Barcelona, the second-largest city in Spain, has committed to achieving climate neutrality by 2030. Given that buildings account for over 40% of its energy consumption, the city identified residential retrofit as a priority for emissions reduction. In June 2025, the municipal housing agency IMHAB and the Bithabitat Foundation released the Guide for Decarbonising Building Rehabilitation, one of the key outcomes of Spain’s multi-city Pilot Activity, URBANEW. This strategic document offers precise criteria, tools, and institutional pathways to scale up low-carbon renovations across the city’s housing stock.
Beyond setting technical criteria, city agencies provide municipal support functions, funding systems, and stakeholder engagement to enable matrixed action on retrofit. It anchors retrofit in long-term housing strategy, notably Plan Viure 2026–2032, and integrates equity, governance, and systems coordination.
Practical Technical Blueprint
At the heart of the initiative is a catalogue of 30 retrofit measures, covering building envelope, systems, nature-based solutions, and user-driven interventions. The measures are mapped to five strategic objectives: energy efficiency, circularity, resilience, health, and biodiversity. Unlike many city guides, Barcelona’s framework goes beyond energy metrics to include embodied carbon and long-term material performance. For example, it promotes natural insulation materials (wood fibre, cellulose), passive cooling, and dry assembly techniques that support reuse and minimise demolition waste.
This lifecycle lens positions decarbonisation as a full-system retrofit challenge, rather than simply an energy upgrade. Each intervention includes performance rationale, co-benefits, and potential integration into modular retrofit workflows.
Centralised Assistance via the Municipal Renovation Office (ORM)
The ORM consolidates grant management, permits, technical guidance, and stakeholder liaison. Between 2022 and 2025, it has served over 50,000 residents, processed €28 million in NextGenerationEU funding, and hosted professionals from architecture, legal services, and social outreach units. In addition, neighbourhood-specific offices also operate in urban regeneration priority areas, such as the Besòs i el Maresme Urban Regeneration Office.
Multi-level Grant System
Barcelona has developed a layered grant structure to support retrofit action at different scales. At the building level, homeowners and associations can access subsidies covering up to 80 % of renovation costs, tied to certified energy improvements. At the neighbourhood level, additional grants are targeted at vulnerable areas, such as Raval and Besòs Maresme, where energy poverty and poor housing conditions intersect. Citywide innovation grants also support more complex or experimental interventions. This structure encourages project developers to integrate social and environmental outcomes while navigating funding through a centralised process.
Pilot Projects and Living Labs
When launched, the guide was accompanied by a technical workshop at Ca l’Alier. Participants, from public officials to architects, tested modular façades, smart glass, heat-recovery systems, and green roof prototypes. These pilots function as design labs and as demonstration platforms to build skills and confidence. The guide links these innovations to specific technical measures, such as pre-insulated wall panels, integrated shading, or green façade modules, creating a real bridge between strategy and delivery.
Digital Tools and Knowledge Exchange
Existing and future mapping tools (massive rehabilitation viewer) enable users to visualise building stock, energy performance, and retrofit potential. These tools help users, renovators, and planners make data-based decisions.
Embedded Equity and Governance
The guide and grant system prioritise vulnerable populations, aim to reduce energy poverty, and align with Plan Viure’s social inclusion mandates. Institutional coordination across IMHAB, IMU, urban planning, and sustainability services ensures alignment from housing access to ecological impact.
What were the key drivers of the initiative?
- Climate-neutral mandate and EU backing: Integration into the NetZeroCities framework and access to NextGenerationEU funds provide clear direction, resources, and align retrofit with broader objectives.
- Institutional collaboration: The joint production of the guide by IMHAB and Bithabitat, along with ORM’s integrated operation, simplified citizen access to support and maintained consistent messaging.
- Investment in demonstration and professional momentum: The living-lab model helps contractors evaluate novel retrofit strategies and tools like smart windows or prefabricated façades.
- Local and political legitimacy: Mayoral support and anchoring in Plan Viure align retrofit with city planning, heritage preservation, and equity goals.
- Attention to urban vulnerability: Financial incentives are geographically targeted to areas most in need, making retrofit part of both climate and social resilience.
What were the challenges and barriers?
- Complex funding and administration: Multiple grant streams and shifting EU regulations require strong coordination to manage eligibility, disbursement, and monitoring.
- Technical capacity constraints: Deep retrofit relies on contractors with advanced skills. The living-lab format helps, but scaling skill development remains a bottleneck.
- Awareness and uptake: While grants address costs, uptake depends on effective outreach. Homeowners and associations may lack the bandwidth to navigate the application process.
- Continuity beyond 2026: NextGenerationEU funding will taper off, requiring budget planning and mainstreaming until 2030.
- Regulatory friction: Aligning retrofit with heritage protections and planning restrictions requires adaptive governance and professional mediation.
Key lessons learned
Barcelona’s framework offers valuable lessons for cities aiming to integrate climate and housing goals through retrofit systems that are technically sound, socially equitable, and institutionally robust:
- Translate standards into action: The guide’s specificity transforms ambition into practice.
- Simplify through institutional coordination: One-stop support via ORM reduces the friction of multi-stakeholder funding and regulations.
- Use pilots to build trust and technical capacity: Demonstrations train professionals and validate solutions before scaling.
- Embed retrofit in broader city strategies: Aligning decarbonisation with housing policy secures political and budgetary stability.
- Prioritise equity from the start: Targeted grants ensure retrofit supports resilience in vulnerable neighbourhoods.
- Build feedback loops: Digital tools and living labs allow adaptive learning, helping the guide evolve and maintain relevance.
Potential for replication
Barcelona’s experience offers a replicable roadmap for cities aiming to scale housing decarbonisation in line with climate neutrality targets. Rather than inventing isolated tools, the city has demonstrated how to align standards, finance, governance, and capacity-building into a cohesive system. Key to this is clarity, both in technical guidance and institutional responsibilities. The combination of practical measures, targeted funding, and one-stop municipal support offers a model that other local governments can adapt to their contexts.
Cities seeking to replicate this model should focus on four pillars: (1) setting actionable standards for retrofit, (2) simplifying access to funding through integrated offices or service platforms, (3) building partnerships across housing, sustainability, and innovation departments, and (4) embedding equity into grant design and area prioritisation. With growing national and EU support for building renovation, Barcelona’s approach shows how cities can lead by structuring the retrofit ecosystem to be transparent, inclusive, and impactful over the long term.
Header Photo: zenilorac, CC BY 2.0, via Wikimedia Commons