1,721,204 research outputs found
VALUTAZIONE SPERIMENTALE DELL’IAQ NELLA NUOVA SEDE DEL COMUNE DI BOLOGNA, ANALISI PRESTAZIONALE DEI SISTEMI DI VENTILAZIONE DEGLI AMBIENTI E INDICAZIONE DI PROPOSTE.
No full textl’obiettivo della convenzione di ricerca consisterà nella conduzione di attività sperimentali volte alla definizione di proposte sugli interventi da attivare al fine di rimuovere le criticità emerse e/o su eventuali indagini di completamento da condurre. L’attività sperimentale è volta alla individuazione :
1. del livello di IAQ (Indoor Air Quality) caratterizzante gli ambienti che saranno indicati dalla Committenza e in cui sembrerebbero manifestarsi disagi da parte degli occupanti, con particolare riferimento alla misura delle portate aria (esterne e di ricircolo), della direzionalità dei flussi di aria (mediante l’uso di gas traccianti), dei valori di T ed UR e velocità dell’aria immessa nelle postazioni operatore, delle temperature superficiali dell’involucro interno degli ambienti, della temperatura operativa e di quella media radiante e infine dell’irraggiamento esterno con metodologie e strumentazioni conformi alle norme vigenti;
2. delle caratteristiche funzionali della catena delle regolazioni degli impianti e della corrispondente variazione dei parametri predetti;
3. del livello di illuminamento naturale interno in funzione di quello esterno, ed in particolare dei contrasti di luminanza presenti;
4. del livello di inquinamento chimico - almeno CO2, PM10, formaldeide ed eventualmente di inquinamento microbiologico.
5. del livello di contaminazione degli impianti da parte della legionell
Thermal Performances of Traditional Houses in Dry Hot Arid Climate and the Effect of Natural Ventilation on Thermal Comfort: A Case Study in Damascus
Full text linkAbstractTraditional houses in hot arid climate of Mediterranean area consist of rooms around one or more courtyards giving a general good comfort conditions especially in hot summer periods. This paper aims to contribution to evaluate the influence of thermal performance of building structures and natural ventilation (cross ventilation, single side ventilation) on the indoor thermal comfort for traditional houses and courtyard located in Damascus old city. The paper shows results of several monitoring data (air temperature, humidity and air velocity) acquired during a summer period, in parallel with occupancy survey for the evaluation of comfort conditions
Servizi di ricera e approfondimento dlle analisi microbiologiche e per sovrintendere agli interventi di miglioramento impiati presso la sede del Comune di Bologna
No full textIn relazione ad alcuni fenomeni di inquinamento emersi nelle precedenti sperimentazioni, sono stat condotte ulteriori indagini microbiologiche, finalizzate alla eventuale individuazione di microorganismi (con particolare riferimento alla presenza di legionella e miceti) all’interno degli apparati dei sistemi di ventilazione del complesso edilizio.
E' stata inoltre verificata l’efficacia sui processi di ventilazione indoor e sulla IAQ degli interventi di risistemazione impiantistica effettuati dal gestore Newco Duc a seguito delle deficienze riscontrate nella prima convenzione di ricerca
Indoor air quality inside a room with a coupled MVHR - fan coil system on building facade
No full textMechanical Ventilation with Heat Recovery (MVHR) systems are widely used in new andrenovated buildings, both for Indoor Air Quality (IAQ) improvement and reduction of ventilationenergy losses. In some approaches, mainly recommended for residential buildings, they are integratedto the windows frame or external façade. These systems are usually combined with a heat emitter tocover the space heating demand. The present study investigates effects of a combined MVHR systemwith a fan coil on IAQ characteristics of a student dormitory room undergone the energy retrofitting,through a Computational Fluid Dynamic (CFD) code. The results obtained by the numericalsimulation allow assessing distributions of the airflow and temperature inside the room andinvestigating the IAQ parameters such as the Mean Age of the Air (MAA), local mean age of the air atexhaust vent, and Air Change Efficiency (ACE). Furthermore, the interaction between MVHR and fancoil systems and its impact on IAQ characteristics are addressed
PRESTAZIONI TERMO-ACUSTICHE DEI COMPONENTI EDILIZI DI FACCIATA – IL RUMORE DEGLI IMPIANTI NELLE COSTRUZIONI CIVILI (GAE/3)
No full textFacade sound insulation: Experimental analysis of different solutions
No full textThe sound insulation of building façade is one of the most important parameters of acoustic performance required for building elements. The choice of particular technical solutions depends on the specific limits set by national rules and regulations, and it is strictly correlated to other environmental parameters, like indoor lighting and ventilation. From this point of view particular cases are analysed, such as schools, hospital, or buildings near public infrastructures (railways, airports). In this paper a critical analysis of different façade sound insulation solutions is presented correlated to national regulations and to experimental data, with particular regard to measurement techniques. Comparison with theoretical predictions according to the method proposed by EN 12354 are also reported
