Developing a durable thermally insulated roof slab system using bamboo insulation panels
- 1.9k Downloads
Traditional roofs can be effectively substituted by reinforced concrete roof slabs while gaining multiple advantages such as cyclonic resistance, possibility of future vertical extension and possibility of utilizing as an extra working space or a rooftop garden. Further, it adds a significant economic benefit from land regaining. However, the immediate space beneath the roof slab results in thermal discomfort and hence the inventions related to insulated roof slab systems have been increased recently. Although the expected thermal comfort could be achieved, most of the inventions use artificial thermal insulation materials such as polystyrene. This paper introduces a novel roof slab insulation system which uses the natural material of transversely cut bamboo layer as the thermal insulator. The proposed system minimizes the negative environmental impacts induced by the use of artificial insulation materials. The optimum insulation layer thickness is found to be 25 mm, which has acquired a 53% peak heat gain reduction with a decrement factor of 0.61 and a 3-h time lag.
KeywordsSlab insulation Natural thermal insulation Bamboo insulation Heat gain reduction Global warming
Countries like Sri Lanka, located close to the equator, experience tropical climatic conditions having a higher humidity level with low seasonal temperature variations. Most of the Asian countries with such climatic conditions are rapidly developing countries with challenges such as energy crisis and scarcity of usable land for construction . As a result of the damages caused by this development, global warming increases at an alarming rate and has become one of the major issues in the planet . Although scientists and researchers attempt to find measures against global warming, its effects do continue to affect. The world is on its path of facing far worse consequences of global warming such as ice melting and rapid rising of sea level, abnormal precipitation, hurricanes and storms, floods and droughts . According to the recent studies, failure to take necessary actions against global warming would result in a 1.1–6.4 °C rise of earth surface temperature by the end of the twenty-first century . Consequently, countries like Germany have determined to reduce the emission of CO2 by 80% by 2050 .
Subsequently, people seek active cooling solutions such as Air Conditioning to overcome the thermal discomfort inside the buildings induced by global warming. Improved economic standards and availability have made the utilization of Air Conditioners popular among the people [1, 6]. But this should never be encouraged due to the higher energy demand and thereby the higher emission of Greenhouse gases [1, 7, 8]. The usage of Air Conditioning equipment in buildings has increased over the years; hence, a proper mechanism of minimizing the need of active cooling measures would reduce both household and national electricity demand [9, 10, 11]. Such systems can be replaced by passive techniques to improve the indoor thermal comfort while reducing the energy consumption [12, 13].
On the other hand, frequent natural disasters have occurred recently highlighting the significance of disaster resistant structures. Recent findings predict that the severity and the intensity of the natural disasters would be increased in the near future . Disaster resistant structures serve the community saving their lives in the events of natural disasters by preventing sudden collapses. Saving the structures indirectly assists in mitigation of the emission of greenhouse gases by minimizing the repeated usage of embodied energy through preventing the rebuilding [1, 15]. Cyclones are a common scenario in tropical countries. Having conventional roofs made of clay tiles and roofing sheets makes the buildings vulnerable. The effect of the cyclones can be mitigated by increasing the robustness of the structures, which can be achieved by concrete roof slabs through its self-weight [1, 16, 17]. Further, it provides additional benefits such as the possibility of future vertical extension, the possibility of using as an extra working space and the possibility of having vegetation on the top. And also it adds a significant economic value by regaining the land [17, 18, 19]. However, the main drawback of roof slabs is the thermal discomfort in the immediate underneath space .
