SESTAO: New outfit for Txabarri Street

Interview with Luis Carlos Delgado, Managing Director of SestaoBerri and leader of Sestao’s EU-GUGLE pilot district.

In Sestao, five buildings have been selected to participate in the EU-GUGLE Smart City Initiative for energy-efficient building refurbishment. In April, renovation was completed in the first of these buildings. Luis Carlos Delgado, Managing Director of SestaoBerri explains the renovation process.

What are the characteristics of the first building refurbished in the framework of the EU-GUGLE project in Sestao? 

Our first building, located in Txabarri street, has a surface area of 4,300m² and included 47 dwellings. The building dates back to 1890, so it had a nice listed façade, but also an ageing wooden structure, no insulation… and no heating system at all other than for domestic water!

Why was it important to renovate this building in particular?

The building is located at the heart of a district suffering from 25% unemployment and a range of other social difficulties that have started to emerge with the decline of the old industrial infrastructures that used to be the main drivers for economic growth. The building itself was in very bad shape, yet it had a listed façade and was still partly occupied. Additionally, the heating demand (75.6 kWh / m2) and CO2 emissions (48.1 kgCO2/m²) of the building were significant. For these reasons, it was decided to make it a symbol of the district’s renewal strategy.

The building before the refurbishment
The building before the refurbishment


What was done to improve the building’s energy efficiency? What are the different measures that have been implemented?

The building went through a very ‘deep’ renovation to achieve nearly-zero energy standards. The interior of the building was mostly demolished and replaced with a timber frame structure to increase stability and optimise space (5 apartments were added). Recycled cotton materials and rock wool were used for internal wall insulation, while two biomass boilers (160Kw and 60Kw) have been installed to cover the building’s needs in terms of heating and hot water. Additionally, electrical appliances in the apartments were replaced with A+ energy rated appliances and new elevators using an energy recovery system were installed. To reduce water consumption, a greywater recirculation system was also added to the toilets. Finally, a new ventilation system with heat recovery was installed in the building, thus further improving its energy performance (and the indoor air quality for its tenants!). Of course, the façade could only be insulated partially from the outside, but the windows were replaced and the façade itself restored to its original state.

Sestao After
The building after the refurbishments.


What were the challenges you had to face before and during the refurbishment work?

Technically, the main challenge was of course to preserve and restore the façade while the inside of the building was being essentially demolished, but this challenge was expected from the beginning. What we did not anticipate was that a fire would break out in the building last October, damaging part of the façade and the roof. But damages were limited: at the cost of a short delay, some burnt insulation was replaced and part of the roof repaired.

Nevertheless, the main challenge was the human factor. Before any work could be considered, the tenants still inhabiting the building had to agree to move temporarily into a nearby building during the works. Additionally, some apartments had to be sold because tenants could not afford to pay for the renovation work, even with the help of the subsidies. Since the structure of the building was going to be altered, former tenants who could afford the renovation would nevertheless not return to their old apartment, but rather to a new one, potentially with a different living surface and orientation. This is not something one necessarily thinks about when planning renovations but it is actually a lot to ask from tenants, even if you promise a new, better apartment. This was overcome through constant dialogue with the tenants, insisting on the benefits of the renovation. But it still took a lot of convincing skills!

How will you monitor the benefits in terms of energy efficiency?

We have installed individual electricity counters as well as thermostats that enable tenants to visualise their energy consumption. At building level, of course, we will have a monitoring phase, but it is not complete yet. The data monitored will include hot and cold water consumption, heating, electricity consumption and indoor air quality. At the end, we expect 60% energy savings compared with the situation before renovation.

Interior from one of the refurbished apartements


What are you particularly proud of? What would be your advice to other cities interested in engaging into a similar renovation process?

User engagement was clearly the main success factor in the process. If we had not involved tenants in the planning phase (and managed to convince them of the benefits of a renovation), we probably could not have launched this project. It is absolutely necessary to take into account the concerns but also the desires of the people living in the building when even just considering a renovation of such scale. It was very hard work, but it was worth it and now it is really satisfying to see that everyone is pleased with the results and that tenants are at ease in their new homes.