in energy. Unfortunately, energy measure-
ments for natural gas are actually possible only in an indirect way by means of complex measurement
chains with a flow-meter, a volume conversion device and a gaschromatograph or gas analyzer.
Moreover, for technical and economic reasons, gas quality is often considered as constant and known
despite the unavoidable variations due to the mixing of gases from different origins and type
(i.e. importations, national productions, liquefied, biogas).
In this paper the authors present the results of a detailed metrological experimental analysis of the
typical energy measurement plants installed in natural gas networks. Modern networks are character-
ized by a wide variety of flow-rate measurement principles, constructive technologies and plant
configurations. Therefore, flow regimes, thermodynamic conditions and chemical properties of the gas
play a crucial role in determining metrological performance of natural gas energy measurements and
uncertainties can become critical for inaccurate billing and unaccounted for gas
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