Retrofit of existing apartment block

Saue, Estonia Construction and Development, Environment and Resource efficiency



In Estonia, more than 70% of the residents live in apartment buildings, constructed before 1990. The majority of those buildings have the same typical problems: high energy consumption levels, insufficient ventilation, uneven indoor temperatures, and insufficient thermal comfort levels. Therefore, a pretty extensive, or ‘deep’ level of renovation is required.

The world’s population is becoming increasingly urban and this trend expected to increase. Demolition of existing buildings and reconstruction with tightened land-use standards the new buildings are not the realistic strategy in Estonia, due to the fact that a total of 82% of dwellings are privately owned. Therefore, it is clear that extensive, ‘deep’ levels of renovation work are required.

The rooftop extension could be a solution to renovation cost efficiency in dense urban environments, and the reuse of existing constructions and stock sites.

Another possibility is the extension of the living area by enclosing the original open balconies. Well enclosed and insulated balconies can eliminate thermal bridges and improve the usability of the dwellings and increase the comfort of living.

Issues tackled

We will realize a deep energy retrofit with the extension of an existing apartment building. The existing apartment building has a high level of replicability in Estonia and other countries in North-East Europe. An example lightweight concrete construction multistory apartment building locates in Saue, Estonia (constructed <1990, net area ~2400m2, exact location to be defined with housing corporation). The current average primary energy use is 211 kW/(m2a). As the indoor climate is insufficient (low ventilation, low temperature), the normalized primary energy use should be around 274 kW/(m2a) (176 kW/(m2a) for heating). To minimize environmental impact and disturbance to residents, the envelope is constructed in prefabricated modules with maximum locally re-used and recycled materials and locally based bio-based materials. This construction method results in a short construction period on sites and occupants will be less disturbed. It is more weather-independent as well.


Expected results and impact in Estonia:

– Deep energy renovation with prefabricated modules with re-used and recycled materials and based bio-based material and building integrated renewable energy technologies

– Extension of the service life of building

– Improved living comfort and IEQ for the occupants achieved by means of the insulated building envelope, moisture safety control, and user-centric operation and management building systems. Balanced ventilation with heat recovery where ventilation pipes are integrated into modular additional insulation elements. The bio-based heat source for heating and domestic hot water

– Rapid improvement of occupants’ operational costs for the occupants, coupled with a minimization of the renovation time

– Increased speed, simplicity, safety and satisfaction for the manufacturers and on-site crew installers in the phase of connection of the integrated systems to the existing building envelope

– Improvement of real estate value for the owners through the extension of flat area to balconies. Improvement of the cost-effectiveness of renovation by additional story extension

– Profit from a higher degree of product and process industrialization, to minimize the impact on the occupants, combined with a remarkable visual exposure and innovation identity of retrofit intervention at city neighbourhood level

– The increase of renovation design accuracy, while reducing construction-associated risks supported by 3D scanning and geomatics technologies to reconstruct the actual geometry of the existing building. BIM and CAD-CAM techniques are utilized in renovation elements and fixing component designing and manufacturing

– Demonstration of the effectiveness and replicability of the proposed solutions to lead to an increased rate of renovation for defined building typologies in several districts/cities/regions in North-East Europe.