Search results

In hot and dry climates, air conditioning accounts for a large portion of total energy consumption; therefore, this paper aims to investigate the impact of sol-air temperature and ground temperature on the loss of cooling energy in hot and dry regions of Iran.

In line with this objective, the values of sol-air temperature along different directions and ground temperature at different depths were assessed with respect to climatic data of Yazd City. The impact of sol-air temperature and ground temperature on the rate of heat loss was investigated. So, energy loss of the walls aligned to four primary directions was calculated. This process was repeated for a 36 m² building with three different shape factors. All analyses were conducted for the period from May to September, during which buildings need to be cooled by air conditioners.

Numerical analyses conducted for hot and dry climate show that sol-air temperature leads to a 41-17 per cent increase in the wall’s energy loss compared with ambient temperature. Meanwhile, building the wall below the surface leads to a significant reduction in energy loss. For example, building the wall 400 cm below the surface leads to about 74.8-79.2 per cent energy saving compared with above ground design. The results also show that increasing the direct contact between soil and building envelope decreases the energy loss, so energy loss of a building that is built 400 cm below the surface is 53.7-55.3 per cent lower than that of a building built above the surface.

The impact of sol-air temperature and ground temperature on the cooling energy loss of a building in hot and dry climate was investigated. Numerical analysis shows that solar radiation increases heat loss from building envelope. Soil temperature fluctuations decrease with depth. Heat loss from building envelope in an underground building is lower than that from building envelope in a building built above the ground. Three different shape factors showed that sol-air temperature has the maximum impact on square-shaped plan and minimal impact on buildings with east-west orientation.

Several calls have been everywhere asking for proper use of passive design tools like shading devices, insulation, natural ventilation and solar panels in building architecture of hot-dry area in order to improve the thermal performance of indoor spaces. This paper examines the effect of these passive tools on indoor thermal performance which in turn helps arrange thermal priorities properly. Herein, basic principles of Successive Integration Method (SIM) have been utilized for an integrated design of two floors with small openings integrated with floor cooling, solar panels, natural ventilation, shading devices, and insulation. As a result, create priorities of passive tools that are structured consequently for ventilation, insulation, solar panels, and shading devices. This structure could guide designers and builders to set their priorities for the new development of building construction.

This research will analyze the traditional Iranian buildings according to the climatic factors by the use of graph theory. By this way, the hypothesis that climate factor has a major effect on the organization of the spaces in traditional Iranian buildings will be tested. Access graphs have been used to clarify the connectivity and depth of a building’s spaces from the socio-cultural point of view. However, it cannot be applied to climate studies. Thus, this study developed the existing technique to define building layouts in terms of climate and thermal comfort. The thermal comfort was graphically evaluated by the two main factors like solar gain and wind effect, with the use of a simple multi-attribute rating technique. All the analysis had been done in the interval of zero (the worst condition) to three (the best condition). The proposed orientation-weighted graph method proved that the thermal comfort factors of the buildings under study match the seasonal movements of their inhabitants. Consequently, the developed orientation-weighted graph method can be used to study space organization in traditional Iranian building in terms of solar gain and wind effect.

The stabilization of earthen blocks improves their mechanical strength and avoids adobe construction erosion due to rainwater. However, the stabilization affects the thermal properties of the earthen blocks, and thus their capacity to provide adequate thermal comfort to occupants. This article examines the influence of cement and geopolymer binders on thermal comfort in compressed earthen buildings in hot and arid climates.

The test cell is on the building platform in Burkina Faso. The building is made of compressed earth blocks (CEB) consisting of laterite, water and binder. The thermal models of the building were implemented in EnergyPlus v9.0.1 software. Empirical validation is used to check whether the model used for the thermal dynamic simulation can reproduce with accuracy the thermal behavior in a real situation. The adaptive thermal comfort model of ASHRAE 55–2010 was used to assess thermal comfort in long-term hot and dry tropical conditions.

The results show that the CEB buildings remain hot despite the use of cement or geopolymer binder. Indeed, with both cement and geopolymer binders, on a daily basis, 19 h and 15 h are uncomfortable during, respectively, the hot and cold seasons. An increase of 1% in cement content raises the comfort hours by 9.2 h during the hot season and 11.7 h during the cold season. Hence, the comfort time varies linearly with the cement content in the building material. Moreover, there is no linear relationship between comfort time and geopolymer rate.

Complementary work should also assess the influence of stabilization on building humidity levels. In fact, earthen materials are very sensitive to outdoor humidity and indoor humidity affects thermal comfort even if it is not taken into account in the ASHRAE adaptive thermal comfort model.

The present study will certainly contribute to a better valorization of clay potential in countries with similar climatic conditions.

The use of geopolymer binder is a suitable ecological option to replace the cement binder. It is important to mention that nighttime comfort can be increased through passive strategies such as natural ventilation.