On the optimisation of age of the air in the breathing zone of floor heating systems: The role of ventilation design
Full text linkFor a mechanically ventilated space, the nominal age of the air can be obtained by the reciprocal of the air change rate. However, values of the local mean age of the air in practice may differ to some extent from the nominal one since the nominal time constant employs as reference the theoretical optimum model. This discrepancy could become more prominent in spaces conditioning with both ventilation and heating system where the indoor air pattern is affected by turbulent mixed convection flow. Given importance of knowledge on the distribution of age of the air in these spaces, the present study provides insights on how ventilation design in floor heating systems can optimise the delivery of fresh air into the breathing zone. In this context, by establishing a computational fluid dynamic (CFD) model validated against experimental data, the local mean age of the air as well as the indoor air quality (IAQ) indices in the breathing zone of the floor heating system are examined under different ventilation modes. Six different ventilation scenarios are regarded in order to find the optimal ventilation design in terms of the delivery of the fresh air and ventilation effectiveness in occupied space. Furthermore, the integrated effects of the floor temperature and inlet supply temperature along with the ventilation design on the distribution of local age of the air are addressed. The obtained results indicate that the up-supply ventilation strategy is more efficient than down-supply one in the ventilation effectiveness and delivery of fresh air into the breathing zone. Moreover, it is shown that the mean age of the air in the breathing zone of the up-supply ventilation increases with increment of the Ri (Richardson number), whereas an increase in Ri improves the delivery of fresh air in down-supply mode. For a given floor temperature, the similar trend is also observed in the variation of age of the air with the characteristic temperature of supply inlet, namely the temperature difference between inlet supply and surrounding walls
Effect of Occupant Behavior and Control Systems on the Reduction of Energy Needs of Residential Buildings
Full text linkAbstractAdoption of energy metering systems in apartments with centralized heating plant will lead to greater awareness of the users on energy consumptions. Moreover control systems allow to manage internal temperature according to kind of occupation of the apartment.Starting from the energy consumption of a case study, an apartment block in Bologna, this paper shows the results, based on dynamic simulation, of reduction of energy needs resulting from retrofitting on the building envelope and the effects of thermoregulation systems. Different setting of the internal temperature in adjacent apartments can lead to a variation of energy consumption up to 30%
Evaluation of Thermal Comfort Inside an Office Equipped with a Fan Coil HVAC System: A CFD Approach
Full text linkAn accurate assessment of thermal comfort inside a building is essential since it is associated to the human’s perception of well-being and comfort. In the present study, a 3D computational fluid dynamic (CFD) code is employed to evaluate the indoor comfort indexes for a university office located in a historical building, built of thick masonry walls and of large single-glass windows, using fan coil as an air conditioning system. The experimental measurement has been carried out to validate the numerical model and to obtain the required initial and boundary conditions. The experimental set-up employs an innovative system for the sensor localization, based on acoustic sources, signal processing and trilateration algorithms. By means of finite volume method, the turbulent air flow, the local heat transfer characteristics and the operative temperature inside the room are obtained for a typical winter day. The results yielded by numerical simulations allow to evaluate thermal comfort condition at working places inside the office and to identify the best comfort areas. The results show that even when the air temperature is quite uniform inside the room, the operative temperature at the positions where occupants are placed is significantly affected by surface temperature of the windows, due to the large window to wall surface ratio and also by the position and operational condition of fan coil. It is concluded that 3D comfort map allows to optimize internal layout of the office room; furthermore, the possibility of thermal comfort optimization in specific workstation together with local control of heating system lead to gain remarkable energy saving results
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