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Experimental determination of time lag and decrement factor
Case Studies in Construction Materials 11 (2019) e00298
Contents lists available at ScienceDirect
Case Studies in Construction Materials journal homepage: www.elsevier.com/locate/cscm
Case study
Experimental determination of time lag and decrement factor Pape Moussa Toure*, Younouss Dieye, Prince Momar Gueye, Vincent Sambou, Seckou Bodian, Sumailla Tiguampo Laboratoire d’Energétique Appliquée,Ecole Supérieure Polytechnique, Université Cheikh Anta Diop, BP:5085 Dakar-Fann, Senegal
A R T I C L E I N F O
A B S T R A C T
Article history: Received 12 June 2019 Received in revised form 4 October 2019 Accepted 25 October 2019
Buildings consume about 40% of the primary energy in the world. This means that buildings are responsible for the majority of greenhouse gas emissions. It’s time to reduce this energy consumption to limit the environmental impact of buildings. The use of high thermal inertia envelopes could be a solution to reduce energy consumption of the building. The thermal inertia is characterize by time lag and decrement factor. This work deals with the experimental determination of time lag and decrement factor of a building envelope. For this purpose, a test cell of 1 m3 made of stabilized earth brick is built at the Cheikh Anta Diop University of Dakar. Stabilized earth bricks are commonly used in Senegal. The time lag and the decrement factor are calculated using the ambient-air temperature inside a test cell and the outdoor average equivalent temperature. The results show that the time lag of a test cell envelope is about 6 h and the decrement factor about 0.4. This reduces the energy needed to cool the building during warm periods, as fluctuations in the outside temperature are not felt. © 2019 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: Time lag Decrement factor Stabilized earth brick Thermal inertia
1. Introduction Buildings consume about 40% of the primary energy in the world [1–2]. This means that buildings are responsible for the majority of greenhouse gas emissions [3]. It’s time to reduce this energy consumption to limit the environmental impact of buildings. The use of high thermal inertia envelopes could be a solution to reduce energy consumption of the building. The decrement factor and time lag are two parameters that characterize the thermal inertia of a material. Many studies have been carried out for the determination of time lag and decrement factor. The evaluation of time lag and decrement factor of a wall having an thermal capacity of 1.512 MJ/(m3 K) and thermal conductivity of 0.62 W/(mK) has been done by Jin et al. [4]. Thongtha et al. [5] calculated the time lag and decrement factor of an autoclaved cellular concrete wall and an autoclaved cellular concrete wall with addition of sugar sediment. The calculation of the time lag and decrement factor of several walls having light or dark colored outer surfaces has been done by Ruivo et al. [6]. Assem [7] has determined the time lag and decrement of the aerated autoclaved concrete wall. Shaik and Setty [8] have carried out the time lag and decrement factor of laterite wall houses. The time lag and decrement factor of different building materials that are commonly used in Iran have been investigated by Fathipour and Hadidi [9]. Al-Sanea and Zedan [10], Asan [11], Yuan [12], Tzoulisa and Kontoleonb [13], Romero-Flores et al. [14], Ozel [15], Kontoleon and Eumorfopoulou [16] have evaluated the time lag and decrement factor of insulation building materials wall. Balaji et al. [17] have studied the decrement factor and time lag of homogeneous building materials wall. Bilgin and Arıcı [18] are interested
* Corresponding author. E-mail address: [email protected] (P.M. Toure). https://doi.org/10.1016/j.cscm.2019.e00298 2214-5095/© 2019 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
2
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
on the determination of time lag and decrement factor of a sandwiched external wall composite of mortar, PCM and concrete. The time lag and decrement factor of a glazed roof filled with phase change material was experimentally investigated by Dong et al [19]. A short term experimental investigation of time lag and decrement factor of aerated lightweight concrete (ALC) wall panels was carried out by Soon et al [20]. All these theoretical and experimental studies concern the calculation of time lag and decrement factor of a wall and roof. In these studies, the walls are exposed to conditions different from tropical climate. This work consists to determine experimentally the time lag and decrement factor using a stabilized earth brick envelope. To do this, an experimental test cell is built at the Cheikh Anta Diop University in Dakar. The originality of this work compared to the work mentioned above is the calculation of time lag and decrement factor using the inside ambient-air temperature and average equivalent temperature. The ambient-air temperature characterizes the simultaneous response of all walls and roof to external solicitations. 