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Thermal performance and optimum insulation thickness of building walls with different structure materials
Abstract
This study deals with thermal performance and optimum insulation thickness of building walls with different structure materials under dynamic thermal conditions. Thermal performance of building walls constructed of concrete, briquette, brick, blokbims and autoclaved aerated concrete (AAC) is determined for uninsulated and insulated wall structures. Extruded polystyrene (XPS) and expanded polystyrene (EPS) as insulation material are selected. The yearly cooling and heating transmission loads are calculated by using an implicit finite difference method under steady periodic conditions. These loads are used as inputs to an economic model including the cost of insulation material and the present value of energy consumption cost over lifetime of 10 years of the building to determine the optimum insulation thickness. The investigation is carried out for a south-facing wall and the climatic conditions of Elazığ, Turkey. Results show that the optimum insulation thicknesses vary between 2 and 8.2 cm, the energy savings vary between 2.78 and 102.16 $/m2, and the payback periods vary between 1.32 and 10.33 years depending on five different structure materials and two different insulation materials. Results are compared with the degree-days method.
... Ozel [25] where he used implicit method under stable periodic conditions and climate of the city of Elazig in Turkey. Figure 6 shows the predicted internal temperature during one day and the results [25] for a concrete wall of the same thickness. ...
... Ozel [25] where he used implicit method under stable periodic conditions and climate of the city of Elazig in Turkey. Figure 6 shows the predicted internal temperature during one day and the results [25] for a concrete wall of the same thickness. As can be seen the behaviour is good showing a maximum difference of about 2 o C, which can be attributed to the different numerical schemes adopted by the respective authors. ...
... Comparison of predicted temperature with the results from Ozel[25] Comparison of the predicted decrement factors and time lags with the results of Asan and Sancaktar[26] ...
Heating and cooling of buildings is responsible for almost 40% of the electricity demand and about 33% of greenhouse gas emissions. Because of the global energy and environment critical situation, there is a need to improve the energy efficiency of buildings and make them more sustainable. The main objective of the present study is to investigate the crushed rubber from unserviceable tires as an insulating material for walls and flat roofs and to provide an additional route for their reuse and deviation from landfills. An experimental rig is constructed and instrumented to determine the thermal conductivity of crushed rubber from used tires and the overall thermal conductivity of composite walls and roofs with crushed rubber insertion. Experimental measurements showed a thermal conductivity of crushed rubber of about 0.25 W/m. A conduction model is formulated for multilayered plane wall, discretized in explicit form and used to elaborate a home built code in MATLAB. The numerical code was tested and validated. Numerical investigation was done to analyze the effects of the wall thickness, thermal conductivity of the material, color, gap dimension and rubber filling on decrement factor, the time lag and total internal heat gain. The simulations indicated 21% reduction in the decrement factor and an increase of about 1.63 times in the lag in comparison with the plastered wall. The flat roof showed 23.3% reduction in solar heat gain, by increasing the rubber layer thickness from 15 to 25 cm.
... The optimum insulation thickness for the AAC wall was one-third of that for concrete wall achieving a payback period of only 10.33-14 years. Applying insulation in the AAC wall is uneconomical due to the high payback period compared to other masonry materials (Ozel, 2011b). As seen in Fig. 14, the cost-saving potential of the insulated envelope increases with the thermal conductivity. ...
... D. Kumar et al. well as multiple indicators. The single indicators use the energy, environment, cost, thermal comfort, and visual comfort separately to investigate optimum building shape (Florides et al., 2002), façade (Li et al., 2018), window glazing and type (Leung et al., 2020), window to wall ratio (Pathirana et al., 2019), orientation (Ramin et al., 2016), material thickness (Ozel, 2011b), and types (PCM (Solgi et al., 2019), insulation (Kumar et al., 2020a), and coating (Santamouris and Yun, 2020)), configuration, ventilation (Jamil et al., 2016), light shelves (Ebrahimi-Moghadam et al., 2020), shadings (Wati et al., 2015) and others. The optimization based on one indicator could be misleading to a building designer because of the indicator's dependency. ...
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.
... A thicker thermal insulation layer leads to higher energy savings, but it is more costly [14]. Therefore, from a cost-effectiveness viewpoint, the efficient use of insulation consists firstly of defining the optimal insulation layer thickness where the sum of the insulation material cost and the heating/cooling energy cost during the lifespan of the building is minimal [15]. ...
... In this study, the LCC function is evaluated "dynamically" in the sense that the annual heating and cooling energy demand varies over time due to the effect of climate change on future weather data. Thus, the LCC formula can be stated as follows [14]: ...
The rise in global temperature is a direct consequence of the climate change phenomenon, whose effect on building energy demands can no longer be neglected. In this regard, thermal insulation is considered an efficient design measure to enhance the energy performance of buildings. The key factor for the cost-effective implementation of insulation in buildings is the proper selection of insulation thickness. However, the consideration of the climate change factor in the optimisation of the insulation thickness for building walls has not yet been addressed by researchers. In this work, the optimum insulation thickness of different wall façades is calculated in three principal climate regions in Morocco, while taking into consideration the effect of climate change over the building lifespan. The calculation used a dynamic life cycle costing method to consider the varying climate conditions over time. The future weather data is elaborated based on the medium-low greenhouse gas emissions scenario RCP4.5 of the intergovernmental panel on climate change fifth assessment report. The obtained results show that the optimum insulation layer thickness would vary between 0.04m and 0.07m depending on the wall orientation and the climate zone. Considering all walls, the life-cycle energy saving ratio would vary between 49.64% and 54.87%.The economic feasibility analysis indicates the payback period would be less than 10 years regardless of the wall orientation and the climate zone. In addition, it is shown that the effectiveness of the insulation would not be adversely affected by the climate change phenomenon in the future.
... It was found that the temperature of roofs with polyurethane foam was lower than that of roofs with polystyrene foam, which resulted in a reduction in the energy required for cooling. The thermal performance of building walls, including extruded and expanded polystyrene with different thicknesses, was studied under dynamic thermal conditions (Ozel 2011). The optimal thickness of polystyrene panels based on local climatic conditions was investigated using an economic model, and it was concluded that the cost of energy saved ranged from $2.78/m 2 to $102.16/m 2 (in 2011) for polystyrene thicknesses between 2 and 8 cm (Ozel 2011). ...
... The thermal performance of building walls, including extruded and expanded polystyrene with different thicknesses, was studied under dynamic thermal conditions (Ozel 2011). The optimal thickness of polystyrene panels based on local climatic conditions was investigated using an economic model, and it was concluded that the cost of energy saved ranged from $2.78/m 2 to $102.16/m 2 (in 2011) for polystyrene thicknesses between 2 and 8 cm (Ozel 2011). The thermal performance of different insulation materials in the brick walls of a historic building was assessed by Walker and Pavía (2015) using heat flow sensors, an infrared camera, thermocouples, and a thermal transmittance meter. ...
This work presents a field investigation and numerical simulation for studying the heat transmission through the walls of two specially designed test rooms exposed to the hot and arid summer climate of the coastal region of eastern Saudi Arabia. The walls of the reference room were constructed of typical hollow-core concrete blocks, while the walls of the second room were made of concrete blocks incorporating expanded polystyrene (EPS) panels. Both test rooms were equipped with thermocouples, heat flux meters, temperature/relative humidity sensors, and power meters that provided continuous measurements during the test period. Infrared scanning and U-value measurements were also performed, and a weather station installed at the site provided the meteorological data. The results of these measurements revealed that the walls made of the concrete blocks incorporating EPS panels have a heat flow resistance about 255% higher than that of the walls built of typical hollow-core concrete blocks. Similarly, the thermal transmittance was lower by about 65%. Accordingly, the second room displayed a reduction of 29% in energy consumption for providing the same level of thermal comfort during the summer months as compared with that in the reference room. Both test rooms were simulated using DesignBuilder software, and the simulation results were validated with the field monitoring data. In addition, parametric studies were subsequently carried out to evaluate the effectiveness of other insulation materials. It was found that the application of the reflective coating and insulating plaster over EPS concrete blocks could further improve the reduction of energy consumption to about 47%.
... For that reason, many researchers have been working on the development and research of building envelope materials. Some researchers have investigated the thermal comfort and performances of the wellknown insulation materials such as mineral wool, expanded polystyrene (EPS), extruded polystyrene (XPS) foam, foamed polyurethane, fiberglass, etc. (Al-Homoud, 2005;Dombaycı, 2007;Özel, 2011;Jelle, 2011;Korjenic et al., 2011;Ekici et al., 2012;Kaynaklı, 2012). Another group of researchers have concentrated on the compositions of the mortar for decreasing the thermal conductivity of the building walls by using some materials such as perlite aggregate, silica fume, fly ash, pumice, blast furnace slag, etc. ( Gül et al., 1997;Demirboga, 2003;Demirboga and Gül, 2003;Uysal et al 2004). ...
... Another group of researchers have concentrated on the compositions of the mortar for decreasing the thermal conductivity of the building walls by using some materials such as perlite aggregate, silica fume, fly ash, pumice, blast furnace slag, etc. ( Gül et al., 1997;Demirboga, 2003;Demirboga and Gül, 2003;Uysal et al 2004). The thickness of the wall and plaster are also play an important role on thermal isolation (Özel, 2011;Ekici et al., 2012;Kaynaklı, 2012). On the other hand, other investigations focused on the behavior of the different build-ing envelope materials in time (Jelle, 2011;Papadopoulos, 2005;Cabeza et al., 2010). ...
Here we describe a new type of environmentally sensitive insulation panels which can be used on exteri-or wall surfaces to minimize all the negative aspects of existing coating materials by taking advantage of natural rock properties. We investigate the decorative characteristics and insulation performance of this new product, obtained by applying materials from different lithologies to Expanded Polystyrene Surfaces (EPS). First, a mortar with 25% acrylic and 75% sand was applied to the EPS by a stripping method using sand size materials from various lithologies (granite, micaschist, basalt, quartzite, and pumice). To determine the optimum thickness, insulation panels containing plaster of 2, 4, 6, and 8 mm thickness were prepared for each lithology. Their thermal conductivity coefficient, bending and compressive strength were tested. Predictably, thermal conductivity coefficient yielded lowest values in 2 mm panels and highest in 8 mm panels for all lithologies. The bending strength also increased proportionaly with thickness. In the compressive strength tests, the highest values were measured for the 2 mm panels while relatively low values were obtained for the 4, 6 and 8 mm panels, except for the micaschist and basalt-based panels. As a result, basalt and pumice offer superior features in the three measured parameters, so, it is expected that different combinations of these two lithologies would offer positive features. In this context, considering its high fire resistance and low thermal conductivity coefficient perpendicular to the planar surface of muscovites, micaschist is the third lithology that can be utilized with the two materials mentioned above. Compared with previous materials, the products investigated in this study are cost effective because they reduce paint costs, application time and total building load. The geomaterials also have aesthetic appeal.
... The above results depend on fuel type and climate [14]. Ozel addressed the thermal performance and optimization of thermal insulation thickness for exterior walls, reporting the following results [15]: 1. At 2 cm, the smallest thickness corresponded to the Extruded Polystyrene (XPS) insulation coupled with Autoclaved Aerated Concrete (AAC). ...
