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- 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 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.
- Energy and thermal comfort evaluation for different passive solutions in a kindergarten in summer conditionsPublication . Conceição, E. Z. E.; Lopes, M. C.; Lucio, M. M. J. R.In this work a numerical model, which simulates the buildings thermal response with complex topology and evaluates the indoor environment comfort, in transient conditions, is used in the energy and thermal comfort evaluation for different passive solutions in a kindergarten, in Summer conditions. After the validation phase, this numerical model is applied in the evaluation of the building thermal behaviour, using the indoor temperature field, and the occupants' thermal comfort levels, using the PMV and PPD indexes. The introduction of a roof placed in the top of the kindergarten, horizontal shading devices placed above the windows level facing South and external pyramidal opaque trees placed in front to the windows facing West and East, used to reduce the indoor temperature level and to increase the indoor thermal comfort level, in Summer conditions, are analyzed.
- Evaluation of thermal comfort conditions in a localized radiant system placed in front and behind two students seated nearby warmed curtainsPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.In this work the evaluation of thermal comfort conditions, that two students are subjected, in a classroom desk equipped with a localized radiant system placed in front and behind the occupants seated nearby windows equipped with curtains subjected to solar radiation, in Winter conditions, is made. In the simulation, performed in a 2.7 x 2.4 x 2.4 m(3) virtual chamber, two occupants seated in a classroom desk, equipped with two localized radiant surfaces placed in front and two localized radiant surfaces placed behind them, a window subjected to solar radiation and an internal curtain are considered. A numerical model, that allows to simulate the human body thermal, clothing thermal and thermoregulatory systems, in non-uniform environments, is used. The Mean Radiant Temperature, with and without correction, and Radiosity methods are used in the study of the influence of the localized radiant surface, the room surrounding surfaces, the lateral occupant's body, the lateral curtain surface and the lateral solar radiation, in the thermal comfort conditions. In the first part of the study three numerical methods used in the evaluation of internal radiant heat exchanges in an acceptable typical thermal situation are analysed, while in the second part the influence of four important thermal parameters in the thermal comfort level is analysed. In the first part of this work, the localized radiant surfaces and the lateral occupant's body are evaluated in the first test, the localized radiant surfaces, the lateral occupants body and the lateral curtains surface are evaluated in the second test and the localized radiant surfaces, the lateral occupants body, the lateral window glass surface and the lateral solar radiation are evaluated in the third test. In the second part of this work, the influence of air temperature, equal to the room surrounding surfaces temperature, the localized radiant system temperature, the lateral curtains temperature and the air relative humidity, in the thermal comfort level, that the two occupants are subjected, is evaluated. (C) 2010 Elsevier Ltd. All rights reserved.
- Air quality inside a school building: air exchange monitoring, evolution of carbon dioxide and assessment of ventilation strategiesPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.This paper presents an assessment of indoor air quality and various ventilation strategies inside a school building located in the south of Portugal. In the first phase, ventilation rate was experimentally evaluated using the tracer gas method. In the second part, different airflow typologies were investigated and, after calculating the air exchange and flow rates for each of them, the evolution of metabolic carbon dioxide inside the spaces was numerically estimated. Ventilation measurements were made in classrooms, auditorium, offices, staff and computer rooms. The assessment of ventilation was based on evaluating the carbon dioxide produced by the occupants for three ventilation approaches; these were: one based on cross-flow natural ventilation (in current use) and two based on forced ventilation systems. In the case of the forced systems, one was based on providing a constant flow to meet the required Portuguese ventilation standard in the main occupied rooms while the other was an adjusted constant rate based on a simple calculation procedure that took into consideration the air quality needs of all the spaces including corridors and atria. This approach was developed to produce an efficient yet inexpensive ventilation approach that did not incorporate expensive sensors and control systems. Carbon dioxide evolution predictions were made using software that evaluated the thermal response and the air quality of a building with complex topology. The numerical model used to evaluate air quality, was based on mass conservation integral equations in which the final equations system was solved through the Runge-Kutta-Fehlberg method with error control. A statistical study of the occupation cycle in the school building during the day was developed.
