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How factory-led retrofit is being deployed across 1960s apartment stock in Hagen.
Berlin-based Ecoworks is applying an offsite-led methodology to one of Europe’s slowest-moving construction segments: the upgrade of ageing residential buildings. Its latest project in Hagen, North Rhine-Westphalia, provides a clear example of how serial refurbishment is being deployed at scale. (main image: Render of the Hagen scheme, illustrating the proposed façade upgrade and external treatment delivered through Ecoworks’ serial renovation system.)
The scheme covers twelve apartment buildings from the 1960s, totalling approximately 15,000 square metres and 192 dwellings. The objective is not redevelopment, but performance improvement — lifting the buildings to Germany’s KfW 55 efficiency standard while enabling a pathway towards net-zero operation.
Serial refurbishment as a delivery model
Ecoworks operates as a general contractor, but its approach aligns more closely with offsite construction than conventional retrofit. The process begins with digital modelling of the existing buildings, allowing façade geometries and structural conditions to be captured and translated into standardised components.
That modelling is informed by detailed digital surveys of the existing structure, typically using laser scanning to capture façade geometry and dimensional tolerances. This allows prefabricated elements to be manufactured to fit buildings that were not originally designed for systemised construction.
These components are then manufactured offsite. Prefabricated façade modules are delivered with insulation, windows and integrated systems already installed. Roof elements are produced to accommodate photovoltaic arrays, while balcony structures are designed as add-on systems rather than bespoke site-built elements.
By shifting up to 80–90 per cent of construction activity into the factory, the model reduces reliance on site-based trades and compresses installation programmes. On-site work becomes a coordinated assembly process, with limited internal intervention required. For occupied buildings, this reduces disruption and allows refurbishment to proceed without large-scale decanting of residents.
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Measured outcomes in Hagen
The Hagen project provides a practical indication of how the model performs. The upgraded building envelope, combined with rooftop photovoltaic generation, reduces final energy demand by around 36 per cent. Annual emissions savings are estimated at approximately 190 tonnes of CO₂, reflecting the combined effect of improved thermal performance and on-site energy production.
The system also supports incremental improvements to the buildings themselves. Existing loggias are replaced with larger, covered balconies, and ventilation strategies are updated through decentralised systems that integrate with the prefabricated envelope.
More broadly, the project reflects a shift in how refurbishment is being approached in Germany. With renovation rates below one per cent per year and a large proportion of housing stock requiring upgrades, traditional site-led methods have struggled to scale. Rising costs and labour constraints continue to limit delivery.
Serial refurbishment, as applied by Ecoworks, attempts to address those constraints through standardisation and manufacturing. By treating existing buildings as repeatable inputs rather than one-off projects, the approach introduces a level of predictability more commonly associated with new-build offsite construction.
The Hagen scheme indicates how refurbishment can be structured in a similar way, combining digital capture, prefabricated systems and controlled installation sequences to support delivery at volume.
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