... Polystyrene (PS)aka. Styrofoam-insulation is a rigid closed-cell insulation material made up of styrol or styrene monomers; 2. At 8 cm, the largest insulation thickness corresponded to the Expanded Polystyrene (EPS) insulation coupled with concrete; 3. The XPS insulation was found to be more effective than EPS in energy saving [15]. Focusing on an existing building in İzmir, Turkey, Yıldız relied on sensitivity analysis to identify the effective construction parameters in a hot and humid climate. ...
Construction is one of the most energy consumed
activities in the urban environment that results in a significant amount
of greenhouse gas emissions around the world. Thus, the impact of
the construction industry on global warming is undeniable. Thus,
reducing building energy consumption and mitigating carbon
production can slow the rate of global warming. The purpose of this
study is to determine the amount of energy consumption and carbon
dioxide production during the operation phase and the impact of
using new shells on energy saving and carbon footprint. Therefore, a
residential building with a re-enforced concrete structure is selected
in Babolsar, Iran. DesignBuilder software has been used for one year
of building operation to calculate the amount of carbon dioxide
production and energy consumption in the operation phase of the
building. The primary results show the building use 61750 kWh of
energy each year. Computer simulation analyzes the effect of
changing building shells -using XPS polystyrene and new
electrochromic windows- as well as changing the type of lighting on
energy consumption reduction and subsequent carbon dioxide
production. The results show that the amount of energy and carbon
production during building operation has been reduced by
approximately 70% by applying the proposed changes. The changes
reduce CO2e to 11345 kg CO2/yr. The result of this study helps
designers and engineers to consider material selection’s process as
one of the most important stages of design for improving energy
performance of buildings.
... The research on exterior walls has been primarily focused on determining the optimal insulation thicknesses for each region and use case worldwide [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]: Ozel [15] studied the optimal insulation thickness for structural materials on the southern walls of buildings in Turkey. Dynamic simulations were performed considering five structural materials (concrete, briquet, brick, blokbims and autoclaved aeration) and two insulation materials (extruded polystyrene (XPS) and extended polystyrene (EPS)). ...
... The research on exterior walls has been primarily focused on determining the optimal insulation thicknesses for each region and use case worldwide [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]: Ozel [15] studied the optimal insulation thickness for structural materials on the southern walls of buildings in Turkey. Dynamic simulations were performed considering five structural materials (concrete, briquet, brick, blokbims and autoclaved aeration) and two insulation materials (extruded polystyrene (XPS) and extended polystyrene (EPS)). ...
To delay fossil energy depletion and implement the Paris Climate Change Accord, the South Korean government is attempting to reduce greenhouse gas emissions with the establishment of the 2030 Roadmap. The insulation performance of external walls is being continuously enhanced in the architectural domain. However, Korea’s policy and construction market focuses only on the heat resistance of buildings’ external walls to enhance the insulation performance, leading to an increased thickness of the insulation materials. In this study, the relationship between the surface reflectivity and insulation thickness of external walls was examined to formulate an effective insulation strategy for buildings in Korea. Office buildings of 12 regions in the Korean Peninsula were considered. The dynamic energy simulation program EnergyPlus was used to perform the heating and cooling load analyses. The present worth method was adopted to perform the economic analysis. The analysis of the cooling and heating loads indicated that a change occurred not only in terms of the latitude but also between the Eastern and Western regions. The energy consumption could be reduced by increasing the reflectivity in the Southern region and lowering the reflectivity in the Northern region, based on the total load. In addition, a higher latitude corresponded to a higher energy saving effect owing to the increased insulation thickness. In the case of Jeju Island and Busan, regions with a relatively large cooling load and small heating load, the total load is little affected by insulation thickness at high reflectivity. If the external skin was considered to have the optimal reflectivity, the regions for optimal insulation thickness could be divided into three categories: north, central and south.
... The optimum insulation thickness for the AAC wall was one-third of that for concrete wall achieving a payback period of only 10.33-14 years. Applying insulation in the AAC wall is uneconomical due to the high payback period compared to other masonry materials (Ozel, 2011b). As seen in Fig. 14, the cost-saving potential of the insulated envelope increases with the thermal conductivity. ...
Lightweight concrete (LWC) panels are becoming popular in buildings because of being lightweight, which allows easy transportation, handling, and installation. They provide the opportunity for modular construction. They also have insulating properties with thermal conductivity of 0.026-1.0 W/m-K. However, they have low thermal mass, which causes overheating during the heatwave period in Mediterranean and temperate climates. Therefore, Phase Change Materials (PCM) are integrated into LWC panels to increase thermal storage, mitigate overheating, and increase energy efficiency. However, the integration of PCM in LWC panels also increases their thermal conductivity, which is not favorable for a sustainable building. There is a need to reduce the thermal conductivity of PCM-integrated LWC panels. Thus, this study aimed to develop new lightweight heat-resistive and thermal storage panels (HRSPs) using porous fillers and PCM for energy-efficient building applications.
First, the optimum PCM melting point for cool temperate climates of Melbourne was identified through parametric analysis considering a typical Victorian house as a case study. The result showed that the optimum PCM melting point for free-running and air-conditioned houses is 30°C and 25°C, respectively. Based on these findings, capric acid (CA) PCM with a 29-32°C melting point was selected. The integration of PCM in cementitious composites may suffer from leakage issues during mixing with cement and other aggregates. The leaked PCM, such as fatty acids, may acidify concrete and reduce its compressive strength. The traditional leakage test proposed by previous researchers was insufficient to identify the microscopic leakage of PCM and its potential acid attack on concrete. Moreover, the conventional Form Stable PCM (FSPCM) synthesis procedures are energy-intensive, increasing the embodied energy of FSPCM. This study proposed a new FSPCM synthesis procedure to reduce energy use, eliminate acid attacks and increase PCM absorption capacity in porous material for energy-efficient buildings. The proposed method was energy-efficient, with CA absorption of 75% in porous hydrophobic expanded perlite (HEP). However, due to acid attack, the compressive strength and thermal conductivity at 75% CA absorption were lower than one with 60% CA.
Hence, the absorption of PCM should not be the only criterion for developing FSPCM. More indicators should be considered to develop an optimum FSPCM.
This study proposed six indicators, including absorption, thermal conductivity, strength, thermal inertia, latent heat storage, and thermal storage, to select the best porous materials to absorb PCM. American Society for Testing and Materials (ASTM) standards were adopted to measure proposed indicators. A comparative study was conducted to select the best porous materials amongst Silica Aerogel Granules (SAG), Hydrophobic Expanded Perlite (HEP), Nano-clay (NC), Recycled Expanded Glass (REG), and Silica Fume (SF) to absorb CA and develop FSPCM. In this study, the FSPCM-integrated concrete panels were named thermal energy storage panels (TESP). The comparative analysis revealed that SAG-based TESP was meeting all five indicators accept compressive strength (3.66 MPa), which was lower than the
minimum compressive strength (4.14 MPa) criteria for non-structural applications. However, HEP-based TESP had acceptable compressive strength and thermal conductivity with the second-best thermal inertia and heat storage, making it a suitable porous material for absorbing polar PCM for buildings. However, the thermal conductivity of TESPs was still higher than LWC because of the higher thermal conductivity of PCM and concrete, although the TESPs have higher thermal storage. Thus, there is a need to develop a TESP with high latent heat storage, low thermal conductivity, and acceptable mechanical properties.
To reduce the thermal conductivity of TESP, sand was volumetrically replaced with SAG to prepare Heat Resistive and Storage Panels (HRSP) using the proposed particle-density-based approach. The developed SAG-based HRSP had lower thermal conductivity than TESP with similar thermal storage. Although HRSP had higher thermal conductivity than SAG-based LWC, it resulted in higher energy savings (9%), emission (24%), and comfort than SAG-based LWC because of higher thermal inertia and storage. Moreover, the HRSPs had lower embodied energy and carbon than SAG-based LWC. However, the SAG-based HRSP still had higher embodied energy than normal concrete panels. Consequently, the SAG was replaced entirely with REG particles to develop eco-friendly HRSP for buildings. Results revealed that REG based HRSP had 27% lower thermal storage then SAG-based HRSP due to high thermal conductivity and slightly lower latent heat storage. The compressive strength of REG-based HRSP (17.77 MPa) was very close to the minimum compressive strength for the structural application of concrete. Applying REG-based HRSP in a building envelope had slightly higher discomfort hours than SAG-based HRSP, and it also reduced annual energy use and CO2 emission by 8.24% and 20% lower than SAG-based HRSP in a typical Victorian house, respectively.
In conclusion, the REG-based HRSP was the best eco-friendly material for buildings with acceptable structural properties and moderate energy savings potential. However, the SAG based HRSP was the most energy-efficient material with acceptable mechanical and thermal properties of the non-load-bearing structure.
... The most common approach to improve the buildings' thermal performance is installing external insulation on walls, window replacement, and insulation of basement ceilings and the building's roof [16][17][18][19]. Implemented simultaneously, these are by far the most efficient measures [20,21]. ...
In most cases, internal insulation is the only solution to improve the energy efficiency of historic buildings. However, it is one of the most challenging and complex energy efficiency measures due to changes in boundary conditions and hygrothermal behavior of the wall, particularly in cold climates. This study presents the long-term monitoring of the hygrothermal performance of an internally insulated historic stone wall building. The study aimed to assess the hygrothermal behavior of the dolomite wall if mineral wool insulation is applied internally on the north-east wall in the rooms with and without high internal moisture load. The measurements included temperature, relative humidity, water content, and heat flux. Monitoring results are compared with 1D hygrothermal simulations and a building energy consumption simulation. The in situ measurement results and hygrothermal assessment shows energy consumption decreased by 55% with relative humidity under the insulation staying belove 60% for most of the time, with short periods of increase over 80%. Energy consumption simulation shows an energy saving potential of up to 72% in the case of proper energy management.
... They concluded that the optimum insulation thickness for any wall type and orientation varies between 7.1 and 10.1 cm. Similarly, Ozel (2011) studied the thermal performance of expanded and extruded polystyrene insulated building walls constructed of concrete, briquette, brick, block bims and autoclaved aerated concrete (AAC). This study concerned cold, snowy winters, hot and dry summers periods in Anatolia, Ozel and Pihtili (2007) expanded and extruded polystyrene 2 to 8.2 Elazığ, Turkey Özel et al. (2015) glasswool 15 Bilecik, Turkey Özel et al. (2015) rockwool 6.4 Bilecik, Turkey Özel et al. (2015) glasswool 1.2 Bilecik, Turkey Özel et al. (2015) rockwool 0.7 Bilecik, Turkey ...
This paper presents a numerical study combining different passive measures to improve the energy efficiency of a building. These measures include night ventilation and physical design such as building materials, thermal insulation as well as window configuration combined with winter and summer solar shading. The study focuses on a basic classroom prototype that complies with the Algerian buildings. It took the city of Constantine in Algeria as a case study for the warm temperate climate of the Mediterranean regions. The results show that adopting such passive measures reduces the building's energy demand from 67.5 to 15.7 kWh/m² for heating and from 7.7 to 5.7 kWh/m² for cooling. This leads to an annual reduction of 53.8 kWh/m², or an energy saving of 72% per year. Furthermore, CO2 emissions were reduced by 72% passing then from 1772 to 499 kg/year. Thus, a correlative reduction between energy demand and carbon footprint is observed. The economic analysis shows that life cycle costs are influenced by energy prices in different countries and that the profitability of these measures strongly depends on whether these prices are subsidised or not.