Roof thermal insulation techniques tested across the world
Applying a cool paint
19% of energy saved on average, saved up to 38% on peak 
Applying a cool paint
Indoor temperature is reduced by 2.5 °C in comparison with outdoor 
6 cm of ventilated air gap
Daily heat gain is reduced by 56% 
25-mm-thick polystyrene insulation on a concrete roof
9 °C reduction in slab soffit temperature, about 75% reduction of heat flow 
A laboratory experiment
Combined application of aluminium reflector and polyurethane insulation
Heat flux reduction of 88% 
A laboratory experiment
10-cm plastic waste thermal insulation
About 70% effective insulation in comparison with ordinary insulation materials. However, considering the economic aspects, this is viable 
Halwatura and Jayasinghe have developed an insulated roof slab system suitable for tropical countries using a polystyrene layer as the thermal insulator [1, 16]. In that system, a 25-mm-thick polystyrene (thermal conductivity of 0.035 W/mK) layer has been used between a 40-mm protective screed layer and a 100-mm-thick structural slab . It has been calculated that the air-to-air thermal resistance and the composite thermal conductivity of the system to be 0.9 m2 K/W and 1.1 W/m2 K, respectively .
Although the invention of Halwatura and Jayasinghe has been proven to be effective in terms of thermally and structurally, the system has been found to have issues related to durability since some water patches were observed on slab soffit in the long run . Moreover, the concrete ratio of insulation layer was 16% . Addressing this and the durability issue without harming the structural integrity, Halwatura and Jayasinghe system was further optimized by Nandapala and Halwatura .
In the system of Nandapala and Halwatura, the continuous strips of Halwatura and Jayasinghe system were converted into a discontinuous strip setup and thereby, the drain paths were added and the concrete ratio of the insulation layer was reduced to 3.3%  resulting a further decrement of composite thermal conductivity (corresponding calculation is as performed in “Appendix A”). Although the strip arrangement has been altered, it has not compromised the structural performance of the system .
Although the system of Nandapala and Halwatura is found to be sound in thermal and structural performance, the thermal insulation material used was polystyrene, (0.033 W/m K thermal conductivity) a product of crude oil extraction that contributes the most to the Greenhouse gas emission [29, 30]. Since it is unfavourable in terms of global warming, it was decided to prepare a suitable natural thermal insulation method to achieve the desired comfort levels. This paper describes a detailed study performed to invent a durable and thermally insulated roof slab system using bamboo insulation panels made of transversely cut bamboo. This system intends to achieve the domestic energy conservation which is highly conferential [31, 32, 33] as well as the energy conservation of other commercial buildings by mitigating the need for air conditioners. And also, the novel insulation system “bamboo heat insulation panels for roof slabs” obtained a patent under Sri Lankan intellectual property act No. 36 of 2003 and under the international patent classification (IPC: E0C 1/100, B28B, B28C) with the patent number: 18880.
The main objectives of the study are to develop a roof slab insulation system using a natural thermal insulation material and assess the effectiveness of the slab insulation system in tropical climatic conditions.
Investigation of natural thermal insulation solutions.
Accessing the possibility of using an air gap as a thermal insulator.
Studying the effect of air confinement through bamboo cut in the transverse direction.
Studying the effect of thickness and number of bamboo layers and optimization.
Calculating the peak heat gain reduction by the bamboo insulation system.
Materials and experimental methods
Investigation on potential natural thermal insulation materials that can be used in local conditions in Sri Lanka
The most important factor in any thermal insulation system is its insulation material. Hence, it is better to select a feasible thermal insulation material to achieve the desired comfort levels. Here, the necessary data of locally available natural materials that can be used as thermal insulators were gathered from the available literature.
Using an air gap as the thermal insulator
Using a bamboo cut in the transverse direction as a thermal insulation material
The experiment described in “Using an air gap as the thermal insulator” was corresponding to an insulation layer of unconfined air. Even in insulation materials such as expanded polystyrene, air confinement is used as a thermal insulator. Hence, it was decided to create an air confinement in such a way that the additional cost for the confinement is minimized and the system is conveniently constructible. Desired air confinement was achieved using bamboo cut in the transverse direction. Since bamboo is a rapidly growing plant which holds the Guinness record for the fastest growing plant in the world  the adverse effect imposed using bamboo for construction purposes is negated in a shorter span of time. In addition, it has been proven that bamboo is a good thermal insulator .
