Dear Hossein. There is an ongoing discussion in RG (See below) on the "ways to reduce energy intensity" with particular reference to the case of Iran. Some answers there (discussions and comments, too) are related to your question.

Back to you question, you can follow the following link to find out 10 Ways to Reduce Energy Use and Costs in Your Building.

http://www.greenbiz.com/research/tool/2010/09/01/10-ways-reduce-energy-use-and-costs-your-building

https://www.researchgate.net/post/What_are_the_ways_to_reduce_energy_intensity

http://www.greenbiz.com/research/tool/2010/09/01/10-ways-reduce-energy-use-and-costs-your-building

Reduce energy consumption needs reducing energy used at home, work, and for transportation. One important way to reduce energy consumption at home is to choose energy efficient appliances for heating and cooling when you replace old appliances.

• Insulating your roof or ceiling will help keep your home a pleasant temperature in summer and winter.

• Draught-proof: Make sure doors and windows are properly sealed..

• Avoid installing downlights — besides using a lot of energy, they penetrate the ceiling and insulation, causing heat loss.

• Close all external windows and doors when your heater or air conditioner is running.

• Shade your windows during hot summer days (to keep the heat out) and during cold nights (to keep the heat in).

• When you expect a hot day, turn on the air conditioner early, rather than wait until your home is hot. Similarly, start heating early when expecting a cold day.

• Ceiling fans are much cheaper than air conditioning and have less impact environmentally, though they don’t cool the air, only move it about to produce a breeze.

• If you have an air conditioner, try to use it only on really hot or humid days. Look for programmable timer and thermostat controls. Set your air conditioner at the highest temperature setting at which you still feel cool enough, 25ºC is usually adequate. Each 1°C increase of the thermostat setting will save about 10% on your energy usage.

Read more at the link:

http://www.choice.com.au/reviews-and-tests/household/energy-and-water/saving-energy/five-ways-to-reduce-your-households-energy-use.aspx

Dear Hossein Harimi . There is another way. Try to build a "Smart Home" !. The main objectives of making a smart home from the view point of energy management and efficiency solutions goals are::

- Reduce residential energy consumption by smart controllers and by improving the public knowledge.

- Develop and use green and renewable energy sources like solar and wind.

- Use energy storage solutions like battery rooms to flatten the load profile.

Some solutions that are applicable (or already applied) to smart homes in each of the above fields and a review of the development process of each technology in Iran is presented in the attached paper..

[1] Nesary Moghadam, M. and H. Taheri. Electrical Design of 21st Century Smart Homes. PDF is attached.

Dear @Hossein, the primer from Serbia. "In order to contribute to global initiatives for reducing energy consumption through energy efficiency increase, Serbia has adopted a set of related national regulations and invested in several large energy-efficient refurbishment projects targeting the sector of public buildings. Efficient energy use means simply using less energy to provide the same level of service." The article is attached!

Buildings energy efficiency resources are given by second link!

http://www.rehva.eu/publications-and-resources/hvac-journal/2012/062012/energy-efficient-refurbishment-of-public-buildings-in-serbia/

http://www.rehva.eu/publications-and-resources/eusew-2014-report/buildings-energy-efficiency/?L=0%2527

Some good examples and papers related to this thread, regarding Serbia, are attached! EVALUATION OF ENERGY EFFICIENCY MEASURES APPLIED IN PUBLIC BUILDINGS (SCHOOLS & HOSPITALS) IN SERBIA ,IMPLEMENTATION OF ENERGY EFFICIENCY POLICY IN REPUBLIC OF SERBIA, Results of Serbian Energy Efficiency Project (SEEP) – first phase. Hope it will be helpful! 

http://www.doiserbia.nb.rs/img/doi/1450-569X/2009/1450-569X0920001S.pdf

http://iet.jrc.ec.europa.eu/energyefficiency/sites/energyefficiency/files/files/documents/events/ee_policy_in_rs_-ws_jrc_jun_2013.pdf

http://www.energy-community.org/pls/portal/docs/558187.PDF

The new ways, to reduce energy in buildings, are really still ideas which have not been moved into applications on a significant scale. There have been suggestions for modifications in the design of buildings so as there can be less costly & more efficient cooling (during Summer) & heating (during Winter). Too much work needs to be done on improving materials of construction of buildings, insulators, heat exchangers, and appliances used within houses. Currently & globally, there is too much wastage of energy & less saving in this respect .  

with reduce the ways that energy is lost

Architecture design of the building will be in such a way that will provide enough light and wind. Use of more no. of switches (use separate switch for each equipment) it will save energy but also create Power quality problem. Rooftop solar can also be used for a building. Don't use higher capacity tube-lights. (if you need 36W Tube-light use two tube-lights in parallel connection).

https://www.theguardian.com/sustainable-business/reduce-buildings-energy-consumption