The Nattugglan 14 office building in Stockholm

Building in city center locations demands careful planning, not least regarding the logistics of getting material to and from the construction site.  This, and the recycled glass composition of Climate Recovery’s ventilation ducts, were important arguments when Bravida was choosing a subcontractor for the new office building being built by Vasakronan in Stockholm’s Södermalm district.

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A new, attractive office property is emerging in the heart of  Södermalm, close to the Medborgarplatsen square – this is Nattugglan 14 on Folkungagatan, where the Swedish Tax Agency used to have its offices.

The property owner, Vasakronan, has demolish-ed the old building to make way for a large, modern office building designed to be LEED certified at the highest level. At street level there will be a restaurant and café. A square will contribute to the welcoming environment in the area, which includes another property.

The new 23,000 square metre office building has eight floors above ground and two below. It will all be ready in 2022. Bravida, which has engaged Climate Recovery as one of its subcontractors, is responsible for the ventilation contract.

“Vasakronan’s pioneering environmental requirements, that do not compromise quality or function, mean that the property will have several innovative technological solutions, in terms of energy supply and ventilation for example,” says Gustav Iggberg, Project Manager for ventilation at Bravida.

“Our goal has been sustainable and circular construction wherever practicable. In other words, using our choice of materials and construction methods to cause as little environmental impact as possible throughout the expected life cycle of the property.”

to use Climate Recovery as the ducting system supplier. In part because our ventilation ducts are

predominantly made of recycled glass, which can be recycled again when that becomes relevant. And in part because Climate Recovery’s solution means straightforward logistics; important to minimize inconvenience for pedestrians and motorists in the area when building in central locations.

Major logistical benefits

“Because Climate Recovery’s ventilation systems come in flat packages that weigh significantly less than traditional sheet metal ducts, and are also less bulky, the number of journeys to site can be reduced, while making unloading quicker at the same time.

Another advantage of flat packages is that it is easier to store them on the different floors as work progresses. The ducts are easy to stack, take up less space and so are not in the way of other work,” Gustav Iggberg continues.

A third advantage of Climate Recovery’s ventilation ducts is that assembly is faster than for sheet metal ducting that needs to be insulated.

“The fitter simply needs to shape the duct in a few simple steps, and then secure it in place. The ducts are factory insulated. The fact that the ducts are made of fiberglass means no heavy lifting and improves ergonomics for the fitter,” Gustav Iggberg concludes.

The Nattugglan 14 building in numbers

Nattugglan 1423 000 m2
Environmental certificationLEED Platinum
HVAC consultantFerax Installationskonsult
Ventilation contractorBravida


All 125-315 supply air ducts on floors 4-10 have been replaced with Climate Recovery products so we can present the following savings as compared to insulated sheet metal ducting.

Energy efficiency

Reduced pressure drop in the T-pieces and bends, reducing fan speed and output. This represents a saving of 1.2 million kWh over 20 years.


Fewer deliveries and a much smaller storage area for material. In addition, ready insulated ducting means fewer days scissor lift and scaffolding hire.

Time savings

600 hours of time savings, thanks to CR’s 2-in-1 system, allowing tenants to move in earlier.

Environmental certification – LEED Platinum

The choice of CR ducts ensures that the project is sustainable at every stage of the process, from manufacture to management and operation.


The lower pressure drop means savings of over 7.2 tonnes during installation and 160 tonnes after 20 years of operation.


CR ducts are able to maintain the desired supply air temperature better than insulated sheet metal ducting.

A new method of soundproofing ventilation

Thanks to the sound absorbing capability of CR ducting, most traditional soundproofing solutions are no longer necessary. This means less material to purchase, better logistics and easier installation.