Initially, the insulation layer was prepared using a set of 25-mm-thick bamboo panels. Since better thermal performance can be achieved by optimizing the insulation layer thickness and the number of layers, the optimization was done. The objective was achieved using a set of small-scale physical model testings containing the models with the dimensions mentioned in “Using an air gap as the thermal insulator”. The thermal performance of the slab systems of 25 mm (1.0″), 50 mm (2.0″) and 75 mm (3.0″) bamboo insulation thickness was observed and the effect of the number of layers was investigated using two layers of 37.5 mm bamboo (1.5″). Here also, GL820 Midi Data Logger was used to measure the slab top and slab soffit temperatures of each model.
Calculation of peak heat gain reduction by bamboo insulation slab system
The heat gain reduction due to the bamboo insulation system was calculated with respect to a 125-mm-thick uninsulated reinforced roof slab. Heat flow calculation was performed using the temperature difference between slab soffit and slab top temperatures and corresponding air-to-air resistivity values (the calculations and material properties are given in “Appendix A”).
Figure 6 shows that the simulation results are much similar to the results obtained through the physical model testing. Hence, air-to-air resistivity and corresponding “U” values of bamboo-insulated slab obtained through the computer simulation were used in heat flow calculations.
Results and discussion
Prevailing locally available natural thermal insulation materials
Properties of locally available natural thermal insulation materials
Natural thermal insulation material
Thermal conductivity (W/m K)
Banana and polypropylene (PP) fibre 
Cotton (stalks) 
Oil palm 
Pineapple leaves 
Sunflower (pitch) 
The thermal conductivity values of considered natural thermal insulation materials were in between 0.03 and 0.182 W/m K, and the thermal conductivity of polystyrene which was used in Nandapala and Halwatura system is in the lower bound of Table 2. Hence, it is clear that there is a possibility of substituting polystyrene by a natural thermal insulator and obtaining a reasonable degree of insulation.
An efficient thermal insulator needs to be a material with high porosity as it disturbs the heat conduction. The pores in the material absorb heat disturbing the conductive heat flow and reduce the composite conductivity of the system [4, 51]. According to this process, increasing the void ratio in the insulation layer should theoretically increase the effectiveness of the insulation system. Therefore, the extreme condition, a system with a 100% void ratio, a layer of air, was selected for a trial analysis.
Natural air gap as a thermal insulator
The peak slab top temperature of the model was observed to be 56.8 °C at 1300 h. The peak had transferred to the soffit within 3 h at 1600 h with a decrement factor of 0.62. These outcomes are significant figures for an insulation system as it considerably reduces the heat flow.
The peak slab top temperature of the system with an air gap was observed to be less than that of polystyrene but found to have reached earlier than polystyrene. This means that the convective heat transfer is quicker in the case of the air gap. However, the heat barrier created by polystyrene was stronger than that of the air gap; hence, polystyrene was concluded to be the better insulator. The soffit temperatures shown in the same figure emphasized this fact. Anyhow, the system with the air gap has shown considerable insulation properties. Assuming that the better performance of polystyrene is due to the air confinement increasing the porosity of the insulation material, it was decided to confine the air gap to check whether there is any improvement in thermal performance.
Replacing the air gap with a transversely cut bamboo layer making an air confinement
Although the slab top temperature of the system with bamboo was lower than that of the system with polystyrene, the soffit temperatures behave conversely, similar to the case of the ventilated air gap. Considering the outcomes illustrated in Fig. 11, it is evident that polystyrene has marginally better insulation properties than bamboo. However, considering the environmental aspects, the achievement of bamboo insulation panels can be concluded to be significant.
Then the study was extended to investigate the effect of bamboo insulation layer thickness and the number of layers towards the thermal performance of the system.
Optimization of bamboo layer thickness and number of layers
Four small-scale models were constructed. Models with 25-mm-, 50-mm-, 75-mm- and two 37.5-mm-thick bamboo layers were used in the experiment. Slab top and soffit temperature readings were obtained using the experimental method mentioned in “Using an air gap as the thermal insulator”.
