9812nd PALENC Conference and 28th AIVC Conference on Building Low Energy Cooling and Advanced Ventilation Technologies in the 21st Century, September 2007, Crete island, Greece

Evaluation of the thermal behavior of two systems of ceilings: reinforced concrete and wather layer

A.C. Silva, E. M. V. Matos, N. R. A. J. Cabral Centro Federal de Educação Tecnológica do Ceará, Brasil G. C. Nolasco, J. L. J. Albores Universidad Autónoma de Chiapas, México

was made to design both cover sistems thermal behav-ior (concrete beam cover and wather blade). The identification and evaluation of the thermal behavior of two systems, at Autonomous University of Chiapas. University of Architecture - Mexico in a typical day of extreme heat, is the main purpose of that investigation. The show room was chosen as reference, because it is a important space in activities scholars and also because its building characteristics ( reinforced concrete layer), wich is a building default used in whole area. Its important to know air temperature variation and its relation with activities were place, for make possible a better use, as well as, for the identification of the most pleasant moments (thermal conditions) for users. This study is part of results from Agreement between Cuerpo Académico of Components y Condicionantes of there Vivienda. COCOVI (FAUNACH - Mexico), and Energy and Environmental Comfort Laboratory (LE-RCA- CEFETCE - Brazil).

2. METODOLOGY

Representative period determination was used as meth-odological process, based on MONTEIRO (1973), in-cluding bibliographical revision in was such as dinamic and classic climatology, thermal behavior, environmen-tal comfort, climatic analysis and concrete bean cover. Then heat representative period was chosen for this study, and thermal behavior of both cover sistems was analysed: the conventional, is used at the show room in Architecture College, UNACH, México, made in concrete bean, and the propose developed by that col-lege, with use a slim layer of reinforced concrete beam ( about 5 cm), cover with a blade water ( about 15 cm ), as shawed in figure 1.

ABSTRACT

The objective of this work is to compare the thermal be-havior of two systems of beam ceilings used in the Col-lege of Architecture of the Independent University of Chiapas - Mexico. The beam ceiling base (show room) is of reinforced concrete with 10 (ten) centimeters of thickness that will be reference for comparative degree how much to the internal temperature of air in relation the construction covered with developed technology of in the College of Architecture of the UNACH that has water blade of 15 (fifteen) centimeters of thickness. As methodology one used sensory for thermal measure-ments (to datalogger HOBO) for the collection of data of temperature and humidity of air, the identification of a representative period, the elaboration of the graphs and its evaluation. As period of analysis, one stipulated the month of September and the day of heat bigger (day 19 of September). Through the evaluation of the gotten data one identify to difference of 3 degrees between su-perficial temperature of the concrete beam covered with water blade. This variation allows to say that the tech-nology of cover with water blade can mean an alterna-tive that if does not adjust for places with predominant hot climate, as the case of Tuxtla Gutiérrez - Mexico, with maximum temperatures of up to 42 degrees.

1. INTRODUCTION

This investigation seeks to contribute for the preserving of thermal confort conditions, by a case study compar-ing two cover systems. Relevant local characteristics were chosen, resulting in important variables such as use, durability, morphology and “adensamento”. Those factors define a ventilation and heat absorption hypothesis. The evaluation was made from data sup-plied for temperature and air humidity sensors (Date-logger Hobo type) installed at the investigation local. Then, temperature and relative humidity temperature were used to draw informations about thermal behavior, through a comfort index aplication, wich could be space. After thermal conditions analysis, a graph-synthesis

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982 2nd PALENC Conference and 28th AIVC Conference on Building Low Energy Cooling and Advanced Ventilation Technologies in the 21st Century, September 2007, Crete island, Greece

Figure 1. Design and detail of water blade cover

Those following steps were made for evaluation: - choose of the local study chose for make possible ther-mal evaluation, considering orientation, using, cover and walls materials. (Figure 1 ); - representative period definition ( 01/09/2006 a 31/09/2006), identifiqued the day 19/09/06 as the typi-cal day of great heat; - implantation of two sensors of air humidity and tem-perature, by data-loggers HOBO, which has capture frequence each every 30 minutes, both located in geo-metrical center of both roams. ( Figure 2);

Figure 2. Enphasis (circles) o sensors located at cover system, which could hold humidity and temperature values automatically.

- episodium and data analysis, and then graphs designs. The figure 3 shaws the implantation of show room at FAUNACH.

Figure 3: Location of the show room at UNACH. Source: CO-COVI, 2005

Physical evaluation was very important for dosing both layers, because show room ( with reinforced cocrete beam layer) as well as Research Laboratory ( COCOVI ) presented layer “flex” of users. Air humidity and temperature data, holded though sen-sors ( Figura 4 ) previously programmed by external memory stick, compatiblewith HOBO shuttler.

Figure 4: Sensor type data –logger HOBO, which was used for air humidity and temperature measurement in both rooms.

Figure 5. Mobile memory called HOBO Shuttler, compatible with HOBO sensor, responsable for up and dow loading, without remotion needs. Source: Gabriel Nolasco, 2005

After loading, data from episodies were analysed and were designed graphs for evaluating and its interpreta-tion ( Figure 6 ) using Excel and Boxcar.

3. RESULTS AND DISCUSSION

The graph 1 shows behavior for both cover systems, at the typical day of greater heat ( 19/09/2006 ) , defined for presenting the greatest peak of heat at analyzed pe-riod ( 01/09/2006 at 31/09/2006).

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9832nd PALENC Conference and 28th AIVC Conference on Building Low Energy Cooling and Advanced Ventilation Technologies in the 21st Century, September 2007, Crete island, Greece

Gráfico 1 - cobertura de concreto x cobertura c/ lâmina de água (19/09/2006)

Figure 6. Graph with both air temperature, at representative day, from both cover systems ( concrete layer and water blade ).

The analysis from both curves could identify a rise in the air temperature, between 12:00 as 16:00h, in the afternoon. The maximum temperature was 29,10°C, at 16:25h, in the water blade. At the same time, reinforced concrete beam layer showed 26,10°C. After 16:00 h there was a dropped in both air tempera-ture, from both cover systems, even though it was slow-ly at water layer. It could be seen a difference of 3°C between reinforced concrete beam layer and water blade air temperatures. The water blade was responsible for retention heat for more time that the other layer.

4. CONCLUSION

This difference of 3° between both cover systems could means that water blade is not an adjusted alternative for those places, which have greater temperatures, live Tuxtla Gutiérrez- México, that presents maximum above 42°C. Restraining heat for a longer time at water blade could to expanding the thermal discomfort sensation to the users. It is very important continuity studies about thermal be-havior at representative periods, as well as studies about the peculiars features of both building systems, that was used in rooms with layer use ( or not ), for allow better ac-tivities distribution and also how the activities are done. Previous analysis of these factors could allow a better energetic engaged, less natural and physical effort, and also to guarantees layer vision about thermal behavior of employed technology.

REFERENCES

AGUAS, M.P.N. e DOMINGOS, J.J.D. (1996) A Investigação no IST no âmbito da norma ISO 7730. 1º Congresso Internacional de Refrigeração, Ar Condicionado, Ambiente e Energia, Lisboa FROTA, Anesia Barros e SCHIFFER, Sueli Ramos. (2003) Man-ual de conforto térmico. Sao Paulo, Studio Nobel, 7a edição. LAMBERTS,R.; PéREIRA, F; DUTRE,L; GOULARTS, S. (1998) Eficiência Energética na Arquitetura (CD e Livro) PW Editores, NOLASCO, G. C.(2006) Evaluación del co�porta�iento tér�i-co de vivienda social techada con el sistema placa-losa ubicada en el proyecto 10x10chiapas de Tuxtla Gutiérrez, Revista de la Facultad de Arquitectura de la Universidad Autónoma de Chia-pas. Tuxtla Gutiérrez, México. QUEIROZ, Tereza Cristina F.(1996)- Avaliação Ambiental das Condições de Ventilação Estudo de Caso: Arsenal da Marinha do Rio de Janeiro, Oficinas de Metalúrgica Naval; Tese de Mestrado em Conforto Ambiental, Programa de Pós-Graduação em Arquitetura FAU/UFRJ, Rio de Janeiro SCIGLIANO, Sérgio; HOLLO,Vilson. (2001) Índice de Venti-lação Natural: conforto térmico edifícios comerciais e indus-triais em regiões de clima quente. São Paulo , Pini . 1a edição

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