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- Application of semi-circular double-skin facades in auditoriums in winter conditionsPublication . Conceição, Maria Inês; EZE, Conceicão; Lúcio, Maria Manuela Jacinto Do Rosário; Gomes, João; Awbi, HazimThe DSF (double-skin facade) system is an important element in building design and is used in adjacent spaces to control the inlet solar radiation, heat the air, reduce energy consumption, decrease the acoustics levels, and produce photovoltaic energy, among other improvements. The DSF system can, for example, be used in winter conditions to heat the air, which is then transported to non-adjacent spaces to improve the thermal comfort level and the indoor air quality that the occupants are subjected to. Smooth DSF systems, which are a focus in the literature, are subjected to higher solar radiation levels at a specific hour of the day. The semi-circular DSF system used in this work, which was built from a group of smooth DSF systems with different orientations, guarantees the reception of the highest incident solar radiation throughout the entire day. This work presents a numerical study of a new DSF system, called the semi-circular DSF. The DSF system consists of a set of 25 smooth DSFs with different orientations, each one consisting of an outer glazed surface and an inner surface provided by the outer facade of the auditorium, both separated by an air channel. In this work, the influence of the radius of the semi-circular DSF system and the opening angle of the DSF system on the thermal response of the auditorium was analysed. Thus, six auditoriums were considered: two sets of three auditoriums with radii of 5 m and 15 m, with each of the auditoriums having a different DSF opening angle (45°, 90°, and 180°). It was found that the greater the radius of the semi-circular DSF and the opening angle of the DSF system, the greater the area of its glazed surface and, consequently, the greater the availability of solar heating power. Therefore, during the occupation period, only the set of auditoriums with the largest semi-circular DSF radius managed to present acceptable levels of thermal comfort, which were verified from mid-morning until late afternoon. As for the opening angle of the DSF system, the influence was not very significant, although slight improvements in thermal comfort were noted when the value of this angle was reduced (see Case F as an example) due to the corresponding decrease in the volume of indoor air to be heated. In all auditoriums (see Case A to Case F), it was verified that the indoor air quality was acceptable for the occupants, so the airflow rate was adequately promoted by the ventilation system.
- Evaluation of thermal comfort conditions in a classroom equipped with radiant cooling systems and subjected to uniform convective environmentPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.The aim of this work is to evaluate numerically the human thermal response that 24 students and 1 teacher feel in a classroom equipped with radiant cooling systems and subjected to uniform convective environments, in lightly warm conditions. The evolution of thermal comfort conditions, using the PMV index, is made by the multi-nodal human thermal comfort model. In this numerical model, that works in transient or steady-state conditions and simulates simultaneously a group of persons, the three-dimensional body is divided in 24 cylindrical and 1 spherical elements. Each element is divided in four parts (core, muscle, fat and skin), sub-divided in several layers, and protected by several clothing layers. This numerical model is divided in six parts: human body thermal system, clothing thermal system, integral equations resolution system, thermoregulatory system, heat exchange between the body and the environment and thermal comfort evaluation. Seven different radiant systems are combined to three convective environments. In the radiant systems (1) no radiant system without warmed curtain, (2) no radiant system with warmed curtain, (3) radiant floors cooling system with warmed curtain, (4) radiant panels cooling system with warmed curtain, (5) radiant ceiling cooling system with warmed curtain, (6) radiant floor and panels cooling system with warmed curtain and (7) radiant ceiling and panels cooling system with warmed curtain are analysed, while in the convective environments (1) without air velocity field and with uniform air velocity field of (2) 0.2 m/s and (3) 0.6 m/s are also analysed. The internal air temperature and internal surfaces temperature are 28 degrees C, the radiant cooling surfaces temperature are 19 degrees C and the warmed internal curtains surfaces temperatures, subjected to direct solar radiation, are 40 degrees C. The numerical model calculates the Mean Radiant Temperature field, the human bodies' temperatures field and the thermal comfort level, for the 25 occupants, for the 21 analysed situations. Without uniform air velocity field, when only one individual radiant cooling system is used, the Predicted Percentage of Dissatisfied people is lowest when the radiant floor cooling system is applied and is highest when the radiant panel cooling system is applied. When are combined the radiant ceiling or the floor cooling systems with the radiant panel cooling system the Predicted Percentage of Dissatisfied people decreases. When the uniform air velocity increases the thermal comfort level, that the occupants are subjected, increases. When the radiant floor cooling system or the combination of radiant floor and panel cooling systems without uniform air velocity field is applied, the Category C is verified for some occupants. However, with a convective uniform air velocity field of 0.2 m/s the Category B is verified and with a convective uniform air velocity field of 0.6 m/s the Category A is verify for some occupants. In the last situation the Category C is verified, in general, for all occupants. (C) 2010 Elsevier Inc. All rights reserved.