... In this context, the beneficial role of insulation thickness was mostly shown to be contradicting. On the one hand, decrement factor variations were shown to rely on insulation thickness, but on the other hand, time lag leanings were slightly affected by the thickness of the insulation [73][74][75]. ...
This study aims to analyse the thermal efficiency of wall elements with varying position-allocation-thickness of insulation, in the aspect of the optical properties of their external paint. A special focus has been placed on the role of solar reflectivity in wall coatings while taking into account the impact of the ambient environment at all cardinal points. In this light, the problem of urban environment warming must be addressed, while considering occupant reliance on air-conditioning. In the initial stage, the key research objective is to shed some light on the performance of analysed wall assemblies in terms of thermal sensitivity (decrement factor and time lag). On the other hand, at the targeting stage, our main intention is to demonstrate the eminence of solar heat-rejecting paints on the cooling power demand of wall arrangements. Furthermore, this work is extended to the assessment of the overall heating and cooling demands on an annual basis. A thermal-network model is developed within this framework to determine temperature variations and heat fluxes in the margins of the examined setups. The potential benefits of the suggested model are two-fold. Accordingly, the findings of the numerical analyses reveal the configurations and operating conditions proving the optimal dynamic thermal parameters and energy demand. Numerical simulations indicate that an optimal cooling power capacity is noticeable for wall surfaces covered with solar heat-rejecting paints; cooling saving can exceed 90% for highly solar-reflective surfaces.
However, when it comes to unveiling the global performability of ultra-white paints the overall improvement of conditions may vary radically; a reflective paint will probably not be sufficient to counterbalance both heating and cooling concerns. In terms of annual heat transmission loads, results exhibit an optimal solar absorptivity of 0.35 for north/east/west facing walls and 0.75 for south-oriented walls. Also, within the confines of our attention, by the increase of insulation level, the energy benefit can reach up to 40% per annum.
... Zhao et al. [20] analyzed ALC wall panels and sandwich wall panels of different densities and thicknesses and demonstrated the superiority of these materials for thermal insulation. Ozel [21] studied the optimal thickness of the thermal insulation layer under different climate conditions in the south of Elaz, Turkey, to evaluate the dynamic heat transfer. The study used ALC boards, polystyrene, and expanded polystyrene as the thermal insulation layer of the wall panel. ...
Due to increasing economic development in recent years, large-scale prefabricated structures have been used for substations. However, the assembly of steel structures suffers from technical problems, such as the mismatch between the fire protection level of the main structure and the enclosure system. This paper proposes an assembled integrated enclosure panel system for covering and fireproofing steel structures, such as beams and columns, consisting of sandwich wall panels and autoclaved lightweight concrete (ALC) wall panels covering the main steel structure. Fire resistance tests were carried out for each part and the entire integrated enclosure panel system to fully investigate its fire resistance performance. ALC and gypsum were selected as the external fire protection materials for the sandwich wall panel test for theoretical analysis and fire resistance test. The fire resistance test results show that the designed solutions of sandwich wall panels and ALC panels covering steel beams and columns meet the fire protection requirements of the ISO-834 standard fire test. The proposed size scheme of the integrated enclosure panel system is an integrated sandwich wall panel composed of 50 mm thick ALC board + 50 mm thick rock wool layer + 50 mm thick ALC board and the integrated structure of 100 mm thick ALC board covering beams and columns. The designed U-shaped connectors between the wall panels are suitable for the assembled integrated enclosure panel system.
... The additional layers of insulation also cause reduced heat gain during sunny seasons, which can impact the need for heating and cooling. In other research, such as Ozel et al. [3] and Axaopoulos et al. [11], this was considered. Since ITO does not consider the need for cooling, this heat gain is less significant, however the results can be considered a worst case on this perspective. ...
Increased insulation reduces the energy needed during operations, but this may be less than the energy required for the extra insulation material. If so, there must be an optimal insulation thickness. This paper describes the development of a tool to determine the optimal insulation thickness, including what parameters are decisive, and presents some results along with a discussion of the success criteria and limitations. To make these considerations manageable for regular practitioners, only the transmission heat loss through walls is calculated. Although the tool is universal, Greenland is used as an example, because of its extreme climatic conditions. The tool includes climate change, 10 locations and 8 insulation materials. It focuses on greenhouse gas emissions, considers oil and district heating as heating sources, and evaluates four different climate change scenarios expressed in terms of heating degree days. The system is sensitive to insulation materials with high CO2 emissions and heating sources with high emission factors. This is also the case where climate change has the highest impact on the insulation thickness. Using the basic criterion, emitting a minimum of CO2-eq, the Insulation Thickness Optimizer (ITO), generally identifies higher insulation thicknesses as optimal than are currently seen in practice and in most building regulations.
... It is estimated that two-thirds of the world's energy consumption will feed air conditioning systems in buildings to provide thermal comfort, and the rest will supply various industrial and commercial activities (Al-Sanea et al. 2012). So, when buildings are isolated, this will be followed by a reduction in the energy consumed in air conditioning systems, which will reduce the amount of oil used for electricity generation and greenhouse gas emissions (Dixon et al. 2010;Ozel 2011). This is what was highlighted in the report of the Fibreglass and Rockwool Insulation Manufacturers Association of Australia (FARIMA 1996), where insulation reduces the heat exchange of the walls by 20-30%, and for the roof by 30-40%, this reduction will result in a decrease in the rate of carbon dioxide emissions into the atmosphere by 3.2 million tons annually. ...
Recently, using rocks, especially limestone, in the facades of buildings has become pervasive due to its characteristics such as hardness, insulation, and aesthetic view. Meanwhile, interest in building insulation materials has been increased to prevent indoor humidity of building walls and provide thermal comfort with less energy usage. As a result, many insulation materials have recently emerged, including the coating material used to isolate the stone facades after being built. This paper aims to evaluate the effect of the silicon coating material on the insulation properties, represented by water absorption and thermal conductivity, on limestone building stones. This material showed positive results in reducing the stone's absorption of water, reducing the absorption up to 53%, where the absorption capacity decreases with increasing the thickness of the coating material on the rock's surface. Correlations between thermal conductivity and rock's porosity, density, and hardness were also presented. The results showed that the effect of the coating material on the thermal conductivity varied according to the hardness of the stones.
... Not only building material for wall that can be used as insulation, even a green wall of plants on the exterior of a building can serve as an additional layer of insulation, lowering the temperature outside the building before it enters [3]. A well-insulated and well-designed home delivers yearround comfort while reducing cooling and heating expenditures, depending on the climate [4]. It follows that greenhouse gas emissions will be reduced as a result. ...
... Similarly, an investigation on insulation materials like foam board and polystyrene was conducted by Ucar and Balo [15] and it was reported that the thickness range of insulation material ranges between 10.6 to 76.4 mm to achieve the best performance. Ozel [16] in his study on the effect of XPS and EPS in building walls, used dynamic thermal analysis and predicted that the optimum thickness of insulation materials falls between 20 to 82 mm. Ekici [17] found that the optimum thickness of the insulation materials like expanded and extruded polystyrene, fiberglass material in different wall assemblies, are in the range of 20 mm to 186 mm. ...
The energy efficiency of a building predominantly depends on the temperature gradient across the wall. The use of Sandwiched Concrete Panels (SCP) to achieve energy efficiency inside buildings is gaining importance all over the world. This study focuses on comparing the temperature gradient across sandwich concrete wall panels made of two different insulation materials viz. Extruded Polystyrene (XPS) and Expanded Polystyrene (EPS) with two different sizes of steel (8 mm and 10 mm dia.) used as reinforcement and shear connectors. Two different concrete grades viz. M25 and M40 were studied. The thickness of concrete wythes on both sides of the SCP and the inner insulation material (XPS and EPS) were varied to understand their effect on thermal insulation. The external surface of the samples was subjected to an elevated temperature of 75 °C for 24 hours continuously and the temperature measurements across the SCP were recorded. This was done by simulating the real-time temperature effect using an indigenously developed oven, designed and fabricated to fit the SCP sample size which comprises an electronic thermostat and temperature sensor unit arrangement. Additionally, a one-dimensional finite element analysis was carried out to predict the theoretical interface temperature and inner surface temperature of the SCP samples with necessary assumptions. Both the experimental and FEA temperature values corroborated well. Further, all the samples were subjected to compression and flexural testing to evaluate their structural properties. Influence of type of insulation material used viz. XPS and EPS, size of steel reinforcement used viz. 8 mm and 10 mm dia. were found to be not that significant in terms of both thermal and structural behavior.
... For each city c and year t, the economic impacts of energy consumption and PV energy generation were analyzed in terms of net present value (NPV * X,c,t ) which allows evaluations according to present purchasing power. The net present values were calculated by multiplying the future costs (FV * X,c,t ) with present worth factor (PWF) (Eq.6) [78][79][80]. The real interest rate (interest rate adjusted for the inflation rate) d was obtained from the inflation rate g and the interest rate i (Eq. ...
This research presents a methodological framework for lifetime energy demand and PV energy generation predictions for a given building considering the CC impacts through multivariate regression models. As a case study, a hypothetical office building in Turkey was selected. An existing linear morphing methodology was utilized to generate future weather files for all 81 cities in Turkey. For each year and city, corresponding weather metrics were calculated, and heating/cooling demand and PV energy generation values were computed through building energy simulations. Obtained data were used to develop two sets of multivariate regression models: (i) models to predict future weather metrics and (ii) models to predict future energy demand and generation. These models allowed lifetime energy demand and generation analysis (including associated GWP and cost) of the building considering CC impacts using only the current weather metrics of its location. For a lifetime of 60 years, considering CC impacts yielded substantially higher cooling (averaging at +0.5 MWh/m² in the warmest region) and lower heating loads (averaging at −0.4 MWh/m² in the coldest region). For Turkey, the carbon intensity and the unit cost of cooling are much higher than those of heating. Therefore, the shift from heating to cooling has significant consequences in lifetime GWP and cost values (averaging +212 kg CO2-eq/m² and +27 $/m², respectively, for the warmest region), emphasizing the importance of the decarbonization of the energy sector. The impact of CC on PV energy generation was limited (all-city average of +0.02 MWh/m² for the building lifetime). Our regression-based approach can be further expanded to include not only various building parameters and types, but also supply-demand matching potentials.
... Le secteur du bâtiment est responsable de plus de 40% de la consommation énergétique mondiale [1]- [3]. Ce secteur est le plus grand consommateur d'énergie en France, représentant 46% de la consommation énergétique en 2016 dont plus de 50% est utilisé pour le chauffage et le refroidissement des locaux. ...
