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The first Bulgarian ‘Association of Flats Private Owners’ in a multi-dwelling residential building successfully completes an energy efficiency refurbishment


The objective of this pilot project was to renovate and maintain a multi-residential building situated in the Zakharna Fabrika housing estate in Sofia, Bulgaria. All of the flats are privately owned by the residents. There were several issues around renovating the building. Not only was the building and its systems in a poor state, another problem was that the owners were low income families that could not afford to pay for the renovation. The variety of interests and priorities for different residents was another issue that had to be dealt with.

Prior to the renovation, the building’s roof was in poor condition, the basement and the external brick walls - almost without plaster - were not insulated and the double glazed windows were in worn-out wooden frames.

Building details

Type of building
Residential, multi-dwelling building

Year built/ Floor area/ Operating hours
The building was erected in 1947 with 1,100m2 living area and 13 flats, all of which are now privately owned.

Heating and cooling installed
District heating

Energy label/ CO2 emissions
After the renovation the building got certificate A according to the Bulgarian certification rating, which has two categories - A and B. All buildings that get an A rating after auditing are released from paying a building tax for ten years. The reference value for certificate A is 121.7KWh/m2/year. The energy consumption of the building was 194.7 KWh/m2/year before the renovation and 105.6KWh/m2/year after it.



The objective of this project was to renovate and carry out follow-up maintenance of the multi-dwelling residential building, overcoming the problems connected with the low incomes of the owners that could not afford to pay for the renovation. The renovation was expected to reduce resident’s energy consumption and improve their comfort.

Key points
The project began in 2004. The following energy saving measures were installed in the building:

- Thermal insulation of the external walls - 0.52 cm
- Water proofing and thermal insulation of the roof – 0.5 cm
- Replacement of the wooden window frames with PVC frames
- Thermal insulation of the basement ceiling
- Improvement of the heating system – balancing and insulation of pipes
- Total reconstruction of the attic floor. Two attic rooms were transformed into small flats. Rent from the tenants of the new flats will help the building owners to pay off the loan used to finance the renovation.


Reason for inclusion as Shining Example
This project was the first attempt to undertake an energy efficiency project for the rehabilitation of a privately owned multi-residential building in Bulgaria. In order to undertake the project, the first ‘Association of Flats Private Owners’ was registered in Bulgaria. The establishment of this association and the strong partnership between the Dutch and Bulgarian housing associations involved in this project were crucial to its success.

Costs &


Costs &


The project cost €52,375 and was financed through a loan from a Netherland’s bank. The 20-year loan was provided at the lowest interest rate available. The monthly payment of the loan is approximately €350, but half of this is paid for from the rent of the two new flats built after the reconstruction of the attic.

There was a 46% energy saving. After the renovation the building got certificate class A according to the requirements of the Bulgarian Law on Energy Efficiency and the corresponding regulations for energy savings.

The energy consumption of the building was:

Heating 162.6kWh/m2/year 60.2kWh/m2/year
Hot water 30.5kWh/m2/year 43.8kWh/m2/year
Total 193.1kWh/m2/year 104kWh/m2/year

Partners details

Partners & Roles
This pilot project for the rehabilitation of Block No. 10 in the Zakharna Fabrika housing estate was initiated and carried out by the Bulgarian Housing Association in partnership with the Housing Association De Nieuwe Unie, Rotterdam and the Housing Association Woondrecht, Dordrecht, both from the Netherlands, in the framework of the “Sustainable Housing Management in Bulgaria; improving the capacity of homeowners associations of multi-family apartment buildings” project financed by Matra Projects Programme of the Netherlands.



_ In September 2003 the idea of the project was presented to the owners of flats from the Zakharna Fabrika housing estate with active support of the local municipal administration. In parallel, neighbouring buildings were assessed for their suitability for the project. After this investigation, the project partners decided to make an offer to the owners of Block No 10 to participate in the pilot project.

_ At the end of 2003 the owners of Block No 10 flats registered the first legal entity of private flat owners in Bulgaria. This entity and the good partnership between the Bulgarian and Dutch housing associations ensured the success of the project. By the end of 2004, the renovation was complete.


The owners of the flats are highly satisfied with the results of the project. The renovation lengthened the life of the building by 40 years. In addition, the insulation of the building envelope led to improved comfort for residents and lower energy bills.

_ The energy audit undertaken before the renovation and the regular monitoring undertaken after the renovation helped to ensure that the project would be a success, with guaranteed, long-lasting results.

Lessons Learned


_ Considering that 97% of residential buildings in Bulgaria are privately owned, there is huge potential for this project to be replicated. There are a lot of residential buildings that need urgent repairs and could be improved to provide greater comfort for residents, lower energy consumption and bills and higher market value of the property. This project can easily be replicated in the neighbouring buildings, as they are the same structurally.

_ This pilot project provides a good example that can be used to encourage and stimulate other owners of multi-dwelling buildings to undertake similar activities in their properties. This successful experience should be broadly promoted, particularly given its wide applicability in the Bulgarian residential building stock and the impact that such activities can have on reducing energy consumption and protecting the environment.

_ The following are some key issues that can help with implementing such projects:

- It is necessary to involve all owners and to organise them into a legal entity
- The costs of the refurbishment can be covered by a low interest, long-term loan. But they can be also be covered, at least partially, by either reconstructing the attic or building an extra floor to create flats and using the resulting rent to contribute to the cost of the renovation. Building such flats should be possible for most multi-residential buildings
- It is important to find financing institutions that are flexible when giving loans for energy efficiency projects. This is important because often the flat owners are on low-medium incomes and this needs to be taken into account by the bank.

Useful info



_ E-bulletin of the Bulgarian Energy Efficiency Network EcoEnergy
issue 3/2004 distributed among all 264 municipalities of Bulgaria
On p. 3, there is an article about the pilot project in Block No 10

To know more



Bulgarian Housing Association

Georgy Georgiev

+359 2 961 13 06



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