- Application of computational fluid dynamics differential model coupled with human thermal comfort integral model in ventilated indoor spacesPublication . Conceição, E. Z. E.; Geraldo, D. R. B.; Lúcio, Maria Manuela Jacinto do RosárioIn this study the coupling of computational fluid dynamics (CFD) differential and human thermal comfort (HTC) integral numerical models is developed and used. The HTC integral numerical model evaluates the thermal comfort in non-uniform environments, while the CFD differential numerical model evaluates the airflow inside the virtual chamber and around the manikins. The numerical simulation, using upper crossed ventilation and made in winter conditions, is applied inside a virtual chamber equipped with two seated manikins, one desk and two seats. In this simulation the numerical airflow values, obtained with two different computational grid discretization with one and two manikins, are compared with experimental measurements. Copyright © 2011 by IPAC'11/EPS-AG.
- Energy production of solar DSF for ceiling-mounted localized air distribution systems in a virtual classroomPublication . Conceição, Eusébio; Gomes, João; Lúcio, Maria Manuela; Awbi, HazimThis paper presents an application of energy production in a solar Double Skin Facade (DSF) used in a Heating, Ventilation and Air-Conditioning (HVAC) system for a ceiling-mounted localized air distribution systems in a virtual classroom. In this numerical work, a virtual classroom, an inlet ceiling-mounted localized air distribution system, an exhaust ventilation system, and a DSF system are considered. The numerical simulations consider an integral building thermal response (BTR) and a coupling of an integral human thermal-physiology response (HTR) and differential computational fluid dynamics (CFD). The BTR numerical model calculates, among other parameters, the DSF indoor air temperature and energy production. The HTR numerical model calculates, among other parameters, the human thermal comfort. The CFD numerical model, among other parameters, calculates the indoor air quality. In this study which is performed for winter conditions, the energy produced in the DSF is used for driving the HVAC system. Six different airflow rates are used. The air temperature and energy production in the DSF are also evaluated. The influence of the airflow rate on the HVAC system performance is evaluated by the Air Distribution Index for mid-morning and mid-afternoon conditions. The results show that energy production reduces when the airflow increases and the operating point can be selected using the acceptable levels of thermal comfort and air quality levels or using the maximum Air Distribution Index value. In this study, the application of the thermal comfort and air quality levels criteria demonstrates that the HVAC system uses an optimum airflow rate.
- Fast determination of the acoustic area of influence of roads, railways, airports and industriesPublication . Rosão, Vitor; Rosão, C.; Conceição, E. Z. E.It is very important to know, as early as possible, what is the acoustic area of influence of a particular project, because this information has influence in other areas, e.g. The extension of cartography necessary. So, it is relevant to find fast and simple methods to determine the acoustic area of influence, based on European Interim Methods, for roads, railways, airports and industries.
- Application of an indoor greenhouse in the energy and thermal comfort performance in a kindergarten school building in the South of Portugal in winter conditionsPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.; Lopes, M. C.In this work a numerical model, which simulates the buildings thermal response and evaluates the indoor environment comfort, in transient conditions, is used in the application of an indoor greenhouse in the energy and thermal comfort performance in a kindergarten school building, in the South of Portugal, in Winter conditions. In the numerical simulation of the kindergarten school building, the 25 compartments, the 498 building main bodies and the 42 windows glasses, as well as two schools and three residential surrounding main buildings, are considered. This numerical model is applied in the evaluation of the kindergarten thermal behavior, using the indoor temperature field, and the occupants thermal comfort levels, using the PMV and PPD indexes. After to be compared the numerical and experimental indoor air temperatures field and identified the indoor thermal uncomfortable spaces, the numerical model is used in the evaluation of the indoor greenhouse performance, in order to increase the indoor air temperature and thermal comfort levels, using solar renewable energy, without increase of the kindergarten energy consumption. It is analyzed in detail the greenhouse ventilation operating time and the warm airflow transport way, using an internal ducts system or a corridor space, from the greenhouse to the indoor coldest spaces.
