Article

Thermal performance and structural cooling analysis of brick, cement block, and mud concrete block

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Abstract

This investigation is apropos the thermal analysis and structural cooling of brick, cement block and mud concrete block walling materials to compare the thermal comfort of different walling materials. Structural cooling is a method of cooling hot temperature by using the structure. Void spaces in a building block can be studied as porosity. It can be measured by assessing solid to void spaces. The thermal performance can be measured by calculating the time lag and the decrement factor. The initial testing was done in order to understand the thermal conductivity and heat capacity in both wet and dry conditions. The real-world analysis and simulation analysis were used to validate the argument. For the case studies, real-world buildings with an identical plan form but constructed with three different walling materials were used and their thermal performances were measured. And then one building was simulated in order to create an identical scenario. With the real-world observation, it was found that brick walling materials have better time lag and decrement factor with the thickness of 225 mm. An overall analysis shows that mud concrete block has better structural cooling ability and the thermal performance than other wall materials.

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... Thermal conductivity, by definition is the amount of heat transferring through a unit area for a unit temperature gradient (Öchsner, Murch and Lemos, 2008). When the requirements of material properties for an insulation material is concerned it was found that it is in direct relation with the porosity and micro structure of a material (figure 2) (Foster, S.K. and Bisby, 2005;Cree et al., 2012;Udawattha and Halwatura, 2018). In a porous material the three main methods of heat propagation are conduction, radiation, and convection. ...
... In a porous material the three main methods of heat propagation are conduction, radiation, and convection. For small size pores, heat transfer through convection is negligible and at high temperatures the radiation plays a substantial role (LOEB, 1954;Udawattha and Halwatura, 2018). The thermal conductivity in a porous material would depend on the pore structure and the fraction of solid particles per volume (Batool, Rafi and Bindiganavile, 2018). ...
... The thermal conductivity in a porous material would depend on the pore structure and the fraction of solid particles per volume (Batool, Rafi and Bindiganavile, 2018). According to the findings of Cree et al (Cree et al., 2012) and Udawattha et al (Udawattha and Halwatura, 2018) the pore space structure would guide towards a better insulation system. Kodur and Baingo (Kodur and Baingo, 1998) suggested that the commercially available fire protection methods for concrete and steel itself can be used in order to acquire the required fire ratings for FRP strengthened structural members. ...
Conference Paper
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The use of fibre reinforcement polymer (FRP) in the construction is increasing rapidly. However, the issue remains that the FRP material is less durable during a fire. Therefore, insulation systems to prevent the composite sections from failing during such occasions are researched throughout the world. Developing an effective insulation system such that the structural adequacy of composites systems could ensure the 2-hour fire rating of commercial buildings is one of its main objectives. This article summarizes the researches carried out on the fire performance of CFRP composites and the extent of insulations that are currently researched in the field. Drawbacks such as less cost effective and aesthetically appealing was noted in the existing insulation systems.
... Thermal comfort analysis of LIG house using CFD is reported in [21], it is reported that varying the sizes of windows do not improve the thermal comfort of house. Energy requirement of building is studied in [22] and revealed that providing a insulating material on building walls and roof reduces the energy requirement of building Many researchers [23][24][25] have studied the effect of thermo physical properties of material and wall thickness on time lag and decrement factor, however none of the papers have reported the effect of time lag and decrement factor for estimating room temperature of house. In present paper semi empirical method has been used for thermal performance analysis of LIG (Low Income Group) house located at Raipur, India. ...
... These Eqs. (19)(20)(21)(22)(23) are obtained as a system of ordinary differential equations and solved numerically using ODE45 in MATLAB. The room temperature is then calculated and reported on hourly basis. ...
... The room temperature is then calculated and reported on hourly basis. For room-1, energy balance equation reduces to 1 = ( 1, 2, 3, 4, 5, 1 ( )) (19) Similarly, Energy balance equation for room-2: 2 = ( 1, 2, 3, 4, 5, 2 ( )) (20) Energy balance equation for room-3: 3 = ( 1, 2, 3, 4, 5, 3 ( )) (21) Energy balance equation for room-4 4 = � 1, 2, 3, 4, 5, 4 ( )� (22) Energy balance equation for room-5 5 = ( 1, 2, 3, 4, 5, 5 ( )) (23) To validate the results obtained through mathematical model, Eqs. (19)(20)(21)(22)(23), on-field data collection has been carried out. ...
Article
Raipur, capital of Chhattisgarh state, India, is located at (21.18° N and 81.78° E). During summer season, the city experiences maximum temperature of 46 ºC. Residents resort to external cooling sources almost throughout the year for achieving thermal comfort. Therefore, thermal performance analysis of house is important to assess the temperature inside the house at different season. In present work, mathematical model of hourly temperature distribution in each room of the Low Income Group (LIG) house has been developed using time lag and decrement factor. A system of differential equations is derived and solved. The results obtained are validated with data collected onsite. The study is reported for three major seasons realized in Raipur. Deviation of room temperature from predefined thermal comfort has been calculated and reported for different season. The report reveals the lack of thermal comfort from the sets standards in post-monsoon and summer season.
... Udawattha and Halwatura [32] studied the thermal performance of houses constructed with brick, hollow cement block and mud concrete block where time lag and decrement factors were considered for comparison of thermal comfort. The study concluded that brick is the most thermally favorable building material, which has a longer time lag and low decrement factor. ...
... Although several studies were conducted on energy-efficient construction material for masonry, most of the studies focused on mechanical and durability characteristics of individual blocks [12][13][14][15][16][17][18][19][20][21] and only selected studies focused on thermal comfort performance analysis. Among those studies, only Udawattha and Halwatura [32] and Fasogbon et al. [31] reported thermal comfort performance of house units constructed with conventional masonry units. All other studies were conducted in house units with agricultural or industrial waste incorporated cement blocks [3,[26][27][28][29], which are not commonly used in Sri Lanka. ...
... All other studies were conducted in house units with agricultural or industrial waste incorporated cement blocks [3,[26][27][28][29], which are not commonly used in Sri Lanka. For both studies by Udawattha and Halwatura [32] and Fasogbon et al. [31], the studies were limited to single-day observations and analyses as well as only simple overheating as a critical parameter (indoor air temperature less than optimum temperature for acceptable comfort limit). Also, humidity data were not considered in any of these analyses. ...
Article
Fired-clay brick, cement-sand block and cement stabilized earth blocks are the most commonly used material for masonry construction in Sri Lanka. Strength, durability and cost are three major factors that influence the selection of material for wall construction. Even though Sri Lanka has a tropical climate, the benefits of insulating the external walls of the house are often not considered. Apart from thermal comfort of the internal environment, there is concern regarding increase in energy consumption. However, in recent years, as awareness of sustainable and green building concepts increased, interest in using sustainable and thermal comfort materials for house construction has increased. Because external walls play a major role in thermal insulation, there is a need to select suitable wall materials that can be energy efficient and reduce cooling load. Therefore, the present study aims to understand thermal comfort in house units constructed with commonly used wall material such as fired brick, cement-sand block and cement stabilized earth block. Temperature and humidity inside and outside house models were observed to compare the impact of masonry materials on thermal comfort. To compare the thermal comfort performance of the house models, three thermal comfort analysis models: steady-state comfort model, adaptive criteria model and deterministic models were used according to the British Standard European Norm (BS EN) 16798, CIBSE TM52 and ANSI/ASHRAE 55. Results show that house units constructed with cement stabilized earth blocks and fired-clay bricks are significantly more comfortable in terms of temperature and humidity variations. Energy-efficient house units thereby minimized energy consumption through reduction in indoor temperature. Therefore the cement stabilized earth block and fired-clay brick house model are found to be a suitable choice for construction.
... The authors developed a correlation matrix between the air temperature, operative temperature, and mean radiant temperature of different zones of the production spaces concerning different building material construction types. Udawattha and Halwatura [19] analysed the field measurements and computer-based simulation studies to understand the thermal efficiency and structural cooling of three common wall materials (brick, cement block, and concrete mud block) in Sri Lanka. The field study was carried out on three selected buildings constructed with three different wall materials of dissimilar thickness. ...
... Building walls form the bulk of the envelope which provide thermal comfort inside the building by regulating variations in outdoor weather conditions and thereby, deciding the heating and cooling loads [28]. Udawattha and Halwatura [19] described building envelope wall as the third skin for the human body that supports to keep the body temperature steady even though the outside temperature fluctuates. Watson [29] stated that building envelope is a system that controls heat exchange between the indoor and outdoor environments. ...
... where f is the decrement factor, ,max of the wall respectively. TL and DF mainly depend on the thermophysical properties, wall configuration, and thickness of the materials since the heat waves need a longer time to pass through the materials with increased thickness, density, and resistivity [19,50]. Besides, TL and DF vary when the outside temperature rises or declines steadily from one day to the next [51,52]. ...
Article
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The building walls which form the major part of the building envelope thermally interact with the changing surrounding environment throughout the day influencing the indoor thermal comfort of the space. This paper aims at assessing in detail the different aspects (thermophysical properties, thickness, exposure to solar heat gain, etc.) of opaque building wall materials affecting the indoor thermal environment and energy efficiency of the buildings in tropical climate (in the summer and winter days) by conducting simplified simulation analysis using the Integrated Environmental Solutions Virtual Environment (IES-VE) program. Besides, the thermal efficiency of a number of selected wall materials with different thermal properties and wall configurations was analysed to determine the most optimal option for the studied climate. This study first developed the conditions for parametric simulation analysis and then addressed selected findings by comparing the thermal responses of the materials to moderate outdoor temperature and energy-saving potential. While energy consumption estimation for a complete operational building is a complex method by which the performance of the wall materials cannot be properly defined, as a result, this simplistic simulation approach can guide the designers to preliminary analyse the different building wall materials in order to select the best thermal efficiency solution.
... Some models have very high thermal insulation properties, making them suitable for zero-energy building (Shibib, Qatta, & Hamza, 2013) and a sample of hollow burnt brick is shown in Figure 2.6. Udawattha and Halwatura (2016) posited that thermal performance of walling materials can be measured by comparing outdoor ambient temperature and indoor ambient temperatures. Thermal performance can be simply compared with U value (thermal conductivity) of walling material. ...
... Thermal performance can be simply compared with U value (thermal conductivity) of walling material. The thermal conductivity was measured by measuring the thermal transmittance (U-Value) of the walling material sample by using a thermal conductivity meter (Udawattha & Halwatura, 2016 , 2008). Thermal conductivity of the bricks depends on their firing temperatures, densities and therefore porosities (Sütc¸ü, 2010). ...
Thesis
Current practices of planning and designing of buildings in Nigeria do not take into consideration the energy and exergy demand of the building, and thermal comfort which are very important from the occupants’ perspective, thus, there is need for a better understanding of exergy analysis during the design, construction, and operation phase of buildings to improve the quality match between energy supply and energy demand in buildings. The aim of this study is to estimate the exergy consumption value for a sandcrete and a burnt brick-walled structure in a tropical sub region. The properties of the building were assessed and measured, eQuest was used to estimate the energy demand of the respective buildings and the exergy analysis was conducted using the exergetic factor of electricity. The annual energy consumption of the existing building per unit area was estimated to be 240 kWh/m2/year, which was categorized as not a good practice for an air conditioned office, while the annual energy consumption of the various control buildings per unit area was 108 kWh/m2/year which was categorized as best practice for an air conditioned office. The cumulative exergy consumptions of the existing, sandcrete and burnt brick-walled building were found to be 68,354 kWh/year, 35,735 kWh/year, and 35,721 kWh/year respectively. The sandcrete building, as well as the brick building were found to be 48 % more energy efficient than the existing building as a result of the reduction in the energy consumption of the electrical equipment. However, the exergy analysis suggested that the burnt brick-walled building perform better than the sandcrete-walled building.
... The water absorption results indirectly showing the porosity level of the materials. For an instant, MCB has the highest porosity comparing to brick and cement blocks [18].And the FSEB and the CP are the lowest water absorbing materials.However, the materials structures such as brick have high pores spaces within the materials. This is due to quick evaporation of excess water within the material.The water absorption shall not impact the materials by GDR or WDR. ...
Conference Paper
This study presents most common phenomena observed on wall facades due to excessive rain in tropical climatic condition in Sri Lanka. The objective of this study is to understand the effect surface decay of walling materials. The most common walling materials such as brick, cement block, earth cement blocks and novel walling materials mud concrete block, geopolymer blocks were subjected to this study. Faade covering materials such as rough cement plaster and cement slurry plaster were studied. Intrinsic material properties were studied prior to natural rain erosion quantification. Basic engineering properties of water absorption, capillary action, surface roughness, compressive strength was studied. Material properties such as water absorption, surface roughness were studied. Ten years of rain was simulated to measure natural surface decay. The results show that, stronger materials and less surface rough materials are resistant to surface decay. Plastering is recommended to protect walling materials reduce the surface decay. Comparatively stronger walling materials are less prone to natural rain decay. Cement plasters and cement slurry plaster covering is the most suitable materials for heavy rain. Cement slurry plaster is the most suitable walling covering for rain drop bouncing areas in outdoor walls in Sri Lanka.
... The external surface of building walls directly expose to outdoor environments while internal surface exposes to the indoor environment. Building walls create the building envelop which act as a thermal and acoustic barrier and create thermal and acoustic comfort inside the building (Degrave-Lemeurs et al. 2018, Udawattha & Halwatura 2016. Indoor air quality is one of the most important factors which directly contribute to improving occupants' healthiness. ...
Conference Paper
Buildings and architectural spaces are built for occupant comfort. Thus tropical climatic condition is the worst climate to achieve the occupant comfort. Tropics are favourable for bio receptive activities such as fungus and moss. Fungus and moss produce mycotoxins, spores and fragments which are toxic to occupants. However, the relationship between buildings envelops and bio receptivity should be studied prior to find a sustainable solution. This study was conducted to understand the relationship with intrinsic properties of wall construction materials and the bio receptivity. The study was conducted after studying several intrinsic properties of walling materials such as organic matter content, surface roughness, water absorption and pH value according to laboratory test standards. Fungus and moss growth standard tests were conducted in the real world-controlled environment. Results of this study showed that surface roughness is the significant intrinsic property on bio receptivity. According to the test results fungus and moss growth on walling materials has a reciprocal connection with surface roughness values and no growth occurs on wall plasters where the surface is smoother. This study concluded that covering walls with cement plaster can reduce the growth of moss and fungus on tropical homes. Therefore smooth, plastered surfaces are best for homes with occupant comfort. But the cost of plastering might prevent poor families from acting on this concept. Therefore it is necessary to develop sustainable, cost effective and environmentally friendly wall, smoothing materials and techniques.
