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

Created on 09-06-2022 | Updated on 05-12-2022

The APROP project in Barcelona appropriates used shipping containers, transforming the lightweight steel structures through off-site construction into temporary social housing units. The project won 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 Ciutat Vella, situated in the city centre, is the first pilot project by the Municipal Housing Institute of Barcelona (IMHAB), which embraces Industrialised Construction to provide more affordable and sustainable housing that is faster to build. The APROP programme provides low-income households facing eviction with temporary social housing as an intermediate solution that can be accessed through an official register, before applying for permanent social housing (Ajuntament de Barcelona, 2019a). The pilot project is a mid-rise apartment block providing 12 dwellings built from 16 upcycled shipping containers, which were pieced together in just four months on site. There are two types of units: four 60m2 two-bedroom homes and eight 30m2 one-bedroom homes, whilst the ground floor houses a healthcare centre. The units 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 programme is a form of “tactical housing” that serves people at risk of 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 rooftops, close to the applicant’s neighbourhood of origin. Following the success of the Ciutat Vella pilot project, IMHAB has committed to expanding the APROP programme and have already identified several new sites to build additional APROP apartments and this year completed the second project in the Poblenou neighbourhood.

Straddle3, Eulia Arkitektura, and Yaiza Terré

Barcelona, Spain

Project (year)

Construction (year)

Housing type
multifamily housing

Urban context
City centre

Construction system
Industrialised Construction and prefabricated unit modules



Innovative aspects of the housing design/building

The APROP design and construction system is based on prefabricated modules, providing dignified and energy efficient dwellings for members of society who have difficulties in accessing housing. 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 upcycled 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 municipality and features in the “Innovation in affordable housing Barcelona” and “Barcelona right to housing” reports (Ajuntament de Barcelona, 2018; Hernández Falagán, 2019). The architectural team includes three practices: Straddle3 and Eulia Arkitektura in the design stage, and Yaiza Terré for the delivery stage. 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). Although APROP is built to the same building standards as conventional housing in Barcelona, it received a critical response from a UK newspaper article (The Guardian, 2019), which raised concerns over the danger of lowering standards in the quality of housing if replicated elsewhere. Re-purposing shipping containers to provide housing has become an established industry in many countries but can typically lead to poor thermal and acoustic performance if it is not done well. This was highlighted in the same article by the principal architect David Juárez from Straddle3, who asserted that "building with containers can bring terrible results unless you really make an effort".


Methodology and research project by ATRI

The APROP programme is the result of research carried out by Tactical Accommodations of Inclusive Repopulation (ATRI), an interdisciplinary team supported by the Barcelona municipality that consists of 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 was 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 on Industrialised Construction and sustainability as further theoretical grounding for the APROP programme (ATRI, n.d.-a; Wadel, 2009). 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 prefabricated construction method and modular design strategy are characteristic of Industrialised Construction. Although the project is based on off-site construction, this did not take place in a factory setting and traditional manual labour was used (Ajuntament de Barcelona, 2019b). The prefabricated modules were transported through the narrow inner-city streets and placed on site within a steel frame using a large tonnage crane. The lightweight corrugated steel containers used were “last trip” containers that are easily available in the coastal port city of Barcelona, meaning the amount of embodied carbon to transport the containers was more minimal compared to further inland locations. Shipping containers are based on international ISO standards and are designed to universal sizes and can support their own weight whilst being stackable. Therefore, making changes to the structure to provide openings for doors and windows compromises their structural integrity and requires additional structural support. Considering the need to scale up production of the programme and the need to modify the structure, the construction system could potentially be modified in the future to use steel beams and columns formed from recycled material, rather than reusing steel in the form of shipping containers.

The apartments 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

The project team claim APROP housing 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 were 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 reuse of shipping containers is reported to have resulted in 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

The interdisciplinary collaboration of stakeholders in the design, community participation, and policy and finance aspects of the programme have been crucial to the successful delivery of the Ciutat Vella pilot project. As the project is ultimately a top-down solution to emergency housing, the project most relates to Design, planning and building and Policy and financing rather than Community participation.


Design, planning and building (Highly related)

The APROP construction system is based on standardised and transportable modules that become more resource efficient through the upcycling 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. High energy efficiency is achieved through passive design strategies and the double-skin façade.


