Australian Journal of Basic and Applied Sciences

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1 AENSI Journals Australian Journal of Basic and Applied Sciences ISSN: Journal home page: Effectiveness of kapok fibre (Ceibapentandra) as roof insulation for residential buildings in hot climate 1 Muhd Fadhil Nuruddin, 1 NadzhratulHusna Ahmad Puad, 2 Azirul Zainal, 1 Syed Ahmad Farhan, 3 MohdFaris Khamidi 1 Department of Civil Engineering, Faculty of Engineering, UniversitiTeknologi PETRONAS,Bandar Seri Iskandar, Tronoh, Perak,Malaysia. 2 Project Management and Delivery Department, Technology and Engineering Division, PETRONAS Holdings Berhad, Level 6, MenaraDayabumi, Jalan Sultan Hishamuddin, Kuala Lumpur, Malaysia. 3 School of the Built Environment, Heriot-Watt University Malaysia, Level 2, MenaraPjH, 2 JalanTun Abdul Razak, Precinct 2, 6 Putrajaya, Malaysia. A R T I C L E I N F O Article history: Received 15 September 14 Accepted 5 October 14 Available online October 14 Keywords: Kapok fibre, roof insulation, residential building, hot climate, thermal discomfort A B S T R A C T Background: Occupants in residential buildings experience high levels of thermal discomfort due to the intense and long hours of solar radiation that causes the indoor temperature to rise. Absence of insulation in the roof structure of residential buildings allows more heat to penetrate into the indoor space through the roof. Many building insulation materials in the market today such as polystyrene, polyurethane and polyethylene are expensive and not environmentally friendly because they are produced synthetically and involve numerous processes that emit carbon dioxide to the environment. Kapok fibre is an organic material that is cheap, environmentally friendly and easily obtained. Previous researchers have conducted laboratory experiments on kapok fibre and proved that it has low thermal conductivity. However, there is lack of research on the performance of kapok fibre as a roof insulation material. This paper evaluates the effectiveness of kapok fibre as roof insulation for residential buildings in hot climate. Two scaled-down experimental house models equipped with temperature data loggers were set up. One house was uninsulated and the other was insulated with kapok fibre. The thickness of kapok fibre insulation was 5 cm and then increased to 10 cm. Hourly outdoor and indoor temperatures for each house were measured for five hot days. The highest outdoor-indoor temperature difference was 6.42 C, which was obtained by 10-cm kapok fibre insulation at hours. The results proved that kapok fibre can reduce indoor temperature of residential buildings. The effectiveness of kapok fibre insulation can be further validated by conducting experiments in actual houses with the presence of occupants, appliances and furniture. 14 AENSI Publisher All rights reserved. ToCite ThisArticle:Nuruddin M.F., Puad, N.H.A., Zainal, A., Farhan, S.A. andkhamidi M.F., Effectiveness of kapok fibre (ceibapentandra) as roof insulation for residential buildings in hot climate. Aust. J. Basic & Appl. Sci., 8(15): 86-91, 14 INTRODUCTION The production of % carbon dioxide in 05 comes from buildings in many developed countries (United Nations Environment Programme, 09). McKinsey & Company (09) stated that greenhouse gases can be reduced through building insulation. Thermal insulation materials can retard heat from solar radiation from penetrating into the building. There are many different types of commercialized insulation materials in the industry. Traditional insulation materials such as mineral wool, cellulose, cork and polyurethane are widely used because of their high thermal resistance (Jelle, 11). However, many building insulation materials in the market are expensive (Al Yacoubyet al., 11) and some of them are hazardous and not environmentally friendly. Many of the commercialized products such as expanded polystyrene, cellulose fibre, cork, glass wool and polyurethane has thermal conductivity ranging between 0.02 to 0.06 W/mK. Insulation materials can be installed in different parts of the building envelope such as walls, ceiling and roof. Other than that, insulation materials can also be mixed into the material that is used to construct the building envelope (Khamidiet al., 14; Farhanet al., 12b). Previous research on building insulation focused more on wall insulation (Farhanet al., 12a).The effectiveness of installing insulation in the roofing system must be explored further as most of the heat gain into the building is through the roof(suehrckeet al., 08; Al- Homoud, 05). Corresponding Author: Dr. Muhd Fadhil Nuruddin, Department of Civil Engineering, Faculty of Engineering, UniversitiTeknologi PETRONAS, Bandar Seri Iskandar, Tronoh, Perak, Malaysia. fadhilnuruddin@petronas.com.my