- Evaluation of integral effect of thermal comfort, air quality and draught risk for desks equipped with personalized ventilation systemsPublication . Conceição, Eusébio; Awbi, HazimThis work evaluates the integral effect of thermal comfort (TC), indoor air quality (IAQ) and Draught Risk (DR) for desks with four personalized ventilation (PV) systems. The numerical study, for winter and summer thermal conditions, considers a virtual chamber, a desk, four different PV systems, four seats and four virtual manikins. Two different PV configurations, two upper and two lower air terminal devices (ATD) with different distance between them are considered. In this study a coupling of numerical methodology, using one differential and two integral models, is used. The heating, ventilating and air conditioning (HVAC) system performance in this work is evaluated using DR and room air removal effectiveness (εDR) that is incorporated in an Air Distribution Index (ADI). This new index, named the Air Distribution Turbulence Index (ADTI), is used to consider simultaneously the TC, the IAQ, the DR and the effectiveness for heat removal (εTC), contaminant removal (εAQ) and room air removal (εDR). The results show that the ADI and ADTI, are generally higher for Case II than for Case I, increase when the inlet air velocity increases, are higher when the exit air is located at a height 1.2 m than when is located at 1.8 m, and are higher for summer conditions than for winter conditions. However, the values are higher for the ADI than ADTI.
- Development of a temperature control model used in HVAC systems in school spaces in Mediterranean climatePublication . Conceição, Eusébio; Lúcio, Maria Manuela Jacinto do Rosário; Ruano, Antonio; Crispim, E. M.In this paper a temperature control model used in heating, Ventilating and air-conditioning (HVAC) systems in school spaces, in Mediterranean climate, is developed. This empirical model considers the indoor preferred environmental temperature, the outdoor environmental temperature and the adaptation to the seasons of the year and to the spaces. In the development of the empirical model, in a school building located in the Algarve region, in the South of Portugal, occupied spaces by the non-teacher staff (administrative and auxiliary), teachers and students were used. In these spaces, equipped with heating, ventilating and air-conditioning systems, the occupants can change, during one year of school activities, the indoor environmental conditions in order to obtain acceptable comfort conditions. The indoor air temperature and relative humidity inside four spaces, namely an office room, a secretary room, a teachers room and a library room, the outdoor air temperature and other parameters related to the spaces and heating, ventilating and air-conditioning systems were measured every minute during one year. This empirical model, based in a group of equations for different months and for several spaces, gives information that can be used in the control of a heating, ventilating and air-conditioning systems, in school spaces, in Mediterranean climate, in order to promote indoor acceptable conditions with energy savings. In this model the adaptation to the outdoor environment, for different seasons, the clothing level and the fact that occupants enter and leave frequently from spaces equipped with heating, ventilating and air-conditioning systems to others not equipped are analyzed.
- Variability of noise levels from railwaysPublication . Rosão, Vitor; Conceição, E. Z. E.; Marques, T.The purpose of this study is to determine the variability of noise levels associated with the pass-by of the same type of train at a point, near a railway, and compare this variability with the standard uncertainty, due to the operation of the source, established in ISO 1996-2: 2007, and in the document "Determination of Lden and Lnigth Using Measurements: 2006", from the European Work Group IMAGINE. With these results we can know the measurement effort required to achieve a certain standard uncertainty.
- Neural networks based predictive control for thermal comfort and energy savings in public buildingsPublication . Ferreira, P. M.; Ruano, Antonio; Silva, S. M.; Conceição, EusébioThe paper addresses the problem of controlling a Heating Ventilation and Air Conditioning (HVAC) system with the purpose of achieving a desired thermal comfort level and energy savings. The formulation uses the thermal comfort, assessed using the predicted mean vote (PMV) index, as a restriction and minimises the energy spent to comply with it. This results in the maintenance of thermal comfort and on the minimisation of energy, which in most conditions are conflicting goals requiring an optimisation method to find appropriate solutions over time. A discrete model-based predictive control methodology is applied, consisting of three major components: the predictive models, implemented by radial basis function neural networks identified by means of a multi-objective genetic algorithm; the cost function that will be optimised to minimise energy consumption and maintain thermal comfort; and the optimisation method, a discrete branch and bound approach. Each component will be described, with special emphasis on a fast and accurate computation of the PMV indices. Experimental results obtained within different rooms in a building of the University of Algarve will be presented, both in summer and winter conditions, demonstrating the feasibility and performance of the approach. Energy savings resulting from the application of the method are estimated to be greater than 50%.