Determination of the energy savings and the optimum insulation thickness in the four different insulated exterior walls

The optimum insulation thickness of the external wall for four cities from four climate zones of Turkey, energy savings over a lifetime of 10 years and payback periods are calculated for the five different energy types and four different insulation materials applied externally on walls. Extruded polystyrene, expanded polystyrene, nil siding and rock wool as wall insulation material are selected. In this study, the net energy cost savings are calculated using the P₁–P₂ method. The results show that energy cost savings vary between 4.2 $/m² and 9.5 $/m² depending on the city and insulation materials. The highest payback period value with 2.25 years in Mersin found by using natural gas as an energy source for heating, while the lowest value is reached by using LPG as an energy source in Bitlis.     

Optimization of insulation thickness for different glazing areas in buildings for various climatic regions in Turkey

Insulation is one of the most effective methods intended for reducing energy consumption in both heating and cooling of buildings. Selecting the right materials and determining the optimum insulation thickness in building insulation application is an important issue. In 2000, the “Thermal Insulation Requirements for Buildings” was enacted in Turkey, energy saving by limiting the energy amount used for heating in buildings being the target. In this study, the effect of the alteration of windows and exterior wall areas on the heating energy requirement of the building and on the optimum insulation thickness has been examined by using P₁–P₂ method. The study has been carried out for four degree-day regions of Turkey for various insulation materials, glazing areas, and fuel types; the results have been presented in charts. In the rest of this study, effects of different insulation thicknesses and fuel on fuel consumption and thereby on emissions of pollutants such as CO₂ and SO₂ are evaluated. For example, in the building where XPS (extruded polystyrene foam) insulation material and natural gas are used and where the ratio of glazing area to exterior wall area is 0.2 (glazing area percentage), energy saving for the four regions has been found to be 13.996, 31.680, 46.613, and 63.071 $/m², respectively, and the payback period of investment has been found to be 2.023, 1.836, 1.498, and 1.346 years, respectively. The emissions of CO₂ are decreased by 50.91% for the cases in which optimum insulation material (XPS) and natural gas are used. The emissions of CO₂ and SO₂ are decreased by 54.67% for the cases in which optimum insulation material (XPS) and fuel oil are used.     

Optimum insulation thickness of external walls for energy saving

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.     

A study on optimum insulation thicknesses of external walls in hot summer and cold winter zone of China

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 0.236 m, and the payback periods vary from 1.9 to 4.7 years over a lifetime of 20 years. The maximum life cycle savings are 54.4 $/m² in Shanghai, 54.8 $/m² in Changsha and 41.5 $/m² in Shaoguan (with a deep-colored northeast wall), and 39.0 $/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.     

Optimizing environmental insulationthickness of buildings with CHP-based district heating system based on amount of energy and energy grade

The increase of insulation thickness (IT) results in the decrease of the heat demand and heat medium temperature. A mathematical model on the optimum environmental insulation thickness (OEIT) for minimizing the annual total environmental impact was established based on the amount of energy and energy grade reduction. Besides, a case study was conducted based on a residential community with a combined heat and power (CHP)-based district heating system (DHS) in Tianjin, China. Moreover, the effect of IT on heat demand, heat medium temperature, exhaust heat, extracted heat, coal consumption, carbon dioxide (CO₂) emissions and sulfur dioxide (SO₂) emissions as well as the effect of three types of insulation materials (i.e., expanded polystyrene, rock wool and glass wool) on the OEIT and minimum annual total environmental impact were studied. The results reveal that the optimization model can be used to determine the OEIT. When the OEIT of expanded polystyrene, rock wool and glass wool is used, the annual total environmental impact can be reduced by 84.563%, 83.211%, and 86.104%, respectively. It can be found that glass wool is more beneficial to the environment compared with expanded polystyrene and rock wool.     

Economic and environmental impacts of insulation in district heating pipelines

The determination of optimum thickness of insulation is often applied to energy technologies and building projects. In this study, the energy, economic and environmental evaluations of thermal insulation in district heating pipeline are discussed. The optimum insulation thickness, energy saving over a lifetime of 10 years, payback period and emissions of CO₂, CO and SO₂ are calculated for nominal pipe sizes and fuel types based on heating loads in Afyonkarahisar/Turkey. The life cycle cost analysis is used to determine the optimum thickness of the pipeline material in order to take into account the change in inflation that directly affect both the cost of pipeline material and fuels depending on fuel type. The results show that the highest value of optimum insulation thickness, energy savings, emissions and the lowest payback period are reached for a nominal pipe size of 200 mm. About three times more energy saving results by making 200 mm nominal pipe instead of 50 mm. Considering the economical and environmental advantages, the geothermal energy is a better choice and then fuel-oil. When thermal insulation is done in a district heating pipeline, there will be a significant reduction of 21% in the amount of CO₂ emitted to the atmosphere.     