2 87 Muhd Fadhil Nuruddin et al, 14 Kapok fibre is an organic material extracted from kapok trees and it has a low thermal conductivity (0.034 to 0.0 W/mK) (Louppeet al., 08). Kapok fibre has a low density and is seven times less dense compared to cotton because it contains unicellular fibres (Chaiarrekijet al., 11; Manohar et al., 06). Kapok fibre shows better performance in thermal properties compared to other natural fibres and allows it to challenge other synthetic fibres (Voumbo, 10). However, Nuruddinet al.(14) reports that based on previous literature, there is presently no research that explores the adoption of kapokfibre as a roof insulation material. Herein, this paper determines the effectiveness of kapok fibre as an insulation roofing material in residential buildings in hot climate. Also, the effect of thickness on its insulation effectiveness is also determined. Experimentation: Measurements of outdoor and indoor temperatures were conducted using two scaled-down experimental house models equipped with temperature data loggers. The house models were built with reference to the minimum dimensions of a room as mentioned in Uniform Building By-Laws (UBBL) 1984 (Legal Research Board, 12a; Legal Research Board, 12b) Dark grey coloured roof tiles were employed to allow maximum absorption of heat from solar radiation. Table 1 presents the insulations installed in the house model variations. Table 1: Insulations installed in the house model variations House Model Insulation A Uninsulated (Figure 1) B 5-cm kapok fibre (Figure 2) C 10-cm kapok fibre (Figure 2) D Radiant barrier (Figure 3) Fig. 1: Top view of attic of uninsulated house model Fig. 2: Top view of attic of insulated house model

3 Temperature for uninsulated house model (Model A) ( C) Muhd Fadhil Nuruddin et al, 14 Fig. 3: Top view of attic of radiant barrier house model Kapok fibre used in this study was obtained from Bota, Perak. Impurities were removed from the kapok fibre before it was placed in the model. Brown paper was selected as the ceiling board material to hold the kapok fibre in place because it is very thin and will not influence the indoor temperature. Radiant barrier used in this study was obtained from a local manufacturer. The radiant barrier is a pure aluminium foil bonded to a layer of woven fabric. and outdoor temperatures were recorded simultaneously for all models using temperature data loggers with built-in thermometers. Hourly temperatures were taken for five hot days. The climate of Malaysia is hot throughout the year and therefore, five hot days is sufficient. Then, hourly outdoor-indoor temperature differences were calculated. RESULTS AND DISCUSSION Figure 4 shows the indoor and outdoor temperature profiles of Model A. In general, daily outdoor temperatures peak in between to hours due to the position of the sun that leads to maximum solar radiation. The highest outdoor-indoor temperature difference recorded was 4.82 C, which was obtained at hours in Day 4. Fig. 4: and outdoor temperature profiles for uninsulated house model (Model A) Figure 5 shows the indoor and outdoor temperature profiles for Model B. The highest outdoor-indoor temperature difference recorded was 5.26 C, which was obtained at hours in Day 3. The outdoor-indoor temperature difference for Model A at this time was 4.63 C, which is 0.63 C lower compared to Model B. Therefore, Model B is effective in retarding heat into the house model.

4 Temperature for 10-cm kapok fibre insulated house model (Model C) ( C) Temperature for 5-cm kapok fibre insulated house model (Model B) ( C) Muhd Fadhil Nuruddin et al, Fig. 5: and outdoor temperature profiles for 5-cm kapok fibre insulated house model (Model B) Figure 6 shows indoor and outdoor temperature profiles for Model C. The highest outdoor-indoor temperature difference recorded was 8.4 C, which was obtained at hours in Day 3. Model B recorded a 5.26 C difference during this time. This proves that the outdoor-indoor temperature difference for Model C is 3.14 C higher than Model B. Therefore, Model C provides better thermal performance than Model B. In addition, the outdoor-indoor temperature difference for Model A is 4.63 C, which is 3.77 C lower than Model C. 45 Fig. 6: and outdoor temperature profiles for 10-cm kapok fibre insulated house model (Model C) Figure 7 shows indoor and outdoor temperature profiles for Model D. The highest outdoor-indoor temperature difference recorded is 7.05 C, which was obtained at hours in Day 4. Model C recorded a 2.79 C difference during this time. This proves that the outdoor-indoor temperature difference for Model D insulated house model is 4.26 C higher than Model C. Therefore, Model D provides better thermal performance than Model C. In addition, the outdoor-indoor temperature differences for Model A and Model B are 4.82 and 2.79 C, which are 2.23 and 2.11 C lower than Model D respectively. Table 2compares the outdoor-indoor temperature differencesof all house models from to hours. The highest average temperature difference is 5.09 C, which was obtained by Model C.