2. Description of experimental device 2.1. Presentation of the experimental cell The experimental system is presented in Fig. 1. This is a test cell of four walls, a vaulted roof and a wooden door. This test cell is built at the Cheikh Anta Diop University of Dakar. The internal dimensions of the test cell are 1 1x1 m3, giving a space area of 1 m2 with a height of 1 m. The envelope of the test cell has a thickness of 14 cm. The four walls and the roof are built with a material commonly used in construction in Senegal. It is the earth brick stabilized with cement. They are manufactured by local brickworkers. The thermo-physical and surface properties of stabilized earth bricks are summarized in Table 1. The thermal properties of the earth brick were measured by the transient asymmetrical hot plate device [21]. The floor of the test cell is in concrete. An insulation material (a 2 cm-thick glass wool) is placed on the floor that is covered with a moisture-proof material. This decreases the influence of heat and humidity exchange between the ground and the floor on the temperature and humidity inside the test cell. 2.2. Instrumentation Two temperature and relative humidity “Log Tag’’ recorders are used for monitoring the outside and the inside temperature of test cell. Its precision is 3 % of relative humidity and 1 C of temperature. During the experimentation, the test cell door remains closed. The global horizontal irradiance and the direct normal irradiance are measured using a pyranometer and a pyrheliometer. These two radiations are used to calculate the global radiation incident on a wall or on the roof.
Fig. 1. Photo of the building.
Table 1 Thermo-physical and surface properties of stabilized earth brick. Density (kg/m3)
2000
Thermal conductivity (W/mK) Specific heat (J/kg.K) Infrared emissivity Solar absorptivity
0.75 997 0.7 0.9
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
3
1 Calculation of time lag and decrement factor The time lag ’ and the decrement factor f are calculated as follows:
’ ¼ tT i;max tT e;max
ð1Þ
Where tT i;max : The time when the ambient-air temperature inside a test cell is maximum tT e;max : The time when the outdoor average equivalent temperature is maximum f ¼
T i;max T i;min T e;max T e;min
ð2Þ
Where T i;max : The maximum ambient-air temperature inside a test cell T i;min : The minimum ambient-air temperature inside a test cell T e;max : The maximum outdoor average equivalent temperature T e;min : The minimum outdoor average equivalent temperature The outdoor average equivalent temperature is calculated as follows: T ext ¼
SS p T p SS p
ð3Þ
Where Sp is the surface of a wall or roof, T p the equivalent temperature of a wall or roof. The outdoor average equivalent temperature is used to materialize the heat received on the envelope of the test cell. Because to calculate the equivalent temperature (eq 4), the outside ambient air-temperature and global radiation incident on each wall of the test cell are taken into account. This temperature is calculated as follows [14]: # " aGinc ðtÞ es ðT 4a T 4surr Þ ð4Þ T p ¼ T a ðtÞ þ he he With e the emissivity of surface of a wall or roof, α the solar absorptivity of surface of a wall or roof, s the StefanBoltzmann constant, Ta the ambient-air temperature outside, Tsurr the average surrounding surface and sky temperature and Ginc the global radiation incident on a wall or on the roof, he the heat transfer coefficient. The emissivity and solar absorptivity values are given in Table1. The heat transfer coefficient has been fixed at 10 W/m2K. In this present study the last term of equation (4) is ignored [16]. The outdoor average equivalent temperature is used to materialize the heat received on the envelope of the test cell. Because to calculate the equivalent temperature (eq 4), the outside ambient air-temperature and global radiation incident on each wall of the test cell are taken into account.
Fig. 2. Daily variation of global horizontal radiation and normal direct radiation.
4
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
3. Results and discussion 3.1. Average equivalent temperature To obtain the daily average equivalent temperature, the daily global horizontal radiation and the daily normal direct radiation are used (Fig. 2). This allowed us to calculate the equivalent temperature on each wall of the test cell (Fig. 3). After obtaining the equivalent temperature on each wall, the average equivalent temperature is calculated. The Fig. 4 represents the variation of average equivalent temperature for four days of measurement. This average equivalent temperature obtained is smoothed (Fig. 5) to remove disturbances that may be due to cloudy passages. 3.2. Time lag and decrement factor The time lag and decrement factor are calculated using Fig. 6. This curve represents the variation of ambient airtemperature inside the cell and the outside average equivalent temperature. In this curve the ambient air-temperature time
Fig. 3. Daily variation of equivalent temperature on each wall of the test cell.
