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Zaragoza is together with Lyon one of the 2 cities involved in the RENAISSANCE project, part of the Concerto Initiative. The project involves El Picarral, an existing community in need of building refurbishment and urban re-generation, and Valdespartera, a new community. Both are linked by the integrated political commitment of all actors and a common set of performance criteria.


Site facts and figures

The 80,840 m2 of buildings involved in the project are leading to an emission reduction of 2,831 tons CO2/year.

  • Estimated population involved: Information will follow
  • Approx. geographical area coverage: 8 ha
  • Approx. energy saving: exp. 70%
  • Approx. energy from RES: over 40%



At Valdespartera several apartment blocks have been built as so-called „Bioclimatic Buildings“. Block number 12 comprises 164 dwellings of 16,950 m² in total and has a solar thermal system of 165 m². Number 17 with almost the identical size (164 dwellings and 16,892 m²) also has a solar thermal system of 165 m². Each building is connected to a 80 kW gas heat pump for cooling. The heat pump has a collective refrigeration system, connected to the new PV system on the roof, which shall provide the power for the compressor  systems.

Number 13 has 144 dwellings with a total floor area of 14,659 m² and thermal collectors with 180 m². At number 18 there is the same number of dwellings, the floor area is 15,525 m² and the solar thermal panels have 144 m² in total.

The Exhibition Centre, named “CUS - Centro de Urbanismo Sostenible” (Sustainable urban planning Centre), with a total floor area of 1,543 m² was opened in June 2010 (Picture 1). It is equipped with a wood fuel boiler (48.5 kW) and a geothermal reversible water-water heat pump (45 kW).

At El Picarral social housing dwellings have been retrofitted. The public school “Cándido Domingo” (6,000 m²) – also situated at El Picarral -  has been retrofitted and an 18 kWpeak photovoltaic plant was installed on the roof. On a building at “Anzanigo“ street solar thermal collectors of 23.4 m² and on a building at  „Yagüe“ street of 14 m² have been installed.


High Efficiency Cooling at Valdesparata Apartment Building

Fifteen owners (out of 96) have contracted with the ESCO for the installation of a high efficiency cooling facility so far (Picture 2 + 3). At the current state the installation consists of 80 kW cooling application (along with 25 kW of heat recovery used for domestic hot water); it is expected to reach 160 kW of cooling (with 50 kW heat recovery for DHW). The residents’ community has contracted the maintenance of the complete thermal facility (heating, cooling and hot water).

The savings achieved due to the efficient cooling system have been 61.8% of natural gas for domestic hot water preparation in 2011. The consumption – including losses in the distribution system – has been 69.7 kWh/m³ (kWh gas per m³ of heated water) instead of 182.6 kWh/m³ in 2010. Taking into account the 15% increase in the price of natural gas and the larger consumption of hot water in summer 2010, economic savings for the community between May and October amounted approximately to 5,000 Euros. That is approximately 4 times of the costs for air conditioning (gas for heat pumps). The gas heat pumps have consumed 1,147 m³ of natural gas in summer 2011, equivalent to 24,476 kWh (based on higher heating value). The invoice paid by the residents is 0.053 Euros per kWh (taxes included), which amounts to 1,297 Euros of gas for air conditioning.


CUS Exhibition Centre

The “Sustainable Town Planning Centre” (CUS in Spanish) is a new prestigious space in the city of Zaragoza, in which the results of the sustainability measures executed in the Valdespartera Eco-City will be disseminated in a general context of Sustainable Town Planning (Picture 4+5). The building itself is supposed to be a “model” of sustainability based on the efficiency of its installations and a “portal” for energy saving bio-climatic techniques applied to town planning. The building and its surroundings have included a large number of innovative technologies and energy appliances: geo-thermal energy with heat pump and radiant floor, biomass boiler, cooling by buried piping, system of absorption for refrigeration.