Les mousses minérales constituent une alternative intéressante pour obtenir des produits constructifs allégés et isolants. Cinq tensioactifs (synthétiques et protéiniques) sont sélectionnés pour cette étude. Leur capacité à réduire la tension de surface et à produire des mousses aqueuses stables est évaluée. Une classification des tensioactifs est proposée. Des mousses minérales à base de gypse et de chaux sont alors produites par moussage direct ou par pré-moussage en faisant varier le temps de malaxage, le type de tensioactif, son dosage et le taux de gâchage. Considérer une mousse minérale comme un mélange d’une mousse aqueuse et d’une suspension concentrée permet d’interpréter les pertes de stabilité constatées ainsi que les réponses rhéologiques des mousses à l’état frais. Ces mousses sont caractérisées à l’état durci en distinguant les contributions des porosités associées aux bulles et à la matrice. Les performances thermiques, mécaniques, hygriques et les perméabilités à l’air et à la vapeur d’eau des mousses sont évaluées. Les interactions entre la formulation, les conditions de moussage et les propriétés d’usage des mousses sont discutées. Pour compléter l’analyse, les structures porales des mousses minérales sont confrontées à celles des mousses aqueuses. Les différents résultats obtenus permettent d’identifier les meilleurs compromis de production au regard de performance ciblées.
... However, from P1 to P3 the gain is not as significant. The same trend for optimum insulation thickness has been proven by similar research [40]. This effect comes only from increasing the insulation levels and improving the glazing and airtightness. ...
In the EU, buildings account for about 40% of the final energy consumption. Space heating (SH) accounts for 65% of the energy demand in buildings. There is thus a large potential in energy savings, simply by focusing on the reduction of space heating demand. In the Netherlands, there are about 6 million residential buildings constructed before 2005 where thermal performance is far from optimal. All these buildings need to reduce their demand as the first step to meet nZEB requirements. For large scale energy retrofit of buildings, the main challenge is to classify each housing type by the severity of the demand reduction. A Dutch district in the city of Apeldoorn has been chosen to investigate the energy-saving potential and the robustness of different retrofit packages. Using a bottom-up approach, the energy-saving potential of the existing building types in the mentioned district was analysed by the parametric study of building energy performance simulations in IES VE. Subsequently, the uncertainty in building (energy) performance was assessed using a minimax regret method to compare the robustness of designs. For the covered building types and construction periods, the results suggest that after the upgrade to insulation level from current regulations, implementation of Heat Recovery Ventilation (HRV) reduces the space heating demand by 50-65% while insulation upgrade to passive house standards on yields an average heat demand reduction of only 15%. In contrast, provided with sufficient ventilation, the results suggest that sufficient ventilation eliminates the demand for space cooling in passive building envelopes (excluding climate change effects). In this regard, detached housing is the most and semi-detached is the least prone to the overheated indoor environment. Relying on natural ventilation as the only source of cooling in the summer increases the risk of overheating. Furthermore, upgrading to the nZEB standard building envelope appears to be around 40-50% less economical (€/unit saved energy) than current requirements for building envelope. Lastly, the results show that packages with HRV are about twice as robust as packages without HRV thus highlighting its optimal cost.
... The investigation is carried out on the south-facing wall. Results show that optimum thickness varies 2-8.2 cm, and energy-saving is possible up to 2.78 and $102.16/m 2 ; results are compared with the DD method (Meral, 2011). Ashok and Suman (2013) work on the different Indian weather zone and use automatic guarded hot plate apparatus to calculate the different insulation materials' thermal conductivity and check the building energy performance's thermal performance. ...
... Several studies either theoretical and experimental have been carried out to develop and improve thermal insulation in the building sector [7][8][9][10][11]. ...
The two-dimensional transient heat conduction through a multilayers wall made of different materials and thicknesses was numerically resolved. The equations system resolution was carried out by Alternating direction implicit method (ADI). The outdoor and indoor temperatures and the convective coefficients used as boundary conditions in the developed Fortran program were from the Algerian regulatory technical document. After validation of the Fortran program with literature, it was used to studying the influence of different boundary conditions (bottom and top sides), on the thermal insulation in the building, for many configurations of external walls, usually used in building construction at Batna city (Algeria). Results showed that for the configurations that give bad thermal insulation, the conditions imposed on the top and bottom of the wall have practically no influence on the internal temperature of the multilayers wall, however, the opposite is observed for the configurations that ensure good thermal insulation.
... ificantly from those obtained using transient analysis(Ozel, 2013a). In order to ascertain the energy consumption trends and thermal comfort performance of envelopes incorporating any type of insulation with better accuracy, dynamic thermal analysis encompassing the thermal inertia of the building envelope is necessary(Verbeke and Audenaert, 2018).Ozel (2011Ozel ( , 2013bOzel ( , 2014 explored several aspects of building insulation such as the effects of insulation position within a building envelope, the effects of wall orientation and the economic as well as environmental analyses for different climatic conditions in Turkey under steady periodic conditions using finite difference method. ...
The after-effects of human-induced climate change pose complex engineering challenges to the building sector. There are possibilities for achieving greater sustainability over the life of a building through environment friendly construction materials and practices as well as reduced use of energy intensive space-conditioning technologies. One of the ways of reducing the carbon footprint of buildings is the use of bio-based construction materials with capacity to passively manage the hygrothermal performance of buildings. Straw, an agricultural residue, with potential for utilization as an insulation, is the focus of the current work. Research during the recent years has led to the emergence of straw as a viable construction material. A comprehensive literature review on straw properties and performance of straw-based constructions showed variability in thermal conductivity owing to several factors and a lack of thermal and moisture diffusivity values.
Moreover, studies on straw-based buildings were concentrated in cold or temperate
climates mostly in Europe and a lack of quantitative thermal and energy performance
evaluation for the different climatic zones of India was apparent. In the current research,
the measurements of the thermal transport properties of rice straw bale samples are carried out using transient plane source technique. The ranges of the influencing
parameters considered are temperature from 25 C to 45 C, packing density from around
0 to 90 kg/m3 for dry samples as well as samples conditioned at 40%, 60%, and 80% RH. The experiments are performed for three different orientations with respect to heat flow:
parallel, random, and perpendicular. The effective thermal conductivity values obtained in the case of perpendicular and random orientations are approximately 1.7 times lower
compared to parallel case. A significantly greater increase, as much as 130% and 60%, in thermal conductivity is found in parallel oriented case than perpendicular and random cases with increase in relative humidity and density, respectively. The thermal diffusivity
values also show significant variation only in the parallel case. Correlations are
proposed for both thermal conductivity and thermal diffusivity for all orientations. With the aim of in situ data extraction from a straw envelope and the subsequent thermal characterization of straw, a test room of 10 cm thick raw rice straw envelope was designed and built. The effective thermal and moisture diffusivities of the straw envelope based on the collected temperature and relative humidity data were evaluated. Four commonly used models were selected to predict the outside heat transfer coefficient for the rough surface of the straw envelope. A comparison was made between the surface temperatures from the experiment and the 1-D transient numerical studies employing the model-derived outside heat transfer coefficients and sol-air temperatures. This pointed to the DOE-2 model being the best suited with 92% of the predicted surface temperatures within ±15% of the experiment values. A similar comparison study was employed to verify the ranges of inside heat transfer coefficient. The insulation potential of straw in the context of the wide-ranging climate of India is taken up next. Cooling and heating load analyses over 24 hours of a representative summer and winter day are performed through transient numerical analysis for five climatic zones of India. Three building envelope configurations possible with retrofitting straw insulation (placed on the outside or inside or equally on either side) over existing walls and roof are compared. Four different thicknesses (10, 20, 30, and 40 cm) of the straw insulation are considered for analysis.
Recommendations of envelope configuration with insulation are proposed based on energy and cost savings for the different climatic zones. Overall, the case of insulation split on either side performs the best. Energy savings in the range of 67-96% is achievable with the addition of just 10 cm thick insulation across different climatic zones. Comparison of straw envelope performance against different envelope types found in literature was also carried out. In order to analyse the capabilities of straw insulation in the case of unconditioned ventilated spaces, transient 3-D conjugate simulation is taken up. After validation of the simulation procedure using literature references, recommendations for effective retrofitting of straw insulation are prescribed for the different climatic zones of India in both summer and winter conditions.
The current research work makes a strong case for the application of straw-based insulations in buildings as a viable alternative for synthetic insulations.
... The SWW's heating performance was also compared with that of the two traditional CSGs' double-layer wall composed of an outer insulating layer and an inner heat-storage layer, which has been regarded as a desirable composite structure for the north wall [35,36]. During the experiment period, the minimum nighttime air temperature in the wellinsulated traditional CSG was up to 1.7 • C higher than that in the control compartment of the experimental CSG (January 25th) (Fig. 13), which lacked thermal storage function by the walls. ...
A high thermal capacity north wall is essential for nighttime heating of Chinese solar greenhouses. However, thermal storage ability of the north wall using regular building materials is limited because of their slow heat conduction restricting heat transfer from wall surface to the depth. This study added an active solar water wall constructed of hollow polycarbonate sheets to the north wall, supplemented by an underground water storage tank, to increase nighttime temperature. To evaluate water wall's thermal effect, a field test was conducted, as well as a theoretical verification. Its performance was evaluated in terms of solar heat collection and release capability, nighttime temperature increase and thermal performance in adverse weather. During the 22 coldest days of winter in Beijing, daily averages of collected heat and heat release rate on the basis of floor area were 0.83 MJ m⁻² and 22.6 W m⁻², respectively. Average heat-collecting efficiency reached 85.8%, and 80.4% of the collected heat was released for greenhouse heating. Compared to the scenario without the water wall, minimum nighttime air temperature increased by 3.3 °C on average. In particular, nighttime temperature maintained above 6.9 °C that was 4.1 °C higher than that in the control greenhouse during three consecutive overcast days. Retrofitting the water wall into Chinese solar greenhouses can make warm-season crop production feasible throughout winter by eliminating supplemental heating. Besides, the water wall-based system can be a self-contained solar heating system, also suitable for traditional greenhouses. Thermal analysis and economic evaluation show considerable practical application prospects.
... Ozeal et al. (2011) in their work have investigated the effect of dynamic thermal performance and optimum insulation material for different building materials, i.e. applying concrete, briquette, brick, and autoclaved aerated concrete. This study compared the insulated and uninsulated wall material in energy saving by using the degree-day method [7]. Naouel Daouas et al. (2011) did their study for the Tunisian climate, where both heating and cooling weather exists. ...
... The vast majority of heat is lost from the external building wall due to inadequate insulation thicknesses, thereby leading to energy waste [7]. Therefore, increasing the insulation layer thickness reduces heat losses from the wall significantly, thereby cutting back on expenses required for thermal comfort in buildings [8]. However, the insulation thickness must be neither too high nor too low to use energy virtually [9]. ...
This study determines the optimum insulation layer thickness to be applied to external building walls considering the heating degree-day (HDD) method, then energy saving costs, payback periods, and carbon dioxide (CO2) emissions are calculated accordingly. The optimisation analysis is performed for four different thermal insulation materials (glass wool, rock wool, extruded polystyrene, and expanded polystyrene). Natural gas is chosen as fuel for heating purposes, and horizontal perforated brick is preferred in the wall. One of the original features in this study is environmental analysis to determine the CO 2 emission for the insulated wall in Turkey provinces. Another feature is that it has the most up-to-date data about HDD values and fuel and insulation material costs. The worst and best insulation materials are obtained as rock wool and glass wool, respectively. The optimum insulation layer thickness for the best case is varied between 0.07 m and 0.23 m, depending on the HDD values of provinces. The annual total energy saving cost is in the range of 4.4-53.5 $/(m2year), and the payback period is 0.11-0.38 years. Besides, the reduction in annual CO2 emission is changed between 53.2% and 94% for the best case, compared to the uninsulated wall.