Most CEB material stabilization analyses including cement and geopolymer ones were mostly investigated at the laboratory scale and less at the building scale. Also, the influence of the binder rate on the thermal performance of buildings made of cement and geopolymer has not yet been assessed. This paper fills this gap of knowledge by assessing the impact of cement and geopolymer binder rates on the thermal comfort of CEB dwellings.

A major challenge faced by West Africa is to find comfortable housing as a result of climate change and population growth. The climatic adaptation of buildings and their indoor environment become an essential condition for maintaining the health and productivity of the occupants. This paper proposes a model to assess the thermal comfort of naturally ventilated buildings in hot and dry climates in Burkina Faso.

The proposed method is an adaptive model which relies on a combination of parameters such as the operative temperature, the new effective temperature and the basic parameters of thermal comfort. It consists in proposing the zones of thermal comfort on the diagram of the humid air for each climatic region.

A decision-making tool is set up for evaluating the comfort of buildings to better consider the bio-climatic concept through a long-term comfort index. This comfort index is defined and is used to assess the degree of thermal discomfort for various types of housing. Two natural ventilation pilot buildings located in Ouagadougou were considered. The results show that the pilot building whose wall are is made of Earth blocks achieves 26.4% of thermal comfort while the building made of hollow cement block achieves 25.8% of thermal comfort.

The decision-making tool proposed in the present study allow building stakeholders to better and easily design, assess and improve the thermal environment of buildings.

The purpose of this paper is to optimize the linear densities of polyester yarn and filament for inner layer and elastane for middle layer with cotton yarn outer layer in plain knitted plated structure for hot and dry environment clothing.

Three levels of polyester yarn linear densities (11.1, 8.4 and 5.6 Tex), filament linear densities (0.8, 1.55 and 2.3 Decitex) and elastane (0, 4 and 8 percent) with 14.75 Tex cotton yarn have been used to knit 15 single jersey plated fabrics based on Box and Benhens experimental design with same loop length. Three cotton–elastane core-spun fabrics were also produced. All the fabrics were analyzed for moisture and ergonomic comfort properties and wet fabric coefficient of friction.

The increase in elastane content and yarn linear density decreases water vapor and air permeability; the increase in filament linear density decreases wicking rate and water absorbency. The optimum solution is 5.55 Tex polyester yarn of 0.8 Decitex filament as inner layer and 14.75 Tex cotton yarn as outer layer which gives good heat and moisture transfer without stickiness.

The implication of this paper is to study thinner polyester, polypropylene and polyethylene fabrics with more micro pores as skin contact layer for quicker heat and moisture transfer.

Outward wickability of sweat from the skin is the prime requirement of all skin contact layer fabrics.

It shifts the social attitude of most comfortable fabric to polyester–cotton plated for hot and dry climate.

This paper employs a more practical method for the selection of fabric.

The geographical range of agricultural crops is shifting because of climate change. Reducing the potential negative impact of this shift requires efficient crop switching at farm level. Yet there are scant studies that examine how crop switching is currently taking place and what factors facilitate the process. Even these few existing studies often based their analysis on inadequately established causal link between climate change and switching decisions. This study aims to identify the specific switching decisions that are primarily motivated by climate change, and their determinants.

The study used a household survey on 190 households in Semien Shewa Zone in Ethiopia. Subjective rating of farmers was used to identify the relative importance of climate change in motivating the different types of switching decisions. A logit model is used to identify determinants of crop switching decisions primarily motivated by climate change.

Farmers in the study area are currently abandoning certain crops as a response to climate change. The adoption of new crops is, however, mainly attributed to price changes. Most farmers who abandoned at least one crop adopted mung bean mainly due to its price advantages. As expected, crop switching as an adaptation strategy is more prevalent particularly in drier and hotter agroecologies. The logit model showed that crop switching is strongly correlated with land size and agroecology.

This paper provides an in-depth examination of crop switching as an adaptation strategy to climate change. Crop switching is an adaptation strategy that is expected to substantially reduce the damage from climate change in agriculture. The findings are particularly relevant for adaptation planning in the context of smallholder agriculture.

Appropriate thermal properties of walls can lead to the improvement of the indoor environment of buildings especially in countries with low energy availability such as Burkina Faso. In order to benefit from these advantages, the thermal properties must be properly characterized. This paper investigates the impact of the design of single- and double-layer walls based on compressed Earth blocks (CEB) on the risk of indoor overheating.

First a building has been used as a tool to measure climate data. Then, a software program was used to define an accurate thermal model. Two indices were defined: weighted exceedance hour (WEH) related to the risk of overheating and cyclic thickness (ξ) related to the thermal properties of the walls. The aim is to define the appropriate values of ξ which minimized the WEH. The study also assesses the sensitivity of these thermal properties to occupancy profiles.