The building is shaped like a trapezoid block, has a floor area of 1,543 m² and comprises 6 levels, which are connected by a ramp that descends smoothly from the rooftop. The surface area of the building envelope is 1,353 m².


Lessons learnt

The following information has been gathered as part of the CONCERTO Premium policy research.

Benefits of CONCERTO:

Key benefits:

Town planning rules have been changed as consequence of CONCERTO regarding refurbishments. The knowledge transfer with the CONCERTO-Project in Lyon was positive. EU projects in general can leverage and mobilise science, public administration etc..

Other benefits:

Final outcomes are very good and provide a model for replicable, affordable projects. The RENAISSANCE project in Zaragoza has proven that significant savings are achievable and that housing planned with bioclimatic characteristics can achieve spectacular results. RENAISSANCE offered a new opportunity to boost and improve other aspects not yet studied. This project has been a booster for following a path towards more sustainable construction models.


Barriers encountered:

Legal barriers:

Ancient laws were not adapted to new situation, such as the “Horizontal ownership Law”.

Planning instruments were not adapted to low-energy renovation, they needed to apply compulsory standards such as those for new buildings. The installation of lift was a core part of future proving the retrofitted buildings, but these encroached on public space. Hence special planning permission had to be obtained to extend into public space.

Technical barriers:

Three reasons for excess energy-consumptions could be identified: construction problems, maintenance, and user behaviour. Inefficient design and improper maintenance combined with excessive use of heating leads to excessive losses (46,3 %). The analysis carried out shows that heating needs correspond to 42.6 % and DHW to 11.1 %. Better control during the construction process and after occupation is required. Training for technicians and monitoring facilities are necessary to ensure optimum efficiency. Furthermore, limitations for feeding in wind power were encountered, due to grid balance issues. The solution was a new goal of self-sufficiency/ grid independence.

Economic barriers:

Private investors/ people could only receive assistance after the work was done, contrary to another CONCERTO project in Tudela, where all subsidies were arranged up-front. The project in Zaragoza happened slightly later than that in Tudela and therefore was hit harder by the financial crisis. The economic crisis is dissuading investors to invest, particularly in the building sector. Even though consent has now been obtained from many owners in the neighbourhood of El Picarral for

proceeding with refurbishment of further blocks of flats, it is currently not possible for them to obtain the required bank loans of about EUR 10000 per household.

There is a cost control system for social housing that makes additional investments for energy measures hardly possible.

Social barriers:

Generally, a demotivated society, lack of communication, reluctance to change, poor awareness on environmental issues was found. Therefore, Good practices poster, where environmental, economic and comfort related benefits can be visualized, were developed. The use of social networks and mass media articles about the neighbourhood allowed reaching a greater number and diversity of users. Additionally, it was very important that users received a real time electricity monitor to check out how energy is used in the housing.

It was challenging to change the role of the inhabitants, from a passive one, as a plain information-receptor, to a proactive one, who is able to provide information and to change his or her habits. Solutions therefore were the following:

Coordinated work between the working group for socio-economic studies and the working group for monitoring allowed tracking of housings appliances and interaction with inhabitants; Carrying out activities as close to people as possible achieved good results for data collection; user training and high participation of neighbours (streets and children oriented activities were carried out at the same time). Collaboration of the project team with agents working for the same objectives (e.g. the City Council) meant joining up of efforts, synergies, exchanges of learning, leading to more creativity and effectiveness for designing the work methodology. At the level of the neighbourhood,, working with a great number of different groups has been key to promote the project and obtain acceptance within the community.


Success factors identified:

Technical Success Factors:

Aggregated information on building groups, through the designing and implementing of a real time monitoring system with over 200 control points for housing allows the evaluation of the different architectural solutions as well as of the daily energy habits of people living in the area. This constitutes a key point for planning information and environmental public awareness on this field. Furthermore, site visits were carried out by RENAISSANCE experts to check for potential air leaks or poor insulation. Infrared images and blower door tests revealed some defects that were corrected. A control of renewable energy systems to identify defaults in installation and maintenance was carried out.