Fig. 4. Variation of average equivalent temperature from midnight to midnight.
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
5
Fig. 5. Variation of average equivalent temperature fitting from midnight to midnight.
Fig. 6. Variation of inside ambient air-temperature and average equivalent temperature from midnight to midnight.
Table 2 Time lag and decrement factor values. Day
Time lag (hr)
Decrement factor
1 2 3 4
6,02 6,27 6,27 6,38
0,41 0,43 0,38 0,40
lag and decrement factor is shown. The values found of time lag and decrement factor are summarized in Table 2. The results show that the time lag inside of cell is around 6 h and the decrement factor around 0.4. The time lag and decrement factor are not significantly variable with day. This can be explained by the fact that time lag and the decrement factor are intrinsic parameters to envelope. With these time lag and decrement factor values the heat is stored in the envelope during the day. This reduces the number hours of cooling during the hot periods of the year.
6
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
4. Conclusion In this work an experimentally determining of time lag and decrement factor using a compressed stabilized earth brick envelope was made. This study was carried out using an experimental cell built in stabilized earth brick through a campaign to measure temperature, normal direct solar radiation and global solar radiation. At the end of this measurement campaign, the time lag and decrement factor were determined to quantitatively evaluate the inertia of stabilized earth brick. The calculation of time lag and decrement factor using ambient air-temperature in the cell and average equivalent temperature has given a time lag inside of cell around 6 h and a decrement factor around 0.4. With these time lag and decrement factor values, the number hours of cooling can be considerably reduced. Because the strong temperatures variations in daytime during the hot periods of the year are not felt inside of building. References [1] S. Mounir, Y. Maaloufa, A.B. Cherki, A. Khabbazi, Review thermal properties of the composite material clay/granular cork, Constr. Build. Mater. 70 (2014) 183–190. [2] S. Bahria, M. El Ganaoui, M. Amirat, A. Hamidat, L. Ouhsaine, A Dynamic simu- lation of the low-energy building using wood based material, Proceedings of the International Conference on Materials and Energy – ICOME 16 (2016) 641–644. [3] A. Abderraouf, B. Naima, G. Fouad, Thermal conductivity and thermal degradation of cementitious mortarsreinforced with doum and diss fibers, Proceedings of the International Conference on Materials and Energy – ICOME 16 (2016) 635–639. [4] X. Jin, X. Zhang, Y. Cao, G. Wang, Thermal performance evaluation of the wall using heat flux time lag and decrement factor, Energy and Buildings 47 (2012) 369–374. [5] A. Thongtha, S. Maneewan, C. Punlek, Y. Ungkoon, Investigation of the compressives trength,time lags and decrement factors of AAC-lightweight concrete containing sugar sediment waste, Energy and Buildings 84 (2014) 516–525. [6] C.R. Ruivo, P.M. Ferreira, D.C. Vaz, On the error of calculation of heat gains through walls by methods using constant decrement factor and time lag values, Energy and Buildings 60 (2013) 252–261. [7] E.O. Assem, Correlating thermal transmittance limits of walls and roofs to orientation and solar absorption, Energy and Buildings 43 (2011) 3173–3180. [8] S. Shaik, A.B.T.P. Setty, Influence of ambient air relative humidity and temperature on thermal properties and unsteady thermal response characteristics of laterite wall houses, Building and Environment 99 (2016) 170–183. [9] R. Fathipour, A. Hadidi, Analytical solution for the study of time lag and decrement factor for building walls in climate of Iran, Energy 134 (2017) 167– 180. [10] S.A. Al-Sanea, M.F. Zedan, Heat transfer characteristics and optimum insulation thickness for cavity walls, Journal of Thermal Envelope and Building Science 26 (2003) 285–307. [11] H. Asan, Effects of wall’s insulation thickness and position on time lag and decrement factor, Energy and Buildings 28 (1998) 299–305. [12] J. Yuan, Impact of insulation type and thickness on the dynamic thermal characteristics