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APROP | Temporary social housing for people at risk to residential exclusion

Created on 09-06-2022 | Updated on 21-06-2022

The APROP project in Barcelona appropriates used shipping containers, transforming the lightweight steel structures through offsite construction into temporary social housing units. The project is the winner of the New European Bauhaus award 2021 within the “Modular, adaptable and mobile living solutions” category; having successfully demonstrated excellence in sustainability, social impact and design.

APROP provides temporary social housing and can be accessed through an official register by low-income households facing eviction as an intermediate solution, before applying for permanent social housing (Ajuntament de Barcelona, 2019a). The pilot project is a mid-rise apartment block located in the Gothic neighbourhood in the city centre consisting of sixteen recycled shipping containers, which were pieced together in just four months on site. The ground floor houses a healthcare centre, above which is situated twelve flats: four 60m2 two-bedroom flats and eight 30m2 one-bedroom homes. The homes are designed to be disassembled with the intention to occupy sites for a maximum period of 5 years, according to the municipality (Ajuntament de Barcelona, n.d.).

From a methodological perspective the APROP system is a form of “tactical housing” that serves people at risk to gentrification. This is achieved through the agile modules that can be quickly installed within infill sites in various urban contexts (such as vacant land and existing roofs) close to the applicant’s neighbourhood of origin. Barcelona’s Municipal Institute of Housing and Renovation (IMHAB) has committed to utilising industrialised housing to increase the public housing stock in Barcelona, having identified several new sites to build additional APROP apartments.

Straddle3, Eulia Arkitektura, and Yaiza Terré

Ciutat Vella in Barcelona, Spain

Project (year)

Construction (year)

Housing type
Mid-rise apartment block

Urban context
City centre

Construction system
Industrialised Construction | off-site construction | recycled shipping containers

Selected option
New building


Innovative aspects of the housing design
The APROP system is based on prefabricated modules, providing dignified dwellings for members of society who have difficulties in accessing housing in a fast and sustainable way. The homes achieve an AA Energy Rating, which the Barcelona Municipality equates to a level of energy consumption four to six times lower than that of a conventional building of the same characteristics (Ajuntament de Barcelona, 2019a). Circularity is integral to the concept of the project, with recycled shipping containers forming the structure, which would otherwise be considered as waste and sent to landfill. In terms of time and cost savings, owing to the dry and lightweight structure the entire building can be disassembled in four weeks are reassembled elsewhere, significantly reducing on-site construction time. APROP has been documented as an exemplary project by the Barcelona municipality and features in the “Innovation in affordable housing Barcelona” and “Barcelona right to housing” reports (Ajuntament de Barcelona, 2018; Hernández Falagán, 2019). Following the announcement of the Bauhaus award, a prize that aims to demonstrate sustainability in alignment with the European Green Deal (European Commission, 2022), Housing Europe declared APROP “an emerging housing model” (Housing Europe, 2021). The project has also been recognised by various other local and international awards (Ajuntament de Barcelona, 2022). The project received a critical response from the UK, with the Guardian news outlet describing APROP as “Sardine tins for the poor” (The Guardian, 2019), highlighting the potential danger of the project being replicated elsewhere to lower standards. In the same article, the principal architect David Juárez from Straddle3 responded "building with containers can bring terrible results unless you really make an effort".

Methodology and research project by ATRI
The project is the result of research carried out by Tactical Accommodations of Inclusive Repopulation (ATRI), an interdisciplinary team consisting of researchers, architects, builders, economists, a lawyer, and a social scientist. The group was initiated in response to a lack of social and emergency housing in the Barcelona region. The project framework formed between the Department of Social Rights, Cooperativa Lacol (the architects responsible for housing cooperative “La Borda”), Bestraten Hormias Arquitectura, and architectural practice Straddle3. ATRI cite the thesis project of architectural scholar Gerardo Wadel from La Salle School of Architecture on Industrialised Construction and sustainability as further theoretical grounding for the APROP system (ATRI, n.d.-b). The methodology crosses disciplines to encompass four key areas: urbanism, architecture, economy, and management. This research culminated into the three main characteristics of an ATRI building: reversibility, being lightweight, and minimising execution time.