Effect of fuel type on the optimum thickness of selected insulation materials for the four different climatic regions of Turkey

The optimum insulation thickness of the external wall for four various cities from four climate zones of Turkey, energy savings over a lifetime of 10 years and payback periods are calculated for the five different energy types and four different insulation materials. Foamboard 3500, Foamboard 1500, extruded polystyrene and fiberglass as insulation material are selected. In this study, it is calculated the value of the amount of the net energy savings using the P₁–P₂ method. The results show that optimum insulation thicknesses vary between 1.06 and 7.64 cm, energy savings vary between 19 $/m² and 47 $/m², and payback periods vary between 1.8 and 3.7 years depending on the city and the type of fuel. The highest value of energy savings is reached in A?r? for LPG fuel type, while the lowest value is obtained in Ayd?n for natural gas.     

Effect of wall orientation on the optimum insulation thickness by using a dynamic method

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 Elaz??, Turkey. The economic model including the cost of insulation material and the present value of energy consumption cost over lifetime of 10 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 5.5 cm for south oriented wall and 6 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.     

A study on residential heating energy requirement and optimum insulation thickness

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.     

A study on optimum insulation thickness in walls and energy savings in Tunisian buildings based on analytical calculation of cooling and heating transmission loads

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.     

聚苯颗粒砂浆保温效果研究

墙体材料主体采用240 mm厚MU10混凝土多孔砖,保温层为25 mm聚苯颗粒保温砂浆。采用热流计法进行了建筑外墙保温性能检测,检测结果表明该种气候条件下25 mm聚苯颗粒保温砂浆无法满足节能标准要求。从采暖能耗、保温材料造价角度出发计算了该墙体的经济保温层厚度为79 mm。     

Energy efficiency in chinese apartment buildings: Parametric analysis with the DOE-2.1A computer program

Using an uninsulated Beijing apartment house of standard design as a base case, the DOE-2.1A energy analysis program is used to study the cost-effectiveness of more energy-efficient designs. Two measures have attractive simple payback times; reduced infiltration (1–2 yr payback) and insulation of the north wall (6 yr). The cost of conserved coal for the insulation measure is less than half the international price of coal. This insulation adds only 0.6% to the first cost of the building, yet, combined with more attention to infiltration, it reduces annual heat load from 230 to 130 MJ/m². Furthermore, the first cost of these two measures may be offset by savings from downsizing the heating plant. In Shanghai, reduced infiltration and insulation are justified not on the basis of saving fuel, but because they make dwellings more comfortable.     

Analytical periodic solution for the study of thermal performance and optimum insulation thickness of building walls in Tunisia

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.     

Thermoeconomic analysis method for optimization of insulation thickness for the four different climatic regions of Turkey

Thermal insulation is one of the most effective energy-conservation measures in buildings. For this reason, the energy savings can be obtained by using proper thickness of insulation in buildings. In this study, the optimum thickness of insulation considering condensed vapor in external walls are found by using exergoeconomic analysis. The four various cities from four climate zones of Turkey, namely, Antalya, ?stanbul, Elaz?? and Erzurum are selected for the analysis. The optimum insulation thickness for Antalya, ?stanbul, Elaz?? and Erzurum are obtained as 0.038, 0.046, 0.057 and 0.0739 m at indoor temperature of 20 °C, respectively. The results show that the optimum insulation thickness at the indoor temperature of 18 and 22 °C are determined as 0.0663 and 0.0816 m for the city of Erzurum, respectively. The energy saving for the city of Erzurum is found as 77.2% for the indoor temperature of 18 °C, 79.0% for the indoor temperature of 20 °C and 80.6% for the indoor temperature of 22 °C, when the optimum insulation is applied.     