The results indicate the arrangements of the thermal properties that can promote comfortable environments. In single-layer wall buildings, ξ = 2.43 and ξ = 3.93 are the most suitable values to minimize WEH for the room occupied during the day and night, respectively. If a double-layer wall is used, ξ = 1.42 and CEB layer inside is the most suitable for the room occupied during the day, while ξ = 2.43 and CEB outside should be preferred in the case of a room with night occupancy profile.

The findings indicate that occupation patterns at room scale should be systematically considered when dealing with wall design in order to improve the thermal comfort.

The purpose of this paper is to move beyond the stage of analysis of exclusively physical microclimatic phenomena and extending ourselves to the study of the impact of the microclimate environment on the user behavior in public spaces. This paper will open up new opportunities for the development of urban open spaces and facilitate the decision-making for urban decision-makers, city managers and planners to make the right urban planning decision.

The methodology for identifying the links between microclimatic quality of urban routes and behaviors was developed on the basis of the results obtained from field surveys carried out in nine public urban areas of the city of Biskra, three urban space are located in a traditional urban fabric (the medina) and the other five in new urban areas, in the two climatic seasons (winter, summer) of 2019. For this exploratory research, two types of instruments were used to collect data from environmental and human monitoring.

Improving microclimatic conditions in urban spaces can allow people to spend more time outside, with the possibility of increasing their social cohesion. The overall objective of this research is to better understand the impact of microclimatic characteristics on pedestrian behavior of nine selected public urban spaces in the city of Biskra, Algeria. To characterize this impact, the authors developed an approach based on crossing data of field surveys, including structured interviews with a questionnaire and observations of human activities (video recordings), as well as microclimate monitoring, conducted during the two climatic seasons (winter, summer) 2019. The analysis of the results allowed to verify the impact of the two climatic seasons (winter, summer) on the variation in the density of occupancy of the different urban areas studied and the duration of the user stations. The authors also illustrated that the number of individuals higher in the traditional urban spaces of the city of Biskra or the conditions of climate comfort are more comfortable than the urban spaces in the new urban areas of the city of Biskra during the summer, which is the season most problematic.

In recent years, there has been a proliferation of scientific studies on the subject of control of microclimatic characteristics and, in particular, on the consideration of the thermal comfort of persons by qualitative analysis, prediction and representation of the perception of external environments. Improving microclimatic conditions in urban spaces can allow people to spend more time outside, with the possibility of increasing their social cohesion. This study highlights the importance of climate-conscious urban design and design flexibility. Urban environments can be modified in summer and winter to provide a better outdoor thermal environment for users. In addition, this study also shows the importance of harmony between microclimate and urban design. Such harmony can be achieved by including requirements for a climate-conscious urban design in the planning regulations for cities in arid zones.

Window shading has always been an effective technique to control the access of solar radiation; however, inappropriate selection of the shading technique, location and optical properties may lead to an increase in energy consumed for cooling and artificial lighting. Venetian blinds (VBs) are a type of adjustable shading devices that can be installed to the interior, exterior or in between glass panes of a window and that can be easily implemented in both new and existing buildings. This study aims to investigate the impact of three VB parameters: slat angle, reflectivity and location on the overall energy consumption of a residential space with a south-facing facade under the hot arid desert climate of Saudi Arabia’s capital, Riyadh. For the purpose of globalizing the findings, the same investigations were applied for two other cities of similar climates: Cairo, Egypt, and Arizona, the USA.

A test room was modelled for energy simulation, with a 20% window-to-wall ratio. A VB was assigned with alternatives of being located to the indoor, outdoor or in between double glass panes. High, medium and low reflectivity values were applied at each location at slat angle alternatives of 15°, 30°, 45°, 60°, 75° and 90°.

Results showed VB performance across slat angles, where up to 20.1% energy savings were achieved by mid-pane high reflectivity VBs in Riyadh, while the value exceeded 30% in case of being externally located. A similar performance pattern occurred in the other two cities of hot arid desert climates: Cairo and Arizona.

The study is limited to VBs at a fixed position, with no upward movement for partial or full openness conditions. The effect of blind control and operation on performance, such as the amount and duration of openness/closure of the blind and changes in slat angle across time, in addition to VB automation, shall be investigated in a future study.

The better understanding of VB energy performance achieved would enhance a more rational selection of VBs, which would benefit the construction industry as it would assist designers, real estate developer companies, as well as end-users in the decision-making process and help to realize energy-efficient solutions in residential buildings. VB production entities would also benefit by manufacturing and promoting for energy-efficient products.

In this study, a matrix of combinations of three VB parameters was developed, and the effect of these combinations on the overall energy consumption of both artificial lighting and heating, ventilation and air conditioning (HVAC) systems was evaluated and compared to identify the combinations of higher efficiency. The literature showed that these three parameters were hardly investigated in a combined form and hardly assessed by considering the overall energy consumed by both artificial lighting and HVAC.