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Energy Saving in Buildings

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17 successful interventions in the domestic sector

Energy saving and Average Investment Cost

Program "Saving at home" - Technical specifications

Directives for Energy saving

In Greece, buildings consume 34% of the total energy consumption (2005) with heating representing 61% of the total, cooking 13%, hot water 10%, food preservation 5%, lighting 3%, cooling 2% and other uses 6%.
Applying new technologies in buildings, energy can be use more efficiently combined with occupants’ optimal comfort and quality of internal air.
Government subsidies energy saving programs that include replacement of frames – glass panes, boilers, additional heat insulation etc. Detailed technical specifications and costs are given below.


17 Successful interventions in the domestic sector

1. Refrigerators and freezers consume about 18% of the total electrical energy consumption of households. Refrigerator’s temperature should be carefully set at 7οC and freezer’s one at -18οC. High-energy efficiency refrigerators (energy label A), preferably with separate doors for freezer and deep-freezer, should be used. Never place the refrigerator near a heat source (e.g. cooker, radiator) and make sure that there is enough air space at the back. Do not place hot foods in refrigerator, do not open the door too often or keep them open for too long. Check door’s insulation and defrost the refrigerator often.

2. Periodically check boiler and burner and measure the internal combustion performance.

3. Install a thermostat that allows the continuous operation of heating system. And regulate it at 20οC. For each degree reduced (during winter) or increased (during summer), 7-10% energy saving is achieved.

4. Place the radiators appropriately (e.g. below the window), using heat insulation plates at the back, so that losses due to overheated walls can be reduced.

5. During summer cool internal spaces using ventilation systems, preferably during night hours. Venetian blinds should be used mainly in spaces with south or west orientation.

6. During summertime, roof fans make us feel comfortable up to 30οC. They are economic to use (they simply stir air) and healthy.

7. Choose to have a shower instead of a bath in a bathtub.

8. Heating water using an electric heater requites a lot of energy. Install a solar heater or a boiler with alternator in the boiler room that is heated through the boiler (oil or natural gas).

9. If you insist in using an electric heater, decrease thermostat’s temperature at 50οC and install more than one heater so that you avoid an extensive and often insufficiently insulated, hot water distribution network that supplies kitchen, bathrooms, etc.

10. Cookers using natural or liquid gas consume less energy.

11. Be careful when boiling water and lower cooking temperature appropriately so that boiling is preserved. Boiling is a waste of energy because, no matter.

12. Air ovens - because of the fan – are more efficient in heat transfer. Do not open oven door during cooking. Do not use the oven to warm small quantities.

13. In general, select electric appliances (refrigerator, freezer, washing-machines, air conditioners etc) rated with a high energy performance (energy class A++, A+, A).

14. Do repair maintenance of air-conditioners every 2-3 years, including the exterior unit.

15. Replace common lamps with fluorescence lamps or lamps of low consumption which offer 10-15 times longer duration and 80% less consumption.

16. Prefer natural lighting, when feasible, and paint walls with light colours since they do not absorb luminous radiation.

17. Switch off all appliances using the central switch (ON/OFF) and not the remote control (Stand-by). For facility, connect all appliances to a multi plug so that you can switch off televisions, computers, stereos, etc with one movement. When appliances are in Standby mode, they consume about 10% of their nominal consumption.


Energy saving and average investment cost.

Average investment cost

Energy saving (%)
Detached house-block of flats

External walls heat insulation

33 € / m2

33 - 60

Roof heat insulation

28 € / m2

2 - 14

Double glass panes

160 € / m2

14 - 20

Central heating maintenance

110 €

10 - 12

New central heating

1180 € / Block

15 - 17

Natural gas central heating

1180 €/ Block

19 - 21


290 € / Detached 1500 €/ Block

2 - 3

External shading

20 €/ m2 Shading

10 - 20

Roof fans

20 €/ fan


Solar collectors for hot water

740 € / solar collector

50 - 80

High performance lamps

1 €/ m2



20 € / household

16 - 21

New air conditioners

700 € / air conditioner

65 - 75


Program "Saving at home" - Technical specifications

Until the start of the program they may be some changes in the specifications below.


Certified heat insulator systems for windows are allowed and all products should be certified for their thermal characteristics. Constructors have to apply for the standard hEN 14351-1: 2006/prA1: 2008 (labeling CE for windows).

Indicative Cost: Materials and work cost from 230€/m2 - 280€/m2.



Boilers should have CE labelling and be certified that construction materials do not contain substances, which may damage humans or the environment.
Boilers should use natural gas for future operation.

Oil boilers

Oil boilers should provide CE labelling and use energy saving and low emissions technology.

Gas boilers – gas boilers on the wall

A technical study for gas network installation is required taking into account the Greek legislation and approval of the Gas Company. Laws Ν.3325/2005, ΚΥΑ 4241/796/1-3-2000 apply for the existing natural gas networks.


Circulators should be water fertilized, of high performance, energy class A, with noiseless operation Inverter technology.


Chimneys should. be stainless steel in one-piece, with straight line - frontal welding and no helical configuration. They should have internal insulation of mineral wool. In any case, the materials of insulation and waterproofing should not contain harmful substances to humans and should have CE labelling.