Decrement factors of tested models
Layer thickness (mm)
Slab top maximum temperature (°C)
Slab soffit maximum temperature (°C)
Time lag (h)
2 × 37.5
During the day of the experiment carried out, the maximum outdoor temperature was recorded as 34.6 °C. Table 3 and Fig. 16 clearly indicate that the minimum slab soffit temperature and the maximum time lag between two top temperature readings were corresponding to the model with 75-mm-thick bamboo layer. Hence, it was concluded that the increment of the height of the confined air layer improves the thermal insulation properties. Although higher thicknesses give higher thermal insulation properties, the heat transfer by convection within confined sections are prevented by own viscosity . Because of that, the layer thickness cannot be increased infinitely and convective heat transfer occurs when the layer thickness becomes greater than 75 mm . The slab soffit temperature difference between bamboo insulation panels of 75-mm and 25-mm-thick bamboo layers was 1.2 °C and the difference between decrement factors was 0.02. Although the least slab soffit temperature and the decrement factor was corresponding to the 75-mm-thick bamboo layer, it has consumed a three-time greater insulator thickness compared to the 25-mm bamboo layer. Because of that, 25 mm was selected as the optimum bamboo layer thickness.
When it comes to the effect of the number of layers, 37.5-mm-thick two bamboo layers were considered representing 75 mm layer thickness. Figure 16 clearly indicates that the line of the graph which represents the slab soffit temperature variation of the two 37.5-mm bamboo layer model behaves significantly different to others. In there, the maximum slab soffit temperature was 36 °C creating a decrement factor of 0.66 without any time lag. Hence, it was concluded that increment of the number of bamboo insulation layers does not significantly contribute to the enhancement of thermal performance of the system. Ultimately, it was concluded that a layer of a 25-mm-thick transversely cut bamboo insulation panel can be effectively used as the optimum insulation layer thickness of the system.
Peak heat gain reduction by bamboo insulation slab system
The peak heat gain through bamboo-insulated and uninsulated slab systems was 38.51 W and 81.67 W, respectively. Figure 17 clearly indicates a significant drop in heat flow with 25-mm-thick bamboo insulation system. According to the ultimate calculation, the peak heat gain reduction due to 25-mm-thick bamboo insulation system with respect to the 125-mm-thick uninsulated slab was 53% (the calculation is given in “Appendix A”). Hence, it is evident that the novel thermally insulated roof slab system with 25-mm-thick bamboo layers can be used as an effective way of achieving the indoor thermal comfort.
Following the necessity of developing an eco-friendly insulation system, a number of experiments have been conducted with different materials and system configurations. Since the increment of void ratio of the insulator is directly proportional to the effectiveness of the thermal insulation system, the extreme condition, an air layer with 100% void ratio was tested initially. Tests on the thermal performance of an air gap as the thermal insulator indicated that no thermal performance enhancement can be obtained by increasing the air gap thickness. Since the results proved that polystyrene acts as a better thermal barrier than the unconfined air layer, an air confinement was introduced using transversely cut bamboo sections. These experiments revealed that the optimum thermal performance can be achieved through a 25-mm-thick bamboo insulation layer and there is no significant effect from the multiple bamboo layers towards the ultimate thermal performance. Since the bamboo is a highly available low-cost natural material with a rapid growth rate, it can be consumed without any risk of scarcity. Utilization of bamboo insulation system to fulfil the thermal insulation aspects assist in achieving the desired comfort levels in a much environmental friendly manner. Due to the structural arrangement with the ability to withstand any practical load on roof, the bamboo-insulated roof slab insulation system is considered as a structural sound as well as a thermally insulated eco-friendly slab insulation solution which can provide a peak heat gain reduction of 53% % under tropical climatic conditions with a decrement factor of 0.61, followed by a 3-h time lag.