- Application of a developed adaptive model in the evaluation of thermal comfort in ventilated kindergarten occupied spacesPublication . Conceição, E. Z. E.; Gomes, João; Antão, N. H.; Lucio, M. M. J. R.In this work the application of a developed adaptive model in the evaluation of thermal comfort in ventilated kindergarten occupied spaces is made. The study, conducted in real conditions, in mediterranean environment for cold and warm thermal conditions is made. The adaptive model is developed in a Kindergarten, using subjective and experimental measurements. Three different trained groups of subjects are used. Each one expressed its thermal subjective response, in different classrooms, for cold and warm thermal conditions. In the study, the classrooms are ventilated by natural airflow, while the indoor playground is ventilated by forced airflow. The natural airflow in the classrooms is measured using tracer gas decreasing concentration. The measurements are made for different window states, from close state to open state. In both warm and cold thermal conditions the simulation is made in real occupation and ventilation conditions. The natural ventilation is promoted, in both thermal conditions, using experimental measurements. In cold thermal conditions the forced airflow is done from the greenhouse to the indoor playground, while in warm thermal conditions the forced airflow is done in the opposite direction. In the thermal comfort level evaluation the developed adaptive model is used, while in the air quality level evaluation the carbon dioxide concentration released by the occupants is used. (C) 2011 Elsevier Ltd. All rights reserved.
- Evaluation of local thermal discomfort in a classroom equipped with cross flow ventilationPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.; Vicente, V. D. S. R.; Rosão, VitorThis paper presents an evaluation of the local thermal discomfort level in a classroom equipped with cross ventilation, for a typical moderate summer day in Portugal. Three different ventilation configurations based on window and door opening were considered. In each, the thermal comfort, air quality and acoustical comfort conditions were also evaluated. This experimental study was made in the South of Portugal, exposed to a Mediterranean climate. Thermal comfort was based on the PMV index, the air quality was based on the air renovation rate and acoustical comfort levels were based on the reverberation time, voice clarity, definition and early reflection ratio. The detailed local thermal discomfort analysis was based on draught risk and uncomfortable air velocity fluctuations. Other measurements included relative humidity, the radiative mean temperature, carbon dioxide concentration (tracer gas decay), and noise level decay of impulsive response. Results showed that for the warmest of weather open windows and classroom door gave the best air quality and comfort conditions.
- Airflow inside school building office compartments with moderate environmentsPublication . Conceição, E. Z. E.; Vicente, V. D. S. R.; Lucio, M. M. J. R.In this paper, the airflow inside school building office compartments with moderate environments, in steady-state conditions, is experimentally and numerically analyzed. The experimental tests are made in a developed experimental chamber, while the numerical results are obtained in a developed numerical model. The air velocity fluctuations are experimentally measured and the air velocity root mean square, the air turbulence intensity, the draft risk, the air velocity fluctuation frequencies, and the air velocity fluctuation equivalent frequencies are calculated. The mean and local air renovation rates, using the decay tracer gases method with a carbon dioxide concentration, are calculated. The three-dimensional air velocity and the air renovation rate are numerically calculated. Both these experimental and numerical results are compared to better understand the airflow topology inside this kind of compartment and evaluate the comfort level, namely the thermal comfort, local thermal discomfort, and air quality levels, to which occupants are subjected. The analyzed airflow topology, with the air forced inlet and outlet located above the occupants' head level, is divided into two areas: the non-occupied upper area, which contains the airflow inlet and outlet, with high air velocity levels, is developed to facilitate the contaminant extraction released by the occupants, while the occupied lower area, with low air velocity levels, is developed to ensure good thermal comfort and reduced local discomfort levels, with the capacity to transport the occupants' contaminants to the upper area.