A case study for influence of building thermal insulation on cooling load and air-conditioning system in the hot and humid regions

Ensuring the effective thermal insulation in regions, where the cooling requirement of building with respect to heating requirement is dominant, is very important from the aspect of energy economy. In this study, the influence of thermal insulation on the building cooling load and the cooling system in case of air-conditioning by an all-air central air-conditioning system was evaluated for a sample building located in Adana, based on the results of three different types of insulation (A, B and C-type buildings) according to the energy efficiency index defined in the Thermal Insulation Regulation used in Turkey. The operating costs of the air-conditioning system were calculated using cooling bin numbers. Life-cycle cost analysis was carried out utilizing the present-worth cost method. Results showed that both the initial and the operating costs of the air-conditioning system were reduced considerably for all three insulation thicknesses. However, the optimum results in view of economic measurements were obtained for a C-type building. The thickness of thermal insulation for the buildings in the southern Turkey should be determined according to the guidelines for a C-type building.     

An Application of Solar Energy Storage in the Gas: Solar Heated Biogas Plants

Abstract

Temperature is an important factor that may affect the performance of anaerobic digestion. Therefore, biogas plants without heating system work only in warmer regions for the whole year. In regions with extreme temperature variations, for instance in Turkey, the biogas plant should be built with heating system. One of the methods is to use solar energy to increase the reactor temperature. In this study, solar heated biogas plants were reviewed. Furthermore, the optimization of insulation thicknesses and solar energy systems for 5 m³ biogas reactor were carried out for two different cities for three different climatic zones in Turkey. Based on the obtained results, the ratio of annually produced biogas used for reactor heating was calculated for each city, with and without solar heating system. Obtained results indicate that the biogas consumption for reactor heating is decreased by approximately 19% for average of six cities when solar heating system is used. This means that available biogas potential would be increased.     

Life cycle energy analysis of a residential building with different envelopes and climates in Indian context

In this paper life cycle energy (LCE) demand of a residential building of usable floor area about 85.5 m² located at Hyderabad (Andhra Pradesh), India is evaluated under different envelopes and climates in Indian context. The house is studied with conventional (fired clay) and alternative wall materials (hollow concrete, soil cement, fly ash and aerated concrete) under varying thickness of wall, and insulation (expanded polystyrene) on wall and roof. The house is modelled for five different climatic zones of India, i.e. hot and dry, warm and humid, composite, cold and moderate. Study suggests that alternative wall materials alone (without insulation) reduce LCE demand of the building by 1.5-5%. Aerated concrete (AC), as wall material, has better energy performance over other materials. LCE savings are significant when insulation is added to external wall and roof. It varies from 10% to 30% depending on the climatic conditions. Maximum LCE savings with insulation are observed for warm and humid climate and least for moderate climate. For same thickness of insulation, LCE savings are much more with roof insulation than wall insulation. But wall insulation is found to be preferable to a thicker wall. It is also observed that there is a limit for thickness of insulation that can be applied on external walls and roof from life cycle point of view. This limit is found to be about 10 cm for composite, hot and dry, warm and humid, and cold climates and 5 cm for moderate climate.     

Energy saving potential in the residential sector of Uzbekistan

In 2003, the residential sector of Uzbekistan has consumed about 15.073 Mtoe (million ton of oil equivalent) of energy or 27.3% of the total energy consumed in the country. This value is approximately twice as much as that of residential sector of Turkey and Romania. The climate of above countries is comparable to that of Uzbekistan. In this article we suggest to use the heating degree-day method for determining the natural gas consumption norms for residential heating. Taking the climatic differences into account, the norms of natural gas consumption in respect to each resident are submitted for each region of Uzbekistan. The realization of suggested proposals allows saving about 9.2 billion m³ of natural gas annually.     

干打垒遗产建筑保护性低碳节能改造研究

以一栋典型干打垒建筑为研究对象,为解决其保护不善问题,提出了多种因素、多个目标综合分析的保护性低碳节能改造策略。建立干打垒建筑信息模型,为后续改造和管理提供数据支撑。在不影响文化和历史价值的基础上,研究了在外墙和屋顶上添加内保温材料以及更换外窗。考虑保护方法、传热系数限制和当地材料等因素,选取了6种保温材料和4种窗户类型,建立了24种工况。分别模拟和估算各个工况的能耗、碳排放和生命周期成本。基于节能、低碳及经济三个目标,采用分类比较与综合比较相结合的方法评价各个工况。结果表明,采用发泡聚苯乙烯(EPS)和90系列隔热铝合金窗,能耗、碳排放及成本最低,是最佳方案。该优化方法可以促进既有建筑创新节能和低碳改造方法的发展。     

Optimizing insulation thickness for buildings using life cycle cost

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.