... This is because a significant amount of heat transfers from tunnel surrounding rock to the airflow in deep underground space, which leads to a large cooling load. The cooling load can be decreased through thermal insulation of the building envelopes, leading to a reduced investment and electricity cost of the cooling system for residential buildings [11][12][13]. Intuitively, thermal insulation is applicable to reduce the overall energy consumption of cooling system in underground spaces [14]. Heat transferred from the surrounding rock into underground space may account for more than 75% of total cooling load in deep mines [15]. ...
The provision of mechanical cooling in deep mines comes with a significant energy cost as a significant amount of heat transfers from surrounding rock to the airflow. Thermal insulation can be applied to reduce such heat transfer, thereby cutting down the cooling load. In this study, the impact of thermal insulation on reducing the heat flux through the rock was analytically investigated. The optimal insulation thickness, life cycle saving and the payback period were also evaluated by using the life cycle cost method as the economic benefit is heavily dependent on the insulation thickness. Results show that heat flux between tunnel and airflow can be significantly reduced by the use of thermal insulation, but the reduction varies with the tunnel and insulation conditions. The total cost associated with using the thermal insulation firstly decreases and then increases when the insulation thickness increases, implying an optimal insulation thickness. Nonetheless, both the optimal insulation thickness and maximum life cycle saving can be increased by a rising rock temperature, eventually leading to a reduced payback period.
... The investigation is carried out on the south-facing wall. Results show that optimum thickness varies 2-8.2 cm, and energy-saving is possible up to 2.78 and $102.16/m 2 ; results are compared with the DD method (Meral, 2011). Ashok and Suman (2013) work on the different Indian weather zone and use automatic guarded hot plate apparatus to calculate the different insulation materials' thermal conductivity and check the building energy performance's thermal performance. ...
... Thus, it is emphasized the importance of heat insulation on reducing environmental impact of building energy consumption. Ozel [16] has presented a series of experimental data for varieties of insulation materials which has been tested under fixed conditions to determine the optimum thickness, saving amount and payback duration. Barrau et al. [17] have researched what kind of criteria should be considered for the determination of the thickness of heat insulation. ...
This work presents an experimental study to investigate the heat conduction coefficient of the density-layered stone wool plates insulation materials used in heat insulation applications. The stone wools, which have 70, 100, and 150 kg/m³ of densities, have been combined in different thicknesses to 60 mm. The aim of this layer combination is to benefit from lower heat conductivity and lightness of the lower density stone wools and the better strength of higher density stone wools. First, the single-layer stone wools with 60 mm of thickness, which is in the insulation market, have been tested. Then, they have been combined in different thicknesses, with a total thickness of 60 mm. A total of 18 samples have been produced, and the thermal conductivity of samples has been measured experimentally. Consequently, the heat conduction coefficient of density-layered stone wools and their weights have been compared experimentally. At the end of the present study, it is observed that density-layered stone wool plates play a critical role in improving the heat conductivity and lowering the weight of high-density plates. When combining 10 mm thick 150 kg/m³ density stone wool with 50 mm thick 70 kg/m³ density stone wool, the heat conductivity has been improved by 3.52% and the weight of the 1 m2 plate has reduced by 4 kg (44%) according to the stone wool with 150 kg/m³ of density.
... In addition, the building façade should behave as an energy-efficient passive or active mechanical system. For instance, the wall material, the thermal insulation type, and its thickness have a significant impact on minimizing the heats transfer, therefore, enhancing thermal comfort [8,9]. Furthermore, the window to wall ratio is an important factor to balance the heat flow and natural light by choosing the appropriate size, orientation, glazing, and shading type. ...
As it is clear, worldwide buildings are the largest consumer of the final energy consumption. In Algeria, it has been reported that 33% of the overall energy consumption was attributed to buildings. This is due to the design and constructional techniques of the residential buildings, which do not address the local climatic condition. To assess this situation, the study is focused on analyzing the existing residential buildings in Algeria, in terms of energy, thermal, daylight, and indoor air quality performance, using a dynamic simulation software. Typical building design in a hot and dry climate was selected. The results revealed that the existing residential buildings do not comply with the energy-efficient design standards. It was concluded that further strategies should be applied in this sector, in terms of building design, materials, and façade configuration.
... The optimum insulation thickness corresponds to the value that provides a minimum total life cycle cost. Most of the studies predict heating and cooling loads on buildings using either degree-day or degree-hour concepts [134,[146][147][148], or dynamic transient methods are used based on numerical and analytical methods [149][150][151][152][153]. Properties that mainly affect the thickness of aerogel are the ambient temperature, length of the heating period, total working period of the heating system, and the properties of insulation material [154]. ...
With the increase in global warming, the demand for more sustainable and thermal insulating cement-based lightweight composite increases. From the past few decades, researchers worldwide have carried out extensive research on lightweight concrete using various lightweight aggregates. The use of aerogel as an aggregate in lightweight concrete is the most promising building application these days. With the exceptional characteristics of thermal insulation, ultra-low density, high adsorption, high surface area, aerogel shows a remarkable behavior. Although, the poor mechanical characteristics and high cost of aerogel have negative effects on the aerogel-incorporated concrete. This article is aimed to present a complete in-depth review of aerogel incorporated cementitious materials in terms of production/synthetisation, fresh rheology and proportioning, mechanical, microstructural, and durability properties, including water absorption, capillary water absorption, fire resistance, and exposure to elevated temperature, thermal insulation properties, and economic perspectives of aerogel. Particular emphasis has been given to study the hygrothermal behavior of aerogel-based cement composites. In addition, the present investigation gives a summary of case studies that have been performed for aerogel-based cementitious products used in buildings. The study suggests the promising future of aerogel as lightweight thermal insulating composites with sufficient mechanical properties.
... Ozel. M. [6] calculated the heating load and cooling load yearly after the application of different thickness of insulation. Mahlia and Izbal [7] had determined the cost saving and emission reduction by the application of insulation at optimum thickness. ...
Energy saving refers to method used to reduce energy consumption. By using proper insulation material and efficient utilisation of energy resources, energy saving can be achieved. A considerable amount of energy may be obtained by minimizing the loss of heat across the outer surface of building walls. The finding of this study is energy saving is maximum at optimal insulation thickness. The heat loss is mainly depending upon the thickness of walls and thermal conductivity of insulation for building construction. In building wall, the thickness of insulation material has important role in saving of energy. Due to lower thermal conductivity and higher thermal mass of mud wall, it is better to constructed mud house as compared to brick construction according to energy saving point of view. During the analysis of energy saving, dimension of demonstrative room is considered as 6 m x 5 m x 3 m. The result shows that 576 kWh of energy in year 2019 has been saved when slurry of mud dung insulation is considered for mud wall construction.
... Generally, materials with a thermal conductivity of less than 0.04 W/mK would have a good performance on thermal insulation. [13][14][15] Although thermal conductivity indicates the degree of ease at which heat can be transmitted (i.e., the energy transmitted with a given time, cross section area, and temperature gradient), it does not consider the geometry (or thickness) of the media being transmitted. Therefore, the thermal impedance Z-value is adopted in this study, which accounts for the thickness of the media (or insulation materials) and is defined as follows: ...
To clarify the influence of boundary insulation on the development of frozen soils, seven artificial ground freezing (AGF) models of Ottawa sand were performed with different thermal impedance Z-values of the boundary insulation system. Results of testing show that the greater
the Z-values, the larger the frozen soil areas for a given time of freezing. When the Z-value is more than 2.27 m2 K/W, however, the extent of frozen soils appears to be stabilized for the AGF model with dimensions of 100 cm (L) by 100 cm (W) by 15 cm (H). Two-dimensional finite element analyses were also conducted to verify the performance of boundary insulation systems of the physical model. Numerical simulations show the development of frozen soils is significantly affected by the ambient temperature if no insulation is covered on the boundary of the AGF model, and the growth of frozen soils would cease at a freezing time of less than 6 h. However, when the Z-value of the boundary insulation system is more than 2.27 m2 K/W, the pattern of the temperature field and the size of frozen soils in the model resemble those for a system with a perfectly insulated boundary with an elapsed time of freezing up to 24 h. Hence, it can be concluded that the thermal impedance Z-value should be at least 2.27 m2 K/W for the boundary insulation system of the current AGF model to be free from the influence of an ambient environment and have a similar temperature response as the perfectly insulated model for a test time up to 24 h.
... Energy saving and economical payback periods are determined for five different fuels and four different insulation materials. Ozel [8] calculated OIT for five different structure materials and two different insulation materials in the Elazig province example. According to the results, it was seen that OIT vary between 0.02m and 0.082m, and payback period vary between 1.32 and 10.33 years. ...
... One of the main issues of energy saving involves heat protection of external building partitions [5]. The most frequently undertaken action to reduce energy consumption is to increase the thermal resistance of external partitions-improving the insulation of partitions by increasing the thickness of the thermal insulation [6]. In this way, attempts to minimize heat loss in rooms are more and more effectively separated from external weather conditions, which can often lead to the deterioration of the microclimate inside the building. ...
Contemporary solar power engineering enables the conceptual interlocking of the shape of a building object with its location, structural design, and external envelope, as well as applied materials. Suitably selected solutions involving the structure, shape, construction, and location of a building can significantly improve the thermal balance of rooms in a building. Particularly valuable and warranted are studies involving various solutions for building partitions contributing to a considerable improvement in the thermal balance of a building. This article presents the results of research on temperature changes on the surface of the external part of a partition coated with layers of different colors. For the lightest coating (white), both the average temperature obtained on the and the maximum temperature obtained on the surface were the lowest. With the darker coatings, these temperatures were both higher. The back analyses that were performed indicated lower and higher absorption coefficients, respectively, for the coating compared with the base value for the red coating. Additionally, it was demonstrated that the average surface roughness (Ra) after tests in a natural environment decreased by 12.1% for the base (red) coating. For the grey and white samples, a more than two-fold increase in roughness was reported, of 198.6% and 202.0%, respectively. The SEM analysis indicated material loss and discoloration on the sample surfaces.
... A few articles consider economically optimum insulation thickness of building construction affected by extreme climatic conditions of Asian regions [16][17][18][19]. ...
In this article, two types of mathematical models for thermal protection level analysis were developed: the economic and energy ones. Both of which allow to calculate the relevant thickness of the selected insulation material under any climatic and economic conditions with any constant layers of building envelope taken from structural considerations. The factors influencing the models were also evaluated. The main factors on which the economic model depends are the costs of energy and insulation material in the region, the region degree-days, the discount rate and the billing period. The key factors to influence the energy model are the region degree-days and the energy consumption rate for the production, transportation and installation of the insulation material. Comparing the two models developed, the following conclusion can be made: The economic model is practically easier to use, as all of the necessary information could be found in the standards, and in the manufacturer catalogs, it allows to get a more precise and accurate result, while the energy approach requires the data, which sometimes has no public access. But, energy model provides us with a more objective assessment when comparing the level of building thermal protection in different countries.
... Calculations in this study was performed by considering exterior walls only; solar radiation values were ignored. Heat loss arising from the unit surface of the exterior wall is shown by using 3 numbered equation [15]. ...
