The Impact of Optimum Insulation Thickness of External Walls to Energy Saving and Emissions of CO 2 and SO 2 for Turkey Different Climate Regions

In this study, the optimum insulation thickness of the external walls of the housing and it’s energy saving and environmental impact in the provinces—Ardahan, Aydın, Eskişehir and Samsun—located in four different climate regions of Turkey was calculated for the expanded polystyrene and polyurethane insulation materials. Natural gas and coal were selected as fuels. Ardahan in the coldest climate region and Aydın in the hottest climate region, for the coal and optimum thickness of expanded polystyrene and polyurethane insulation materials, the reduction of CO2 and SO2 emissions. In the study, the relations between annual energy cost saving and insulation thickness are given. The value of energy cost saving increases up to optimum insulation thickness and beyond this level, the energy cost saving is decreased. For coal and optimum thickness of expanded polystyrene and polyurethane insulation materials, the energy cost savings was higher for the cold climate regions when it was compared with the hot climate regions.


Introduction
Energy, because of the world's population and standard of living with constant increase, has become an important resource and power.Continuously and cheap supply of energy is insurance for the economic and social development [1].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.One of the easiest ways to employ the growing demand was to utilize fossil fuel sources.However, due to the limited amount of fossil fuels, increase of the energy price, environmental problems and global warming, it is important to use energy efficiently [2] [3] [4].
The area of Turkey is 783,502 km 2 .Turkey is located at the meeting point of three continents-Asia, Europe and Africa.Turkey can be considered a natural bridge between West and East or Europe and Asia [5] According to the data of Ministry of Energy and Natural Resources (MENR), total energy consumption in Turkey in 2013 was 120.3 Million Tons of Oil Equivalent (MTOE).The total energy demand in Turkey increased 127% from in 1990 to 2013.In 2013, imported primary energy supply was 75.5%.Currently, primary energy demand in Turkey is met by natural gas (31.3%), oil (28.2%), hard coal (14.7%) and lignite (11%).Turkey imports nearly 98% of the natural gas and 93% of the oil it consumes and coal import of Turkey increases steadily [6].
Generally, major energy end-use sectors are commercial, industrial transportation and residential.In many countries, the highest energy was consumed in residential sectors.Energy consumption for the space heating is about two times higher than domestic hot water, cooking, refrigeration, cooling etc. for residential sector.It is possible to significantly reduce the energy consumption with the insulation of the housing [7].
Insulation is the most important part of energy efficiency all over the world.The aim of the TS825 "Thermal Insulation Requirements for Buildings" is to decrease the energy consumption of space heating for the residential sector.This may help the energy saving and reducing CO 2 and SO 2 emissions [8] [9].
According to the International Energy Agency energy indicators in 2008, per capita primary energy consumption worldwide average of 1.83 of oil equivalent (toe/person) and the OECD average of 4.56 toe/person.In 2009, the energy-related greenhouse gas emission per person was 3.7 tons of carbon dioxide (CO 2 ) equivalent.In the same period, per capita emission was 10.6 tons of CO 2 equivalent/personfor the OECD, 5.1 tons of CO 2 equivalent/person for non-OECD Europeand average of 4.4 tons of CO 2 equivalent/person for the world.Turkey's total greenhouse gas emissions in 1990 amounted to about 187 million tons of CO 2 equivalent, while this value in 2009 amounted to about 370 million tons of CO 2 equivalent.Total sectoral distribution of emissions: energy 278.33 Mton CO 2 equivalent (75.3%),Waste 33.93 Mtoe of CO 2 equivalent (9.2%), industrial processes 31.69Mtoe of CO 2 equivalent (8.6%) and agriculture 25.7 Mtoe of CO 2 equivalents (7%) [10].
Calculation of optimum insulation thickness of external walls of housing by using Life-Cycle Cost was discussed by Refs [11]- [33].Çomaklı and Yüksel [34] selected Erzurum province of Turkey to analyze the optimum insulation thickness, fuel consumption and emission of CO 2 .This analysis showed that CO 2 emissions amount decreased 50% by using optimum insulation thickness.
The purpose of this study is to determine the optimum insulation thickness of the external walls of the housing and it's energy saving, fuel consumption and environmental impact in the provinces-Ardahan, Aydın, Eskişehir and Samsun-located in four different climate regions of Turkey by using Life Cycle Cost Analysis (LCA) method.Expanded polystyrene and polyurethane were selected as insulation materials and natural gas and coal were selected as fuels.The geographic location of these provinces has been given in Figure 1.

