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.     

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.     

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.     

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 external walls using different energy-sources

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 14.09 $/m² and 1.43 years, respectively.     

Determination of optimum insulation thicknesses of the external walls and roof (ceiling) for Turkey's different degree-day regions

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), Eski?ehir (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.     

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.     

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.     

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.     

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.     

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.     

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.     

Cost benefits analysis and emission reductions of optimum thickness and air gaps for selected insulation materials for building walls in Maldives

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.     

Experimental performance evaluation of a closed‐loop vertical ground source heat pump in the heating mode using energy analysis method

An experimental study is performed to determine the performance of a ground source heat pump (GSHP) system in the heating mode in the city of Erzurum, Turkey. The GSHP system using R‐134a as refrigerant has a single U‐tube ground heat exchanger (GHE) made of polyethylene pipe with a 16 mm inside diameter. The GHE was placed in a vertical borehole with 55 m depth and 203.2 mm diameter. The average coefficients of performance (COP) of the GSHP system and heat pump in heating mode are calculated as 2.09 and 2.57, respectively. The heat extraction rate per meter of the borehole is determined as 33.60 W m^?1. Considering the current gas and electric prices in Erzurum city, the equivalent COP of the GSHP system should be 2.92 for the same energy cost comparing with natural gas. The virgin ground in Erzurum basin has high permeability and low thermal conductivity. In order to improve the thermal efficiency of GHE and thus improve COP of a GSHP in the basin, the borehole should be backfilled with sand as low‐cost backfill material and a 1 to 2 m thick surface plug of clay should be inserted. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of electricity tariff on the optimum insulation-thickness in building walls as determined by a dynamic heat-transfer model

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 (L_opt). 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 L_opt 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.     

Optimum insulation thickness of walls for energy-saving in hot regions of India

In India, the energy consumption in the building sector is rapidly increasing due to improvement in living standards. Effective thermal insulation of building walls is one of the most effective energy conservation measures for heating, ventilation, and air conditioning applications in buildings. In this study, the thermoeconomic optimisation of insulation thickness on walls of buildings is analysed based on degree days. Thermoeconomic parameters such as optimum insulation thickness, annual electrical energy consumption, annual energy cost and payback period is determined for three different insulation materials for the cities located in India. Database on insulation materials for five cities of India are provided.     

Determination of optimum insulation thickness of external walls with two different methods in cooling applications

Thermal insulation is one of the most effective energy conservation for the cooling applications. For this reason, determination of the optimum thickness of insulation and its selection is the main subject of many engineering investigations. In this study, the optimum insulation thickness on the external walls in the cooling applications is analyzed based on two different methods used to determine annual energy consumption. One of the methods is the degree-hours method (Method 1) that is the simplest and most intuitive way of estimating the annual energy consumption of a building. The other is the method (Method 2) which using the annual equivalent full load cooling hours operation of system. In this paper, a Life Cycle Cost (LCC) analysis is used to evaluate accuracy of these methods, and the results are compared. The results show that the life cycle savings are overestimated by up to 44% in Method 2, while the optimum insulation thickness and payback period are respectively overestimated by up to 74% and 69% in Method 1.     

Determination and selecting the optimum thickness of insulation for buildings in hot countries by accounting for solar radiation

Determination and selecting the optimum thickness of insulation is the prime interest of many engineering applications. One of those applications is insulating buildings with an appropriate insulation. Calculations have been done for the determination of the optimum thickness of insulation for some insulating materials used in order to reduce the rate of heat flow to the buildings in hot countries. Reducing heat flow rate would reduce the electricity cost for the house lifetime. The solar energy radiation is calculated and used to calculate the solar-air temperature which is employed for the determination of the heat flow rate. Some results were obtained for a typical house in Qatar which is an example of hot area. The wallmate insulation is found to have the best performance for houses in Qatar.     

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.