Community participation (Minimally related)

The APROP project is a top-down solution to provide emergency housing, which did not include the direct involvement of future residents. Despite this, the project demonstrated inclusivity with a five-day free exhibition about the project prior to its construction in 2018, which was promoted in collaboration with architecture cooperative Lacol (2018). The public exhibition included a full-scale one-bedroom and two-bedroom unit which were showcased in an outdoor space, complimenting a film screening and talks about the design and aspirations of the project.


Policy and financing (Highly related)

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. The APROP programme is currently being expanded by IMHAB and 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).

Design, planning and building

Community participation

Policy and financing

* This diagram is for illustrative purposes only based on the author’s interpretation of the above case study

Alignment with SDGs

The APROP project is directly related to the following Sustainable Development Goals (SDG):


GOAL 3: Good Health and Well-being – A living environment designed to provide optimum comfort.

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 9: Industry, Innovation and Infrastructure – An innovative and resilient construction system that promotes inclusive and sustainable industrialisation.

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 – Reduction in embodied carbon with the reuse of shipping containers.

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


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). Construction Systems with an Ecological Perspective. Retrieved March 14, 2022, from

ATRI. (n.d.-b). 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.

Wadel, G. (2009). La sostenibilidad en la arquitectura industrializada: la construcción modular ligera aplicada a la vivienda [Universitat Politècnica de Catalunya].

Related vocabulary

Design for Dissassembly

Industrialised Construction

Area: Design, planning and building

Design for Disassembly (DfD), also referred to as Design for Deconstruction or Construction in Reverse, is the design and planning of the future disassembly of a building, in addition to its assembly (Cruz Rios & Grau, 2019). Disassembly enables the non-destructive recovery of building materials to re-introduce resources back into the supply chain, either for the same function or as a new product. Designing buildings for their future disassembly can reduce both the consumption of new raw materials and the negative environmental impacts associated with the production of new building products, such as embodied carbon. DfD is considered the “ultimate cradle-to-cradle cycle strategy” (Smith, 2010, p.222) that has the potential to maximise the economic value of materials whilst minimising harmful environmental impacts. It is therefore a crucial technical design consideration that supports the transition to a Circular Economy. Additional benefits include increased flexibility and adaptability, optimised maintenance, and retention of heritage (Rios et al., 2015). DfD is based on design principles such as: standardised and interchangeable components and connections, use of non-composite products, dry construction methods, use of prefabrication, mechanical connections as opposed to glues and wet sealants, designing with safety and accessibility in mind, and documentation of materials and methods for disassembly (Crowther, 2005; Guy & Ciarimboli, 2008; Tingley & Davison, 2011). DfD shares commonality with Industrialised Construction, which often centres around off-site prefabrication. Industrialising the production of housing can therefore be more environmentally sustainable and financially attractive if building parts are produced at scale and pre-designed to be taken apart without destroying connecting parts. Disassembly plays an important role in the recovery of building materials based on the 3Rs principle (reduce, reuse, recycle) during the maintenance, renovation, relocation and reassembly, and the end-of-life phases of a building. Whilst a building is in use, different elements are expected to be replaced at the end of their service life, which varies depending on its function. For example, the internal layout of a building changes at a different rate to the building services, and the disassembly of these parts would therefore take place at different points in time. Brand’s (1994) Shearing Layers concept incorporates this time aspect by breaking down a building into six layers, separating the “site”, “structure”, “skin” (building envelope), “services”, “space plan”, and “stuff” (furniture) to account for their varying lifespans. DfD enables the removal, replacement, and reuse of materials throughout the service life of a building, extending it use phase for as long as possible. However, there is less guarantee that a building will be disassembled at the end of its service life, rather than destructively demolished and sent to landfill.

Created on 18-10-2023

Author: A.Davis (ESR1)


