Compressed stabilized earth block: environmentally sustainable alternative for villages housing

Construction materials contribute to environmental pollution and the impoverishment of natural raw materials. The villages of Upper Egypt were exposed to high thermal loads owing to their geographical location. Moreover, the current building materials do not comply with the principles of sustainability and environmental adaptation of the residents of these buildings. Therefore, attaining admission to one sustainable building material in Upper Egypt and using it as an environmentally compatible, inexpensive, accessible, and easy building material for the users of these blocks is essential. In this study, the author selected various sites in Upper Egypt, analyzed climate and urban data, and after that, suggested prototypes with many variables and measured using the DesignBuilder V5 computer simulation program to select an optimal building type. Reached that can be saved energy about 40:50% and decreased annual discomfort hours more than 50%, finally, discussed with community members by a questionnaire on societal acceptance. The research concluded that building with compressed stabilized earth block is an environmentally sustainable solution applied in residential areas in the villages of Upper Egypt to reduce deficiencies in environmental adaptation.


Introduction
Environmental problems are central in the consciousness of researchers. Buildings and their materials are an essential part of the architectural product and have received much attention for preparing sustainable natural materials.
Soil has been a major component of buildings since antiquity, used in 6000 BC as a building material in Mesopotamian civilizations, the Tibetan and Andean in Peru, in the fertile valleys in China and Thebes in Egypt. Therefore, thousands of years ago, people lived sustainably, in accord with nature, and respected and benefited from it. However, construction using reinforced concrete and burned bricks has extended to negative impacts on the environment. Therefore, it is critical to produce environmentally friendly building materials and improve the characteristics of building materials, manufacturing, lower energy consumption, and simultaneously cut costs. Therefore, this study highlights the compressed stabilized earth block used in Upper Egypt villages as a solution to the problem of constructing housing units in these degraded areas [1][2][3][4][5].
The applied study was used to define areas as a case study. Thus, the research identified the analytical field area data and properties of the suggested material and deduced a set of variables measured according to their classification using a computer simulation program to find an optimal architectural model. Community members completed a questionnaire to examine the research hypothesis of the feasibility of construction using compressed stabilized earth block (CSEB) in the villages of Upper Egypt. Finally, the results are discussed, and recommendations are proposed.

Research aim and methodology
The research aim investigates a sustainable building material for the construction of residential areas in Upper Egypt. Therefore how to use them as environmentally compatible, inexpensive, available, and easy to use materials. Furthermore, the study investigates the impact of these materials on the environmental adaptation of users of these areas.

Methodology
A research methodology was implemented to achieve the research objectives. First, qualitative research and analysis of the data were collected about construction using compressed stabilized earth block. Moreover, climate, urban, and building status of Upper Egypt villages. Then, qualitative and quantitative approach to suggested prototypes, its variables, and questionnaire. Analysis was used to identify the system through the data from the literature review, as well as knowing the degree of acceptance and satisfaction with this technology. The research limitations are Upper Egypt villages and CSEB as construction building materials.
Consequently, CSEB was identified as a low-cost and environmentally friendly material found in developing countries with hot climates or in tropical [6,7].
The various components and stabilizers, such as Portland cement or lime, are mixed with clay soil and sand, with different percentages of mixing. The mold is compressed in the process (manual or automatic compression) and dried for 28 days; however, it does not burn [10][11][12] (CSEB = soil + water + stabilization (fixing material) ( Table 1). Natural building materials, such as soil in general and specially CSEB are an ideal solution in hot areas because of the thermal comfort and insulation of the soil and its low impact on the environment. Table 2 lists the advantages and disadvantages of the CSEB technique [17][18][19][20].
Also by CSEB in constructions, it decreases carbon dioxide emission 2 to 7 times less than that of burned bricks (Fig. 2).
Several buildings with different activities and designs in many hot-climate countries (not limited to developing countries) and clarifies the advantages of using the CSEB, Table 3 shows some examples.  Recently, the Egyptian Center for Housing and Building Research interested in CSEB as the best method for sustainable construction, especially in developing areas of state development efforts. The rise of prices for building materials has resulted in higher housing prices in Egypt, such as iron and cement. Therefore, Egypt adopted the Egyptian building code of CSEB [38].

Methods/experimental
Six villages were chosen from different governorates in Upper Egypt (Giza, Fayoum, Dahkla, Assuit, Aswan, and the Red Sea) as a case study, shown in Fig. 3.
Reasons to choose villages in Upper Egypt as a case study are as follows: 1-These villages are deprived, with challenges for economic growth are characterized by low construction standards and comfort for users and a lack of services and infrastructure. 2-With the increasing population of these villages, the need to provide low-cost construction materials for housing is an alternative to using traditional building materials. 3-Burned clay blocks remain the main construction material, even though it is a huge source of greenhouse gasses (GHGs) [39,40]. 4-In general, Upper Egypt is in the southern part of Egypt. The warm, arid climate provides a comfort zone for construction and urbanization. Overall, a lack of sustainability exists in the villages in Upper Egypt (socially, economically, and ecologically). Therefore, the Upper Egyptian villages were chosen as a case study [41]. Table 4 conclude its main data.
Climatic data for case studies was higher temperatures in summer reach 35-45°C, whereas lower temperatures in winter can reach 15-20°C, and rain is scarce [42] (Fig. 4).
The figure shows that most of the temperatures are outside the thermal comfort zone (shaded part).
The main building material in these villages is burned brick in most buildings in the village and wood and stones (Fig. 5).
The aim is to build and retrofit buildings in Upper Egypt using local and stronger materials to obtain a better thermal and esthetic shelter.
Method: After the analytical study, a set of variables was observed and evaluated using the alternative proposal design to arrive and an ideal suggested model.
Design variables: The variables chosen were reduced energy loads, thermal comfort, energy consumption, budget, lifecycle, and social acceptance. Table 5 shows the design parameters.  Each variable was measured using either computer simulation or a questionnaire, depending on the variable type.