This work was financially supported by the Senate Research Committee, University of Moratuwa [Grant number SRC/LT/2011/17].
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author; Madujith Sagara Chandra states that there is no conflict of interest.
- 1.Halwatura, R., Jayasinghe, M.T.R.: Thermal performance of insulated roof slabs in tropical climates. Energy Build. 40(7), 1153–1160 (2007)Google Scholar
- 2.Miezis, M., Zvaigznitis, K., Stancioff, N., Soeftestad, L.: Climate change and buildings energy efficiency—the key role of residents. Environ. Clim. Technol. 17(1), 30–43 (2016)Google Scholar
- 3.‘Global Warming Effects’, National Geographic, 09 Oct 2009. [Online]. https://www.nationalgeographic.com/environment/global-warming/global-warming-effects/. Accessed 06 Mar 2018
- 4.Aditya, L., et al.: A review on insulation materials for energy conservation in buildings. Renew. Sustain. Energy Rev. 73, 1352–1365 (2017)Google Scholar
- 5.Galvin, R., Sunikka-Blank, M.: Economic viability in thermal retrofit policies: learning from ten years of experience in Germany. Energy Policy 54(C), 343–351 (2013)Google Scholar
- 6.Mallik, F.H.: Thermal comfort and building designing in the tropical climates. Energy Build. 23, 161–167 (1996)Google Scholar
- 7.Nandapala, K., Chandra, M.S., Halwatura, R.U.: Effectiveness of a discretely supported slab insulation system in terms of thermal performance, In: Sustainability for People—Envisaging Multi Disciplinary Solution, Galle, Sri Lanka, pp. 91–98 (2018)Google Scholar
- 8.Besagni, G., Borgarello, M.: The determinants of residential energy expenditure in Italy. Energy 165, 369–386 (2018)Google Scholar
- 9.Brounen, D., Kok, N., Quigley, J.M.: Residential energy use and conservation: economics and demographics. Eur. Econ. Rev. 56(5), 931–945 (2012)Google Scholar
- 10.Filippini, M., Pachauri, S.: Elasticities of electricity demand in urban Indian households. Energy Policy 32(3), 429–436 (2004)Google Scholar
- 11.Longhi, S.: Residential energy expenditures and the relevance of changes in household circumstances. Energy Econ. 49, 440–450 (2015)Google Scholar
- 12.Kamal, M.A.: An overview of passive cooling techniques in buildings: design concepts and architectural interventions. Civ. Eng. 55(1), 14 (2012)Google Scholar
- 13.Sorrell, S.: The Rebound Effect, an Assessment of the Evidence for Economy-Wide Energy Savings from Improved Energy Efficiency. UK Energy Research Centre (2007)Google Scholar
- 14.Vázquez-Rowe, I., Kahhat, R., Lorenzo-Toja, Y.: Natural disasters and climate change call for the urgent decentralization of urban water systems. Sci. Total Environ. 605–606, 246–250 (2017)Google Scholar
- 15.Venkatarama Reddy, B.V., Jagadish, K.S.: Embodied energy of common and alternative building. Energy Build. 35, 129–137 (2013)Google Scholar
- 16.Halwatura, R.U., Jayasinghe, M.T.R.: Influence of insulated roof slabs on air conditioned spaces in tropical climatic conditions—a life cycle cost approach. Energy Build. 41(6), 678–686 (2009)Google Scholar
- 17.Nandapala, K., Halwatura, R.: Design of a durable roof slab insulation system for tropical climatic conditions. Cogent Eng. 3(1), 1196526 (2016)Google Scholar
- 18.Halwatura, R.U.: Effect of turf roof slabs on indoor thermal performance in tropical climates: a life cycle cost approach. J. Constr. Eng. 2013, 1–10 (2013)Google Scholar