5 Temperature for 10-cm kapok fibre insulated house model (Model D) ( C) Muhd Fadhil Nuruddin et al, Fig. 7: and outdoor temperature profiles for radiant barrier insulated house model (Model D) Table 2: -indoor temperature differences of insulated and uninsulated house models Time (hours) - Temperature Difference ( C) Model A Model B Model C Model D Average Analysis of Variance (ANOVA): Analysis of variance (ANOVA) was used to determine the significant differences between uninsulated and insulated house model. A one-way analysis was performed to compare the means of subgroups. The analysis included standard deviations, variances and 95% of confidence interval means. The results are considered significant when the P-value is lower than However, it is considered marginally significant if the P-value is lower than 0.1. The ANOVA results are shown in Table 3. Results showed a marginally significant preference for Model A (M = 3.087, SD = 1.137, p = 0.089) and Model B (M = 3.446, SD = 1.539, p = 0.068). The outdoor-indoor temperature difference for Model A is marginally significant at and (p = 0.084). However, there are no statistically significant differences for Model C (M = 5.090, SD = 1.579, p = 0.221) and Model D (M = 4.697, SD = 1.395, p = 0.139). Table 3: Results of ANOVA on insulated and uninsulated house models House Model Mean (M) Standard Deviation (SD) P-Value (p) Model A Model B Model C Model D Conclusion: Findings suggest that kapok fibre is effective as a roof insulation material in residential buildings in hot climate. In addition, thicker kapok fibre improves its effectiveness. The highest outdoor-indoor temperature difference was 5.09 C for 10-cm kapok fibre insulated house model, which is 2.37 C higher than the uninsulated house model. For future research, it is recommended that higher thicknesses of kapok fibre are used for evaluation. Also, the evaluation can be conducted in actual houses with the presence of occupants, appliances and furniture. REFERENCES Al-Homoud, M.S., 05. Performance characteristics and practical applications of common building thermal insulation materials, Building and Environment, (3): 3-366, DOI: /j.buildenv Al Yacouby, A.M., M.F. Khamidi, Y.W. Teo, M.F. Nuruddin, S.A. Farhan, S.A. Sulaiman, A.E. Razali, 11. Housing developers and home owners awareness on implementation of building insulation in Malaysia. WIT Transactions on Ecology and the Environment, 148: 219-2, doi: /RAV Chaiarrekij, S., A. Apirakchaiskul, K. Suvarnakich and S. Kiatkamjornwong, 11. Kapok 1: Characteristics of kapok fibre as a potential pulp source for paper making. Bioresources, 7(1): Farhan, S.A., M.F. Khamidi, A.M. Al Yacouby, A. Idrus, M.F. Nuruddin, 12a. Critical review of published research on building insulation: Focus on building components and climate. BEIAC IEEE

6 91 Muhd Fadhil Nuruddin et al, 14 Business, Engineering and Industrial Applications Colloquium.article number , , doi: /BEIAC Farhan, S.A., M.F. Khamidi, M.H. Murni, M.F. Nuruddin, A. Idrus, A.M. Al Yacouby, 12b. Effect of silica fume and MIRHA on thermal conductivity of cement paste.wit Transactions on the Built Environment, 124: , doi: /HPSM1291. Jelle, B.P., 11. Traditional, state-of-the-art and future thermal building insulation materials and solutions Properties, requirements and possibilities. Energy and Buildings, 43: Legal Research Board, 12a. Space, Light and Ventilation in "Uniform Building By-Laws 1984," rule no. 42, Selangor, Malaysia: International Law Book Services,. Legal Research Board, 12b. Space, Light and Ventilation in "Uniform Building By-Laws 1984," rule no. 44, Selangor, Malaysia: International Law Book Services,. Louppe, D., A.A. Oteng-Amoako, M. Brink, 08. Plant Resources of Tropical Africa 7: timbers 1. PROTA Foundation. Leiden, the Netherlands. Backhuys Publishers. Khamidi, M.F., C. Glover, S.A. Farhan, N.H.A. Puad and M.F. Nuruddin, 14. Effect of silica aerogel on the thermal conductivity of cement paste for the construction of concrete buildings in sustainable cities. WIT Transactions on the Built Environment, 137: , doi: /HPSM1601. Manohar, K., D. Ramlakhan, G. Kochhar and S. Haldar, 06. Biodegradable fibrous thermal insulation. J. Braz. Soc. Mech. Sci. Eng., 28(1): McKinsey and Company, 09. Pathways to a Low-Carbon Economy Version 2 of the Global Greenhouse Gas Abatement Cost Curve. Nuruddin, M.F., N.H.A. Puad, K.A.M. Azizli, S.A. Farhan and A. Zainal, 14. Prospect of adopting kapok fibre as roof insulation, Applied Mechanics and Materials, 567: , doi: 10.28/ Suehrcke, H., E.L. Peterson, N. Selby, 08. Effect of roof solar reflectance on the building heat gain in a hot climate, Energy and Buildings, (12): , doi: /j.enbuild United Nations Environment Programme (UNEP), 09. Buildings and Climate Change Summary for Decision Makers, UNEP DTIE Sustainable Consumption & Production Branch, Paris, France. Voumbo, M.L., 10. Characterization of the Thermal Properties of Kapok. Ecole Nationale Supérieure Polytechnique, UniversitéMarienNgouabi, Congo Brazzaville. 2, s.l. : Maxwell Scientific Organization, Vol. 2. ISSN: