Project name: Rannaliiva

Location: Võru/Estonia, Liiva 26a

Owner: Apartment association “Rannaliiva”

Built in: late 80's

Site and building description

  • 16 dwellings in one building with 2 floors
  • Every apartment has a different owner
  • Including the following dwelling typologies:
  • 8 one-bedroom flats, 4 two-bedroom flats and 4 three-bedroom flats.
  • Size overall living area: 1307 m2 net area
  • Built in late 80's

BIM and Point Cloud Models

Existing heating ventilating and Cooling facilities

  • Energy Performance: 270 kWh/m2.year Energy for heating and domestic hot water (DHW)
  • The existing solution of heating and DHW is based on District Heating, produced with heat exchanger. District heating provided by private company. Source of energy is biomass, price, 66 EUR/MWh, a bit lower than Estonian average.
  • Type of ventilation: Natural ventilation. An exhaust done by ventilation tubes, no mechanical ventilation system used. Natural infiltration, thus heat losses are very large and the air quality is poor.
  • None of the buildings have onsite generation facilities (RES, CHP). The electricity supply to the buildings of the district is solved through connection to national electric grid

Construction characteristics

Facade/external wall (U value [W/m2.K])Clay brick and light blocks. U=0,8 W/m2.K
Roof (U value [W/m2.K])Stainless roof (Insulated), U=0,8 W/m2.K
Windows (U value [W/m2.K] and g-value)Double-glazing with wooden frame, U= 2,5W/m2.K
External shading device typePlaster, plasterboard, wood (up to owner)

Building Retrofitting during the RenoZEB Project


The intervention on the envelope of the building to be refurbished will include the complete façade. The façade solution to be installed will be externally insulated with the developed multifunctional solution with the thickness of insulation material necessary to provide a U value of 0,18 [W/m2K]. At the same time, this solution will contribute to increase the air tightness of the façade and to reduce the energy loss associated to infiltration.

Additionally, all the windows of the building will be substituted by RenoZEB windows with high performance low emissive glazing. The deployed triple glazing windows solution will provide the following thermal and optical features:

  • U value: less or average of 1,0 [W/m2.K],
  • g value: 0,6
  • Light transmittance: 0,7
  • The material of frames will fulfil all the applicable norm and regulations in relation to its thermal performance.

Ventilation Type

The RenoZEB low invasive ventilation system will be deployed to provide heat recovery (minimum energy efficiency of 80%). Thanks to the multifunctional facade solution the ventilation ducts will be fully integrated in the facade providing optimal insulation of the ducts. This will enable minimizing the energy loss of the ducts up to negligible values.

Heating And DHW Production Facilities

The heating system of the buildings will be replaced with a new one. The main effect of this is that temperature in apartments can be balanced out and temperature differences between apartments can be avoided. The other effect is developing a system for the hot water. This will help reduce the additional costs for hot water that is today produced by local electric boilers. Old heat exchangers in boiler rooms will be removed and new ones will be installed. Similarly, old piping will be replaced. At the same time, a system for smart metering and regulation will be implemented.

Control Systems and Energy Metering

In order to allow the efficient operation of energy consumption metering system will be installed. The system will include the necessary energy meters required to measure the thermal energy consumption of each dwelling in order to enable accurate system cost allocation to inhabitants.

Expected Energy Demand Reduction

According to the analysis, with the implementation of the designed retrofitting measures reductions of 60% for energy consumption and primary energy respectively.

Other demo cases

Durango - SpainLaubideta 6 built in 1965
Bilbao - SpainKUBIK - full-scale R&D test facility

Contact information

Project coordinator:

Solintel, Spain
Michele Vavallo