... Mud concrete block is a building material invented by the University of Moratuwa, Department of Civil Engineering. The concept is to use available soil and mix them with 6% of cement and used alternative to the brick and cement blocks, mostly available in the market [1][2][3][4][5]. The concept is to aggregate 'Concrete' made using earth/soil. ...
Chapter
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Cement is one of the key stabilizers for earth constructions since Roman civilization. The invention of cement was one step in the human civilization. But cement has many issues especially when it comes to the environmental conservation. The production of cement creates a lot of carbon dioxide and destroys the natural setting to some extent due to the high consumption of clay and lime. Therefore, this study was conducted to alter the cement in mud concrete block. The study started with an inventory of alternative stabilizers can be found in nature as well as in the human production. And then the chemical patterns of those stabilizers were carefully identified to alter the typical Portland cement. Several mix proportions were tested and developed to alter the cement and found that following materials can be developed to alter cement. A natural stabilizer such as tree resins, latex rubber stabilizer, waste ash, rice husk ash and many others ashes can be developed to chemically stabilize the earth blocks. However, out of the invented stabilizers fly ash and rice husk ash has the high potential to replace cement.
... Districts covered for case studies strategy of improving the thermal comfort is the use of novel building materials. There is a tremendous trend of using these types of materials and Udawatta and Halwatura [21,22] have compared the thermal performance and the structural cooling analysis of bricks, cement blocks and mud concrete blocks. According to the results, the materials like mud concrete blocks reduce the thermal heat gain improving a thermally comfortable environment inside the building. ...
Conference Paper
Full-text available
The aim of this study is to evaluate the thermal comfort state in residential buildings in Sri Lanka and to study the possibility of getting them into the comfort zone without air conditioning. Located near the equator, Sri Lanka has a tropical climate with high temperature and relative humidity level. Therefore, the need of having a thermally comfortable living environment is a must in these conditions. A case study approach has been made in this study to evaluate the research problem. The selected 14 case study houses were optimized using Design-Builder, energy simulation software. The evaluation results highlight that the comfort level of the houses can be improved using mud concrete blocks as the external wall material and clay tiles as roofing. The optimization results further indicate that thermal comfort level of the residential buildings in Sri Lanka can be achieved without using air conditioning if designed properly.
... Moreover, the majority of the studies have used chemical binders, such as cement and lime, with agro-wastes to produce the samples. These chemical binders are responsible for environmental degradation, with a high carbon footprint and embodied energy [50]. Hence, the production of agro-wastes incorporated into unfired earth blocks without these binders provides the greatest advantages in terms of sustainability. ...
Article
Full-text available
Sawdust and coconut coir dust are agro-wastes/by-products which are suitable for use as raw materials to manufacture unfired clay blocks due to their excellent physical and mechanical properties. A limited number of studies have been conducted on the utilisation of these agro-wastes in clay block production, and they have mostly been devoted to investigating the physicomechani-cal properties, with less attention given to the thermal properties. Moreover, the majority of the studies have used chemical binders (cement and lime) in combination with agro-waste, thus increasing the carbon footprint and embodied energy of the samples. Furthermore, no research has been performed on the thermal performance of these agro-wastes when incorporated into clay blocks at the wall scale. Therefore, to address these limitations, the present study developed unfired clay blocks incorporating sawdust and coconut coir dust (0, 2.5, 5, and 7.5% by weight), without the use of chemical binders, and evaluated their thermal performance, both at the individual and wall scales. The experiments were divided into two phases. In the first phase, individual sample blocks was tested for basic thermal properties. Based on the results of the first phase, small walls with dimensions of 310 mm × 215 mm × 100 mm were built in the second phase, using the best performing mixture from each waste type, and these were assessed for thermal performance using an adapted hot box method. The thermal performance of the walls was evaluated by measuring the heat transfer rate from hot to cold environments and comparing the results to the reference wall. The results showed that thermal conductivity decreased from 0.36 W/mK for the reference sample, to 0.19 W/mK for the 7.5% coconut coir dust sample, and 0.21 W/mK for the 7.5% sawdust sample, indicating an improvement in thermal insulation. Furthermore, the coconut coir dust and sawdust sample walls showed a thermal resistance improvement of around 48% and 35%, respectively, over the reference sample wall. Consequently, the findings of this study will provide additional essential information that will help in assessing the prospective applications of sawdust and coconut coir dust as the insulating material for manufacturing unfired clay blocks.
... This strategy was validated by building energy simulation (BES) in DOE-2. Similarly, Udawattha and Halwatura (2018) have conducted a study focused on the influence of the wall materials on the indoor thermal performance of different houses in the low-latitude, but hot climate of Sri Lanka. The authors conclude that the brick is the best material for increasing the thermal inertia. ...
Article
Full-text available
Equatorial high-altitude regions are typically characterized by low non-extreme temperatures with a high diurnal oscillation. Therefore, typical constructive practices, in these regions, do not include the use of air-conditioning equipment or energy criteria in building design. As a consequence, dwellings behave out of the comfort temperature ranges most of the year. This work aims to investigate the influence of the main building parameters on the thermal behaviour of residential buildings in these regions. Results may be very helpful to outline recommendations in early design. A simplified model of a building located in Quito city (0 ∘ latitude, 2800 MASL) using fourdifferent boundary conditions was developed. The model was validated by comparison with experimental measurements of indoor temperature for two dwellings. The model was used to conduct a parametric study as well as a sensitivity analysis of the influence of the window-to-wall ratio, infiltration ratio, wall material and thickness, facade orientation and use of single or double glass on the windows. Results showed that thickness and window-to-wall ratio and walls material are the most influencing parameters. Likewise, the use of insulation on the envelope, mainly in the roof, may help to reduce the discomfort, but always accompanied with other measures.
... Porosity is the measure of the amount of void spaces present in the material. The high porosity increase water absorption capacity of the material [43]. The total porosity (ϕ) is defined by the ratio of the volume of void space (VV) to the total, or bulk volume of the material (VT). ...
... Hence, discoveries of Sri Lankan ancestors (wattle and daub) වරිච්චි බැම්ම and develop it with modern technologies such as developed stabilizers would be a considerably advanced research problem (Udawattha, Arooz, & Halwatura, 2016c). In addition to the cost, earth as a walling material gives cooling effect and structural cooling to reduce the outdoor temperature into favourable indoor temperature (Udawattha & Halwatura, 2016c;Udawattha, Galabada, & Halwatura, 2017;Udawattha & Halwatura, 2016a;Udawattha, Arooz, & Halwatura, 2016a). The shelter is the secondary main requirement for a human being (Corvalán, Hales, McMichael, Program, & Organization, 2005) (Pogge, 2008). ...
Conference Paper
The Mud concrete block (MCB) is a novel walling unit manufactured using cement as stabilizers to provide adequate compressive strength and durability. Even though the cement has been used as a stabilizer, the energy content of the cement demands a study to replace cement with an alternative stabilizer. This experimental study was conducted to prepare mud concrete block using lime as a replacement for cement in order to improve long-term build up the strength of the mud concrete block. Several proportions of lime were taken into the experimental criteria and the destructive method of compressive strength test according to (test method) was used to understand the effectiveness of different formulas of the lime-MCB mixture. The study shows that mud concrete blocks prepared with an optimum quantity of lime along with 4% cement have led to the continuous development of compressive strength. However, the strength improvement delays even take months to come to the optimum strength. Interestingly, mud blocks made of cement alone shows short period strength improvement. Therefore, the study needs to re-attend at the chemical formulation and stabilization effect of lime addition to mud concrete block. Finally, adding lime as an alternative stabilize would benefit by reducing cost as well as it can improve the long-term durability of the mud concrete block.