of an external wall structure, Sustainability 10 (2018) 28–35. [13] T. Tzoulisa, K.J. Kontoleonb, Thermal behaviour of concrete walls around all cardinal orientations and optimal thickness of insulation from an economic point of view, Procedia Environmental Sciences 38 (2017) 381–388. [14] M. Romero-Flores, L.M. Becerra-Lucatero, R. Salmon-Folgueras, Thermal performance of scrap tire blocks as roof insulator, Energy and Buildings 149 (2017) 384–390. [15] M. Ozel, The influence of exterior surface solar absorptivity on thermal characteristics and optimum insulation thickness, Renewable Energy 39 (2012) 347–355. [16] K.J. Kontoleon, E.A. Eumorfopoulou, The influence of wall orientation and exterior surface solar absorptivity on time lag and decrement factor in the Greek region, Renewable Energy 33 (2008) 1652–1664. [17] N.C. Balaji, M. Mani, B.V. Venkatarama Reddy, Dynamic thermal performance of conventional and alternative building wall envelopes, Journal of Building Engineering 21 (2019) 373–395. [18] F. Bilgin, M. Arıcı, Effect of Phase Change Materials on Time Lag, Decrement Factor and Heat-Saving, International Conference on Computational and Experimental Science and Engineering ICCESEN (2017) 1101–1105 132. [19] D. Li, Y. Wu, G. Zhang, M. Arıcı, C. Liu, F. Wang, Influence of glazed roof containing phase change material on indoor thermal environment and energy consumption, Applied Energy 222 (2018) 343–350. [20] Ng. Soon-Ching, K.S. Low, N.H. Tioh, Thermal inertia of newspaper sandwiched aerated lightweight concrete wall panels: Experimental study, Energy and Buildings 43 (2011) 2956–2960. [21] P.M. Touré, V. Sambou, M. Faye, et al., Mechanical and hygrothermal properties of compressed stabilized earth bricks (CSEB), Journal of Building Engineering 13 (2017) 266–271.
Contents lists available at ScienceDirect
Case Studies in Construction Materials journal homepage: www.elsevier.com/locate/cscm
Case study
Experimental determination of time lag and decrement factor Pape Moussa Toure*, Younouss Dieye, Prince Momar Gueye, Vincent Sambou, Seckou Bodian, Sumailla Tiguampo Laboratoire d’Energétique Appliquée,Ecole Supérieure Polytechnique, Université Cheikh Anta Diop, BP:5085 Dakar-Fann, Senegal
A R T I C L E I N F O
A B S T R A C T
Article history: Received 12 June 2019 Received in revised form 4 October 2019 Accepted 25 October 2019
Buildings consume about 40% of the primary energy in the world. This means that buildings are responsible for the majority of greenhouse gas emissions. It’s time to reduce this energy consumption to limit the environmental impact of buildings. The use of high thermal inertia envelopes could be a solution to reduce energy consumption of the building. The thermal inertia is characterize by time lag and decrement factor. This work deals with the experimental determination of time lag and decrement factor of a building envelope. For this purpose, a test cell of 1 m3 made of stabilized earth brick is built at the Cheikh Anta Diop University of Dakar. Stabilized earth bricks are commonly used in Senegal. The time lag and the decrement factor are calculated using the ambient-air temperature inside a test cell and the outdoor average equivalent temperature. The results show that the time lag of a test cell envelope is about 6 h and the decrement factor about 0.4. This reduces the energy needed to cool the building during warm periods, as fluctuations in the outside temperature are not felt. © 2019 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: Time lag Decrement factor Stabilized earth brick Thermal inertia
