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Ombú is a transformative office building built for the Spanish infrastructure and energy company ACCIONA. This retrofit project breathes new life into a historic industrial building in Madrid, creating a sustainable exemplar of building reuse and revitalising the surrounding area. With over 10,000 square metres of new office space, the project unifies a unique mix of private and public land with green landscaping that extends to the adjoining Méndez Álvaro station.

Originally built in 1905 by the architect Luis de Landecho, the building once supplied energy to the surrounding areas. It later fell into disuse until ACCIONA acquired it in 2017, saving it from demolition, a fate that other similar structures in the area had experienced in recent years. The project capitalises on the existing load-bearing structure that supports the pitched steel trusses. The historic building envelope has been retained to conserve over 10,000 tonnes of original brick and mitigate the environmental impact.

The lightweight structure inserted inside the space is made from sustainably sourced timber from local forests and allows for spatial flexibility, while also integrating lighting, ventilation and other services. The timber structure will save more than 1,600 tonnes of CO2 and is recyclable and demountable. A central skylight brings natural light to the interior, reducing the need for artificial lighting, while the glazing incorporates photovoltaic technologies that generate electricity.

Taking advantage of Madrid’s temperate climate, a new courtyard offers the option to comfortably work outdoors. The courtyard connects to a large 12,400 square-metre park with 350 trees featuring outdoor working spaces and areas for informal meetings sheltered by a green canopy of trees. Local species have been carefully selected to reduce water consumption, which will come from local sources. The new green, public space connects the building with the surrounding community and generates a positive social impact. Located in the lively Arganzuela district, Ombú also benefits from direct access to rail and bus networks, encouraging employees to travel by public transport.

One of the most sustainable projects by Foster + Partners, the project was presented at COP26 in Glasgow as a case study for the World Green Building Council. Its environmental impact is compatible with the original 2°C aim of the Paris Agreement and its carbon footprint has been carefully measured and controlled. The design reduces embodied carbon by 25 percent when compared to a new build over the whole life of the project, while making allowances for future refurbishment. The operational energy is calculated to be 35 percent below normal expectations.

Using the concept of ecological footprint, the life cycle impact of the project was quantified and improved across all aspects of the development. When contextualised in terms of planets the result was approximately equal to 1. This means Ombú’s carbon emissions will be absorbed by the capacity of the earth, achieving the balance of sources and sinks required by the Paris Agreement.

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