Insulation Thickness Of External Walls Research Articles

Integrated optimization of the building envelope and the HVAC system in office building retrofitting

Increasing the energy efficiency of existing buildings is the major strategy to reach carbon neutral targets, given that the building sector is a major emitter. In particular, one major part of building energy usage is the building heating, ventilation and air-cooling system, which are highly depending on the thermal performance of building envelope and increase the challenge of selecting optimal packages of energy efficiency measures. This paper thereby presents a method for optimizing the building envelope and heating, ventilation and air-cooling system. The simulation-based NSGA-III approach developed in this paper is based on coupling the dynamic simulation models created in EnergyPlus software with the non-dominated sorting genetic algorithm, as the engine that performs an optimization process. A large domain of energy efficiency packages combined with heating, ventilation and air-cooling systems and building envelope are investigated to minimize energy consumption, retrofit cost and thermal discomfort in indoor environments, which including ideal loads air system, four pipe fan coil system and variable refrigerant flow system, insulation materials and insulation thickness for external walls and roof, different types of external windows, and window-wall ratio. An office building in Chongqing was chosen as a case study to demonstrate the practical implementation of the proposed method. The results show that the four pipe fan coil system was superior in the diversity and performance of the Pareto front. Then, the optimal packages were generated by a synthetic method, which have 58.57 kWh/m2 of energy consumption, 30.76 CNY/m2 of retrofit cost and 40.67 % of the percentage of thermal discomfort hours. The results also indicate that the yearly energy savings rates are 17.30 %, 23.05 % and 21.10 % separately for ideal loads air system, four pipe fan coil system and variable refrigerant flow system after performing optimization. These results highlight the importance and necessity of performing an optimization procedure for existing buildings to select the optimal retrofit measures.

Optimising of thermal insulation thickness based on wall orientations and solar radiation using heating-degree hour method

Buildings consume more than a third of the world's energy demand, and painstaking adjusting the insulation thickness of external walls is an effective way to save energy. Thermal insulation plays an important role by reducing the heat transfer rate to save energy, and it is important to determine the thickness of the appropriate insulation material in the walls. In this research, considering only the heating factor, four different building materials (Pumice, Hollow concrete block - HCB, Hollow red clay block - HRCB and Reinforced concrete - RC) and eight different insulation materials (Extruded polystyrene - XPS, Expanded polystyrene - EPS, Expanded polyurethane - PUR, Wood fiber - WF, Hemp fiber - HF, Linen fiber - LF, Fiber glass - FG and Sheep wool - SW) are investigated on the exterior of a building in Sivas province of Türkiye. To reach more accurate results, life cycle cost analysis is taken as a basis, and the optimal insulation thicknesses, payback periods and energy savings of 32 different wall + insulation combinations with solar radiation (SR) are estimated using heating degree-hours. The heating requirement of a building covers more than three quarters of the year in Sivas, depending on different facing walls. These rates are calculated as 85 % (without SR), 80 % (North), 78 % (West), 77 % (East) and 75 % (South). Results also showed that the total minimum heating cost, the total maximum energy saving cost and the shorthest payback period are obtained HRCB + FG + South with 14.19 €/m2, RC + FG + solar radiation free with 72.76 €/m2 and RC + LF + solar radiation free with 1.60 year.

Optimum insulation thickness of external walls by integrating indoor moisture buffering effect: a case study in the hot-summer-cold-winter zone of China

Optimum insulation thickness of external walls by integrating indoor moisture buffering effect: a case study in the hot-summer-cold-winter zone of China

Effect of thermal insulation on building energy efficiency in Turkey

In light of the current energy problems, building envelopes must achieve thermal insulation in buildings by consuming the least amount of energy, thereby minimising energy consumption. This study determined the optimum insulation thickness of external walls, ceilings and floors of buildings as well as energy saving and payback periods in 81 city centres in Turkey. The calculations were performed for commonly used walls, ceilings and floor constructions. The life-cycle cost analysis and Turkish standard TS 825 (‘Thermal insulation requirements for buildings’) were also considered. In the calculations, the decreasing factor applied in TS 825 for surfaces that have no contact with outer air was considered. The results showed that the optimum insulation thickness of the external walls, ceilings and floors ranged between 3.5 and 20.0, 4.6 and 19.7 and 0.7 and 14 cm, respectively, depending on the type of energy and insulation material used. These findings suggest the possibility of saving up to 75% energy on the external walls, 90% on the ceilings and 85% on the floors. Additionally, a saving of 12–13% is likely obtainable in Turkey's total energy consumption when the optimum insulation thickness is applied to all residential buildings in the country.

