Sustainable hospital construction thanks to Cobiax

The Aller-Weser-Klinik relies on void former technology for concrete and CO2 savings on its new extension

On the site of the Aller-Weser-Klinik gGmbH (AWK) in Verden, construction work on a new ward block has been underway since November 2019, to plans by Architektengruppe Schweitzer. The investment scale for this extension, which will connect to the existing building, is around 38 million euros. A modern four-storey clinical block with room for 120 patients and four operating theatres is to be built on the hospital site by the time it is finished in 2022. The concept of sustainability is also becoming increasingly important in hospital buildings. Relevant standards for sustainability in the construction and operation of hospitals are set out in VDI Guideline 5800 Part 1 (Association of German Engineers), and also play an important role at Verden. In order to contribute to a sustainable life cycle for the new building, right from the design phase, the structural engineers at WTM Engineers GmbH recommended using void former modules from Heinze Cobiax Deutschland GmbH, to reduce the amount of concrete and thereby achieve a CO2 saving of 66 tons.

The new clinical block has been under construction since November 2019, over a floor area of around 10,500 m². With a total usable area of around 9,200 m², it will mean state-of-the-art running for this hospital. Since the new block connects directly to the existing building, its foundations had to be secured beforehand from slipping into the excavations, and an existing staircase had to be demolished. The hospital’s facilities are only marginally affected by the new block, this being located on the side of the building facing away from patient rooms.

Concrete savings from void former technology

Comprehensively sustainable design is of great importance for the financial operation of hospitals. The new VDI Guideline 5800 Part 1 offers a summary of the sustainability of hospital operation over the entire life cycle, from planning and construction, to use and maintenance, to demolition and disposal. Possible savings potentials were identified for the construction phase of the new block at Verden, too, and options sought for delivering them. In order to reduce the amount of concrete, it was decided to use our patented void former technology in the form of Cobiax modules type SL-M-180-200. In the new block at Verden, around 310 m³ of concrete is being saved by using around 3,715 modules, consisting of up to 26,000 individual void formers.            

“At the Aller-Weser-Klinik project, using our technology and the resulting reduction in the amount of concrete meant that around 39 concrete mixer journeys were avoided,” says Volkmar Wanninger, Managing Director of Heinze Cobiax Deutschland GmbH. “When you add up the savings from cement production, transport and delivery journeys, we were able to avoid the emission of around 66 tons of CO2 at Verden.” Apart from the ecological benefit, Cobiax modules have a positive impact on the total weight of the building. The resulting reduction in weight of the clinic by 775 tonnes had a beneficial structural effect.

Cobiax modules can also be used by beginners

Shell construction for the hospital block was entrusted to the company Dipl.-Ing. -Ing. Albert Holzkamm Bauunternehmung GmbH + Co.KG from Verden. Since this building contactor did not yet have any experience working with void former technology, we delivered training on-site to all construction workers. “Cobiax modules are easy to work with and, especially after the training at the construction site, using them posed no problems for us,” explains Markus Janßen, construction manager at Dipl.-Ing. -Ing. Albert Holzkamm Bauunternehmung GmbH + Co.KG. “Training in handling and the explanations behind planning the layout went perfectly, so we had no problems with the installation during the construction process”.

Since there is plenty of space available at the construction site, the necessary reinforcing steel girders and SL-M modules were delivered as separate parts and only assembled on site. Once assembled, the construction workers position the 2.5 metre-long modules following the specifications of the layout plan and start concreting the slab. Across all four floors, having a total area of 7,360 m², our sustainable void former technology is used on around 3,200 m². “We are pleased to be meeting sustainability standards with the new ward block, and can make a contribution to climate protection in so doing,” underlines AWK managing director, Marianne Baehr. “The fact that our technology was also so impressive in this project and that it is making such a real contribution to CO2 savings is incentive enough for us to continue pursuing our goals. “Within the next 5 years, we want to reduce CO2 emissions from construction using reinforced concrete, by a total of one million tonnes,” added Wanninger.