Case 5: Apartment building, Saue


Case parameters:

Type of construction: Renovation of existing building
Typology: Residential, multistorey
Owner: Private
Construction systems: Lightweight concrete
Location: Estonia, Saue

The challenge we faced

In Estonia, more than 70% of the residents live in apartment buildings constructed before 1990. The majority of those buildings have the same problems: high-energy consumption levels, insufficient ventilation, uneven indoor temperatures, and insufficient thermal comfort levels. The world’s population is becoming increasingly urban and this trend is expected to increase. Demolition of existing buildings and reconstruction with tightened land-use standards for new buildings are not the realistic strategy in Estonia, due to the fact that 82% of the dwellings are privately-owned. Therefore, extensive, ‘deep’ levels of renovation work are required. Possible solutions are the extension of rooftops and living area by closing open balconies, which can eliminate thermal bridges and improve the usability of the dwellings and increase the indoor comfort.

What we did

We realised a deep energy retrofit with the extension of an existing apartment building. The building has a high level of replicability in Estonia and other countries in North-East Europe, being an example of lightweight concrete construction located in Saue, Estonia.

The average primary energy use before the renovation was 211 kW/(m2a). As the indoor climate was insufficient (low ventilation, low temperature), the normalised primary energy use should have been around 274 kW/(m2a) (176 kW/(m2a) for heating). One year after deep renovation the avarage primary energy use was measured to be 93 kW/(m2a) (53 kW/(m2a) for heating). To minimise environmental impact and disturbance to residents, the envelope was constructed in prefabricated modules with maximum locally re-used and recycled materials and locally based bio-based materials. This construction method resulted in a short construction period on sites and occupants were less disturbed. It was more weather-independent as well.

Find the technical drawings (plans, sections, etc) here.

The results we met

We achieved the following results in Estonia:

Case-specific impacts:

  • 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;
  • 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 were 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.