Optimization of external wall insulation thickness in buildings using response surface methodology

Optimization of external wall insulation thickness in buildings using response surface methodology

Optimal insulation thickness of walls using improved Particle swarm optimization

Uninsulated external walls and inappropriate insulation of buildings are the main reason for energy losses. In this study, novel configurations of multi-layer pre-fabricate wall elements were used to enhance the ability of energy-saving and decrease the payback periods and investments in residential houses in five cities in Iran with different energy demands. Also, an optimization strategy is applied to determine optimum insulation thickness for external walls. The evaluation process is based on using natural gas and electricity in Iran’s buildings for heating and cooling, respectively. The optimum required insulation thickness in Cities with different climates according to their degree/day value for four different insulation materials (extruded polystyrene, glass wool, rock wool, and polyurethane) is achieved using a novel optimization method (Improved PSO). According to the obtained results, annual cost saving for of the wall in case of simultaneous heating & cooling is more than cooling and heating alone. However, for the payback period, simultaneous heating & cooling has a lower payback period than cooling and heating alone. The results revealed that the cost of rock wool is higher, and the cost of polyurethane is higher than the cost of all other insulating materials in Ardabil. Also, the optimal insulation thickness for the Ardabil city with hollow brick walls and heating and cooling needs is and for the XPS, respectively.

Investigation of Optimum Insulation Thickness for External Walls of Poultry Farms in Bandırma

Poultry plants have an important place in the economy of Bandırma. This study examined the optimum thickness of insulation, energy saving, payback period, and emissions of CO2 for poultry plant buildings' external walls in Bandırma. Calculations were based on five various fuels (natural gas, coal, LPG, electricity, and fuel oil). This study used two various insulation materials (Expanded Polystyrene and Extruded Polystyrene) were used. The Life Cycle Cost method has been applied as the approach. The equilibrium temperature, on which the calculations were based, was the temperature values required by broilers during the 6-week production season (Tbase= 31, 29, 25, 23.50, 22.50 and, 20.50°C). The degree day values calculated according to these equilibrium temperatures were obtained as 3111 for heating and 79 for cooling. The results showed that the optimum thickness of insulation varied in the range of 0.065-0.233 in heating. The amount of savings and payback period vary between 17.75-122 $/m2 and 1.72-1.20 years, respectively. It was calculated that a reduction by 80-90% in fuel quantity and CO2 emissions could be achieved after application of the optimum insulation thickness. This study aims to contribute to Bandırma's becoming an important place in the poultry sector.

Optimal Combination of External Wall Insulation Thickness and Surface Solar Reflectivity of Non-Residential Buildings in the Korean Peninsula

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.

Optimizing thermal insulation of external building walls in different climate zones in Libya

An efficient way to reduce the energy required for conditioning buildings and therefore to reduce CO2 emission is the use of proper thermal insulation in buildings’ external walls. This measure requires data from metrological stations that can be used in the optimization of the thermal insulation. The main objectives of this study are to construct thermal climatic zones for Libya and to specify the optimum insulation thickness for external walls for the different zones. This work is comprehensive as the metrological data from all existing 33 weather stations has been collected and used for identifying thermal zones. For the optimization of the construction of external walls, the most commonly used local wall structures are investigated: hollow concrete block, limestone block and hollow brick. In addition, four thermal insulation materials: extruded polystyrene, expanded polystyrene, rock wool and foamed polyurethane are used with every wall type. Optimum insulation thickness, energy savings, energy cost and payback periods were estimated for the 33 locations using life cycle cost analysis. A map is constructed for the thermal zones based on degree-day values for the entire country. The results show that limestone blocks with expanded polystyrene insulation form the optimum wall construction as it provides the minimum total cost for all locations. Depending on the Degree-day values, the optimum insulation thickness varies between 5.4 and 15.3 cm across the country with energy saving varies between 28 and 178 $/m2. Using the optimum thickness, the average CO2 emissions can potentially be reduced by about 85%. Finally, a contour map represents the optimum thickness of expanded polystyrene is presented in this work.

