European construction materials giant Kijlstra commissioned the research by UK-based company Carbon Clear to quantify the greenhouse gas emissions associated with the production of its square pre-cast concrete manholes that have recently been launched in the UK and are currently being installed by main contractor Bam Nuttall on a large project in Stratford, London, that is due for completion in 2012.
The report reveals the emissions per Kijlstra unit ranged from 0.4 to 2.3 tonnes CO2e compared to 1.2 to 4.5 tonnes for traditional installations.
The report compared three sizes of Kijlstra and traditional manholes to depths of two, four and six metres in the areas of raw materials, transportation to installation site and other activities such as energy consumption, waste and inbound delivery of materials.
Independently conducted to international standards ISO 14064 and PAS 2050, the report is the critical first stage of a comprehensive and commercially focused carbon management plan that will enable Kijlstra to offset the emissions from all its UK installations to help projects throughout the world, making its manholes carbon neutral.
Manholes and other pre-cast systems are manufactured at Kijlstra’s two state-of-the-art production facilities in the Netherlands so although the company has formed partnerships with key distributors within the UK to keep lead times to a minimum, a greater proportion of its carbon footprint is due to transport … but in terms of distance rather than weight.
However, the main component of the products’ carbon footprints is the raw materials used in manufacture and construction and in this area the Kijlstra system outperforms traditional ones by more than 20%.
The Kijlstra system also outperforms traditional ones in all other respects. For instance, Kijlstra’s precast product is manufactured in the factory and transported whole to site, compared to traditional systems which are partly made in the factory and partly produced on-site with poured concrete.
In addition, the Kijlstra product weighs between 2.5 and 14.3 tonnes compared to traditional ones of between 7.7 and 27.2 tonnes and the Kijlstra product replaces up to 40% of cement with slag – waste product with lower associated carbon emissions (the actual recipe is protected intellectual property).
The prefab concrete manufacturing process with Kijlstra is a wet method which sets and dries naturally overnight, while the traditional one is a dry method which requires the mixture to be agitated and steam-processed which is more energy intensive.
The Kijlstra system does not require concrete to be poured at the installation site whereas the traditional system uses significant amounts of poured concrete for (bases, benches and vertical rings) which takes several days to pour, then to dry. This process then has to be repeated which means installation can take several days compared to the Kijlstra system which takes only hours.
Andy Lowe, co-author of the report, said: “Carbon Clear’s product footprint assessment shows that Kijlstra’s prefabricated manholes provide significant cost- and carbon-saving benefits compared to traditional manhole systems.
“We envisage that pioneers such as Kijlstra will increasingly win business over their competitors as developers look for low-carbon solutions to meet their commitment to cost efficiency and environmental sustainability.”