One of the most effective techniques that is used for energy wastage in buildings is heat insulation. It is possible due to this application to minimize the fuel quantity and accordingly tolerate toxic emissions by finding the optimum point that gives the maximum efficiency. This study was conducted for Jaipur province in Indian climate geography. Climatic characteristics of the region are Mid-Latitude Steppe and Desert Climate (Bsh). Energy need and heat losses in exterior wall were determined by accepting cooling degree day value as T > 24°C. Optimum insulation thickness, payback period, annual return and annual return rate for XPS and EPS of two different insulating materials respectively are 0.0383-0.0731, 2.35-1.79, 10.95-12.92, 46.84-37.25.
Advanced building materials have significant contribution for developing better construction and retrofitting of present buildings, and this can be possible by understanding the various building performance parameters through proper planning and design. However, today’s unpredicted climatic variation has a major role for the selection of building materials for construction of house and buildings all over the world. Keeping these on mind, the current investigation is focused on the influence of climatic condition on the existing and advanced buildings materials. The climatic zone of Kolkata as a major city from eastern zone of Indian subcontinent is selected. The overall year’s performance on different building materials, considering these materials for wall as well as roof of a building. The objectives will focus on the influence of the conventional materials, advanced alternative building materials and bio-based insulating materials. This will be helpful in developing thermal comfort building and an energy-efficient occupation. Apart from these, the role of overall heat transfer coefficient will definitely be helpful for the designers to develop a building. The effect of various wall and roof configurations on thermal load is studied according to all-weather conditions. The investigation exhibited that addition of bio-based insulation increased the time lag value up to 10.97 h and thermal transmittance value around 0.665 W/m2 K.KeywordsBuilding materialsClimate comfortWeather conditionsBio-based insulating materials
The utilization of solar energy to maintain a stable and comfortable air temperature in the built environment has opened up many opportunities for energy saving. However, the periodical nature of the sunlight intensity introduced extra difficulty in the utilization of solar energy. In this paper, a novel concept of jointly using a thermal diode bridge (TDB) and phase change materials (PCMs) was proposed to continuously control the air temperature in built environments during the heating seasons. During the daytime, the solar energy was efficiently harvested and stored in the PCMs, so the indoor temperature was significantly reduced; at nighttime, the thermal energy stored in the PCMs could be used for space heating without heat loss to the outdoor through heat convection. Because of the existence of the TDB, the heat flux going through the building envelope could be passively controlled. An analytical study to evaluate the operating performance of applying such TDB to controlling the zone air temperature in a built environment was carried out and the results were presented. It was demonstrated that the zone air temperature variation in the built environment was significantly reduced, without any electrical energy consumption and greenhouse gas emission.
Today, thermal insulation is generally required to be used in building envelopes by building energy standards worldwide. It is also well-known that thermal insulation provides space conditioning energy savings and improvement of the internal thermal comfort. However, the impact of the placement of thermal insulation within the building envelope and insulation interaction with thermally massive components are not commonly understood. Static and dynamic thermal processes in buildings and building components, together with associated heat transfer, thermal mass effects, and thermal storage play an important role in overall building energy efficiency, utilization of renewable energy sources, and energy demand management. Building enclosures, which include both fenestration and the opaque portions of the envelope, effectively control the influence of the outdoor climate on the interior environment, reducing the heating, cooling, and lighting requirements to maintain the desired indoor conditions. The above factors directly affect the corresponding energy usage and its dynamics. Among all of the internal fabric and external enclosure of buildings, external walls are often one of the most dynamic components since they are exposed to intense solar radiation and temperature fluctuations that are subject to seasonal climatic conditions. Following the currently rising interests in demand-side management, building energy dynamics, and the thermal response characteristics of building components, the impact of the insulation placement and resulting wall material configuration on the dynamic thermal performance is theoretically and numerically analyzed in this chapter for typical wall material configurations. It is demonstrated that due to different arrangements of thermal insulation and structure-related, thermally massive layers, walls constructed of similar materials can present a wide range of dynamic thermal characteristics.
Energy Efficiency Measurement by utilizing SMART windows on building facades
Bioclimatic design strategies are an efficient architectural approach to improve thermal comfort, save energy, and reduce buildings’ carbon footprint. In this study, the effect of five bioclimatic design strategies on energy demands of an office building, considering window-to-wall ratio, solar heat gain coefficient, sun shading with overhangs, thermal insulation and natural ventilation, is investigated along with their associated economic and environmental benefits in the Mediterranean region using EnergyPlus software. For this purpose, six locations were identified to represent different climate’s types. The results revealed that the highest energy savings shares were achieved by incorporating thermal insulation and natural ventilation designs in the hot desert climate with 90.69% and 20.21%, respectively. Furthermore, sun shading and small glazing area with low solar heat gain coefficients are recommended for hot climates and vice versa for cold ones. Moreover, the investigated designs exhibited high economic benefits, which translated by lower life cycle costs and payback periods, and higher savings-to-investment ratios, especially thermal insulation and natural ventilation designs. Additionally, significant CO2 emissions are avoided using these designs. The findings of this work could serve as a guideline for building stakeholders to choose the appropriate designs according to the building climatic conditions.
In this study, lightweight concretes were produced using the expanded glass and natural sand in different proportions (expanded glass ratio: 5%, 10%, 15%, 20%). The same mortar mixtures were re-prepared by adding the fluidizer. Lightweight aggregate concretes produced in the volume of 100 mm × 100 mm × 100 mm were investigated in terms of compressive strengths, elasticity modulus, thermal conductivity, water absorption rates, and unit weights. The density of concrete samples containing expanded glass was 1.5–2.2 g/cm3, water absorption rates were 4–16.69%, heat conduction coefficient was 1–0.063 W/m K, the 28-day compressive strengths varied between 18.3 and 68.8 MPa. As the expanded glass rate increased, the density of concrete samples, the water absorption rate, heat conduction coefficient, and compressive strengths decreased. This reduction was caused by the fact that the expanded glass had a low density (0.17–0.23 g/cm3), a low water absorption rate (23%), and a low heat conduction coefficient (0.0639 W/m K). In the article, the elasticity module of the concrete was investigated using UPV method. The dynamic elasticity module of the concrete samples containing expanded glass was 6–40.23 GPa. The dynamic elasticity module of sand containing concrete samples was higher.
With increasing global warming, the skiing season is shortened to different degrees all over the world. As a crucial way to ensure the sustainable development of the ski industry, snow storage has been gradually studied and applied in Europe. Covering thermal insulation materials is a key engineering measure for the success of snow storage. This study used numerical methods rather than an experimental method to evaluate the thermal insulation performance of nine snow storage coverage schemes in Harbin, Beijing, and Altay, China. We investigated the thermal insulation performance of nine snow storage coverage schemes (three natural materials and six artificial ones) using a solar radiation method and an implicit finite difference method. Sensitivity analyses were conducted, and the cost performance of schemes 5‒9 were analyzed. Based on the cost and thermal insulation performance, we used schemes 4 (geotextile, straw bale), 5 (geotextile, extruded polystyrene foam), and 7 (geotextile, polyurethane foam) to evaluate the snow storage effects in Harbin, Beijing, and Altay. Results showed that among schemes 1‒9, scheme 7 has the best thermal insulation performance. If natural materials are used, then scheme 4 gives the best thermal insulation performance. Among schemes 5‒9, scheme 5 is the most economical. The heat transfer in Beijing is higher than that in Harbin and Altay, while the latter two show similar heat transfers. The combination of meteorological conditions and coverage schemes influence the melting rate of snowpacks. The melting rate of snowpacks can be reduced with an optimized coverage scheme. The proposed methods can serve the selection of coverage schemes for snow storage.
This study focus on foaming properties of three surfactants: α-olefin sulphonate sodium salt (Hostapur OSB), Trimethyl tetradecyl ammonium bromide (Cetrimide) and Hexadecyl trimethyl ammonium bromide (CTAB) usable for mineral foaming. The ability of these surfactants to reduce surface tension is evaluated. Foamability and foam stability of aqueous foams made up with these surfactants are assessed at different concentrations, using the Dynamic Foam Analyzer providing parameters which describe the foaming and decay phases. They considerably depend on the type of surfactant and its concentration. By analysing the bubble size distribution, the relationship between the stability and the foam structure can be observed. The Hostapur OSB appears to be the most efficient surfactant in terms of stability and foamability, representing the thinnest foam structure and the highest characteristic times (deviation, transition and half-life) at CMC (critical micelle concentration).
Due to the high share of energy consumption in the building sector as well as accurate calculation of heating and cooling loads of a building, one of
the most studied methods to reduce heat energy consumption is building insulation. In this study, the aim is to investigate the effect of optimizing the
insulation thickness on the emission of carbon dioxide gas in different climatic conditions. First, a model building in different climatic conditions is
modeled using Design Builder software and then to optimize the genetic algorithm optimization with MATLAB software. Finally, using the obtained
results, environmental analysis (CO2) and comparison of the optimal thickness of building insulation for a period of ten years have been discussed.
The results showed that the total emission of carbon dioxide gas over a period of ten years in climatic regions of cold and dry (Tabriz) and hot and
humid (Bandar Abbas) is the lowest (equal to 350 𝒌𝒈/𝒎𝟐) and the highest (equal to 770 𝒌𝒈/𝒎𝟐) respectively
The amount of energy needed for HVAC (Heating, Ventilation and Air Conditioning) systems in the building depends on a variety of factors, and one of the most important is the conduction load through the building envelope. Due to its higher strength and large cavities, concrete hollow blocks have become more common in several countries. The thermal conductivity, thermal resistance and thermal transmittance (U value) of various complex hollow brick geometries are reviewed on the basis of modelling and simulation studies. Various techniques for improving thermal properties (K, R and U values) of hollow brick are addressed in order to increase building energy efficiency. Large hollow brick cavities provide higher transmittance values, which indirectly improve the overall heat transfer, radiation and insulation efficiency.
India is a developing country and thus has to cater to high energy demands in both rural and urban areas. Buildings and construction together account for 36% of global final energy use and 39% of energy-related carbon dioxide (CO2) emissions when upstream power generation is included. In India, the building sector consumes around 30% of the total energy. This research work is divided into two parts. The first one is the comparative evaluation of insulation materials for optimization of energy, and the other one is direct encapsulation of PCM material into the wall. The selection of building insulation materials such as EPS, XPS, PUF, GW and RW etc is based on market availability and suitability to weather conditions at building location. The Indian weather conditions have been classified into 6 different categories as per ISHRAE namely hot and dry, warm and humid, moderate, cold and cloudy, cold and sunny, and composite and similarly classified as Very Hot–Humid (1A), Dry (1B) as per ASHRAE 90.1 2007. Five locations of India with different climatic conditions have been chosen covering all Indian climatic zones which are Delhi (composite), Mumbai (Warm & Humid), Ahmedabad (Hot & Dry), Bangalore (Composite), and Srinagar (Cold). Selected types of insulation materials have been tested for thermal load performance of the building envelope in each of the above weather conditions including life cycle cost (LCC) analysis for 20 year period, carried out to select the best alternative amongst the selected insulation materials for each of the weather conditions. The parameters for the selection of insulation material are based not only on saving energy but also on protecting the environment from harmful gases. In Delhi state, The best suitable insulation material is RW since its payback is 1.08 years with maximum energy saving of 17.82%. In the case of Ahmedabad, GW gives maximum energy saving with optimum thickness, but the payback period is much lesser for Rock Wool viz.,1.06 years. In the case of Bangalore, the suitable material is RW with the payback period of 1.84 years. For Mumbai city, RW is the optimum material with a payback period of 2.02 years.