Optimization of Insulation Thickness of External Walls of Residential Buildings in Hot Summer and Cold Winter Zone of China

It is important to reduce primary energy consumption and greenhouse gas emissions associated with residential buildings in the hot summer and cold winter (HSCW) zone of China. Changing the insulation thickness of the external walls of residential buildings (ITEWB) is regarded as an effective way to manage such problems within a budget. This paper aims at developing an innovative way to select the optimal insulation thickness of external walls for residential buildings (OTWRB) in the HSCW zone of China, considering economic, energy and greenhouse gas emissions issues associated with the ITEWB. Four different cities and two different operation modes of the air conditioners (continuous and intermittent) are considered in this study. To explain the selection process, typical hypothetical buildings are simulated in Wuhan, Changsha, Hangzhou and Chengdu. Expanded polystyrene is chosen as the material of the insulation layer while split air conditioners are selected as the equipment for space heating and cooling. Integrated Environmental Solutions-Virtual Environment is used for the dynamic operational energy consumption of buildings. Life cycle cost method is adopted to calculate the economic impact of ITEWB on building performance. The Chinese life cycle database is used to quantize the impacts of ITEWB on building performance in the aspect of energy and greenhouse gas emissions based on the life cycle theory. The most appreciated insulation thickness is chosen from the thickness range of 30 mm to 150 mm. We find that for continuous operation mode of air conditioners in Wuhan, the optimal economic insulation thickness is 70 mm, whereas when considering only energy and environmental aspects, the OTWRB is 150 mm. These are all larger than the current insulation thickness which is 30 mm. When the weighting efficiencies of the economy, energy, and greenhouse gas emissions are different, the OTWRB varies from 70 mm to 150 mm for continuous operation mode. The different cities have little influence on the OTWRB while the different operation modes of air conditioners have some influence on the OTWRB.

Analysis of optimum insulation thickness for external walls at different orientations based on real-time measurements

In this study, the optimum insulation thickness was calculated for the heating season for external walls in the different directions of a building. For this reason, a building used for housing in Istanbul, Turkey was taken as model. The indoor and outdoor temperatures, along with the interior and exterior surface temperatures of the building?s external walls, were continuously measured using thermocouples and recorded in four different directions throughout the year. The effects of solar radiation, which vary based on the direction, were assessed for the heat transfer through the external walls. The results of this study indicate that the optimum insulation thickness for the north, south, west, and east facing walls should be 6.47, 2.87, 6.97, and 6.98 cm, respectively, based on the differences in the amount of solar radiation exposure of the walls in the different directions. The optimum insulation thickness of the building?s external wall was calculated as 5.25 cm, regardless of its direction. An economic analysis of the thermal insulation cost was conducted using the P1-P2 method, and then the payback periods were calculated. The heating energy consumption of the building designed using the optimum insulation thicknesses, as identified separately based on the direction, decreased by 17%, compared to the present building with 3 cm of thermal insulation.

Calculation of optimum insulation thickness of external walls in residential buildings by using exergetic life cycle cost assessment method: Case study for Turkey