1. Introduction Buildings consume about 40% of the primary energy in the world [1–2]. This means that buildings are responsible for the majority of greenhouse gas emissions [3]. It’s time to reduce this energy consumption to limit the environmental impact of buildings. The use of high thermal inertia envelopes could be a solution to reduce energy consumption of the building. The decrement factor and time lag are two parameters that characterize the thermal inertia of a material. Many studies have been carried out for the determination of time lag and decrement factor. The evaluation of time lag and decrement factor of a wall having an thermal capacity of 1.512 MJ/(m3 K) and thermal conductivity of 0.62 W/(mK) has been done by Jin et al. [4]. Thongtha et al. [5] calculated the time lag and decrement factor of an autoclaved cellular concrete wall and an autoclaved cellular concrete wall with addition of sugar sediment. The calculation of the time lag and decrement factor of several walls having light or dark colored outer surfaces has been done by Ruivo et al. [6]. Assem [7] has determined the time lag and decrement of the aerated autoclaved concrete wall. Shaik and Setty [8] have carried out the time lag and decrement factor of laterite wall houses. The time lag and decrement factor of different building materials that are commonly used in Iran have been investigated by Fathipour and Hadidi [9]. Al-Sanea and Zedan [10], Asan [11], Yuan [12], Tzoulisa and Kontoleonb [13], Romero-Flores et al. [14], Ozel [15], Kontoleon and Eumorfopoulou [16] have evaluated the time lag and decrement factor of insulation building materials wall. Balaji et al. [17] have studied the decrement factor and time lag of homogeneous building materials wall. Bilgin and Arıcı [18] are interested
* Corresponding author. E-mail address: [email protected] (P.M. Toure). https://doi.org/10.1016/j.cscm.2019.e00298 2214-5095/© 2019 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
2
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
on the determination of time lag and decrement factor of a sandwiched external wall composite of mortar, PCM and concrete. The time lag and decrement factor of a glazed roof filled with phase change material was experimentally investigated by Dong et al [19]. A short term experimental investigation of time lag and decrement factor of aerated lightweight concrete (ALC) wall panels was carried out by Soon et al [20]. All these theoretical and experimental studies concern the calculation of time lag and decrement factor of a wall and roof. In these studies, the walls are exposed to conditions different from tropical climate. This work consists to determine experimentally the time lag and decrement factor using a stabilized earth brick envelope. To do this, an experimental test cell is built at the Cheikh Anta Diop University in Dakar. The originality of this work compared to the work mentioned above is the calculation of time lag and decrement factor using the inside ambient-air temperature and average equivalent temperature. The ambient-air temperature characterizes the simultaneous response of all walls and roof to external solicitations. 2. Description of experimental device 2.1. Presentation of the experimental cell The experimental system is presented in Fig. 1. This is a test cell of four walls, a vaulted roof and a wooden door. This test cell is built at the Cheikh Anta Diop University of Dakar. The internal dimensions of the test cell are 1 1x1 m3, giving a space area of 1 m2 with a height of 1 m. The envelope of the test cell has a thickness of 14 cm. The four walls and the roof are built with a material commonly used in construction in Senegal. It is the earth brick stabilized with cement. They are manufactured by local brickworkers. The thermo-physical and surface properties of stabilized earth bricks are summarized in Table 1. The thermal properties of the earth brick were measured by the transient asymmetrical hot plate device [21]. The floor of the test cell is in concrete. An insulation material (a 2 cm-thick glass wool) is placed on the floor that is covered with a moisture-proof material. This decreases the influence of heat and humidity exchange between the ground and the floor on the temperature and humidity inside the test cell. 2.2. Instrumentation Two temperature and relative humidity “Log Tag’’ recorders are used for monitoring the outside and the inside temperature of test cell. Its precision is 3 % of relative humidity and 1 C of temperature. During the experimentation, the test cell door remains closed. The global horizontal irradiance and the direct normal irradiance are measured using a pyranometer and a pyrheliometer. These two radiations are used to calculate the global radiation incident on a wall or on the roof.
Fig. 1. Photo of the building.
