At the end of their service life: how Troldtekt acoustic panels can be recycled

Troldtekt works with return models that can give acoustic panels one or even more extra life cycles. Programmes for cement-bonded wood wool leftovers from Troldtekt’s own production and customer building sites have been established in Denmark. Our ambition is also to reuse, recycle and upcycle panels from demolition sites.


The length and number of life cycles play a key role in the circular economy of construction. Basically, it's all about:

1. extending the life of the materials

2. and then recycling them to become useful once more.

To make that possible, a material must have strength and durability that enable it to fulfil its function for many years. It's more sustainable to keep a ceiling for 70-80 years, for example – and even relocate it to a new building along the way – than to switch to a new ceiling after just 20 years.

The prerequisite for the circular economy is that the material is healthy – i.e. without harmful chemicals. Sending harmful chemicals into circulation is a bad solution for people and the environment, and it reduces the possibility of recycling.

In Troldtekt’s case, the lifetime in environmental product declarations (EPDs) is calculated as at least 50 years, based on a German database of building material categories. As building certifications such as DGNB are based on a building lifetime of 50 years, calculations with Troldtekt are also based on 50 years.

However, real-life experience indicates a lifetime of at least 70 years. The material health of the acoustic panels is certified at gold level according to the Cradle to Cradle Certified® product standard.

The vision behind Cradle to Cradle is a world without waste. Troldtekt therefore has high ambitions in terms of recycling and reuse, and works with several different circular models and scenarios for different waste fractions:

A large amount of recycled materials has been used outside and inside the high-rise TRÆ (wood) building.

Prevention and recycling

Tina Snedker Kristensen, Head of Sustainability and Communications at Troldtekt, has been deeply involved in Troldtekt’s strategic approach to Cradle to Cradle Certification since 2011. She refers to the EU Waste Directive from 2008 when she talks about Troldtekt’s ambitions:

"For us, it’s about moving as high up in the hierarchy as possible. Preventing waste is the best solution. Fortunately, we're seeing that several developers and consultants opt to preserve the Troldtekt ceiling when they transform their buildings for new purposes. We also want to help the market ensure that the fully functional acoustic panels are reused in another building. We intend to do so in collaboration with contractors, developers and consultants, so that we can establish the most value-creating circles for the used panels. We want to avoid end-of-life risk for the panels, and ensure that they get a second life instead," says Tina Snedker Kristensen.

For example, you can read more about the Aarhus building, TRÆ (wood), here.

She adds that Troldtekt attaches great importance to providing support and advice for repairing and painting Troldtekt ceilings. And that pilot projects have already been carried out regarding the reuse and recycling of Troldtekt panels.

Discarded panels and offcuts are processed by North Trade House to give them a totally new function in the biological cycle.

Leftovers and waste attain new value

The steps under prevention and recycling is upcycling and downcycling. Troldtekt has already established return schemes for the cement-bonded wood wool waste that never make it to the building.

Most established is the scheme regarding production waste in the form of discarded panels and cut wood wool concrete from the bevelling of panels. A local partner near the factory – North Trade House A/S – receives discarded panels and offcuts, which are given a new function in the biological cycle.

In practice, North Trade House crushes the panels, which are then given a new function such as livestock bedding, turf for horse riding grounds, weed-inhibiting ground cover in forestry and plantations, and for stabilising damp roads.

Cement supplier Aalborg Portland takes waste from Troldtekt’s edging workshop and returns it for use in cement production. The wood content of Troldtekt sawdust contributes to the combustion process and replaces fossil fuels (energy), while the cement content becomes a raw material (filler) in new cement.

From building site to biological cycle

Troldtekt has introduced a return scheme for cement-bonded wood wool that is cut or sorted on construction sites. Customers can use the scheme to return their clean offcuts and waste, which will then be downcycled in the biological cycle via our Danish collaborative partner, North Trade House, in the same manner as the production waste from Troldtekt’s own factory.

"The next step is to enter into similar cooperation agreements in our other primary markets, such as Germany and Sweden, so that we can downcycle waste locally at the highest possible value level," says Tina Snedker Kristensen.

Potential in upcycling

When Troldtekt acoustic panels have reached the end of their first life cycle in a building after 50–80 years, reuse, recycling and upcycling can all come into play. Troldtekt’s Manager for Circular Solutions, Darma Louise Duus, explains:

"After many decades, the panels have reached a state where it no longer makes sense to keep or directly recycle them, so we want to ensure they enter a new cycle in another way. This could be recycling through some of the same schemes that we have for production and construction site waste. But we expect that some of the panels will still be in a condition that allows them to be upcycled into new products via our own production – in other words, they get a second life.

"We now examine how much of the dismantled panels can typically be given a second life. Complete panels that are in good condition can be relatively easily reintroduced to the market. When it comes to panels that are processed during installation or are later on in their first life cycle, we need to assess how resource-efficient and carefully we can upcycle and process. They will typically come back in different obsolete sizes, because they are adapted to the end of a ceiling, cut to fit lamp sockets or similar," says Darma Louise Duus and continues:

"We cannot find a solution for redesign that fits optimally for all returned panels if we are to maintain scale and economic sustainability. So instead of “one size fits all”, we must design solutions based on the principle of “sizes that fit most”. In addition, we work with several scenarios so that we can recycle all qualities and thus avoid waste."

A long service life is the best scenario

In future, schemes such as the new material passport will make it easier to obtain documentation for processing acoustic panels in the use phase – for example with paint. That's why Troldtekt is working on return agreements, giving customers a guarantee that they can return their panels over many decades, as long as certain conditions during the in-use phase are met. But with such a long lifespan, such agreements have to be phased in with a long horizon.

"It's also important to state that we must never see the long service life of materials as a problem. Long lifetimes are the best scenario in a circular economy. So first and foremost, we should be pleased that Troldtekt is a robust and naturally strong material that can withstand wear, moisture and repeated layers of paint without reducing their strength or ability to absorb sound," says Darma Louise Duus.