... In order to understand the actual thermal conductivity of these waling material, real world model houses (see Fig. 4) were built. Their thermal performances were tested by using thermal data loggers [34]. ...
... For instance, earth materials can absorb heat more than concrete and act as thermal mass. As well as earth materials assist evapotranspiration of water better than concrete [3]. In additional following advantages are there to use earth as construction materials; ...
Article
Population growth and rapid urbanization have led to mass infrastructure development in many sectors such as buildings, roads, urban public areas, etc. However, little attention has been given to human comfort and environmental sustainability of paving blocks. This is an attempt to search for alternative eco-friendly earth paving material for public walkways with both the strength and durable properties of concrete while ensuring pedestrian comfort. Approaches were made to change the fine particle percentage while keeping the sand and gravel constant, once the optimum most practical mixture was known, the standard tests were done. The results obtained revealed that the proposed self-compacting block can be produced by using soil with less than 5% fine particles, 55% of 65% sand particles and 18% of 22% cement by weight together with the moisture content between 14% and 15%The tested mud concrete paving blocks were already used in practical application in Sri Lankan urban context.
... Districts covered for case studies strategy of improving the thermal comfort is the use of novel building materials. There is a tremendous trend of using these types of materials and Udawatta and Halwatura [21,22] have compared the thermal performance and the structural cooling analysis of bricks, cement blocks and mud concrete blocks. According to the results, the materials like mud concrete blocks reduce the thermal heat gain improving a thermally comfortable environment inside the building. ...
... Mud-Concrete is one outcome of these researches which has been developed in University of Moratuwa. Mud-Concrete is a soil based building material which is made by mixing soil with cement (stabiliser) and water [6], [7], [8]. Mud-Concrete could be used in different forms in Building construction. ...
... The precise gravel percentage governs the strength of Mud-Concrete. In this research fraction of soil has been classified as follows; 35% Gravel (sieve size 4.25 mm gravel 20 mm), 65% Sand (sieve size 0.425 mm and 4.25 mm) 5% Fine (silt and clay) -( sieve size 4.25 mm) [4][5][6][7][8][9]. The cement in this concrete is also used as a stabilizer in very low quantities. ...
Article
This study was conducted to develop an alternative method of utilizing fly ash as an alternative stabilizer to build affordable earth masonry units named “mud concrete blocks”. Mud concrete masonry block is a novel invention in which the mud helps to self-compact the mixture to reduce the production of energy content. This study uses fly ash from electric power generating plant with an alkaline solution made of Sodium hydroxide and Sodium chloride. Different combinations of mixtures (fly ash, sodium chloride, sodium hydroxide and soil) were taken into consideration to study a suitable mix design. And compressive strength was tested to understand each mix suitability. Results of this study have manifested that suitable mix is to use Fly Ash 20% of the dry weight of soil, Sodium hydroxide 5% and Sodium Chloride 2% of the total dry weight. The suitable water ratio is 15%–20% of the dry weight. And then the suitable soil mix proportion was developed. It was found that the soil mix proportion of Gravel 10–20% (sieve size 4.25 mm ≤ gravel≤ 20 mm) range of (35%–45%), the Sand 70–80% (sieve size 0.425 mm ≤ sand ≤4.25 mm) proportion of (60%–70%) and Fine ≤10% (≤sieve size 0.425 mm) content of 5% makes the best mix to develop. Scanning electron microscope images were taken to understand the geo polymerized fly ash bond result on the total strength of the soil mixture.
... Moreover, the thermal conductivity of eco-concrete and sustainable wall material was lower than the commonly used construction materials in Tunisian (Rahmouni et al., 2019) and Nigerian buildings (Odunjo et al., 2015). Udawattha and Halwatura (2016b) determined that the building constructed using mud concrete block had higher thermal performance than that made up of brick and cement concrete block in Sri Lanka. Asadi et al. (2018) extensively revised the literature regarding thermal conductivity of concrete materials and concluded that the lightweight concrete materials were more sustainable than other concrete building materials. ...
Article
Heat transfer through building opaque envelope is responsible for approximately half of the total heat loss and gain to and from the surroundings. Therefore, insulation materials are commonly used in the building envelope to reduce the heat transfer. Recently, lightweight wall materials with lower thermal conductivity are used in construction along with the commonly used materials such as heavy concrete and earthen materials. In this perspective, there is a need to understand the optimum insulation thickness for different types of building construction materials to minimize unnecessary usage of insulation materials. This study investigated the optimum insulation thickness for different construction materials following a life-cycle approach, where an analytical optimization methodology based on the degree-days method and life-cycle cost analysis was used. In total, 4 insulation materials and 15 building construction materials were considered in the optimization study. The objective function was to minimize life-cycle cost corresponding to the decision variables including insulation thickness and the thermal conductivity of insulation and wall materials. The results showed that the use of insulation in lightweight wall materials is not economically feasible because of their negligible cost-saving potential (below US$2.5/m ² -year). However, the walls with heavy concrete and earthen materials that have high thermal mass must be insulated due to their highest cost-saving potential (US$14–26.39/m ² -year).
... In order to understand the actual thermal conductivity of these waling material, real world model houses (see Fig. 4) were built. Their thermal performances were tested by using thermal data loggers [34]. ...
Article
The energy consumption of affordable housing industry plays a vital role in the environmental sustainability, waste generation and energy consumption. The development of sustainable housing construction methodology helps its country’s economic development and sustainable development. Wall and roof are the most significant building component in a dwelling unit. The walling materials can determine the cost of the building as well as the total life cycle cost of a dwelling unit. In this study, the total life cycle cost of a basic dwelling unit in Sri Lanka, made of mostly available walling materials such as Brick, Hollow cement block, and Cabook, the Mud concrete blocks were calculated by using energy accounting hierarchical structure. The life cycle cost incurred due to change in above-mentioned walling materials were calculated and measured. Additionally, total LCC compared and analyzed. The results show that mud concrete block is the most suitable walling material. The brick has the highest account for the embedded energy. The hollow cement block is the worse building materials in tropics and its carbon footprint is comparatively higher. Even though the brick has higher embedded energy and construction cost, in a long run brick is less expensive than hollow cement block and Cabook walling material. Concluding, mud concrete block is comparatively most sustainable walling material for building affordable housing in tropics.
... CB are made of a mixture of cement, sand and stone chips and they are considered as a high strength and durable masonry unit [34]. Mud concrete bricks are made from soil in the same way as traditional mud bricks, but contain gravel and sand to improve their strength [34,35]. Similarly all five walling materials were significantly different from each other. ...
Article
In tropical countries such as Sri Lanka, wall care putties are applied as primers in building constructions providing a smooth shield for the wall. This research study was conducted to investigate the durability performance in terms of rain surface erosion and the bonding strength by shear testing of different wall care putty materials along with walling materials. Four types of walling materials and ten types of wall care putty mixtures were selected. Accelerated erosion test and lap shear strength test were conducted and bond breaking patterns were examined. X-ray diffraction analysis was conducted to investigate the chemical compositions of putty mixtures. Results demonstrate that cement block walling material and putty C+10% cement wall care putty mixture have the highest bonding strength. Similarly, cement added putty mixtures showed higher durability and bonding strength than putties in their pure form.