Area: Design, planning and building

Industrialised Construction, also referred to as Modern Methods of Construction in the UK (Ministry of Housing, 2019) and Conceptueel Bouwen (Conceptual Building) in the Netherlands (NCB, n.d.), is a broad and dynamic term encompassing innovative techniques and processes that are transforming the construction industry (Lessing, 2006; Smith & Quale, 2017). It is a product-based approach that reinforces continuous improvement, rather than a project-based one, and emphasises the use of standardised components and systems to improve build quality and achieve sustainability goals (Kieran & Timberlake, 2004).  Industrialised Construction can be based on using a kit-of parts and is often likened to a LEGO set, as well as the automotive industry's assembly line and lean production. Industrialisation in the construction sector presents a paradigm shift, driven by advancements in technology (Bock & Linner, 2015). It involves both off-site and on-site processes, with a significant portion occurring in factory-controlled conditions (Andersson & Lessing, 2017). Off-site construction entails the prefabrication of building components manufactured using a combination of two-dimensional (2D), three-dimensional (3D), and hybrid methods, where traditional construction techniques meet cutting-edge technologies such as robotic automation. Industrialised construction is not limited to off-site production, it also encompasses on-site production, including the emerging use of 3D printing or the deployment of temporary or mobile factories. Industrialised Construction increasingly leverages digital and industry 4.0 technologies, such as Building Information Modelling (BIM), Internet of Things, big data, and predictive analysis (Qi et al., 2021). These processes and digital tools enable accurate planning, simulation, and optimisation of construction processes, resulting in enhanced productivity, quality, and resource management. It is important to stress that Industrialised Construction is not only about the physical construction methods, but also the intangible processes involved in the design and delivery of buildings. Industrialised construction offers several benefits across economic, social, and environmental dimensions. From an economic perspective, it reduces construction time and costs in comparison to traditional methods, while providing safer working conditions and eliminates delays due to adverse weather. By employing standardisation and efficient manufacturing processes, it enables affordable and social housing projects to be delivered in a shorter timeframe through economies of scale (Frandsen, 2017). On the social front, Industrialised Construction can enable mass customisation and customer-centric approaches, to provide more flexible solutions while maintaining economic feasibility (Piller, 2004). From an environmental standpoint, industrialised construction minimises waste generation during production by optimising material usage and facilitates the incorporation of Design for Disassembly (Crowther, 2005) and the potential reusability of building elements, promoting both flexibility and a Circular Economy (EC, 2020). This capability aligns with the principles of cradle-to-cradle design, wherein materials and components are continuously repurposed to reduce resource depletion and waste accumulation. Challenges remain in terms of overcoming misconceptions and gaining social acceptance, the slow digital transformation of the construction industry, high factory set-up costs, the lack of interdisciplinary integration of stakeholders from the initial stages, and adapting to unconventional workflows. However, Industrialised Construction will undoubtedly shape the future of the built environment, providing solutions for the increasing demand for sustainable and affordable housing (Bertram et al., 2019).

Created on 09-11-2023

Author: C.Martín (ESR14), A.Davis (ESR1)


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Solar Decathlon Competition and LCA | Secondment with UPV

