Challenge / Goal
One third of Europe’s housing stock was built between 1950 and 1970. By refurbishing these older buildings using new construction techniques, energy consumption can be reduced by up to 75 percent. Within the Grow Smarter project, Naturgy has implemented retrofitting actions with the aim of lowering the energy consumption of buildings in nearly 20,000 m2 of residential floor in Barcelona: Canyelles, Ter, Lope de Vega and Melon District.
Passive measures aim to solve typical problems of the Mediterranean climate such as thermal discomfort due to cold bridges and lack of insulation:
1. Façade insulation, roof insulation
- External Thermal Insulation Composite Systems (ETICS) are incorporated into the façades, as part of the building’s structural rehabilitation. For roof insulation, the use of external or internal solution depends on the construction solution chosen.
- External thermal insulation helps reduce heating demand and to improve the internal comfort in winter. In summer, eternal insulation reduces heating of the façade caused by solar irradiation and prevents heat dispersion from inside to the exterior. It is also important to use natural ventilation and avoid direct sunlight, using solar protection systems.
- Furthermore, external insulation reduces cold bridges more easily than internal insulation.
2. Change of windows and removal of cold bridge between window and façade
- In the buildings where windows have been replaced, the principal requirements were:
- Double glazing, transmittance U < 2W/m2K, solar factor g < 0,6, to improve thermal insulation and reduce solar transmission
- Thermal break, to solve the cold bridge
- Air permeability class 3 (UNE EN 12207), to reduce infiltration
- Special requirements for wind resistance and water resistance have been included for windows in high buildings.
3. Blinds installation
- Control direct solar transmission inside the dwelling, reducing cooling demand.
- Reduce thermal discomfort at night during the winter, providing additional protection to the window glass.
- Adjustable roller blinds provide further benefits: changing the orientation of the slats can better control the transmitted solar radiation, ensuring that natural ventilation cools the dwelling effectively.
Active measures aim to reduce consumption and emissions, by using more efficient systems and/or renewable energy:
1. Change of boilers
2. Connection to district heating
3. Efficient water taps
4. HEMS (Home Energy Management System) installation to monitor and control energy (gas and electric) consumption. The components for gas and electric monitoring and control are:
- Smart home automation centre
- Smart thermostat
- Smart Plug (control of consumption and on/off).
- Energy monitor
- Sensors and actuators for monitoring gas consumption through low-range RF technologies.
In Canyelles, 32% of dwellings participated in the substitution of old boilers and shading elements were installed. In Melon District, the building was connected to local DH network, which is not widely used in Barcelona.
Want to learn more about the lessons learned, financial details and results?
Naturgy, construction company, City of Barcelona
Naturgy, construction company
Owners of dwellings
Decreasing energy consumption in buildings,
Improving energy usage efficiency,
Reducing energy bills,
Increasing share of renewables,
Improving life quality,