... Mud being a natural material, the healthy living in earthen homes is primarily extended to living spaces made of CSEB. Bioclimatic performance in terms of thermal comfort rendered by CSEB is significantly better than other bricks or cement blocks [12]. The blocks absorb the heat from the sun during the day, making interiors cool and radiate back during the night, making them warm. ...
Conference Paper
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The benefits of earth architecture in terms of environmental sustainability, climate responsiveness and cost-effectiveness have been proven in the literature. Locally available mud has been used as the vernacular construction material for centuries. However, in the modern-day, they are classified as temporary structures and are increasingly discouraged in India, considering their vulnerability to natural hazards like cyclones. Instead, a few modern earth architecture techniques have evolved that harnessed the benefits of using earth and structurally perform similar to brick and concrete structures. One such technique is Cement Stabilized Earth Blocks, where the blocks are made out of the earth with a mix of a small proportion of cement. In contemporary construction practices in India, project performances are frequently measured in terms of time, cost and structural performance. Compared to the prevalence of conventional materials, earth architecture practices in India are still limited to small scale sporadic projects. There is less research on project management of earthen structures, and this paper intends to fill this gap. This paper aims to critically appraise the challenges faced in using Cement Stabilized Earth Blocks at all stages of the project life cycle. The methodology involved dialogue with engineers, contractors, architects and occupants of modern earth structures and trace the challenges faced in five projects. The research found that the structures which finished in exposed blocks needed to take extra measures for weather protection. The use of modern earthen material does not have cultural popularity and is accepted only by self-motivated, environmentally conscious individuals. Scepticism related to its structural performance prevails. Availability of skilled workers and equipment locally is minimal, and assembling a team often results in time and cost escalation. Earth blocks do not match commercial and real estate projects' rapid and massive construction or cost expectations. Further innovation and policy governance are needed for earth architecture to compete with conventional techniques.
... Porosity, time lag and decrement factor(Chameera and Rangika, 2018) ...
Article
Decrement factor and time lag play an essential role in determining the thermal performance of a building envelope. Building walls, which form a major part of a building, have great influences on the energy consumption and indoor environment of a room. The indoor temperature considerably increases as the outdoor temperature increases. This scenario leads to excessive reliance on the mechanical cooling system, thereby increasing energy consumption. Therefore, this study aims to investigate the thermal performance and energy efficiency of different wall types. A building with a built-up area of 387.85m2 with six different wall materials is modelled and inputted in Energy Plus simulation software as an Intermediate Data Format file. The maximum and minimum surface indoor and outdoor temperatures are then obtained to determine the thermal performance of the wall material in terms of time lag and decrement factor. The energy efficiency of the wall materials is investigated by obtaining the annual cooling energy of the building made up of different wall materials. Results show that with the time lag of 1 hour, decrement factor of 0.86, annual cooling energy load of 9.52 GJ and cost consumption of RM 608.12, aerated lightweight concrete wall is the most suitable material amongst the six wall materials.
... As the main aim is to enhance the panels' ability to retain water in order to provide the best habitat for mosses [23]. This has been presented extensively in Ref. [23], exploring the research gaps, challenges, and possibilities related to the application of bio-receptive façade panels in construction, environmental, and materialisation contexts [29][30][31][32][33][34][35][36][37][38][39]. ...
Article
Bio-receptive façade panels that support the natural growth of mosses, micro-organisms, and small plant species are more advanced alternatives than traditional green walls. Supporting the moss's development naturally could offer great potential for achieving ecologically richer, healthier, and zero-carbon cities. In particular, a limited amount of hydration is required for mosses to grow on these bio-receptive surfaces, which is ideal for the hot, humid environment of north Egypt. This review paper is aimed at identifying the feasibility and influencing factors of implementing such a façade innovation in a hot, humid climate (north Egypt). To investigate this feasibility, first, it is essential to compare the critical factors for moss growth with the target environmental conditions. These key feasibility factors for the approach were classified as environmental and physical growth factors. Second, a field study was undertaken to confirm the availability of such moss resources in north Egypt since the climatic conditions correspond to the acceptable range necessary for application of the approach. This study resulted in promising families of mosses being available, in which great potential for the use of bio-receptive concrete with a cover of moss to expand the green areas vertically is expected. Especially, this green expansion will be with moss, which blooms randomly in the natural environment. This technique may bring additional advantages by generating new sustainable materials from low-cost and readily available resources. It is considered to be an approach to enhance greening and reduce urban environment's susceptibility to climate change without requiring extensive irrigation and maintenance.
... Nevertheless, most of these solutions remained neither sustainable nor cost-effective. Udawatta and Halwatura [26] pointed out that, if the material is porous, the pores could withstand the heat within and let the material act as insulation. A similar behavior could be obtained when EPS is incorporated in cement plasters since the EPS particles contain air itself within the material [10]. ...
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EPS (Expanded Polystyrene) is a well-established insulation material in the Civil Engineering Industry. This paper presents an experimental and numerical investigation of cementitious insulation developed using EPS for Carbon Fiber Reinforced Polymer (CFRP) – Concrete composites. An EPS blended insulation was applied to the CFRP/Concrete composites and tested at elevated temperatures. A numerical model was also developed to predict the heat transfer behavior of the CFRP/Concrete composites with the developed insulation under standard fire conditions. The simulations showed that the bond line has reached the glass transition temperature within a short period of time while the insulated members withstood more time. The model results indicated that the CFRP/Concrete which composites with coarser EPS can achieve 75% to 94% of fire resistance, and composites with finer EPS can achieve 83% to 99% of fire resistance than the insulation materials already commercially available.
... Authors have been proposing the use of various materials combined with cement matrix trying to solve this challenge (Alyousef, Benjeddou, Soussi, Khadimallah, & Jedidi, 2019;Callejas, Durante, & Oliveira, 2017;Dimitrioglou et al., 2016;Fajardo, Torres, & Moreno, 2015;Kanchanapiya, Methacanon, & Tantisattayakul, 2018;Kus, Özkan, Göcer, & Edis 2013;Udawattha & Halwatura, 2018;Xu, Chen, Zhang, Gao, & Huang, 2016;Zaetang, Sata, Wongsa, & Chindaprasirt, 2016;Zhu, Dai, Bai, & Zhang, 2015). Research, Society andDevelopment, v. 9, n. ...
Article
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The Glass Fiber Reinforced Polymer (GFRP) waste despite having excellent physical and mechanical properties is still largely unexplored besides presenting large volume of waste with very low degradability. The use of concrete block presents high resistance to compression, low price high masonry coating ratio by material weight, however high thermal conductivity. Therefore, the study aimed to produce and investigate the effect of adding GRFP residues to concrete blocks due to physical, mechanical and thermal properties. The compositions were made by replacing the fine gravel between 0 to 10% in mass by the GFRP residue. They were evaluated from physical, mechanical and thermal tests. The results showed that the use of GFRP residue did not interfere in water absorption and compressive strength, despite the significant increase in mechanical energy absorption of the material. Thermal conductivity reduced by 46% and the concrete blocks were 7% lighter. In addition to providing a destination for a considerable quantity of the waste, the commercial value of the final product is higher due to using a residue with low degradability and high energy power due to burning during recycling.
