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Torrelago district case from H2020 STUNNING project

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The project STUNNING aims at building up a stakeholder community around a Renovation Hub designed as a knowledge sharing platform, providing information on innovative solutions for building renovation and novel business models for their adoption and large scale replication.


The provided solutions involve affordable and adaptable refurbishment packages, taking into consideration the whole renovation value chain.


STUNNING’s Renovation Hub and knowledge sharing platform is open to various European renovation stakeholders, allowing them to get engaged with the STUNNING community and provide or obtain information on refurbishment solutions. It also a source of learning case studies.


Among the STUNNING case studies, we find the Torrelago district, which is an apartment block built between 1977-1981.


Torrelago district involves 31 private multi-property residential buildings (1488 dwellings) that were constructed in the 1970s–1980s, more than 140,000 m2 and 4000 residents involved.


Former conditions of the district were very low in terms of efficiency, comfort and costs, which fostered the intervention.


Main energy measures implemented at the building scale are buildings external insulation (Composite System-ETICS, ventilated façade), connection to district heating (twelve new heat exchange substations at building level), individual metering to raise users’ awareness.


Refurbishment package


This package provides a comprehensive thermal insulation of a building and includes the following components:

  • Roof insulation, using either an insulation panel/roll or a spray foam under the roof. External roof insulation is also possible (i.e. built-up roof insulation under waterproofing)
  • Energy efficient windows (double or triple glazing)
  • Floor insulation
  • Wall insulation, in this case with an External Thermal Insulation Composite System (ETICS)


Techniques: External Thermal Insulation Systems (ETICS) can be applied in two ways:

  • insulating materials (glued or screwed to the wall) protected by coating
  • Insulating materials protected by cladding. In that case the insulating panels are installed on a frame fixed to the wall. An air gap is maintained between the external cladding and the insulation


The application of ETICS ensures a continuous thermally insulated envelope, however the big number (~10/m²) of fasteners crossing the insulation (if this technique is used) can raise an issue of thermal bridging, unless thermally decoupled fasteners are used.


Reduction of thermal bridges in concrete balconies: The slab acts as thermal bridge, which results in heat losses and potential formation of condensation and mould. The balcony can be cut-out to remove this bridge.


The slab can be partially cut – in which case thermal breaks are inserted between the balcony and the wall, or completely cut which requires the creation of a self-bearing structure.


As double or triple-glazed windows will be more airtight than the original single-glazed frames, condensation can build up in the building due to the reduced ventilation.


If there is not a sufficient level of background ventilation in the room, replacement windows should therefore have trickle vents incorporated into the frame, that let in a small amount of controlled ventilation.


Energy performance: thanks to the renovation package, the consumed primary energy for heating, cooling, ventilation and DHW passed from 138 kWh /m² to 89 kWh /m², enabling a saving of 35% from the initial situation.


SWOT analysis of the renovation packages



  • Excellent thermal properties of the insulation, which can be adjusted to climate and regulatory requirements
  • Different available materials, including bio-sourced ones (hemp and sheep wool, timber framed Windows)
  • Easy to implement
  • Low cost solution
  • Common retrofitting solution, well established in building codes and with extensive references
  • Benefits in terms of acoustic comfort



  • The installation of insulation and Windows shoul be handled with care to ensure the quality of the implementation, reduce the risk of condensation or draughts.
  • On-site safety during construction phase of ETICS : Risk of burning and spreading during construction phase, when plaster is not yet applied
  • Duration of works, disturbance to building occupants and neighbours
  • Embodied energy
  • Composite System with synthetic materials and potentially hazardous substances – difficult for recycling
  • In case of fire: toxic gases and smoke (depending on the insulation material)
  • Need biocides and herbicides to avoid alga, and fungi



  • Suitability to new thermal regulations
  • Important market in Europe
  • New insulation materials more environmental-friendly than EPS



  • Compliance with fire regulations (e.g. phase out of flame retardant HBCD by mid-2015 in Europe)
  • EPS and XPS meet growing criticism (with regard to hazardous substances and combustibility)
  • Compliance with future building codes

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