Indicative equipment cost

Oil burners: 25 - 40.000 Kcal/h 480 €
Natural gas burners: 25 - 40.000 Kcal/h 1.150 €
Steel boilers (oil): 30 - 50.000 Kcal/h 800 €
Cast iron boilers: 25 - 40.000 Kcal/h 1.250 €
On the wall gas boilers: 24 kW 1.300 €
Circulators: 20 - 40.000 Kcal/h 270 €
Double stainless, insulated chimneys: Φ 150 180 € /sq meter


Thermal solar domestic systems should have a trials report (Standard EN 12976-2) and a minimal limit of annual energy output of 520 KWh/m2. (in Athens) – A minimum of 5 years guarantee should be also provided.

Indicative Cost for 120Lit : 700 - 850 euros.


The total loss factor for glass panes, U, should be less than 1.9 W/m2 /K and the factor G should be the lowest possible. U and G values should be certified and the equipment should have CE labelling.

Indicative Cost Double glass pane placed in new frame = 90 €/sm.


Covering materials must be reflective for the entire spectrum of solar radiation with a value higher than 0.7 (according to ASTM E 903) certified by a specialized laboratory.


Heat insulating material (or combination of materials with a radiation barrier) should have a minimum factor of thermal resistance R > 2,8 or a combined thickness of at least 10 cm.
The application methods should be according the ΠΕΤΕΠ 03-06-02-03 Heat insulations of tile roofs and ΠΕΤΕΠ 03-06-02-01 Heat insulations of lofts


Exterior heat insulation of ETICS or SET should be according to one of the specifications: EN 13499:2003, EN 13500:200, [PETEP] 03-06-02-04.
Due to the lack of European or National Specifications, the certification ETAG 004 is allowed. Minimum insulation thickness 5 cm (Area A, B) and 7cm (Area C, D).


Insulations should either have CE labeling (P.D. 334/1994, KYA 9451/208 OFFICIAL JOURNAL OF THE HELLENIC REPUBLIC 815/2007) or be according to one of the European models presented in the Official Newspaper of the European Communities.

Indicative Cost For retrospective loft heat insulation: 35€/m2 max. For exterior heat insulation of vertical structural elements: 55€/m2 max.


Directives for Energy saving


Turn off the lights you do not use.

Exploit natural lighting.

Install energy saving lamps

Place time switches for lighting in communal places, or movement control sensors in places periodically used.


Refrigerator - Freezer

Choose appliances of low energy consumption. (Energy class A or more)

Defrost often so that the ice created is less than 0.5 cm.

Do not place the refrigerator or freezer near heat sources, in narrow spaces or in places exposed to solar radiation.

Check regularly the rubber insulation of refrigerator and freezer so that doors close hermetically.


Washing machine - dishwasher

Choose appliances of energy class A or more that can also regulate water consumption. Choose washing machines with separate supply of hot and cold water for a possible use of hot water from e.g. solar collectors.

Regulate the washing temperature from 60oC to 35oC, decreasing energy consumption by 25%. Modern detergents are also effective at low temperatures.

Use the washing-machine when it is full, without overloading it. The overloading minimizes life duration of the engine of the appliance.

Avoid the use of dryers of that consume a lot of energy.

Use the dishwasher when it is full. Select the economic washing program avoiding the presoak of dishes.


Electric cooker

Choose cookers of energy class A.

Make sure that the utensiles are suitably placed on the hotplates, suiting the size of utensile-hotplate. The pots and the utensiles with double walls, decrease the consumption of electric energy by 50-75%.

Avoid the extended warm-up of the oven and the continuous opening of the door during the operation.

Make sure that the door of the booth apllies properly. Replace the rubber if it is required.

Turn off the hotplates or the oven a few minutes before the food is ready so that the remaining heat can be exploited.


Heating - Refrigeration

Regulate the thermostat at a lower temperature during the evening or when you out of building. For every degree lowered you save 1-2% of thermal energy.

Close the fireplace chimney when you not in use.

Open the curtains of south- facing windows during day and keep shutters closed during night.

Reduce heat losses using specific airtight films on frames.

Volatilize radiators to improve their performance.

Check heating installation periodically so its performance is optimum, fuel consumption is decreased, and the equipment lasts longer.

Reduce heat losses using double panes and wall heat insulation.

Limit direct sunlight and consequently cooling charges using the appropriate shadings.

Ventilate internal spaces during night thus reducing cooling charges. Do not ventilate the house when outdoor temperature is high.

Use roof fans in order to improve the sense of thermal comfort and reduce cooling charges.

Adjust the thermostat of air-conditioner at 25-26οC.

Select air conditioners with high-energy performance, thus decreasing energy consumption by 20-50%.

Apply the principles of bioclimatic architecture in new buildings.


Hot water

Prefer showers instead of baths to decrease the hot water use. Limit the continuous flow of hot water.

Limit the hot water required for washing dishes or clothes.

Use solar thermal collectors for hot water production.

Select an electric heater with the capacity you need and regulate temperature at 45-50οC, instead of 60οC.