AbstractEnergy is one of the most fundamental event of the universe and it is impossible to imagine an area where energy is not used. The energy demand is also increasing with the ever‐increasing population of the world. We also use energy to meet our heating and cooling needs. Heat loss from the exterior walls of buildings is important, so thermal insulation on the wall is very critical. In this study, optimum insulation thickness is determined for four provinces and two different insulation materials selected from four different climatic regions of Turkey. In order to calculate insulation thicknesses, the number of the degree‐day and exergetic environmental impact factor have been used. Natural gas is used as fuel. By using exergetic life cycle cost assessment method for rock wool and glass wool as insulation materials, the changes of CO2 emission values, the environmental impact factor, and energy saving values are determined for optimum insulation thickness. The optimum insulation thickness, which are calculated by using the number of the degree‐day and exergetic environmental impact factor for glass wool and rock wool is 0.1103 m and 0.04375 m for Antalya, 0.1667 m and 0.07292 m for Isparta, 0.1667 m and 0.0625 m for Bursa, and 0.2188 m and 0.1021 m for Erzurum, respectively. The reduction of carbon dioxide emission values for glass wool and rock wool 86% and 64% for Antalya, 90% and 76% for Isparta, 92% and 82% for Erzurum, and 90% and 73% for Bursa, respectively. Net exergetic environmental impact saving values for glass wool and rock wool: 589 mPts/m2‐yr and 342 mPts/m2‐yr for Antalya, 1,318 mPts/m2‐yr and 642 mPts/m2‐yr for Bursa, 1,315 mPts/m2‐yr and 878 mPts/m2‐yr for Erzurum, and 2,248 mPts/m2‐yr and 1,687 mPts/m2‐yr for Isparta, respectively.

An innovative method to determine optimum insulation thickness based on non-uniform adaptive moving grid

It is well known that thermal insulation is a leading strategy for reducing energy consumption associated to heating or cooling processes in buildings. Nevertheless, building insulation can generate high expenditures so that the selection of an optimum insulation thickness requires a detailed energy simulation as well as an economic analysis. In this way, the present study proposes an innovative non-uniform adaptive method to determine the optimal insulation thickness of external walls. First, the method is compared with a reference solution to properly understand the features of the method, which can provide high accuracy with less spatial nodes. Then, the adaptive method is used to simulate the transient heat conduction through the building envelope of buildings located in Brazil, where there is a large potential of energy reduction. Simulations have been efficiently carried out for different wall and roof configurations, showing that the innovative method efficiently provides a gain of 25% on the computer run time.

Optimizing the insulation thickness of external wall by a novel 3E (energy, environmental, economic) method

One of the main challenges in the building industry is determining the thickness and material of insulations that are used in the external wall. The selection of the above-mentioned parameters depends upon various aspects, including energy, environment, and economy. In many cases, the analysis which is carried out based on each of these aspects leads to different results. In the present study, a comprehensive analysis was carried out based on energy, environment, and economy criteria where the energy, environment, and economic costs of producing insulations are also taken into account. Accordingly, material and optimum thickness of insulation for the external wall of an office building were determined. The results showed that Polyurethane with the thickness of 8 cm, EPS with the thickness of 20 cm, and Rockwool with the thickness of 7 cm were optimum states with regard to the aspects of energy, environment, and economy respectively. Finally, a novel function, which considered all three parameters simultaneously, was defined. Consequently, 3E (energy, environmental, and economic) analysis was carried out and led to the presentation of the Mineral wool insulation with the thickness of 11 cm as the optimum state of investigated cases according to the 3E criterion.

The life cycle assessment related to insulation thickness of external walls of the airport

In this study, energy savings to be gained by the insulation of the external walls of airport buildings are examined according to Turkish Building Insulation Standard (TS 825) which is renewed in December 2013. In addition, life cycle total (LCT) cost and life cycle savings (LCS) are calculated. Unlike the residences, the airport buildings indoor temperatures should be 20°C during the heating period according. The optimum insulation thickness was determined for the external walls of the airport buildings. The degree-of-day method is used in calculations. Optimum insulation thickness is the lowest polyurethane insulation material in the highest glass wool insulation material. The optimum insulation thickness is calculated as 0.044-0.090 m for the polyurethane insulation material and 0.122-0.233 m for the glass wool insulation material. Also, extruded polystyrene (XPS) insulation material was found between 0.062-0.125 m.