Table 1 Thermo-physical and surface properties of stabilized earth brick. Density (kg/m3)
2000
Thermal conductivity (W/mK) Specific heat (J/kg.K) Infrared emissivity Solar absorptivity
0.75 997 0.7 0.9
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
3
1 Calculation of time lag and decrement factor The time lag ’ and the decrement factor f are calculated as follows:
’ ¼ tT i;max tT e;max
ð1Þ
Where tT i;max : The time when the ambient-air temperature inside a test cell is maximum tT e;max : The time when the outdoor average equivalent temperature is maximum f ¼
T i;max T i;min T e;max T e;min
ð2Þ
Where T i;max : The maximum ambient-air temperature inside a test cell T i;min : The minimum ambient-air temperature inside a test cell T e;max : The maximum outdoor average equivalent temperature T e;min : The minimum outdoor average equivalent temperature The outdoor average equivalent temperature is calculated as follows: T ext ¼
SS p T p SS p
ð3Þ
Where Sp is the surface of a wall or roof, T p the equivalent temperature of a wall or roof. The outdoor average equivalent temperature is used to materialize the heat received on the envelope of the test cell. Because to calculate the equivalent temperature (eq 4), the outside ambient air-temperature and global radiation incident on each wall of the test cell are taken into account. This temperature is calculated as follows [14]: # " aGinc ðtÞ es ðT 4a T 4surr Þ ð4Þ T p ¼ T a ðtÞ þ he he With e the emissivity of surface of a wall or roof, α the solar absorptivity of surface of a wall or roof, s the StefanBoltzmann constant, Ta the ambient-air temperature outside, Tsurr the average surrounding surface and sky temperature and Ginc the global radiation incident on a wall or on the roof, he the heat transfer coefficient. The emissivity and solar absorptivity values are given in Table1. The heat transfer coefficient has been fixed at 10 W/m2K. In this present study the last term of equation (4) is ignored [16]. The outdoor average equivalent temperature is used to materialize the heat received on the envelope of the test cell. Because to calculate the equivalent temperature (eq 4), the outside ambient air-temperature and global radiation incident on each wall of the test cell are taken into account.
Fig. 2. Daily variation of global horizontal radiation and normal direct radiation.
4
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
3. Results and discussion 3.1. Average equivalent temperature To obtain the daily average equivalent temperature, the daily global horizontal radiation and the daily normal direct radiation are used (Fig. 2). This allowed us to calculate the equivalent temperature on each wall of the test cell (Fig. 3). After obtaining the equivalent temperature on each wall, the average equivalent temperature is calculated. The Fig. 4 represents the variation of average equivalent temperature for four days of measurement. This average equivalent temperature obtained is smoothed (Fig. 5) to remove disturbances that may be due to cloudy passages. 3.2. Time lag and decrement factor The time lag and decrement factor are calculated using Fig. 6. This curve represents the variation of ambient airtemperature inside the cell and the outside average equivalent temperature. In this curve the ambient air-temperature time
Fig. 3. Daily variation of equivalent temperature on each wall of the test cell.
Fig. 4. Variation of average equivalent temperature from midnight to midnight.
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
5
Fig. 5. Variation of average equivalent temperature fitting from midnight to midnight.
Fig. 6. Variation of inside ambient air-temperature and average equivalent temperature from midnight to midnight.
Table 2 Time lag and decrement factor values. Day
Time lag (hr)
Decrement factor
1 2 3 4
6,02 6,27 6,27 6,38
0,41 0,43 0,38 0,40
lag and decrement factor is shown. The values found of time lag and decrement factor are summarized in Table 2. The results show that the time lag inside of cell is around 6 h and the decrement factor around 0.4. The time lag and decrement factor are not significantly variable with day. This can be explained by the fact that time lag and the decrement factor are intrinsic parameters to envelope. With these time lag and decrement factor values the heat is stored in the envelope during the day. This reduces the number hours of cooling during the hot periods of the year.