This work focuses on the experimental study of a standard dwelling and a high energy performance dwelling, located in the city of Djelfa in Algeria whose climate is semi-arid, in order to study their thermal performance for 12 months. The high energy performance dwelling was built as part of the pilot project of 600 dwellings in 11 locations spread all over the different climatic zones in Algeria and the first to be finalised compared to the other locations. According to measurements, the temperature and the relative humidity were maintained in the thermal comfort range with the use of electricity for air-conditioning and the natural gas for heating. The results indicate that the reduction of heating demand is 57% and of air-conditioning is 51% by using the passives energy efficiency techniques in the buildings. In order to improve the economic profitability of the thermal insulation, new correlations were used for the payback period and financial profits realised that can be achieved in countries that subsidise energy. It was found that depending on the assumed correlation on the energy used, the investment in thermal insulation and double glazed window can be profitable from a payback period of 4 years or less.
Highlights
• Monitoring done on two dwellings in semi-arid climate region.
• Comparison between a standard dwelling and high energy performance dwelling.
• Experimental determination of hygrothermal and energy consumption during twelve months.
• Use of new correlations to estimate the payback period for different scenarios and different energies.
• Estimation of realised profits by the reduction of energy consumption during building life cycle.
zet Bu çalışmada binalarda ısı yalıtımı hakkında ayrıntılı bir literatür taraması verilmiştir. Binalarda kullanılan ısı yalıtım malzemeleri, uygulama yöntemleri tanıtılmıştır. Isı yalıtım hesaplamalarında kullanılan "Derece-Gün", "Termoekonomik Optimizasyon" ve "TS 825 Standardı" metotları hakkında karşılaştırmalı bilgiler verilmiştir. Çalışmada Türkiye'nin farklı coğrafi konumlarında, binalarda ısı yalıtımını ve bina duvarlarında değişen koşullara göre EPS, XPS, taş yünü, cam yünü vb. yalıtım malzemelerinden hangilerinin kullanılacağını, kullanılacak malzemenin optimum kalınlık ve geri ödeme sürelerini inceleyen çalışmalar derlenerek tablolar halinde sunulmuştur. Abstract In this study, a detailed literature review about thermal insulation in buildings is given. Thermal insulation materials used in buildings and their application methods are introduced. Comparative information has been compiled on the "Degree-Day", "Thermoeconomic Optimization" and "TS 825 Standard" methods those are used in thermal insulation calculations. In the paper, the studies examining, which insulation materials to use (EPS, XPS, rock wool, glass wool etc.) in buildings envelop, depending on the changing conditions are compiled and presented in tables. The literature review was performed for different geographic locations of Turkey.
In Tunisia, the energy consumption in the building sector is rapidly increasing. Recently, very high electric
energy consumption, used for air-conditioning loads, is reached during summer days. Insulation of
building walls is recently applied with an insulation layer thickness typically ranging between 4 cm
and 5 cm, regardless of the climatic conditions, type and cost of insulation material and other economic
parameters. In the present study, an optimum insulation thickness is determined under steady periodic
conditions. An analytical method, based on Complex Finite Fourier Transform (CFFT), is extended to rigorously
estimate the yearly cooling transmission loads for two types of insulation materials and two typical
wall structures. Estimated loads are used as inputs to a life-cycle cost analysis in order to determine
the optimum thickness of the insulation layer. Results show that, the most profitable case is the stone/
brick sandwich wall and expanded polystyrene for insulation, with an optimum thickness of 5.7 cm. In
this case, energy savings up to 58% are achieved with a payback period of 3.11 years. The thermal performance
of the walls under optimal conditions is also investigated. Then, comparison of the present study
with the degree-days method is performed for different values of indoor design temperature.
In Tunisian climate, both heating in winter and cooling in summer are required to reach comfort levels. Due to the significant increase in building energy consumption, insulation of external walls is recently applied with a thickness typically ranging between 4 cm and 5 cm regardless of structure and orientation of walls and of economic parameters. In the present study, optimum insulation thickness, energy saving and payback period are calculated for a typical wall structure based on both cooling and heating loads. Yearly transmission loads are rigorously estimated using an analytical method based on Complex Finite Fourier Transform (CFFT). Considering different wall orientations, the west and east facing walls are the least favourite in the cooling season, whereas the north-facing wall is the least favourite in the heating season. A life-cycle cost analysis over a building lifetime of 30 years shows that the south orientation is the most economical with an optimum insulation thickness of 10.1 cm, 71.33% of energy savings and a payback period of 3.29 years. It is noted that wall orientation has a small effect on optimum insulation thickness, but a more significant effect on energy savings which reach a maximum value of 23.78 TND/m2 in the case of east facing wall. A sensitivity analysis shows that economic parameters, such as insulation cost, energy cost, inflation and discount rates and building lifetime, have a noticeable effect on optimum insulation and energy savings. Comparison of the present study with the degree-days model is also performed.
The external walls and roof of a building are the interface between its interior and the outdoor environment. Insulation of the external walls and roof is the most cost-effective way of controlling the outside elements to make homes more comfortable. Although insulation is generally accepted as a factor increasing the building costs, with the calculations we have shown that this is not the case. Fuel consumption and operational costs are reduced by increasing the thickness of the external walls and roof (ceiling), despite an increase in the investment costs. According to Turkish Standard Number 825 (TS 825), there are four different degree-day (DD) regions, and the required heat loads for the buildings in these regions exhibit large differences. Therefore, a method based on costs is needed for the determination of optimum insulation thicknesses of different DD regions. In this study, optimum insulation thicknesses for different DD regions of Turkey, namely, Izmir (DD: 1450), Bursa (DD: 2203), Eskişehir (DD: 3215) and Erzurum (DD: 4856), have been determined for a lifetime of N years, maximizing the present worth value of annual energy savings for insulated external walls.
The optimum thickness of insulation applying on external walls of building was investigated under dynamic thermal conditions. Therefore, the yearly heating transmission load was calculated by using an implicit finite differences method under steady periodic conditions. Calculations were done by considering external environment conditions of Elaziǧ city. Extruded polystyrene was used as the insulation material, and coal, fuel-oil and natural gas were used as fuel. Then, cost analysis was done for a south facing wall insulated on outside. The optimum insulation thicknesses, the energy savings and payback periods were calculated for every fuel type. As result, optimum insulation thickness for Elaziǧ was obtained to be 0.040 m when natural gas was used.
The optimum thickness of insulation layers in cavity walls in buildings is determined under steady periodic conditions using the climatic data of Riyadh, Saudi Arabia. Different insulation materials are investigated at different locations in the cavity for a west-facing wall. The yearly cooling and heating transmission loads are calculated by an implicit finite-volume procedure that has been previously validated. These loads are used in an economic model based on the present worth analysis in order to minimize the total cost. Air spaces and insulation layers with different surface conditions and thickness are investigated and compared with the limiting cases with no air space or with no insulation. The results show that the most economical cavity configuration depends on the insulation material used. Under the conditions of the present study, polyurethane board and rock wool are found to be more cost effective when used alongside air spaces, while polystyrene is most cost effective when used with no air space. Among all configurations and insulation materials considered, a 9-cm-thick molded polystyrene layer with no air space is found to be the most economical. Thermal characteristics in the form of yearly transmission loads, and yearly averaged-dynamic R-value, time lag and decrement factor are presented versus insulation thickness.
The optimum thickness of an insulation layer in a typical building wall is determined under steady periodic conditions using the climatic data of Riyadh. A finite-volume implicit procedure, which has been previously validated, is used to compute the yearly heat transmission loads for various insulation thicknesses. These loads are input to an economic model, based on the present worth method, in order to minimise the total cost of insulation and energy consumption over the lifetime of the building. Cooling and heating loads are integrated separately over the year and treated with different costs in the economic analysis. The wall yearly transmission loads, yearly-averaged dynamic R-value, time lag and decrement factor are presented versus insulation thickness and compared for different wall orientations. A parametric study is performed to establish the sensitivity of the results to changes in economic parameters. The optimum insulation thickness is found to increase with the cost of electricity, building lifetime and inflation rate; and decrease with increasing cost of insulation material, coefficient of performance of air-conditioning equipment and discount rate. The results also show that the wall orientation has a significant effect on the thermal behaviour but a relatively smaller effect on the total cost and consequently the optimum insulation thickness. The south-facing wall is the most favourite orientation since it gives about 12% lower yearly transmission load and 5% lower total cost compared to the least favourite orientation which is the west-facing wall. Among the insulation materials investigated, molded polystyrene is found to be the most economical type with an optimum thickness of 9.3 cm.
Heating the houses in cold climates requires large quantities of heat energy to be spent. The building sector consumes more energy in the form of heat than other sectors. Therefore, considerable energy savings can be obtained by using natural rocks with low thermal conductivity in insulating the buildings. In this study, the amount of energy conserved by using porous tuff stone in external walls of buildings is calculated. It was shown that considerable energy savings can be achieved by using tuff stone for facing buildings in cold climate zones such as Isparta region. The cost of installing tuff stone panels for facing buildings will be paid back in four years by savings in heat energy.
In this study, the maximum load levelling of periodic heat flux entering a room through a composite roof consisting of different insulation layer has been evaluated for different insulation positions in the roof. A numerical model based on implicit finite difference scheme was applied for 12 different roof configurations during typical winter and summer days. For this purpose, total insulation thickness was kept constant and insulation was placed as equally two pieces and as equally three pieces in different locations within the roof thickness. Then, insulation layers were moved 1cm at a time across the roof thickness for 12 different configurations. Maximum and minimum values of periodic heat fluxes for each sweeping process in the roof were calculated for achieving the maximum levelling of the heat flux entering through the roof. It was found that the best load levelling was achieved in the case where three pieces insulation of equal thickness were placed one at the outdoor surface of the roof, the second piece of insulation was placed in the middle of the roof and third piece of insulation was placed at the indoor surface of the roof.
In this study, to determine optimum location and distribution of insulation in a wall, an analysis was made of 12 different wall configurations with different configurations of insulation layers. The investigation was carried out by using an implicit finite difference method for multilayer walls during typical summer and winter days in Elazığ, Turkey. For this purpose, the location of insulation layers was varied across the wall thickness for each configuration while the masonry thickness and the total insulation thickness were held constant. The optimum location of insulation for the configurations analysed was obtained from consideration of time lag and decrement factor for various wall orientations in both summer and winter conditions. Results showed that the best thermal performance was obtained in the case that one of three equal pieces insulation layers was placed in the outdoor surface of wall, the second piece of insulation was placed in the middle of wall and third piece of insulation was placed in the indoor surface of wall. Furthermore, it was found that equal thicknesses of insulation layers placed in the indoor and outdoor surface of wall was better than different thicknesses from the point of view of maximum time lag and minimum decrement factor.
The book focuses on solar radiation characteristics, solar radiation
available for practical applications, heat transfer, radiation
characteristics of opaque materials, theory of flat-plate collectors,
and concentrating collectors. Also discussed are solar process
economics, solar water heating, solar heating system design, solar
cooling, conversion to mechanical energy, evaporative processes, and
selfgradient ponds.