- 19.Nandapala, K., Halwatura, R.: Developing a structurally sound and durable roof slab insulation system for tropical climates. In: Presented at the 8th International Conference of Faculty of Architecture Research Unit (FARU), University of Moratuwa, Taj Samudra Hotel, pp. 201–214 (2017)Google Scholar
- 20.Sterner, E.: Life-cycle costing and its use in the Swedish building sector. Build. Res. Inf. 28(5–6), 387–393 (2000)Google Scholar
- 21.Schmidt, M., Crawford, R.H.: A framework for the integrated optimisation of the life cycle greenhouse gas emissions and cost of buildings. Energy Build. 171, 155–167 (2018)Google Scholar
- 22.Robati, M., McCarthy, T.J., Kokogiannakis, G.: Integrated life cycle cost method for sustainable structural design by focusing on a benchmark office building in Australia. Energy Build. 166, 525–537 (2018)Google Scholar
- 23.Dwaikat, L.N., Ali, K.N.: Green buildings life cycle cost analysis and life cycle budget development: practical applications. J. Build. Eng. 18, 303–311 (2018)Google Scholar
- 24.Vijaykumar, K.C.K., Srinivasan, P.S.S., Dhandapani, S.: A performance of hollow clay tile (HCT) laid reinforced cement concrete (RCC) roof for tropical summer climates. Energy Build. 39(8), 886–892 (2007)Google Scholar
- 25.Parker, D.S., Barkaszi, S.F.: Roof solar reflectance and cooling energy use: field research results from Florida. Energy Build. 25(2), 105–115 (1997)Google Scholar
- 26.Romeo, C., Zinzi, M.: Impact of a cool roof application on the energy and comfort performance in an existing non-residential building. A Sicilian case study. Energy Build. 67, 647–657 (2013)Google Scholar
- 27.Dimoudi, A., Androutsopoulos, A., Lykoudis, S.: Summer performance of a ventilated roof component. Energy Build. 38(6), 610–617 (2006)Google Scholar
- 28.Alvarado, J.L., Terrell, W., Johnson, M.D.: Passive cooling systems for cement-based roofs. Build. Environ. 44(9), 1869–1875 (2009)Google Scholar
- 29.Megri, A.C., Achard, G., Haghighat, F.: Using plastic waste as thermal insulation for the slab-on-grade floor and basement of a building. Build. Environ. 33(2), 97–104 (1998)Google Scholar
- 30.Gavenas, E., Rosendahl, K.E., Skjerpen, T.: CO2-Emissions from Norwegian Oil and Gas Extraction. Norwegian University of Life Sciences, School of Economics and Business, 07–2015 (2015)Google Scholar
- 31.Grossmann, K.: Energetic Retrofit: Considering Socio-spatial Structures of Cities | Energetische Sanierung: Sozialräumliche Strukturen von Städten berücksichtigen. Gaia Okologische Perspekt. Nat.- Geistes- Wirtsch. (2014)Google Scholar
- 32.Wolff, A., Schubert, J., Gill, B.: Risiko energetische Sanierung? In: Großmann, K., Schaffrin, A., Smigiel, C. (eds.) Energie und soziale Ungleichheit: Zur gesellschaftlichen Dimension der Energiewende in Deutschland und Europa, pp. 611–634. Springer Fachmedien Wiesbaden, Wiesbaden (2017)Google Scholar
- 33.Michelsen, C., Müller-Michelsen, S.: Energieeffizienz im Altbau: Werden die Sanierungspotenziale überschätzt? Ergebnisse auf Grundlage des ista-IWH-Energieeffizienzindex. Wirtsch. Im Wandel 16(9), 447–455 (2010)Google Scholar
- 34.Li, T.: What can bamboo do about CO2? Ecology Global Network, 15-May-2013. [Online]. Available: http://www.ecology.com/2013/05/15/what-can-bamboo-do-about-co2/
- 35.Mounika, M., Ramaniah, K., Prasad, A.V.R., Rao, K.V.M., Reddy, K.C.: Thermal conductivity characterization of bamboo fiber reinforced polyester composite. J. Mater. Environ. Sci. 3(6), 1109–1116 (2012)Google Scholar
