Paços do Concelho: smarter and more sustainable – Lisboa Green Capital 2020

Paços do Concelho: smarter and more sustainable

Lisbon is not only Portugal’s capital, but also Europe’s capital in terms of the number of hours of sun exposure. That light that fascinates tourists and residents and turns the city into a magical place, is Lisbon best chance in the transition to renewable energies.

It is thus easy to see the way to go is towardst solar energy. Despite being easy and cheap to implement, only 0.2% of the energy used in Lisbon is solar, revealing a great untapped potential.

However, since 2018 the City Hall building is smarter and more energy efficient. After an intervention, the annual energy consumption decreased by 20%, which was reflected in an annual saving of around 20 thousand euros. Energy costs are currently around 83,000 euros per year.

This adaptation of Paços do Concelho to the principles of energy efficiency took place within the Sharing Cities project. This project, which includes cities such as London, Milan, Burgas, Bordeaux and Warsaw, provides a living example of how public service buildings, in operation, can improve energy performance and still preserve their architectural character.

As the only historic building in Portugal to undergo profound energy efficiency modernisation measures, the completion of this project represents an important milestone in the Sharing Cities programme and a major boost to the Lisboa European Green Capital 2020 adaptation strategy.

According to the most recent data for monitoring the building’s energy performance, savings reached 36% between June 2019 and February 2020, showing that through modernization and the use of renewable energy sources it is possible to be more efficient.

The adaptation interventions were defined according to the regulations for the protected heritage, comfort levels, energy reduction and environmental impact targets.


The set of interventions included:

Energy management – An intelligent computer system (Automated Demand Response) adjusts the consumption of air conditioning equipment according to the energy price and the energy production capacity of the building. The accumulated thermal energy is used, when necessary, in the air conditioning. Energy that is not consumed, mainly at weekends, is later sold to the grid.

Water heating – There are six electric water heaters distributed over the four floors of the building, which provide hot water for the bathrooms and kitchen. Connected to a management platform, their operation is defined according to energy cost, water temperature and photovoltaic production surplus.

Climate control – The building’s climate control is guaranteed by a VRF – Variable Refrigerant Flow system. There are 16 outdoor units, located in a technical area under the roof tile, connected to 58 indoor units. The building also has ten conventional units for the air conditioning of specific spaces such as backstage, IT, police surveillance rooms, telephone operator’s office, among others.

Solar energy – The 60 photovoltaic solar panels installed on the roof of the south wing allow the production of up to 15 KWp of energy, the maximum instantaneous production.

Lighting – At the end of 2018, all incandescent lamps were replaced by LED lamps, which led to a 72% reduction in installed power. Although it meant a greater investment in the purchase of LED lamps, their lifetime is about five to six times longer than traditional ones. Previously, the lamps were changed on average every six months.

The only intervention in the building’s exterior was the renovation of the existing windows, which had significantly deteriorated due to age and exposure to atmospheric elements.

As this is a protected historic building, it was used kambala wood, a harder wood than the original shell wood, which does not absorb water and has a high degree of resistance to fungi.

As the preservation of the frames was not compatible with the installation of double glazing, the original 4mm glass is being replaced by 9mm laminated glass, which is more effective in insulation.

The significant energy savings obtained here represent a high replication potential for other cities, which face the same kind of sustainability challenges, mainly in historic buildings.

The building

Considered one of the most important heritage buildings in Portugal, this neoclassical building houses an incredible central staircase designed by architect José Luís Monteiro and a pictorial decoration by several artists such as Pereira Cão, Columbano Bordalo Pinheiro, José Malhoa and José Rodrigues.

It was originally built according to the project of Eugénio dos Santos at the time of the Pombaline reconstruction of Baixa, after the famous earthquake of 1755. In November 1863 it was completely destroyed by a fire. In 1880 the new building was completed by the architect Domingos Parente da Silva.

In 1996 another fire affected the ceilings and paintings on the first floor. Architect Silva Dias conducted the intervention plan for the recovery of the building, opting to bring the building closer to the initial plan of Domingos Parente da Silva.