The life cycle assessment related to insulation thickness of external walls of the airport

In this study, energy savings to be gained by the insulation of the external walls of airport buildings are examined according to Turkish Building Insulation Standard (TS 825) which is renewed in December 2013. In addition, life cycle total (LCT) cost and life cycle savings (LCS) are calculated. Unlike the residences, the airport buildings indoor temperatures should be 20°C during the heating period according. The optimum insulation thickness was determined for the external walls of the airport buildings. The degree-of-day method is used in calculations. Optimum insulation thickness is the lowest polyurethane insulation material in the highest glass wool insulation material. The optimum insulation thickness is calculated as 0.044-0.090 m for the polyurethane insulation material and 0.122-0.233 m for the glass wool insulation material. Also, extruded polystyrene (XPS) insulation material was found between 0.062-0.125 m.

Determination of the economical insulation thickness of building envelopes simultaneously in energy-saving renovation of existing residential buildings

ABSTRACTWhen the energy saving rate of existing residential buildings renovation is determined, the thermal performances of external walls, windows, and roof interact with each other. Therefore, it is necessary to study the determination of economical insulation thickness of building envelopes considering the interaction among building envelope performances. The objective function and its bound of envelope thermal performance optimization in the energy-saving renovation of existing residential buildings in severe cold and cold zones in China were established. It is the conditional extremum problem and can be solved through Lagrange’s method of multipliers to determine the economical insulation thickness of external walls and roofs simultaneously. The method is proved to be feasible by an existing residential building in Beijing. When the same window types are selected, the energy-saving renovation program of the building envelope determined by the Lagrangian optimization method can produce the minimum investment in insulation, minimum investment payback period, and the largest net present value (NPV) of the life cycle.

Optimum external wall insulation thickness considering the annual CO2 emissions

Increasing the insulation thickness in residential buildings leads to the reduction of operational CO2 emissions but simultaneously increases the embodied CO2 due to the insulation material. The environmentally optimum insulation thickness exists at a point where the total CO2 emissions are minimum. This work presents the optimum insulation thickness for external walls of different composition and orientation, for both the heating and the cooling period. Three different wall types and insulation materials are being presented. The dynamic thermal behavior of the external walls simulation is based on the heat conduction transfer functions method and using the hourly climatic data available for the city of Athens, Greece. The optimization methodology uses a single objective function approach, combining the simulation of the thermal behavior of external walls with an optimization algorithm. The results indicate that the optimum insulation thickness varies from 11.2 to 23.4 cm and is different for each orientation, wall type, and insulation material. In addition, the total annual CO2 emissions per unit area of the wall can be reduced by 63.2%–72.2%, depending on the insulation material and its position on the wall.

Optimizing insulation thickness of external walls in cold region of Morocco based on life cycle cost analysis

One of the effective ways to reduce energy consumption of buildings is the use of thermal insulation. This study focuses on the optimization of thermal insulation thickness of typical building’s wall in the cold regions of Morocco based on life cycle cost analysis and national technical and economic data. It demonstrates the profitability of the thermal insulation of building’s wall in these regions for expanded polystyrene, polyurethane and cork using degree-days method. The optimum insulation thickness varies significantly as a function of the selected insulation material, the source of energy and its pricing. The maximum recorded optimum thickness is 16.8 cm and the minimum is 3.4 cm.

Thermoeconomic method for determination of optimum insulation thickness of external walls for the houses: Case study for Turkey

The increment of the population, globalization of the world, improvement in technology and the increment of the welfare level causes to increase of energy use of goods and services. Energy consumption is commonly observed to occur in four main sectors: industry, residential, transport and agriculture. Residential sector in many countries is one of the largest energy consumers. The aim of this study to determine the optimum insulation thickness of the external wall of the housing for the selected province in four different climate regions in Turkey. As the insulation material, the polystyrene and polyurethane were used in the study. The optimum insulation thickness of the external wall was calculated using thermoeconomic method considering the effect of the inflation and interest rate, which is also called as Life Cycle Cost Analysis (LCA). For two different insulation materials, the minimum thickness was calculated for warm temperate climate region and the maximum thickness was calculated in the cold climate region as accepted. Also, the maximum savings was calculated for the cold climate region and the minimum savings was calculated for the warm temperate climate region.