- 36.Annie Paul, S., Boudenne, A., Ibos, L., Candau, Y., Joseph, K., Thomas, S.: Effect of fiber loading and chemical treatments on thermophysical properties of banana fiber/polypropylene commingled composite materials. Compos. Part Appl. Sci. Manuf. 39(9), 1582–1588 (2008)Google Scholar
- 37.Manohar, K., Ramlakhan, D., Kochhar, G., Haldar, S.: Biodegradable fibrous thermal insulation. J. Braz. Soc. Mech. Sci. Eng. 28(1), 45–47 (2006)Google Scholar
- 38.Panyakaew, S., Fotios, S.: New thermal insulation boards made from coconut husk and bagasse. Energy Build. 43(7), 1732–1739 (2011)Google Scholar
- 39.Pinto, J., et al.: Characterization of corn cob as a possible raw building material. Constr. Build. Mater. 34, 28–33 (2012)Google Scholar
- 40.Paiva, A., Pereira, S., Sá, A., Cruz, D., Varum, H., Pinto, J.: A contribution to the thermal insulation performance characterization of corn cob particleboards. Energy Build. 45, 274–279 (2012)Google Scholar
- 41.Zhou, X., Zheng, F., Li, H., Lu, C.: An environment-friendly thermal insulation material from cotton stalk fibers. Energy Build. 42(7), 1070–1074 (2010)Google Scholar
- 42.Agoudjil, B., Benchabane, A., Boudenne, A., Ibos, L., Fois, M.: Renewable materials to reduce building heat loss: characterization of date palm wood. Energy Build. 43(2), 491–497 (2011)Google Scholar
- 43.Chikhi, M., Agoudjil, B., Boudenne, A., Gherabli, A.: Experimental investigation of new biocomposite with low cost for thermal insulation. Energy Build. 66, 267–273 (2013)Google Scholar
- 44.Khedari, J., Charoenvai, S., Hirunlabh, J.: New insulating particleboards from durian peel and coconut coir. Build. Environ. 38(3), 435–441 (2003)Google Scholar
- 45.Manohar, K.: Experimental investigation of building thermal insulation from agricultural by-products. Br. J. Appl. Sci. Technol. 2(3), 227–239 (2012)Google Scholar
- 46.Yarbrough, D.W., Wilkes, K.E., Oliver, P.A., Graves, R.S., Vohra, A.: Apparent thermal conductivity data and related information for rice hulls and crushed pecan shells. Therm. Conduct. 27, 222–230 (2005)Google Scholar
- 47.Tangjuank, S.: Thermal insulation and physical properties of particleboards from pineapple leaves. Int. J. Phys. Sci. 6(19), 4528–4532 (2011)Google Scholar
- 48.Vandenbossche, V., Rigal, L., Saiah, R., Perrin, B.: New agro-materials with thermal insulation properties. In: 18th International Sunflower Conference, Mar del Plata, Argentina, pp. 949–954 (2012)Google Scholar
- 49.Goodhew, S., Griffiths, R.: Sustainable earth walls to meet the building regulations. Energy Build. 37, 451–459 (2005)Google Scholar
- 50.Pruteanu, M.: Investigations Regarding the Thermal Conductivity of Straw. Gheorghe Asachi Technical University, Jassy, Department of Civil and Industrial Engineering (2010)Google Scholar
- 51.Al-Homoud, M.S.: Performance characteristics and practical applications of common building thermal insulation materials. Build. Environ. 40(3), 353–366 (2005)Google Scholar
- 52.Moss, K.: Heat and Mass Transfer in Building Services Design. London; New York: Routledge (1998)Google Scholar
- 53.Progelhof, R.C., Throne, J.L., Ruetsch, R.R.: Methods for predicting the thermal conductivity of composite systems: a review. Polym. Eng. Sci. 16, 615–625 (1976)Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.