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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.
- 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.
- 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.
- Evaluation of thermal comfort in slightly warm ventilated spaces in nonuniform environmentsPublication . Conceição, E. Z. E.; Lúcio, Maria Manuela Jacinto do Rosário; Lourenço, T. M. C.; Brito, A. I. P. V.The present work analyzes and evaluates the global thermal comfort and local thermal discomfort levels of an occupant subjected to a symmetric nonuniform airflow, originated in common use ventilators. Several incident airflow directions are studied and their effects are described. The global thermal comfort level is evaluated through a multi-nodal numerical model that simulates human and clothing thermal responses, while the local thermal discomfort level is analyzed using an empirical model that predicts draft risks. The computational model of the human body and clothing thermal systems is based on the energy balance integral equations for human body tissue, blood, and clothing, as well as mass balance integral equations for the blood and transpired water in skin surface and the clothing. The human body is divided into 35 elements, each one in several layers of tissue, which could be protected through some clothing layers. A thermoregulatory system model was adapted to control the human body tissue temperature. The experimental tests were carried out in a test chamber in controlled environmental conditions; a thermal manikin was used to simulate the human posture, an indoor climate analyzer was used to measure the environmental variables around the occupant, and two ventilators were used to produce an airflow field around the occupant. The frontal and ascendant airflows from the ventilators placed in front of the occupant are characterized and their velocities around the occupant are measured for several incident angles. The global thermal comfort conditions of the occupant are evaluated both with and without ventilation, and the local thermal discomfort level is evaluated with ventilation for slightly warm, moderate environments.
- Numerical Study of the Thermal Efficiency of a School Building with Complex Topology for Different OrientationsPublication . Conceição, E. Z. E.; Lúcio, Maria Manuela Jacinto do RosárioIn this work a numerical model that simulates the thermal behavior of a building with complex topology and evaluates the indoor thermal and air quality, in transient conditions, is used for a school building thermal project. The program calculates the building surfaces solar radiation field, the building's temperatures, the internal environmental variables, and the occupant's comfort levels. Initially, after the numerical model is validated, the software is used to evaluate the school building's thermal response for four different orientations, either in winter or summer conditions. The work then aims to identify uncomfortable spaces in order to propose, as an example, several solutions that could be introduced for each orientation, that would improve the thermal comfort and air quality levels to which the occupants are subjected, and decrease the building's energy consumption levels. The information obtained from this study could be used to help a designer choose which thermal systems and solutions function best for a preferred school building orientation.
- Prediction of building's temperature using neural networks modelsPublication . Ruano, Antonio; Crispim, E. M.; Conceição, Eusébio; Lúcio, Maria Manuela Jacinto do RosárioThe use of artificial neural networks in various applications related with energy management in buildings has been increasing significantly over the recent years. In this paper the design of inside air temperature predictive neural network models, to be used for predictive control of airconditioned systems, is discussed. The use of multi-objective genetic algorithms for designing off-line radial basis function neural network models is detailed. The performance of these data-driven models is compared, favourably, with a multi-node physically based model. Climate and environmental data from a secondary school located in the south of Portugal, collected by a remote data acquisition system, are used to generate the models. By using a sliding window adaptive methodology, the good results obtained off-line are extended throughout the whole year. The use of long-range predictive models for airconditioning systems control is demonstrated, in simulations, achieving a good temperature regulation with important energy savings.
- Production of thermal energy in university building greenhouses in cold climate conditionsPublication . Conceição, Eusébio; Gomes, João; Lúcio, Maria Manuela Jacinto Do Rosário; Awbi, HazimThe present work focuses on the production of thermal energy in University building greenhouses in cold climate conditions. The building model uses a system of energy and mass balance integral equations, which are solved by the Runge–Kutta–Felberg method with error control. This numerical study is about the thermal behaviour of a university building with complex topology, in winter and transient conditions. The thermal comfort of the occupants, using the Predicted Mean Vote index, and the indoor air quality, using the carbon dioxide concentration, are evaluated. This building has 319 compartments distributed by four floors and it is equipped with one internal greenhouse in the third floor. This greenhouse is located on the south facing facade and the heated air in this space will be transported to compartments located on the north facing façade. The spaces subject to the influence of the heated air coming from the greenhouse improve the level of thermal comfort of its occupants. The level of indoor air quality in occupied spaces is acceptable according to international standards.
- Human thermo-physiological sensation control based in the adaptive comfort philosophyPublication . Conceição, E. Z. E.; Farinho, J. P.; Lúcio, Maria Manuela Jacinto do RosárioIn order to improve the building thermal efficiency, increase the human thermal comfort level and to reduce the building energy consumption, in this work, the human thermo-physiological sensation control, based in the adaptive comfort philosophy, is applied. In this control methodology the occupants, during a lesson activity, can choose among the clothing level, the activity level and the natural ventilation system. The PMV and PPD indexes are used in the numerical simulation. This work is made in a classroom school building, in the Algarve region, with Mediterranean characteristics, in Spring conditions, based in air temperature and relative humidity measurements. The comparison of the human thermal comfort level without and with control strategies is made. The obtained results are used to define an applicable activity, clothing and ventilation strategy, during the day.
- Numerical simulation of passive and active solar strategies in buildings with complex topologyPublication . Conceição, E. Z. E.; Lúcio, Maria Manuela Jacinto do RosárioIn this paper a numerical software, that simulates the building thermal behaviour with complex topology in transient conditions, was developed and used in the study of kindergarten thermal response and the occupants' thermal comfort and air quality in Mediterranean conditions. In this numerical model a new building three-dimensional grid generation philosophy, closer to the reality, that considers the building and the surrounding buildings used in the long and short-wave calculus, the external and internal shading devices, the energy and mass balance integral equations philosophy generated by the building geometry, the equation system resolution done by the Runge-Kutta-Felberg with error control and the human thermal comfort level evaluated through human thermo-physiology, are developed. In the simulation, with a real occupation cycle, the compartments, the building opaque bodies, the building transparent bodies, and the external shading devices were considered. In passive strategies the kindergarten is equipped with multiple inclined aluminium shading devices placed above the transparent windows level and in front to the transparent door facing south, removable inclined tissue shading devices placed in front to the transparent windows facing east, and horizontal fabrics shading devices placed above the transparent panel levels facing south, south-west and west. In this study, made with natural and forced ventilation, the summer and winter conditions were used. In summer conditions, the forced ventilation active strategies in all spaces with cold air from the external environment during the night, and in occupied spaces with stored cold air from the underground space were used. In winter conditions forced ventilation from an internal greenhouse, to heat the internal occupied cold spaces, was used.
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