6
P.M. Toure et al. / Case Studies in Construction Materials 11 (2019) e00298
4. Conclusion In this work an experimentally determining of time lag and decrement factor using a compressed stabilized earth brick envelope was made. This study was carried out using an experimental cell built in stabilized earth brick through a campaign to measure temperature, normal direct solar radiation and global solar radiation. At the end of this measurement campaign, the time lag and decrement factor were determined to quantitatively evaluate the inertia of stabilized earth brick. The calculation of time lag and decrement factor using ambient air-temperature in the cell and average equivalent temperature has given a time lag inside of cell around 6 h and a decrement factor around 0.4. With these time lag and decrement factor values, the number hours of cooling can be considerably reduced. Because the strong temperatures variations in daytime during the hot periods of the year are not felt inside of building. References [1] S. Mounir, Y. Maaloufa, A.B. Cherki, A. Khabbazi, Review thermal properties of the composite material clay/granular cork, Constr. Build. Mater. 70 (2014) 183–190. [2] S. Bahria, M. El Ganaoui, M. Amirat, A. Hamidat, L. Ouhsaine, A Dynamic simu- lation of the low-energy building using wood based material, Proceedings of the International Conference on Materials and Energy – ICOME 16 (2016) 641–644. [3] A. Abderraouf, B. Naima, G. Fouad, Thermal conductivity and thermal degradation of cementitious mortarsreinforced with doum and diss fibers, Proceedings of the International Conference on Materials and Energy – ICOME 16 (2016) 635–639. [4] X. Jin, X. Zhang, Y. Cao, G. Wang, Thermal performance evaluation of the wall using heat flux time lag and decrement factor, Energy and Buildings 47 (2012) 369–374. [5] A. Thongtha, S. Maneewan, C. Punlek, Y. Ungkoon, Investigation of the compressives trength,time lags and decrement factors of AAC-lightweight concrete containing sugar sediment waste, Energy and Buildings 84 (2014) 516–525. [6] C.R. Ruivo, P.M. Ferreira, D.C. Vaz, On the error of calculation of heat gains through walls by methods using constant decrement factor and time lag values, Energy and Buildings 60 (2013) 252–261. [7] E.O. Assem, Correlating thermal transmittance limits of walls and roofs to orientation and solar absorption, Energy and Buildings 43 (2011) 3173–3180. [8] S. Shaik, A.B.T.P. Setty, Influence of ambient air relative humidity and temperature on thermal properties and unsteady thermal response characteristics of laterite wall houses, Building and Environment 99 (2016) 170–183. [9] R. Fathipour, A. Hadidi, Analytical solution for the study of time lag and decrement factor for building walls in climate of Iran, Energy 134 (2017) 167– 180. [10] S.A. Al-Sanea, M.F. Zedan, Heat transfer characteristics and optimum insulation thickness for cavity walls, Journal of Thermal Envelope and Building Science 26 (2003) 285–307. [11] H. Asan, Effects of wall’s insulation thickness and position on time lag and decrement factor, Energy and Buildings 28 (1998) 299–305. [12] J. Yuan, Impact of insulation type and thickness on the dynamic thermal characteristics of an external wall structure, Sustainability 10 (2018) 28–35. [13] T. Tzoulisa, K.J. Kontoleonb, Thermal behaviour of concrete walls around all cardinal orientations and optimal thickness of insulation from an economic point of view, Procedia Environmental Sciences 38 (2017) 381–388. [14] M. Romero-Flores, L.M. Becerra-Lucatero, R. Salmon-Folgueras, Thermal performance of scrap tire blocks as roof insulator, Energy and Buildings 149 (2017) 384–390. [15] M. Ozel, The influence of exterior surface solar absorptivity on thermal characteristics and optimum insulation thickness, Renewable Energy 39 (2012) 347–355. [16] K.J. Kontoleon, E.A. Eumorfopoulou, The influence of wall orientation and exterior surface solar absorptivity on time lag and decrement factor in the Greek region, Renewable Energy 33 (2008) 1652–1664. [17] N.C. Balaji, M. Mani, B.V. Venkatarama Reddy, Dynamic thermal performance of conventional and alternative building wall envelopes, Journal of Building Engineering 21 (2019) 373–395. [18] F. Bilgin, M. Arıcı, Effect of Phase Change Materials on Time Lag, Decrement Factor and Heat-Saving, International Conference on Computational and Experimental Science and Engineering ICCESEN (2017) 1101–1105 132. [19] D. Li, Y. Wu, G. Zhang, M. Arıcı, C. Liu, F. Wang, Influence of glazed roof containing phase change material on indoor thermal environment and energy consumption, Applied Energy 222 (2018) 343–350. [20] Ng. Soon-Ching, K.S. Low, N.H. Tioh, Thermal inertia of newspaper sandwiched aerated lightweight concrete wall panels: Experimental study, Energy and Buildings 43 (2011) 2956–2960. [21] P.M. Touré, V. Sambou, M. Faye, et al., Mechanical and hygrothermal properties of compressed stabilized earth bricks (CSEB), Journal of Building Engineering 13 (2017) 266–271.