Construction characteristics, materials and processes
The architectural team includes three practices; Straddle3 and Eulia Arkitektura in the design stage, and Yaiza Terré for the delivery stage. The prefabricated construction method and modular design strategy are considered as Industrialised Construction (IC). Although the project is based on off-site construction, this did not take place in a factory setting and traditional manual labour (as opposed to robotics) was used (Ajuntament de Barcelona, 2019b). The modules were built over the course of 26 weeks (Ajuntament de Barcelona, 2022) before being transported through the narrow inner-city streets and placed on site within a steel frame using a large tonnage crane. Shipping containers are based on international ISO standards and are designed to universal sizes and can support their own weight whilst being stackable. The lightweight corrugated steel containers used here are “last trip” containers that are easily available in Barcelona, which is a coastal city with a busy Mediterranean port. The apartments themselves integrate underfloor heating to provide efficient thermal comfort for residents, whilst the double skin façade ensures the homes do not overheat. The skin includes a translucent outer layer made from cellular polycarbonate and timber to increase natural daylight. This also serves to visually adapt the building to its context and allows the shipping containers beneath to be visible. Knauf products were used to create a double plate system in the ceilings and partitions for a structural 60-minute fire rating. The modules, façade and roof incorporate dismountable dry joints for disassembly, recycling, and to enable the easy relocation of parts or whole buildings if necessary.

Energy performance characteristics
APROP reduces energy consumption by 25% and greenhouse gas emissions by 54% (European Commission, 2021). The double skin façade, layout, and the use of photovoltaics significantly contributed to the achievement of the AA energy certification. These design decisions had been tested during the design process using energy simulation models and collaboration with an energy and resource efficiency consultancy (European Commission, 2021). Energy is supplied by an aerothermal heat pump that extracts energy from the ambient air, which is more energy efficient compared to conventional methods. Passive design strategies are also incorporated with exterior openings positioned to produce cross ventilation and maximise sunlight during the winter and shade in the summer months. These techniques significantly reduce heating and cooling demands and further improve the energy efficiency performance.

Financial benefits
The APROP Gothic pilot project cost €940,000. The use of recycled shipping containers is reported to have afforded a 10% material reduction in construction costs compared to traditional methods, in addition to cost savings from a much shorter project programme. These savings are referred to as the Pre-Manufactured Value (PMV) in relation to Industrialised Construction methods, as outlined in the Farmer report (Farmer & Thornton, 2021). The APROP system offers the possibility of further cost savings if the project is replicated through economies of scale; plans are already underway for multiple APROP projects in the city to provide permanent social housing in additional to temporary housing. Work on the second pilot project, a block of 42 dwellings in El Parc i la Llacuna del Poblenou, began in January 2022.

Alignment with project research areas

Design, planning & building
The APROP system is based on standardised and transportable modules that are resource efficient through the recycling of shipping containers, which are also dismountable to enable material reuse and relocation. The design methodology facilitates a city-wide strategy for resource efficiency - a concept known as the urban mine – where the transportable modules are treated as a bank of resources to be managed. The system also improves energy efficiency largely achieved through passive design strategies and the double-skin façade.

Community participation
The research group ATRI, who are behind the proposed methodology for APROP, propose working together with the future inhabitants. This is envisaged through participation in the design of common spaces and providing the opportunity to have input on apartment finishes. Dr. Eva Morales (ATRI, n.d.-a) who is a researcher, architect, and expert in participatory processes in collective housing projects, will promote ATRI's aspirations for equality and social integration. This is to be achieved with the assistance of professionals in “Do It Yourself” (DIY) and “Do It With Others” (DIWO) workshops (ATRI, n.d.-c). For this phase, residents will be able to choose from various materials, equipment, and techniques (carpentry, kitchen furniture, cabinets, faucets, lighting, painting, etc.). These solutions can then be implemented with technical assistance.

