The very first white roofing based on >15% recycled bitumen is in Heerenveen

Producer, processor and end user join hands in route to circular economy

At Ecopark De Wierde, renovation of two buildings of waste collector and processor Omrin began in early May. An important part of the work is the renovation of the roofing. On behalf of Omrin, Feenstra Dakbedekking is installing approximately 3,700 m2 of Derbicolor NT white from Derbigum, which contains at least 15% of recycled bitumen. This project gives stakeholders a circular first...

Omrin handles the collection and/or processing of waste in 35 municipalities in Friesland, Groningen and far beyond. "From worn jeans to empty milk cartons and from old newspapers to cloches: waste is of great value to us," says head of communications Jelmar Helmhout. "After all, it is full of raw materials, which we like to give a sustainable second life. The choice of roofing with at least 15% recycled bitumen fits this perfectly."

Leader in circularity and sustainability

"As an organization, we are leaders in the circular economy and in making processes more sustainable," Helmhout emphasizes. "We are going through a rapid transition, working on ever better techniques to separate our waste. For example, through careful source and post-separation." The Heerenveen site is the center for post-separation, he explains. "Using various installations, the household waste from 1.7 million inhabitants is sorted here and divided into raw materials, which can be reused in the chain. Here, for example, we distinguish between plastics and organic material, with the organic material being fermented into green gas for our vehicles. Products that do not qualify for recycling are converted into renewable energy in our incinerator in Harlingen."

3,700 m2 of circular roofing

The buildings in Heerenveen that are currently being renovated are a 2,000 m2 waste separation hall and a 1,700 m2 digestion hall. "An inspection showed that the waterproof layer of both roofs had reached the end of its technical lifespan," says Folkert van den Bosch, civil and building services engineer at Omrin. "In addition, the halls themselves were in need of revitalization. We approached various market parties to advise us on this. Are there products in the market that match our circular ambition?" Helmhout: "As an organization, we actively seek collaborations with (local) market parties who think the same way about sustainability and circularity. For this reason, we are also affiliated with Circulair Friesland and Circulair Groningen." Van den Bosch: "Moreover, we challenge suppliers to think along with us. How can we further implement our circularity idea in our grounds and buildings? Feenstra Dakbedekking surprised us with Derbicolor NT white; a new product from Derbigum with a high percentage of recycled bitumen as well as a white shingle."

Combination of three waste streams

"At least 15% of Derbicolor NT white consists of recycled bitumen, which is extracted from three waste streams: our own production residues, the residual and waste streams of our authorized processors and suitable old roofing materials from demolition roofs," says Erik van Emst, North/East Netherlands regional manager at Derbigum. "All residual and waste streams are carefully processed at our recycling plant in Perwez, Belgium, after which they are reused again and as a fully-fledged secondary raw material in our production. Without making concessions on quality and lifespan. Because both the extraction, processing and transport of new raw materials are dealt with effectively, we emit considerably less CO2. The exact amount of this saving is demonstrated per project in a CO2 reduction certificate. This makes it possible to include the CO2 reduction of roofs in a CO2 savings process, for example." The CO2 reduction calculation has been validated by PWC. 

Cool Roof effect of white roofing

The white color of Derbicolor NT white is achieved by adding a white coating to the mineral slate, which can provide substantial energy benefits. "With our properties, we are increasingly moving to white roofing," says Van den Bosch. "Mainly because this color blocks the sun's heat (Cool Roof effect). Our factory halls contain a variety of sorting and processing machines, which produce a lot of heat. As a result, the indoor heat load is already basically high. By keeping the temperature on the roof as low as possible, we prevent additional heating of the halls and it is much more pleasant work for our operators."

Two-layer roofing system

"Because the existing roofing structure is still good, it will be permanently preserved during the renovation," says Willem Feenstra, director at Feenstra Roofing. "In several places in the waste separation hall there were skylights, which had become porous after years of loyal service. These skylights will be removed during the roof renovation, after which the steel roof structure, roof insulation and roofing will be carefully lifted. Because a new machine must be lifted in through the roof, this section will also be lifted, after which the entire roof will be intensively cleaned. We then apply a new and two-layer roofing system. The first layer is mechanically attached to the existing roofing, after which a new Derbicolor NT white top layer is burned onto the new underlayment. This keeps Omrin ahead of leaks and other problems." Just before the summer vacations, the final work should be completed.

'Everyone must participate'

By recommending circular products whenever possible, Feenstra Roofing contributes to more sustainable construction, Feenstra says. "Moreover, this sets us apart from other roofing companies.  

Because although the production, quality and lifespan of roofing materials are getting better and better, recycling is still an underdog in our industry. We are trying to make a difference here. For example, we have also been actively collecting Derbigum cutting waste for recycling for years." Van Emst: "For the circular economy to succeed, truly all stakeholders must participate. From producer to processor and end user. In Heerenveen, we are proving that this is possible."

National Environmental Database

Derbigum's ambition is to convert all traditional roofing products into circular products in the coming years. "The introduction of Derbicolor NT white is an important step in this ambition," Van Emst concludes. "The new roofing membrane will soon be added to the National Environmental Database (NMD). With each completed Derbigum roof, we also offer a take-back guarantee, thus ensuring our circular ambition also in the future."