Material and Methods
The amount of heat lost from the unit external wall surfaces of houses in selected provinces and the annual fuel consumption due to the heat loss for natural gas and coal as fuel were calculated.The optimum insulation thickness by using LCA method and the emissions of CO 2 and SO 2 from fuel combustion equations of chemical formulas were calculated for each province.
The external wall structure which is used in the calculations has been shown in Figure 2. As seen from the figure, the external wall also called as the "sandwich wall", consists of 2 cm inner plaster, two 8.5 cm horizontal hollow bricks and 3 cm exterior plaster and insulation material.
The Life Cycle Cost Analysis (LCA) for a project or piece of equipment is the most  commonly method used to assess the economic benefits of energy conservation projects over their lifetime [39] [40].The parameters of calculation are given in Table 1.
Heat loss from unit external wall surface, where, U is coefficient of heat transfer.In the heating season, the annual heat loss from unit external wall surface and the annual energy demand which is depends on this heat loss are calculated by using heating degree day numbers (HDD) [36], 86.4 for the typically wall given by, where, i R and o R the thermal resistance of interior and exterior air film respectively and w R , the thermal resistance of non-insulated wall layers.
The thermal resistance of insulation material given by, where and are the thickness and thermal conductivity of insulation materials respectively.
The annual energy consumption (kJ/m 2 •year), Annual fuel consumption (kg/m 2 •year), where, annual fuel consumption, HDD, heating degree day numbers, R wt , thermal resistance of the external wall insulation material excluding and H u , the lower calorific value of the fuel.The total cost from LCA method [8] [36], where, PWF is the present worth factor, is the total cost, C ins is the unit insulation material cost ($/m 3 ), is the unit fuel cost ($/kg) and x is insulation thickness (m).
The total cost of the derivative based on insulation thickness by equalizing to zero, the optimum insulation thickness is calculated [41].
( ) and, The optimum insulation thickness is obtained from (11) equation.Energy cost saving ($/m 2 •year) [36], ( ) ( ) where, ( ) T C nins and ( ) T C ins , the total energy costs for non-insulated and insulated walls respectively.Assuming the complete combustion, the chemical reactions for annual n kmole fuel consumption and the parameters in Table 2 by using.

Results and Discussion
In this study, the optimum insulation thickness and it's energy saving and environmental impact of the external wall of the housing in the provinces-Ardahan, Aydın, Eskişehir and Samsun-located in four different climate regions of Turkey was calculated for the expanded polystyrene and polyurethane insulation materials.Naturalgas and coal were selected as fuels.Although reduced heat loss from walls in the houses with increasing thickness of the insulation material, the insulation cost is higher.As seen in Figures 3-18, total cost which is the sum of fuel cost and insulation cost decreases up to specific valufe of the insulation thickness and then the total cost is increased.The value of optimum insulation thickness that corresponding to the minimum total cost value.For coal and expanded polystyrene insulation material, optimal                          respectively, for natural gas and optimum thickness of expanded polystyrene and polyurethane insulation materials, the reduction of CO 2 emission of Aydın 69% and 64.2% respectively.For coal and optimum thickness of expanded polystyrene and polyurethane insulation materials, the reduction of CO 2 and SO 2 emissions of Ardahan 85.6% and 83.3% respectively, for natural gas and optimum thickness of expanded polystyrene and polyurethane insulation materials, the reduction of CO 2 emission of Ardahan 69% and 64.2% respectively.The relations between annual energy cost saving and insulation thickness are shown in Figures 31-38.The values of energy cost saving increases up to optimum insulation thickness and beyond this level, the energy cost saving is decreased.For coal and optimum thickness of expanded polystyrene and polyurethane insulation materials, the energy cost savings of Aydın 19 $/m 2 •year and 16 $/m 2 •year respectively, for natural gas and optimum thickness of expanded polystyrene and polyurethane insulation materials, the energy saving of Aydın 13.9 $/m 2 •year and 11.8 $/m 2 •year respectively.For coal and

Conclusion
It has been calculated that Ardahan is located in the coldest climate region and Aydın is located in the hottest climate region.Thickness of the insulation material reduces the CO 2 and SO 2 emissions.It has been indicated that the reduction of CO 2 and SO 2 emissions for expanded polystyrene was higher than the polyurethane for the different climate regions.It can be concluded that the energy cost savings for coal is higher than the natural gas for the different regions.Also the energy cost savings for the expanded polystyrene was higher than the polyurethane insulation materials.Submit your manuscript at: http://papersubmission.scirp.org/Or contact epe@scirp.org

Figure 1 .
Figure 1.The geographic location of selected provinces.

Figure 2 .
Figure 2. The model of external wall.

Figure 3 .
Figure 3. Annual cost versus insulation thickness for expanded polystyrene insulation material for Aydın.

Figure 4 .
Figure 4. Annual cost versus insulation thickness for polyurethane insulation material for Aydın.

Figure 5 .
Figure 5. Annual cost versus insulation thickness for expanded polystyrene insulation material for Aydın.