... The term bio-aggregate concretes refers to the mixture of binders (lime, clay, plaster, and cement) and natural fibers (hemp, straw, flax, bamboo, and animal hairs) [1]. In this context, the use of eco-friendly concrete such as hempcrete [2], wood-concrete [3], papercrete [4], and mud-concrete [5] has been growing considerably. Hempcrete is most widely used in the field of green construction owing to its remarkable environmental quality as a non-CO2 producer [6,7]. ...
Article
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Construction materials made of renewable resources have promising potential given their low cost, availability, and environmental friendliness. Although hemp fibers are the most extensively used fiber in the eco-friendly building sector, their unavailability hinders their application in Iraq. This study aimed to overcome the absence of hemp fiber in Iraq and develop a new sustainable construction material, strawcrete, by using wheat straw and traditional lime as the base binder. A comparable method of developing hempcrete was established. The experimental program adopted novel Mixing Sequence Techniques (MSTs), which depended on changing the sequence of mixed material with fixed proportions. The orientation of the applied load and the specimen's aspect ratio were also studied. The mixing proportion was 4:1:1 (fiber/binder/water) by volume. Results showed that the developed strawcrete had a dry unit weight ranging from 645 kg/m3 to 734 kg/m 3 and a compressive strength ranging from 1.8 MPa to 3.8 MPa. The enhanced physical and strength properties varied with the MST and loading orientation. The properties of the developed hempcrete were compared with those of strawcrete.
... Similar results were previously reported by Udawattha and Halwatura (2018) who investigated time lag and decrement factor of concrete blocks. They reported a time lag of about 1-3 h and a decrement factor of 0.962-0.978 ...
Article
In this study, the influence of phase change materials (PCM) on the thermal behaviour of concrete sandwich panels was investigated. Sandwich panels are known for their high thermal efficiency however, this research proposed the integration of a PCM concrete layer to maximize the ability of PCM to store heat and slow down the rate of heat transfer. The thermal behaviour was tested by supplying heat energy to specimens until the core temperature reached 60°C. Specimens were allowed to cool until the core temperature returned to 40°C. The thermal behaviour was recorded and analysed. Three specimen types were tested: solid panels (SL), sandwich panels (SW) with and without a PCM concrete layer. For all SW panels, a 10-mm air gap was introduced between two layers at three different locations. Results showed that the air gap behaviour was modified with the heat transfer process by creating temperature lagging, thus resulting in a slower rate of heat transfer across the specimens. The temperature lagging was observed in SW panels and varied depending on the location of the air gap. The application of PCM in SW panels further reduced the rate of heat transfer and decreased the fluctuation of temperature lagging magnitude.
Article
Natural polymers have been tested for soil stabilization since prehistoric age. This study evaluated the behavior of seven natural polymers as earth stabilizer. Seven polymers were selected from Sri Lankan vernacular polymer technologies. Natural Polymers were extracted from plants and trees. And then mix designs were developed by mixing soil and natural polymers (5, 10, 15 and 20%) by the dry weight. Compressive strength was subjected to understand the initial performance of each natural polymer. And the series of performance tests were conducted to understand the engineering and mechanical performances. The initial experiment shows only three natural polymers are suitable for stabilizing earth blocks such as pines resin, Dawul Kurudu, and sugarcane bagasse. And then different soil mix design experiment shows that natural polymers are good at gaining strength when soil particles are smaller (15% gravel sieve size 4.25–20 mm, 80% sand sieve size 0.425–4.25 mm, and 5% fine sieve size below 0.425 mm). Maximum compressive strength with pines latex was given as 2.65 N/mm². It reached the construction material required the dry strength of 2 N/mm² and wet strength of 1 N/mm². Further studies should be conducted to understand the bond development and e values of selected polymer stabilized earth blocks.
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Energy use in the building is responsible for one-third of total carbon dioxide (CO2) emissions globally. Nearly half of the energy loss occurs through the building envelope due to heat transfer to/for the surroundings. Therefore, there is a need to design an optimum building envelope to reduce energy use in buildings that depend on several parameters. This study aims to review different building parameters and provide a conceptual framework to optimize the building envelope. In total, 260 papers were reviewed, and the building envelope design consideration was categorized into: 1) Design Parameters (design and geometry), 2) environmental conditions (indoor and outdoor) and 3) performance criteria (energy, environment, economic, comfort). Energy use and CO2-emission in buildings increase with high thermal conductivity, low thermal mass, and low solar absorption of its envelope. Geometrically, building orientation impacts energy use more than the building shape factor. Changing set point temperature according to surrounding conditions has reduced energy use and CO2-emission by 30% and 56%, respectively. However, indoor air quality, velocity, and occupancy have meagerly affected building energy use. Energy and emission optimization criteria are directly related, but the emission-based optimized envelope is thicker than the energy one. Other criteria such as economy and comfort (thermal and visual) are inversely proportional to the energy-efficient building envelope. Based on the comprehensive review, this study proposed a conceptual framework to design a sustainable building envelope that includes life cycle assessment, occupant's satisfaction, and social benefits. Several future research recommendations were made, including 1) the use of switchable reflective materials to minimize heat transfer, 2) dynamic insulation material to control insulation value as needed, and 3) smart windows with tunable optical properties.
Article
Purpose The sluggish progression of disaster-induced housing reconstruction (DHR) in Sri Lanka provoked the assessment of drywall technologies as a mode of improving efficiency. The purpose of this paper is to investigate the applicability of drywall technologies to adopt a technical solution to DHR. Design/methodology/approach The research contextualized a mixed research design via a case-study strategy integrating semi-structured interviews, documentary reviews and observations. Two cases based on the 2016 Samasarakanda landslide were investigated. Within-case-analysis and cross-case-analysis were performed to derive conclusions. Findings Enablers for drywall technologies application are time saving, cost-saving, less water consumption and logistical easiness. Less strength of drywall technologies will not be a critical obstruction owing to the expected disaster resilience from the concrete frame and the subsequent requirement of non-load bearing walls for landslide DHR. Labor source, community acceptance, durability are potential settings of barriers. Observing model houses, researching the resistance of drywall technologies to landslide-induced vibrations and impulsive waves are some further research areas discovered. Research limitations/implications Empirical findings are centered on the 2016 Samasarakanda DHR. Practical implications Because of many issues in updating guidelines, drawings and BOQs, a protocol should be gazetted in the parliament to improve its updating flexibility allowing provisions to apply novel technologies for DHR. Originality/value Being one of the very first of this kind of research, contextually, the research is original. This study provokes insightful investigation of drywall technologies for DHR beyond its overlooked properties. This study reveals many wall construction challenges of the 2016 Samasarakanda DHR which have not yet been explored in research.
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Any building must be insulated to prevent excessive heat absorption and thereby reduce the cost of running the installed air condition system. This is especially the case in hot countries such as the United Arab Emirates (UAE). Among the popular construction materials used in the UAE are Insulated Concrete Blocks (ICB). This block is a combination of a unique block design and insulating inserts that enable this block to be highly energy efficient and cost effective. Although it has been used extensively in many buildings in hot regions, there is a shortage of thermal studies of this block reported in the literature. Consequently, this paper aims at investigating the thermal performance of this block during different climatic seasons. An experimental model was constructed in the emirate of Sharjah, mainly using this block. Its thermal behaviour was thoroughly studied over the course of one year by using Continuous Method (CM) and the Infrared Technique (IR) method. The main thermal parameters were focused on the Decrement Factor (DF), the Temperature Differences Ratio (TDR) and the Time Lag (Tg). It was found that the ICB does not perform similarly in all seasons, and/or in all orientations. The results show that ICB will perform best in Autumn with an average DF of 0.23, and with an average TDR of 0.56. The biggest value in terms of the Tg is found in Spring with 14.85h. Wind fluctuations can also affect these three parameters. In addition to wind, rain also affects the thermal performance of the ICB. Calibration between the CM and IR methods will be discussed, and detailed analysis will be provided in this paper with recommendations for future research.