Simulations
The simulation program is DesignBuilder V5 and design proposal type as shown in Table 6.

Questionnaires
A sample is taken from the chosen community, and 20 questionnaires were distributed in each village.
Factors and variables, to research the drivers and barriers of CSEB building technology in Upper Egypt, with analytical, and not statistical, generalization. Questionnaire forms were filled out from the sample of the study population with semi-structured interviews. The issues under question were shown in Table 7.

Simulation
The simulation program is DesignBuilder. All 84-simulation readings in six countries and two classes of readings were obtained from the annual energy consumption and annual thermal comfort indicators. The analysis is as shown in Table 8.
From Table 8, we conclude a better-proposed building model in each governorate, which achieved the least number of hours of thermal discomfort and less energy consumption. Figures 6 and 7 show the energy consumption in the model and the amount of energy saving. Questionnaire A sample was taken from the study community and 20 questionnaires were distributed in each village (quantitative method) to obtain the residents' ability to use CSEB construction as an alternative to the traditional building materials used in the region. Fig. 8.

Discussion
CSEB is an environmentally friendly substance with high thermal insulation properties and strength and durability, contributing to the thermal comfort of its users and enhancing the health of the population (indoor houses are cooler in summer and warmer in winter). The model with code B 1 T 2 R 2 F 2 C 1 includes CSEB with 5% cement, 24 cm wall thickness, a curved roof type, ground and one floor with a vertical courtyard position is achieves the best results in most governorates, which can be generalized in Upper Egypt and its results analyzed below in Table 9.
The residents' opinions were obtained regarding the proposed model and the results correlated with most of the sample (Fig. 9).
CSEB will have great potential in the future to build low to medium-cost housing and contribute to sustainable development and was accepted by the residents of the villages, as indicated in the results of the questionnaire.   Table 6 Building specification Using this technology in the villages of Upper Egypt will achieve many advantages and benefits (economic, social, and environmental) and enhance urban development in the villages of Upper Egypt.

Conclusions
Compressed Stabilized Earth Block is one of the world strategies and trends towards back to nature to saving the planet, and producing zero-energy buildings, preserving the environment and quality of life.
The study proved that replacing the traditional building material with CSEB while fixing the other proposed variables in the six governorates in Upper Egypt  under investigation reduced the thermal discomfort hours, raising the efficiency of the built environment and the Energy consumption decreased from 35 to 50%. Therefore, building with compressed stabilized earth block is an environmentally sustainable solution applied in residential areas in the villages of Upper Egypt to reduce deficiencies in environmental adaptation. Therefore, the research hypothesis is right. The proposed design considerations, such as the wall thickness, the shape of the roof, and internal court position help to increase energy efficiency and reduce consumption. The best model with the code B 1 T 2 R 2 F 2 C 1 (Fig. 7) is effective for the thermal comfort of users.
From the questionnaire analysis for residents, there was a great tendency towards adopting these new ideas in construction, the environmental and thermal impact of CSEB would positively affect user satisfaction rate at~65%, due to currently environmental pollution. Some also supported the idea because it is economically, rising in housing prices in Egypt because of higher prices for building materials, such as iron and cement, which reflected resident, so The cheapness of CSEB and the ease of use had the greatest impact on its social acceptance, at a rate of~75%.
Some were worried about maintenance, the rate at~30% of people were concerned about the durability and its final look and needing a multistory building (more than 5 floors).
Land locations like Egypt's sandy desert soil are suitable construction materials and achieve sustainability.
The research concludes that the CSEB house is a promising passive solution for saving energy. The hot desert climate in Egypt has resulted in a decrease in energy demand of between 35% and 50%.    prefer CSEB houses because it has potential in energy saving, reduced maintenance and operating costs, lower environmental impact, construction efficiencies facing expansions and contractions in arid climates, dual land use with minimal visual impact because landscaped areas replacing the building leave better visual images, and lower noise. Furthermore, it has low carbon emissions, does not disturb the ecosystem, and is an adaptable subject and suitable for culture, customs, and traditions.
Abbreviations CSEB: Compressed stabilized earth block; WWR: Window wall ratio; R value: Resists the flow of heat from the window or a complete wall or ceiling; SHGC : The fraction of incident solar radiation admitted through a window