Posted on 27-10-2022

Leading up to the summer I completed my first secondment of three months at the Universitat Politènica de València (UPV), which was conveniently only a three-hour journey south along the Spanish coast from my host institution in Barcelona.   Life in Valencia involved drinking copious amounts of horchata (a local drink made from tiger nuts called Xufa) and enjoying Jardin del Turia, a park that was once a river which today hosts attractions such as gardens, sports facilities, and futuristic cultural buildings designed by architect Santiago Calatrava. I had the pleasure of working with my co-supervisor Ignacio Guillén and Life Cycle Assessment (LCA) expert Alberto Quintana Gallardo, Ph. D. in the department of Applied Physics. Together they provided excellent support with my plans to investigate housing projects from this year’s Solar Decathlon competition and to learn and apply LCA to built case studies during my stay.   As my project investigates Design for Disassembly (DfD) – in addition to Industrialised Construction – the Solar Decathlon competition was an exciting and unique opportunity to observe the disassembly and reassembly of sustainable homes, including the Spanish entry from team Azalea at UPV. As a former practicing architect where I worked with sustainability consultants who normally carry out LCA’s, I was also very eager to learn how to actually do an LCA myself.   Solar Decathlon So what is the Solar Decathlon competition? It is an international competition where teams from universities build prototype homes known as ‘House Demonstration Units’ (HDU) that showcase the best in innovation and energy efficiency using renewable energy. Although the design aspect of the competition focusses on minimising operational carbon, the build challenge requires teams to first construct their HDU at a site in their home country, disassemble it, then transport and reassemble it in only two weeks at the competition site, also known as the Solar Campus. This means designing for disassembly is integral to the competition, making it a fantastic opportunity to study how housing can be more resource efficient over the building life cycle and understand practical building issues.   The competition and reassembly of the houses took place this year in May at the Solar Campus in Wuppertal, Germany. The 16 teams that made it to the build phase heralded from the Netherlands, France, Sweden, Romania, Czech Republic, Turkey, Taiwan, Germany itself, and of course Spain.   I seized the opportunity to observe and ask questions about the disassembly process, the reassembly process, and carry out interviews with each of the Solar Decathlon teams. When I arrived at UPV at the start of May, Team Azalea from UPV had finished building their HDU called the Escalà project on campus and had just held their inauguration event. Over the first two weeks of my secondment, I visited the house every day whilst it was slowly disappearing as it was taken apart and loaded onto five trucks headed to Germany, where the team would shortly reassemble it all over again! During this time, I got to know the team members who had bonded immensely during the intense competition period until this point. Before heading to Wuppertal myself, I was able to pilot interview questions covering technical and environmental sustainably aspects of the project with the Azalea team, as well as remotely with the SUM team from TU Delft.   The energy at the Solar Campus in Wuppertal was palpable as the teams were busy reassembling their HDU’s, each had an internal floor area of around 70m2 to give an idea of scale. I quickly got to know each of the projects and schedule interviews with the 16 teams, who kindly volunteered their time during the middle of the hectic reassembly period before the houses were judged and opened to the public. I managed to interview 13 teams on-site (the remaining teams were later interviewed online), including participants from different fields and both students and professors. Each team had a unique solution to the brief which called for either vertical and horizontal extensions or in-fill proposals. It was not only insightful but a pleasure speaking with true pioneering experts in housing designed for disassembly. Now’s time to complete the analysis of all that data!   Check out my Instagram highlights of SDE-22 for some on-the-ground footage.   LCA Life Cycle Assessment (LCA) is an increasingly popular methodology and decision-supporting tool used by industry professionals and scholars to measure and compare the environmental impacts of buildings (European Commission, 2010). An LCA can be used to calculate Whole Life Carbon (WLC), which includes both embodied carbon from all the materials, processes, and transport to construct buildings and the operational carbon produced whilst a building is inhabited. WLC assessments are crucial to set environmental targets to decarbonise our building stock. There is currently a big knowledge gap around LCA amongst architectural practitioners and other stakeholders involved in the delivery of housing, partly due to the time-consuming nature of LCA’s. An LCA can be calculated simply with an excel spreadsheet or using various online platforms and plug-ins such as OneClick LCA, but amongst scholars more heavy software is called for, such as SimaPro – which is was what I would be learning to use whilst at UPV. My aim here was to carry out cradle-to-cradle LCA’s of case studies to quantify the benefits of DfD and the consideration of different lifespans for different parts of the building.   Work began on the first case study of a house designed and delivered by my co-supervisor Ignacio Guillén called Edificación Eco-Eficiente, or ‘EEE’, this was awarded a Class A energy rating and was the first single-family home in Spain to achieve the maximum VERDE* rating of 5 leaves. EEE was built using Industrialised Construction and prefabricated 2D elements that were assembled on-site in only 19 days. I was also able to visit the house on the UPV campus, though due to security reasons it can’t be used as a living-lab, which is a shame as it could provide some great in-use data on energy efficiency!   Using Simapro was (and still is) a steep learning curve with an incredible amount of precise and technical information that needs to be included. Imagine having to enter every single built element manually into a software, and not just modelled 3D objects but also coatings such as the surface area of zinc needed to galvanise steel, the grouting between tiles… the list goes on. Needless to say, LCA is an invaluable tool and will contribute greatly to my doctoral research project.     ¡Hasta pronto! I will be seeing my colleagues in Valencia again next month for the VIBRArch conference held by UPV to present my ongoing work on LCA. My secondment was invaluable in learning new skills and creating connections, particularly through the Solar Decathlon competition that I am continuing to follow up. Thank you to everyone at UPV, the Azalea team, and Solar Decathlon participants who provided such positive experiences and research opportunities!      *VERDE is a sustainability certification developed by Green Building Council Spain     Bibliography   Solar Decathlon Europe Competition website and knowledge platform with previous year’s entries   Team Azalea’s Instagram page and website   London Energy Transformation Initative ‘LETI’ provide an excellent embodied carbon primer for further reading on Whole Life Carbon     References European Commission. (2010). ILCD Handbook - General Guide for Life Cycle Assessment: Detailed Guidance (1st ed.). Publications Office of the European Union.  

Author: A.Davis (ESR1)



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