A comprehensive economic analysis has been performed to inter-relate the optimum thickness of insulation materials for various wall orientations. The yearly cooling and heating transmission loads of building walls were determined by use of implicit finite-difference method with regarding steady periodic conditions under the climatic conditions of ElazIg, Turkey. The economic model including the cost of insulation material and the present value of energy consumption cost over lifetime of 10Â years of the building was used to find out the optimum insulation thickness, energy savings and payback periods for all wall orientations. Considered insulation materials in the analysis were extruded polystyrene and polyurethane. As a result, the optimum insulation thickness of extruded polystyrene was found to be 5.5Â cm for south oriented wall and 6Â cm for north, east and west oriented walls. Additionally, the lowest value of the optimum insulation thickness and energy savings were obtained for the south oriented wall while payback period was almost same for all orientations.
The aim of this study is to find time lag (TL), decrement factor (DF) and total equivalent temperature difference (TETD) values for multilayer walls and flat roofs of buildings using experimental and theoretical methods, and to compare the experimental results with theoretical ones. The TETD is a method for calculating cooling load due to heat gain from the walls or flat roofs, and it can be obtained using values of inside and outside air temperatures, solar radiation, TL and DF. The TL and DF depend on the highest and the lowest temperatures at the inner and outer surfaces of the walls or flat roofs, and the time periods involved in reaching these temperatures. Hence, two testing rooms each consisting of four multilayered walls and a flat roof, air conditioner, measuring elements are built to measure all required temperatures. The required temperatures, which are hourly inside and outside air temperatures, and surface temperatures of each structure layer, are measured in every minute during testing periods of the 2007 summer season of Gaziantep, Turkey. Hourly solar radiation values on the walls are computed using hourly measured solar radiation on a horizontal surface. The TL, DF and TETD values of eight different walls and two different flat roofs commonly used in Turkey are computed utilizing the measured temperature and solar radiation values. The computed values for the TL, DF and TETD are compared with theoretical results obtained numerically using periodic solution of one dimensional transient heat transfer problem for the same structures.
The employ of thermal insulation is one of the most effective ways of building energy conservation for cooling and heating. Therefore, the selection of a proper insulation material and the determination of optimum insulation thickness are particularly vital. Four typical cities of Shanghai, Changsha, Shaoguan and Chengdu are selected to represent A, B, C and D subzone of hot summer and cold winter zone in China, respectively. The optimum thicknesses of five insulation materials including expanded polystyrene, extruded polystyrene, foamed polyurethane, perlite and foamed polyvinyl chloride are calculated with a typical residential wall using solar-air cooling and heating degree-days analysis and P1-P2 economic model. And then, life cycle total costs, life cycle savings and payback periods are calculated based on life cycle cost analysis. Considering different orientations, surface colors, insulation materials and climates, optimum thicknesses of the five insulations vary from 0.053 to 0.236Â m, and the payback periods vary from 1.9 to 4.7Â years over a lifetime of 20Â years. The maximum life cycle savings are 54.4Â $/m2 in Shanghai, 54.8Â $/m2 in Changsha and 41.5Â $/m2 in Shaoguan (with a deep-colored northeast wall), and 39.0Â $/m2 in Chengdu (with a light-colored northwest wall). Finally, an approach to analyze economical efficiency of insulation materials is developed, result shows that expanded polystyrene is the most economic insulation material of the five because of the highest life cycle saving and lowest payback period.
In countries that import most of their energy, like Turkey, energy saving and the effective usage of energy become much more important. Energy consumption for heating is too high in Turkey because buildings have almost no insulation. Also the high prices of heating energy in Turkey, emphasize the need for energy saving. Therefore, the optimum insulation-thickness of the external wall for the five different energy-sources (coal, natural gas, LPG, fuel oil and electricity) and two different insulation materials (expanded polystyrene, rock wool) are calculated for Denizli. The optimization is based on a life-cycle cost analysis. According to the results, the optimum has been obtained by using coal as the energy source and expanded polystyrene as the insulating material. When the optimum insulation-thickness is used the life cycle saving and payback period are 14.09Â $/m2 and 1.43 years, respectively.
The demand for electricity in the Maldives continues to increase by more than 11% in recent years. This is mainly due to the growing number of high-rise air-conditioned buildings and the increasing use of electrical appliances in the residential and commercial sector. This paper investigates potential cost savings and emission reductions achieved by installing different insulation materials of optimum thickness in building's walls. The paper also investigates the effect when air gaps are introduced in the wall. The optimum insulation thickness is based on the cost benefits of each insulation material over its lifetime. This study found that by introducing optimal thickness of different insulation materials and by having air gaps of 2 cm, 4 cm and 6 cm, energy consumption and emissions can be reduced by 65–77%, in comparison to a wall without insulation or air gaps. And, hence have considerable cost savings.
Heat loss from buildings has a considerable share in waste of energy especially in Turkey since no or little insulation is used in existing and new buildings. Therefore, energy savings can be obtained by determining of heat loss characteristics with using proper thickness of insulation. For this purpose, in this study, calculations of optimum insulation thickness are carried out on a prototype building in Bursa as a sample city. Considering long term and current outdoor air temperature records (from 1992 to 2005), degree-hour (DH) values are calculated, and the variation of annual energy requirement of the building is investigated for various architectural design properties (such as air infiltration rate, glazing type, and area). Then, the effects of the insulation thickness on the energy requirement and total cost are presented. Based on life cycle cost (LCC) analysis, the optimum insulation thicknesses are determined for different fuel types. As a conclusion, the length of the heating period is average 221 days, and the mean heating DH value is found as 45 113.2 besides changing between 38 000 and 55 000. The optimum insulation thicknesses for Bursa vary between 5.3 and 12.4 cm depending on fuel types. In addition to this, the variation in Turkey is more dramatically.
Thermal insulation is one of the most effective energy conservation measures for cooling and heating in buildings. Therefore, determining and selecting the optimum thickness of insulation is the main subject of many engineering investigations. In this study, the determination of optimum insulation thickness on external walls of buildings is comparatively analyzed based on annual heating and cooling loads. The transmission loads, calculated by using measured long-term meteorological data for selected cities, are fed into an economic model (P1−P2 method) in order to determine the optimum insulation thickness. The degree-hours method that is the simplest and most intuitive way of estimating the annual energy consumption of a building is used in this study. The results show that the use of insulation in building walls with respect to cooling degree-hours is more significant for energy savings compared to heating degree-hours in Turkey's warmest zone. The optimum insulation thickness varies between 3.2 and 3.8 cm; the energy savings varies between 8.47 and 12.19 $/m2; and the payback period varies between 3.39 and 3.81 years depending on the cooling degree-hours. On the other hand, for heating load, insulation thickness varies between 1.6 and 2.7 cm, energy savings varies between 2.2 and 6.6 $/m2, and payback periods vary between 4.15 and 5.47 years.
A systematic approach for optimization of insulation material thickness is developed in this paper and then applied to Palestine. The optimization is based on the life cycle cost analysis. Generalized charts for selecting the optimum insulation thickness as a function of degree days and wall thermal resistance are prepared. Life cycle savings of the insulated buildings are computed for Palestine. Savings up to 21 $/m2 of wall area are possible for rock wool and polystyrene insulation. Payback periods between 1 and 1.7 years are possible for rock wool and payback periods between 1.3 and 2.3 years for polystyrene insulation, depending on the type of wall structure.
Most of energy is used up to space heating in the cold regions of Turkey. Insulation in external walls of buildings has been gaining much more interest in recent years not only for the environmental effect of the consumed energy but also the high cost of the energy. Therefore, the optimum insulation thickness was investigated in this study for the coldest cities of Turkey like Erzurum, Kars and Erzincan. The optimization is based on the life cycle cost analysis. As a result considerable energy saving is obtained when the optimum insulation thickness is applied. Savings up to 12.113 $/m2 of wall area can be maintained for Erzurum.
Thermal insulation is one of the most effective energy-conservation measures in buildings. Despite the widespread use of insulation materials in recent years, little is known regarding their optimum thickness under dynamic thermal conditions. Insulated concrete blocks are among the units most commonly used in the construction of building walls in Saudi Arabia. Typically, the insulation layer thickness is fixed at a value in the range 2.5–7.5 cm, regardless of the climatic conditions, type and cost of insulation material, and other economic parameters. In the present study, a numerical model based on a finite-volume, time-dependent implicit procedure, which has been previously validated, is used to compute the yearly cooling and heating transmission loads under steady periodic conditions through a typical building wall, for different insulation thicknesses. The transmission loads, calculated by using the climatic conditions of Riyadh for a west-facing wall, are fed into an economic model in order to determine the optimum thickness of insulation (Lopt). The latter corresponds to the minimum total cost, which includes the cost of insulation material and its installation plus the present value of energy consumption cost over the lifetime of the building. The optimum insulation thickness depends on the electricity tariff as well as the cost of insulation material, lifetime of the building, inflation and discount rates, and coefficient of performance of the air-conditioning equipment. In the present study, the effect of electricity tariff on the computed optimum insulation thickness is investigated. Different average electricity tariffs are considered; namely, 0.05, 0.1, 0.2, 0.3 and 0.4 SR/kWh (designated as Cases 1–5, respectively; 1 US$ = 3.75 Saudi Riyals). Results using moulded polystyrene as an insulating material show that the values of Lopt are: 4.8, 7.2, 10.9, 13.7 and 16.0 cm for Cases 1–5. Under the conditions of optimal insulation thickness for each electricity tariff, Case 1 gives the lowest total cost of 17.4 SR/m2, while Case 5 gives the highest total cost of 53.1 SR/m2. Corresponding thermal performance characteristics in terms of yearly total and peak transmission loads, R-value, time lag and decrement factor are presented.
In Turkey, heat loss from buildings is one of the primary sources of energy waste since no or little insulation is used in existing and new buildings. Therefore, considerable energy savings can be obtained by using proper thickness of insulation in buildings. Given the significant climatic variations that exist in different parts of Turkey, 16 cities from four climate zones of Turkey are selected for analysis and optimum insulation thicknesses, energy savings, and payback periods are calculated. The annual heating requirements of buildings in different climates zones were obtained by means of the heating degree-days concept. The optimization is based on life-cycle cost analysis. Five different fuels; coal, natural gas, fuel oil, liquefied petroleum gas (LPG), and electricity, and as an insulation material polystyrene are considered. The results show that optimum insulation thicknesses vary between 2 and 17 cm, energy savings between 22% and 79%, and payback periods between 1.3 and 4.5 years depending on the city and the type of fuel.
The study concerns the evaluation and comparison of the thermal performance of building roof elements subject to periodic changes in ambient temperature, solar radiation and nonlinear radiation exchange. A numerical model, based on the finite-volume method and using the implicit formulation, is developed and applied for six variants of a typical roof structure used in the construction of buildings in Saudi Arabia. The climatic conditions of the city of Riyadh are employed for representative days for July and January. The study gives the detailed temperature and heat flux variations with time and the relative importance of the various heat-transfer components as well as the daily averaged roof heat-transfer load, dynamic R-values and the radiative heat-transfer coefficient. The results show that the inclusion of a 5-cm thick molded polystyrene layer reduces the roof heat-transfer load to one-third of its value in an identical roof section without insulation. Using a polyurethane layer instead, reduces the load to less than one-quarter. A slightly better thermal performance is achieved by locating the insulation layer closer to the inside surface of the roof structure but this exposes the water proofing membrane layer to larger temperature fluctuations.