- Study of Airflow around Occupants Seated in Desks Equipped with Upper and Lower Air Terminal Devices for Slightly Warm EnvironmentsPublication . Conceição, E. Z. E.; Rosa, S. P.; Custodio, A. L. V.; Andrade, R. L.; Meira, M. J. P. A.; Lucio, M. M. J. R.This paper will discuss' the study of turbulent and mean airflow exiting air terminal devices and surrounding occupants sewed in classroom desks for slightly warm environments equipped with personalized ventilation systems with upper and lower air terminal devices. In the turbulent airflow analysis the air root mean square. the air turbulence intensity, and the air velocity fluctuations,frequencies are calculated, while in the mean airflow analysis the mean air velocity and temperature, the human body skin temperature, and the thermal comfort indexes are evaluated using a multi-node thermal regulation model for two different airflow rates. In the experimental tests made in a wood chamber a manikin, a ventilated desk, and two interior climate analyzers are used. The fluctuations of air velocity and temperature are measured in the air terminal devices and in 15 human body sections around the manikin, while the mean value of air relative humidity and mean radiant temperature are evaluated inside the experimental chamber. The mean air temperature in the air terminal devices is around 28 degrees C (82.4 degrees F), while the mean radiant temperature in the occupation area, the mean air temperature far from the occupation area, and the internal mean air relative humidity in the occupation area are around 28 degrees C (82.4 degrees F), 28 degrees C (82.4 degrees F), and 50%, respectively. The airflow rate in tests I and II are 25.75 m(3)/h (15.16 ft(3)/min) and 48.04 m(3)/h (28.27 ft(3)/min), respectively. The mean air velocity, root mean square, and turbulence intensity for test I are 0.59 m/s (1.94 ft/s), 0.13 m/s (0.43 ft/s), and 22.4%, in the upper air terminal device, and 0.9 m/s (2.96 ft/s), 0.15 m/s (0.49 ft/s), and 16.7%, in the lower air terminal device; while, for test II they are 1.72 m/s (5.64 ft/s), 0.16 m/s (0.52 ft/s), and 9.4%, in the upper air terminal device, and 1.06 m/s (3.48 ft/s), 0.16 m/s (0.52 ft/s and 14.9%, in the lower air terminal device. In test I the mean air velocity and the airflow rate are higher in the lower exit air terminal device than in the upper exit air terminal device; while in test II, the opposite is true. It is also true that the skin temperature is slightly lower in test II than in test I, mainly in human body sections near the air terminal devices, such as the chest, arms, and legs. The occupant in test I conditions is thermally uncomfortable; however, in test II conditions, the obtained results are near the comfort recommendations.
- Comfort and airflow evaluation in spaces equipped with mixing ventilation and cold radiant floorPublication . Conceição, E. Z. E.; Lucio, M. M. J. R.; Awbi, H. B.In this work the comfort and airflow were evaluated for spaces equipped with mixing ventilation and cold radiant floor. In this study the coupling of an integral multi-nodal human thermal comfort model with a computational fluid dynamics model is developed. The coupling incorporates the predicted mean vote (PMV) index, for the heat exchange between the body and the environment, with the ventilation effectiveness to obtain the air distribution index (ADI) for the occupied spaces with non-uniform environments. The integral multi-nodal human thermal comfort model predicts the external skin and clothing surfaces temperatures and the thermal comfort level, while the computational fluid dynamics model evaluates the airflow around the occupants. The air distribution index, that was developed in the last years for uniform environments, has been extended and implemented for non-uniform thermal environments. The airflow inside a virtual chamber equipped with two occupants seated in a classroom desk, is promoted by a mixing ventilation system with supply air of 28 A degrees C and by a cold radiant floor with a surface temperature of 19 A degrees C. The mechanical mixing ventilation system uses a supply and an exhaust diffusers located above the head level on adjacent walls.