Policy & Financing
The APROP initiative has been developed through close communication amongst various social agents such as the Federation of Neighbourhood Associations of Barcelona (FAVB), the Technological Institute of Construction of Catalonia (ITeC), and Hàbitat3 Foundation, and has been monitored by the Social Housing Council of Barcelona (CHSB) and the Energy Agency of Barcelona. There has also been input and international collaborators based in Amsterdam and Munich. The APROP programme is currently being expanded by the Municipal Housing Institute of Barcelona (IMHAB). A deal with the European Investment Bank (EIB) is set to provide funding for the construction of eleven additional social housing blocks around the city, providing 489 homes. According to council this project has a budget of €36.2 million, which may be extended up to €65 million (Ajuntament de Barcelona, 2021).

Alignment with SDGs

The APROP project is directly related to the following Sustainable Development Goals (SDG):
GOAL 1: No Poverty – Providing a decent standard of living and quality of life.

GOAL 3: Good Health and Well-being – A clean and safe living environment.

GOAL 6: Clean Water and Sanitation – Dwellings with access to clean drinking water and bathroom facilities for each home.

GOAL 7: Affordable and Clean Energy – Passive design reduces energy consumption alleviating fuel poverty and the use of photovoltaics and aerothermal heat pumps rather than fossil fuels.

GOAL 8: Decent Work and Economic Growth - The project will create over 570 jobs per year during the construction stage.

GOAL 9: Industry, Innovation and Infrastructure – A resilient construction system that promotes inclusive and sustainable industrialisation whilst fostering innovation.

GOAL 10: Reduced Inequality – Housing to populations that would potentially otherwise be homeless.

GOAL 11: Sustainable Cities and Communities – Making cities more inclusive through anti-gentrification solutions.

GOAL 12: Responsible Consumption and Production – Ensures sustainable consumption and production patterns through circular economy principles.

GOAL 13: Climate Action – Fast solutions to combat climate change and its impacts through the recycling of shipping containers with a short construction time.

GOAL 17: Partnerships to achieve the Goal – Long term partnerships between council departments and funding for planned future projects.

The SDGs which are not directly connected are:
GOAL 2: Zero Hunger GOAL 4: Quality Education

GOAL 5: Gender Equality

GOAL 14: Life Below Water

GOAL 15: Life on Land

GOAL 16: Peace and Justice Strong Institutions


Ajuntament de Barcelona. (n.d.). APROP. Retrieved March 14, 2022, from

Ajuntament de Barcelona. (2018). Barcelona Right to Housing Plan 2016-2025.

Ajuntament de Barcelona. (2019a). First APROP temporary homes in Ciutat Vella ready to tackle the housing emergency.

Ajuntament de Barcelona. (2019b). Primer edifici APROP al Gòtic.

Ajuntament de Barcelona. (2021). European funding to create more housing with affordable rents.

Ajuntament de Barcelona. (2022). Building gets under way on the second APROP provisional local housing block.

ATRI. (n.d.-a). Collaborative Design with Future Users. Retrieved March 14, 2022, from

ATRI. (n.d.-b). Construction Systems with an Ecological Perspective. Retrieved March 14, 2022, from

ATRI. (n.d.-c). Construction Systems with an Ecological Perspective. Retrieved March 14, 2022, from

European Commission. (2021). New European Bauhaus: APROP Summary Information.

European Commission. (2022). Questions and Answers on the 2022 New European Bauhaus Prize.

Farmer, M., & Thornton, J. (2021). Pre-Manufactured Value-Cast Technical Manual.

Hernández Falagán, D. (2019). Innovation in affordable housing Barcelona 2015 -2018.

Housing Europe. (2021). An insight into the New European Bauhaus winner, APROP.

The Guardian. (2019). Sardine tins for the poor?: Barcelona’s shipping container homes.

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