Flokk’s partnership with Hydro adds new dimension of sustainability to HÅG Celi

Flokk’s partnership with Hydro adds new dimension of sustainability to HÅG Celi

Flokk’s design collaboration with aluminium experts Hydro combines cutting edge recycling technology with innovative furniture design, resulting in a chair with the lowest carbon footprint possible

For decades, Flokk has been on a journey to create increasingly environmentally conscious furniture. Using recycled materials is a crucial aspect of this approach, conserving natural resources whilst reducing waste, energy usage and carbon emissions.

When designing the HÅG Celi, early on aluminium was singled out as a key material for many of the components. In order to ensure the lowest environmental impact possible, Flokk teamed up with aluminium industry experts to truly revolutionise the way Flokk uses this highly recyclable material. Working with Hydro, we were able to create the perfect blend of high strength, low weight, low carbon footprint components for this latest HÅG design.

Watch below – Flokk & Hydro on making the HÅG Celi


Hydro is one of the world’s largest aluminium producers and manufacturers of extruded aluminium components and solutions. Founded in Norway, they currently operate in over 40 countries, pushing the boundaries of high-quality recycled aluminium, drastically reducing their carbon footprint. Aluminium can be recycled endlessly without losing its properties. It is the perfect example of a circular economy material.

There are many different aluminium alloys commonly used in manufacturing, with hundreds of slight variations to improve certain characteristics. Historically, sorting post-consumer scrap aluminium – aluminium that has already been used in other applications, then discarded, such as window frames – has been too difficult to do in large enough quantities to be economical. As a result, they are all recycled together, with primary aluminium brought in to dilute the mix to a consistent level.


Hydro addressed the recycling issue by investing in ways to accurately sort scrap aluminium. Their state-of-the-art sorting facilities in several locations across Europe are equipped with the most advanced technology available. Each location is set up to take different types of scrap, from drinks cans to window and door frames reclaimed from building demolitions.

This scrap feeds through a series of shears, shredders and magnets to produce weed out non-metal parts and produce a consistent material flow. In the most advanced facility, this flow passes through an x-ray transmission machine that can accurately detect and eject unwanted alloys using an array of synchronised air jets. The chips then pass through a de-lacquerer before melting and recasting. Each facility produces 100 tonnes of sorted aluminium chips a day, allowing Hydro to provide high-quality recycled aluminium on an industrial scale.

This unique process enables Hydro to create CIRCAL, one of the world’s most sustainable aluminium alloys available with a post-consumer recycled content minimum of 75% – resulting in an extremely low carbon footprint.

Watch below – How Circal is made


The next stage on the journey from scrap to new product is where Flokk and the HÅG Celi come in. Early on, the design team behind the HÅG Celi identified aluminium as the best material to use for the legs and frame, and Hydro as the perfect provider. Working together, Flokk and Hydro identified the key characteristics the aluminium components would require, and began to explore the various aluminium alloys they could use. This process relies on the decades of research and experience conducted by Hydro, which has been compiled into their signature modelling program called Pro3.

Speaking about the collaboration, Morten Kildahl, Senior Project Manager at Flokk says, “We initially evaluated several concepts for the frame of the chair, looking for solutions and materials that would minimize our environmental impact, while at the same time answering our demands for visual design, durability, and industrialization. It became clear that a welded construction from extruded aluminium would tick all the boxes. Welding aluminum was however a new production process for us at Flokk, so the cooperation with Hydro was crucial in optimizing the design of the extruded profiles for this process”

PRO3 is an innovative methodology that has been developed for optimization of product properties, production costs, and environmental impact (e.g CO2 footprint) in fabrication of aluminium alloys (see Figure I). The PRO3 software utilises mechanical models in combination with physics-based, ranging from meter to atomic level (see Figure III), which can predict the impact of adding various alloying elements into the mixture.

The process begins with the Flokk design team providing models of the aluminium components and the minimum requirements of various properties, including weight, strength, and carbon footprint to name a few (see Figure II). The program will then run simulations of hundreds of alloys available, providing all the data to select the best material that meets the requirements. It is a delicate balancing act, with an increase in one property likely to affect another, to find the right compromise, including potential reshaping of the parts.

Once the optimum recipe has been identified, the components are ready to be produced. Hydro uses extrusion, where a cast log of aluminium (known as a billet) is heated to approximately 500 degrees, before being passed through a steel die which creates the required shape of the component. The component is then quenched in air or water, stretched in order to release any residual tension and artificially aged to meet strength requirements. Once the aluminium components are ready, they are cut to length and then shaped and welded to the customer’s specification before shipping for assembly.



Each HÅG Celi contains 2.5kg of Hydro CIRCAL aluminium that has passed through this entire process, from the scrap heap to a new life, imbued with characteristics to ensure it remains in use for many years to come.

‘’Our environmental philosophy contains a number of no-compromise elements. Maximizing the use of post-consumer recycled material is one of them.” Says Christian Lodgaard, Senior Vice President of Product & Brands at Flokk, continuing, “With Hydro we found a perfect match in this thinking, and the technological savviness & determination to bring new sustainable solutions to life at scale’’

With additional time and resources, the model devised for the HÅG Celi can be improved, using less metal, with thinner walls whilst still providing the same desired properties. CIRCAL too, is also just a stepping stone to new developments, with HYDRO currently working on a 90% post-consumer content aluminium.

“Our ambition is to deliver the first commercial volumes of near-zero carbon aluminium already in 2022, based on 100% recycled post-consumer scrap,” says Hilde Merete Aasheim, Hydro’s President & CEO.

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