Social Success factors:

CONCERTO added value: A new social acceptance on bioclimatic construction with the result of a local ordinance including green mobility (tram and bikes) and training activity. Intensive engagement with residents of the refurbishment projects was instrumental.

Institutional success factors:

A political consensus is necessary on construction, energy saving and efficiency politics. In the municipal framework it is important to boost political changes that affect private property using and urban planning approach. It is necessary to implement environmental criteria in urban plans and general regulations on construction and refurbishment. Zaragoza Vivienda (a municipal housing agency) was very pro-actively involved in the Picarral refurbishment process. Assistance to neighbour communities in their decision process was given with the selection of materials for the refurbishment works.


Business models used:

An ESCO (URBIC) has been used to deliver sustainable heating and cooling using a heat pump and to optimize operation and maintenance for 20 flats (+ 20 in future). URBIC has financed installations costs over a 5 year term, including a guarantee for the same period. Furthermore, Two municipal companies have been created for developing the two projects in the CONCERTO demonstration: ECOCIUDAD VALDESPARTERA ZARAGOZA PLC., (a joint venture funded with both, public and private participation) and Zaragoza Vivienda, responsible for social housing, for El Picarral district refurbishment.


Legacy – follow-on projects:

“Taking as a starting point this demonstration action, we have the possibility of using this knowledge and experience in every municipal building and equipment, a task we are right now focusing on.” In el Piccaral, there is scope to roll out the refurbishment concept trailed on a few buildings across the area, subject to solving the difficulties surrounding the required bank loans.


Legacy - Policy Developments

The master plan used in Valdespartera received national recognition as pioneering development and was deemed suitable for replication. A series of agreements were made between Ministry for Housing, the Government of Aragon and the City of Zaragoza to develop a renovation program for low-income and vulnerable housholds in Zaragoza, based on the pilot experience in Picarral. There was a certain influence of the Zaragoza experience in Valdespartera and Picarral on national policy improvements. The CONCERTO results have allowed the City of Zaragoza to endorse on 24 July 2009 the “Municipal Bylaw on Energy Eco efficiency” and “Use of Renewable Energy in Buildings and its Facilities”, and the “Municipal Bylaw on Rehabilitation” on 25 June 2010. Zaragoza now has a regulating and legal tool requiring every new building and comprehensively refurbished dwelling in the municipal area to comply with guidelines on energy saving, energy efficiency and use of renewable energy. This is a landmark municipal regulation as it is only through collective community decisions and behaviour that a better, sustainable, use of resources can be obtained.

The CONCERTO approach

The common objective involves a bioclimatic approach of social housings, with high energy-efficiency criteria, in order to have an impact on the whole urban fabric. Socio-economics research should enable us to better understand the perception and the social acceptance linked to innovative techniques and the habits to have.

The Sustainable Town Planning Centre main objective is to advocate and promote energy policy. It organises as well exhibitions as seminars and provide the inhabitants with training sessions. It enables also to advise them regarding their energy consumption thanks to the monitoring of a significant share of the constructed or retrofitted dwellings under the project. The experience of the “Colegio Domingo” (Public School) refurbishment is disseminated through specific trainings.


Researchers are setting-up an innovative model of ESCO (Energy Service COmpagny) that may become an exemplary model all over Europe.

RES in the Zaragoza RENAISSANCE community supplies over 40% of the total energy demand. Poly-generation involves a small scale 50kW bio-mass system providing power, heating and cooling integrated with a solar thermal based cooling system included in the Valdespartera interpretation centre.

In Zaragoza the demonstration area aim is to show how energy savings can best be achieved with a limited budget in social housing. Intervention is expected in wall and roof insulation and glazing replacement.


José A. López
Universitad de Zaragoza (UdZ)

Thematic Field

  • New Building(s)
  • Refurbished Building(s)

Exhibition centre

View more visualisations of RENAISSANCE Site Zaragoza