Figure 6 .
Figure 6.Annual cost versus insulation thickness for polyurethane insulation material for Aydın.

Figure 7 .
Figure 7. Annual cost versus insulation thickness for expanded polystyrene insulation material for Ardahan.

Figure 8 .
Figure 8. Annual cost versus insulation thickness for polyurethane insulation material for Ardahan.

Figure 9 .
Figure 9. Annual cost versus insulation thickness for expanded polystyrene insulation material for Ardahan.

Figure 10 .
Figure 10.Annual cost versus insulation thickness for polyurethane insulation material for Ardahan.

Figure 11 .
Figure 11.Annual cost versus insulation thickness for expanded polystyrene insulation material for Eskişehir.

Figure 12 .
Figure 12.Annual cost versus insulation thickness for polyurethane insulation material for Eskişehir.

Figure 13 .
Figure 13.Annual cost versus insulation thickness for expanded polystyrene insulation material for Eskişehir.

Figure 14 .
Figure 14.Annual cost versus insulation thickness for polyurethane insulation material for Eskişehir.

Figure 15 .
Figure 15.Annual cost versus insulation thickness for expanded polystyrene insulation material for Samsun.

Figure 16 .
Figure 16.Annual cost versus insulation thickness for polyurethane insulation material for Samsun.

Figure 17 .
Figure 17.Annual cost versus insulation thickness for expanded polystyrene insulation material for Samsun.

Figure 18 .Figure 19 .
Figure 18.Annual cost versus insulation thickness for polyurethane insulation material for Samsun.

Figure 20 .
Figure 20.Variation of SO2 emission with insulation thickness for coal for Aydın.

Figure 21 .
Figure 21.Variation of CO2 emission with insulation thickness for natural gas for Aydın.

Figure 22 .
Figure 22.Variation of CO2 emission with insulation thickness for coal for Ardahan.

Figure 23 .
Figure 23.Variation of SO2 emission with insulation thickness for coal for Ardahan.

Figure 24 .
Figure 24.Variation of CO2 emission with insulation thickness for natural gas for Ardahan.

Figure 25 .
Figure 25.Variation of CO2 emission with insulation thickness for coal for Eskişehir.

Figure 26 .
Figure 26.Variation of SO2 emission with insulation thickness for coal for Eskişehir.

Figure 27 .
Figure 27.Variation of CO2 emission with insulation thickness for natural gas for Eskişehir.

Figure 28 .
Figure 28.Variation of CO2 emission with insulation thickness for coal for Samsun.

Figure 29 .
Figure 29.Variation of SO2 emission with insulation thickness for coal for Samsun.

Figure 30 .
Figure 30.Variation of CO2 emission with insulation thickness for natural gas for Samsun.

Figure 31 .
Figure 31.Variation of energy saving with insulation thickness for coal for Aydın.

Figure 32 .
Figure 32.Variation of energy saving with insulation thickness for natural gas for Aydın.

Figure 33 .
Figure 33.Variation of energy saving with insulation thickness for coal for Ardahan.

Figure 34 .
Figure 34.Variation of energy saving with insulation thickness for natural gas for Ardahan.

Figure 35 .
Figure 35.Variation of energy saving with insulation thickness for coal for Eskişehir.

Figure 36 .
Figure 36.Variation of energy saving with insulation thickness for natural gas for Eskişehir.

Figure 37 .
Figure 37. Variation of energy saving with insulation thickness for coal for Samsun.

Figure 38 .
Figure 38.Variation of energy saving with insulation thickness for natural gas for Samsun.

C
cost ($) C f unit cost of fuel ($/kg) C t total heating cost at present value ($) C ins unit cost of insulation material HDD heating degree-days PWF present worth factor k thermal conductivity coefficient (W/m•K) q A annual heat loss (kJ/m 2 ) U heat transfer coefficient (W/m 2 •K) m mass (kg) M(m) molecular mass (kg/kmol) n mole(kmol) E A annual energy needs(kJ/m 2 -year) E C annual energy consumption (kJ/m 2 -year) E costsaving annual energy cost saving ($/m 2 •year) R thermal resistance (m 2 •K/W)x insulation thickness (m) η efficiency of the heating system Subscripts or recommend next manuscript to SCIRP and we will provide best service for you:Accepting pre-submission inquiries through Email, Facebook, LinkedIn, Twitter, etc.A wide selection of journals (inclusive of 9 subjects, more than 200 journals) Providing 24-hour high-quality service User-friendly online submission system Fair and swift peer-review system Efficient typesetting and proofreading procedure Display of the result of downloads and visits, as well as the number of cited articles Maximum dissemination of your research work

Table 1 .
Parameters used in calculations of optimum thickness.

Table 2 .
Chemical formulas and boiler efficiency of fuels used in calculations.