Thermal Insulation and Saving

05.02.2015
In addition to the below mentioned direct advantages, thermal insulation has many indirect benefits. For thermally insulated new buildings, the number of the materials which will be used for the central heating system will decrease. Since less energy will be required for heating, boiler size, radiator number and number of other materials will decrease. When number of radiators and core sections are decreased, usage area of rooms will increase. If thermal insulation becomes widespread, investments in this field will increase and therefore, unemployment rate will fall.

2.5.1 Comparison of insulated and uninsulated buildings

Hard savings on operating and initial investment costs of a building constructed in Istanbul after the insulation is applied are presented in the example below. In calculations, a 200 m2 four-storey building (where two apartments of 90 m2 are located on each floor) is taken as an example. The building has a total exterior wall surface of 561.8 m2 consisting of reinforced concrete beam, a 264.4 m2 column and a brick-filled wall of 297.4 m2. The building has glazing of 86.2 m2 and each floor is 2.7 m high.

2.5.1.a) Uninsulated condition (current condition):

An uninsulated building has no thermal insulation material. The exterior walls are brick 19 cm on which there are 2 cm of internal and external plastering. Thermal insulation is not applied to the ground or ceiling.

2.5.1.b) Insulated condition (conforms to TS 825):

For an insulated building, it is assumed that the thermal insulation materials are used to apply insulation to the ceiling, ground and exterior walls of the building according to TS 825 "Thermal Insulation Rules in Buildings" and "Thermal Insulation Regulation". It is assumed that thermal insulation materials of 12 cm, 4 cm and 4 cm are used for the ceiling, ground and exterior walls (jacketing) respectively.

Thus, it is possible to make a comparison between the insulated and uninsulated conditions of the building in terms of natural gas saving and insulation cost. In the comparison, the effects of windows are neglected. In both situations, it is assumed that the windows of the building are double-glazed windows having a separation of 12 mm and plastic profile.

According to TS 825, the insulation thickness to be applied in the building is determined and details of structural elements are created. The heating load of the building is calculated as per TS 2164. Results obtained are compared as below.

2.5.2 Results:

1) With the thermal insulation application performed in the sample building, approximately 60% decrease is calculated in the annual heating requirement necessary to create healthy and comfortable living conditions.

Total heat loss in the uninsulated building is 79 kW. On the other hand, total heat loss in the insulated building is 32 kW. The effect of insulation applications performed on buildings reduces heat loss and therefore influences both operating and initial investment costs economically.

2.5.2.a) Comparison in terms of initial investment costs

Reduced total heat loss ensures that the boiler capacity and radiator number is decreased and tube diameters used in heating installation are reduced. This leads to a decrease in the initial investment cost which is necessary for the heating system.

While the capacity of the boiler should be 82 kW based on the total heat loss in the uninsulated building, a boiler of 35 kW meets all requirements in the insulated building. The boiler's capacity primarily determines the cost of the boiler. While the cost of the boiler which should be installed in the uninsulated building is $ 2531, the cost of the boiler is $ 893 in the insulated building which conforms to TS 825. Thus, in this example, $ 1,638 is saved on the cost of the boiler after the insulation is applied to the building.

Similarly, since the heating load is reduced with the insulation application, the number of radiators which provide a heat transfer surface is decreased and therefore their costs are reduced. While the cost of the radiator which should be used in the uninsulated building is $ 1250, the cost of the radiator is $ 534 in the insulated building which conforms to TS 825. Thus, in this example, $ 716 is saved on the cost of the boiler after the insulation is applied to the building.

Therefore, when insulated and uninsulated buildings are considered in terms of the initial investment, while an investment of $ 3781 is required for the heating system of the uninsulated building, for the insulated building the value of the required investment is $ 1427. $ 2354 is saved on the installation of the heating system after the insulation application. This expenditure is for one time only.

Another benefit of the low total heat loss is that the fuel amount necessary for heating and therefore operating costs is reduced. Throughout the heating period, while 23413.75 m3 natural gas valuing $ 4683 is used per year for the uninsulated building; within the same period, it is enough to use only 9993.67 m3 natural gas valuing $ 2000 for the insulated building. Therefore, when operating costs are considered, $ 2683 is saved per year after the insulation is applied.

It is inevitable that the insulation application will have a certain cost. Insulation of this building creates an initial investment cost of $ 11,980. However, after saving $ 2354 from the initial investment cost of the heating system, the initial investment cost of the insulation application can be considered as $ 9626. Considering the saving ($ 9626/$ 2683) obtained from operating costs, the aforementioned investment cost shows that the insulation application is a profitable investment which returns profit to its user during the 4th year of the building after insulation.

In this example, it is considered that the building is not cooled in summer. Therefore, it is concluded that with the effect of insulation applications, which ensure that a significant amount of savings made from the initial investment and operating costs of both heating and cooling systems, only on the heating; the investment required to be made for insulation amortizes itself in 4 years. In buildings which also have cooling systems, these systems can amortize themselves at short notice.

Total heat loss in the uninsulated building is calculated as 79 kW and total heat loss in the insulated building is calculated as 32 kW. The two buildings can be compared as follows in terms of initial investment costs.

Boiler (Heating unit) Costs
Boiler cost in the uninsulated building: $ 2,531
Boiler cost in the insulated building: $ 893
Saving on boiler cost: $ 1,638


Radiator Costs
Radiator cost in the uninsulated building: $ 1,250
Radiator cost in the insulated building: $ 534
Saving on radiator cost: $ 716

Total cost of the heating system
System cost in the uninsulated building: $ 3,781
System cost in the insulated building: $ 1,427
Saving on total system cost: $ 2,354

2.5.2.b) Comparison in terms of operating costs

Necessary fuel amount and cost per year
Fuel cost in the uninsulated building (23413.75 m3 natural gas): $ 4,683
Fuel cost in the insulated building (9993.67 m3 natural gas): $ 2,000
Saving on the operating cost: (13420.08 m3 natural gas): $ 2683

Even if it is assumed that there is no inflation and the fuel price is stable, the payback period will be calculated as 3-4 years. The payback period is approximately 2-3 years when the inflation rate is 5%; the period is 2 years when the inflation rate is 10%.

(Insulation cost - Saving from the heating system)
Saving from the operating costs

3.5 year
Isı Yalıtım Tasarruf
2.5.3 Assumptions:

Assumptions in the calculation are listed as below;

  • 1 m3 natural gas price is assumed as $ 0.2.
  • It is assumed that the heating system is central heating and that it is operated 14 hours a day.
  • External temperature value is -3 C for Istanbul according to TS 2164.
  • Alarko-Carrier catalogues are used in the boiler selection.
  • Demirdöküm panel radiator catalogues are used in the radiator selection.