Conference Paper
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In this paper, optimum insulation thickness (OIT) for building wall is estimated using life cycle cost analysis. A heating-degree method was used to calculate the heat losses through the building wall. In analysis rock wool was used as insulation material, electricity as energy source and fifteen wall construction materials. An appropriate mathematical model was used and simulated in Engineering Equation Solver to calculate cost savings and payback period of an initial investment. The results reveals that the light concrete materials saves negligible life cycle cost of just under 2 $/m2-year with minimum payback period of 6-47 years, while the heavy concrete materials, laterite bricks and concrete block are found most cost effective in terms of respective savings i.e. 12-16 $/m2-year with minimum payback period of 3 years. As a result, it is concluded that the wall made of light concrete materials and fire bricks should be uninsulated because the payback of insulation cost is too long, whilst, the wall construed from heavy concrete block, laterite bricks and concrete block must be insulated with minimum optimum insulation thickness of 54 to 98 mm as it has the lowest rate of return.
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Rejuvenating social interaction within community is an essential factor to survive together for a long time success. Designing buildings for war victim communities is challenging, thus it should be planned with great care, involving the people in the community to the design process, addressing their issues in poverty and fundamental needs through utilizing readily available materials and using locally available cost effective resources. As a new sustainable material, Mud-Concrete block (MCB) technology was introduced to build community centres for selected war victim communities in Batticaloa through 'UN Re-settling programme'. Thus, different walling materials were introduced to build the community centers in identified areas in Batticaloa. Among those constructions, Mud concrete block (MCB) technology was identified as a highly viable solution which could use locally available soil in construction sites. This paper explores the up-to-date research process of introducing a new sustainable material to restore a war victim community within their context through community architecture.
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Time lags and decrement factors for multi-layer materials without air gaps under air-conditioned and free floating conditions were obtained using the response factor and finite volume methods. The definitions under free floating conditions, which are independent of the external environmental conditions, are proposed for the first time. A special version of the finite volume method was employed in which the surfaces of materials were used as computational nodes and temperatures and heat fluxes on surfaces as primitive (state) variables. While the time lag is defined as a phase shift, the decrement factor is defined as the ratio of the amplitude of the temporal evolution of the temperature on the inner surface of the multi-layer material to that of the sol-air temperature or the outer surface temperature. To verify this analytical method, the time lags and decrement factors calculated by the response factor method were compared with the published results. The analytical expressions for the time lag and decrement factor of multi-layer materials under freefloating conditions were then obtained. Recommendations are made for choosing a proper definition for the time lag and decrement factor.
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Alumina has high heat resistance and corrosion resistance compared to other ceramics such as silica or mullite. However, for its application to refractory bricks, its high thermal conductivity must be reduced. To reduce this thermal conductivity by increasing the porosity, a GS (gelation of slurry) method that can produce high porosity solid foam was applied here to produce the alumina refractory brick. This method was successfully applied to produce alumina foam with high porosity and thermal conductivity of the foam is evaluated. At room temperature, the thermal conductivity was about 0.12 W/mK when the foam density was 0.1 g/cm3. At elevated temperature above 783 K, thermal conductivity of the foam was strongly affected by heat radiation and increased with increasing temperature, in contrast to the thermal conductivity of alumina itself, which decreased with increasing temperature. The alumina foams developed here achieved sufficient thermal insulating properties for use in refractory bricks.
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Lime-hemp concrete (LHC) is a sustainable building material that combines hemp shiv and building limes. Moisture fixation and thermal properties of LHC were determined so as to gain knowledge about the material's behaviour in a cold, wet climate. Sorption isotherms were produced over the whole moisture range for two LHC mixes by means of glass jar tests and a pressure plate apparatus. Thermal properties were determined for the mixes at different relative humidities using a transient plane source method. The results showed relatively low thermal conductivity and a steep sorption isotherm in the interval between 95% and 100% RH.
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Permeable pavement functions as a porous infrastructure interface allowing the infiltration and evaporation of rainfall-runoff while functioning as a relatively smooth load-bearing surface for vehicular transport. Hydraulic conductivity (k) of permeable pavement is an important hydraulic property and is a function of the pore structure. This study examines k for a cementitious permeable pavement (CPP) through a series of pore-structure models. Measurements utilized include hydraulic head as well as total porosity, (phi(t)), effective porosity (phi(e)), tortuosity (L(e)/L) and pore size distribution (PSD) indices generated through X-ray tomography (XRT). XRT results indicate that the permeable pavement pore matrix is hetero-disperse, with high tortuosity and phi(t) not equal phi(e). Power law models of k-phi(t), and k-phi(e) relationships are developed for a CPP mix design. Results indicate that the Kruger, Fair-Hatch, Hazen, Slichter, Beyer and Terzaghi models based on simple pore-structure indices do not reproduce measured k values. The conventional Kozeny-Carman model (KCM), a more parameterized pore-structure model, did not reproduce measured k values. This study proposes a modified KCM utilizing phi(e), specific surface area (SSA)(pe) and weighted tortuosity (L(e)/L)(w). Results demonstrate that such permeable pavement pore-structure parameters with the modified KCM can predict k. The k results are combined with continuous simulation modeling using historical rainfall to provide nomographs examining permeable pavement as a low impact development (LID) infrastructure component. (c) 2010 Elsevier B.V. All rights reserved.
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The effect of compositions of saw dust admixture on thermal conductivity and other mechanical/refractory properties of Ifon Clay was investigated. The raw clay gotten from Ifon in Ondo state was first processed to very fine particles and characterized using SEM/EDX, XRD and XRF. Sawdust from mahogany tree procured from a saw mill in Akure the State capital of Ondo State was also dried to remove moisture present. A composite mixture of this dried saw dust with the processed clay was made at various proportions of the saw dust, with a little addition of water for plasticity. Sam- ples of cylindrical dimensions were then produced from the mounting press by the process of compaction with a very high pressure. The samples were dried and then finally fired in the furnace at 1000°C for a final curing. Properties which include thermal shock resistance, bulk density, cold crushing strength, thermal conductivity and porosity were obtained by the appropriate standard test methods. The microstructures of the fired samples were also characterized with SEM using back scattered secondary imaging. The results show that the amount of sawdust admixture affects the properties variously; porosity increases with percentage increase in sawdust admixture while the thermal conductivity and other properties of the sample reduce with percentage increase in sawdust admixture. It was concluded that for structural insulating bricks where compressive strength is important the sawdust admixture should not exceed 10 to 15 percent.
Book
‘Design for Micro-Combined Cooling, Heating & Power Systems’ provides a manual for the technical and structural design of systems for supplying decentralised energy in residential buildings. It presents the micro-combined cooling, heating & power systems Stirling engines & renewable energy sources (mCCHP-SE-RES) systems in an accessible manner both for the public at large, and for professionals who conceive, design or commercialise such systems or their components. The high performance levels of these systems are demonstrated within the final chapter by the results of an experiment in which a house is equipped with a mCCHP-SE-RES system. The reader is also familiarized with the conceptual, technical and legal aspects of modern domestic energy systems; the components that constitute these systems; and advanced algorithms for achieving the structural and technical design of such systems. In residential buildings, satisfying demands of durable development has gradually evolved from necessity to obligation and institutionalisation. Consequently a major paradigm change has appeared in the supply of energy to residential buildings, from the centralised production of energy using fossil fuels to the decentralised production of energy using local renewable sources. Furthermore, on the energy system market, energy micro systems which use renewable energy sources are increasingly commercialised. From among these, the mCCHP-SE-RES systems are particularly striking because they offer a high performance and they enhance the relationship between humans and the environment. This book is intended for postgraduate students of electrical engineering, applied mathematicians, and researchers of modelling and control of complex systems or power system technologies.
Chapter
Ventilation is required in buildings for many different reasons [1]. We shall confine our discussion to that required for domestic and commercial applications, industrial applications being outside the scope of this book.
Article
In recent years, interest in green building materials and the valorisation of by-products from multiple industries has been increasing. As the brick industry allows various compounds to be added during the mixing procedure, much research has been conducted to highlight the impact of additions on fired clay bricks. This paper examines the significance of adding organic matter coming from agricultural solid waste (Olive Stone Flour, OSF, and Wheat Straw, WS residues) to improve thermal performance while maintaining load bearing capacity. The results show a decreasing bulk density for mixtures containing OSF, ranging from -6% to -19% compared to clay alone, and for WS mixtures, where the bulk density reduction is from -4% to -20%. Total porosity increases by 5-56% for OSF, and by 7-67% for WS, implying lower thermal conductivity for WS (-23% relative to clay alone) compared to OSF (-16%) when 5%.wt is incorporated. The compressive strength, for 5%.wt WS and 5%.wt OSF is -52% and -31% respectively. There is a significant positive correlation between the increasing amount of organic matter and the porosity. The most striking result to emerge from the data is that, for the same %.wt, WS creates higher total pore volume than OSF owing to the difference of grain size distribution. Consequently the pore size distribution of new materials containing OSF is more structured and leads to a better compressive strength than WS.
Article
This paper presents the results of tests of mass moisture content in saline burnt solid clay brick by the non-destructive dielectric, resistance and microwave methods. Several groups of bricks, kept in respectively aqueous nitrate, chloride and sulphate media varying in their ion content, and in salt-free water (as the reference) were subjected to tests. It is shown that brick salinity considerably influences the indications of the dielectric meter and the resistance meter and this influence is similar for different salt concentrations, resulting in the significant overrating of the evaluated moisture content relative to the real moisture content. It is also shown that brick salinity has little influence on the indications of the microwave meter. The test results were generalized by determining appropriate correlations between mass moisture content Um and indications X of the dielectric, resistance and microwave meters, to be used in building practice.
Article
In this paper, the porous ceramic pipes with high water sucking ability have been constructed for the evaporative cooling wall. Due to the water soaking-up ability of the porous pipes and the evaporation of water when their lower end is placed in water, the cooling of the combining wall can be supplied continuously. A mathematical model on the heat and mass transfer in the unsaturated porous media is developed to analyze the effects of ambient condition and the phase content on the cooling performance of the porous evaporative pipe. The influences of the wind speed (WS) or air speed (AS) on the temperature of the wet porous pipe surface are relevant to the ambient relative humidity. The temperature and the moisture content in the porous pipe as well as the temperature gradient and the vapor moving speed influence the water evaporating or the vapor condensing in the porous pipe. The experiments have also been conducted to study the evaporative cooling of the wet porous pipe, the water sucking characteristics of the porous pipe and the influences of the porous pipe arrangement on the cooling performance of the combining wall. The temperature variations of the porous pipe in the simulation accord with the test data. All these results should be taken into account for the promotion and application of the evaporative cooling of wet porous media.
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We provide a quantitative understanding of the relationship between thermal mass and cooling load, i.e. the effect of thermal mass on energy consumption of air-conditioning in office buildings. A simple office-building model with air-conditioning at daytime and free cooling at nighttime is analyzed in detail to quantify the hourly and overall variation of cooling load of air-conditioning. As an important parameter, an increase of time constant can effectively reduce the cooling load, by as much as more than 60% when the time constant is more than 400 h. However, when the time constant is larger than 1000 h, a further increase may slightly increase the cooling load, as a too large time constant may also postpone the heat release of thermal mass until the daytime. For the most effective reduction of cooling load, the interior and exterior convective heat transfer numbers need to be matched.
Article
In this study, time lags and decrement factors for different building materials have been investigated numerically. For this purpose, one dimensional transient heat conduction equation was solved using the Crank–Nicolson scheme under convection boundary conditions. To the outer surface of the wall, periodic boundary conditions were applied. Twenty-six different building materials were selected for analysis. The computations were repeated for eight different thickness of each material and the effects of thickness and the type of material on time lag and decrement factor were investigated. It was found that thickness of material and the type of the material have a very profound effect on the time lag and decrement factor. The results of present study are useful for designing more effective passive solar buildings and other related areas.
Article
District cooling technology is advantageous in warm and hot climatic regions, in that chilled water from a central refrigeration plant is delivered through a distribution network to groups of buildings. The technology is most suitable for new urban developments where system design and construction receive much freedom. With a focus on the energy use, this paper outlines an energy modelling methodology and decision approach to derive the most desirable scheme for a given project. The process involves a series of building design load computation, dynamic simulation, and plant energy consumption analyses for different phases of development. A proposed scheme for the South East Kowloon Development Project in Hong Kong is quoted as an example to illustrate the approach.
Article
In this study, the effects of thermophysical properties and thickness of a wall of a building on time lag and decrement factor have been investigated. For this purpose, one dimensional transient heat conduction equation was solved using Crank-Nicolson scheme under convection boundary conditions. To the outer surface of the wall, periodic boundary conditions were applied. A very general code which can take care of composite walls under any kind of boundary condition was developed. Single and combined effects of the thickness and thermophysical properties on the time lag and decrement factor were investigated. It was found that thermophysical properties have a very profound effect on the time lag and decrement factor. The computations were repeated for different building materials and the results are discussed.
Article
A new type of ion gun is described which greatly improves the resolution of a nonmagnetic time‐of‐flight mass spectrometer. The focusing action of this gun is discussed and analyzed mathematically. The validity of the analysis and the practicability of the gun are demonstrated by the spectra obtained. The spectrometer is capable of measuring the relative abundance of adjacent masses well beyond 100 amu.
Article
Studies, around the world, have demonstrated that envelope colour has significant effect on building thermal performance and the use of thermal mass can usefully modify the thermo-physical signature of buildings. However, their influences under hot-humid climate have not been investigated in details. In view of the issue, a testing facility has been established in the Department of Architecture of the Chinese University of Hong Kong; the facility allows study of the effect of various building design features on indoor temperatures. This paper presents the results of investigation about the effect of envelope colour and thermal mass on indoor temperatures. The study reveals that the use of lighter surface colour and thermal mass can dramatically reduce maximum indoor temperatures. However, their applications in building design could be very different, and to a large extent, depend on the circumstance. Furthermore, the paper demonstrates the possibility to develop predictive formulas for daily maximum indoor air temperature.
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