Wise methods for reducing CO2 in construction

Laura Sariola
Senior Sustainability Consultant
Environment & Land Use Planning
AFRY Finland Oy
Finland

laura.sariola@afry.com

The construction and real estate sectors are called great polluters: great amounts of energy and virgin raw materials, both sustainable and non-sustainable will be consumed every year. At the same time, the industry produces a lot of waste. This should be fiction by the year 2040. IPCC, SBTi and CRREM trendlines show that the consumption levels should decrease by nearly 70% by 2040 to follow the reduction pathways limiting global warming to 1.5°C or 2°C. At the same time, other environmental aspects should also be considered, like biodiversity including eutrophication and acidification. How will that be possible?

Most of the Baltic Sea countries are members of the European Union. EU has published and updated EU taxonomy, and energy, construction and, waste directives to strengthen commitments to green transition and reduction of GHG emissions. The transition toward a greener future has been finally launched. In addition, a lot of international and EU-level standardization work is in progress to get common rules for enterprises. In the construction sector, the improvement projects will concern e.g. digital UpToDate data flows, IoT, BIM, data management and storage, simulations, energy and ESG reports. On the other hand, different construction methods will be considered in diminishing GHG emissions at the grass root level. The effectiveness in reductions is higher if focused on sources that produce most of the GHG: construction materials, site, assembly methods and place, and energy use.

The construction project will start by considering the needs and objectives of a complete project. If the new building could be replaced by modifying an existing real estate, up to 60% of carbon emissions from construction materials could be avoided. In addition, a site does not need carbon-intensive excavation and infrastructure work. However, it is essential to pay attention to demolition methods, waste logistics and processing. Up to 65% of the demolition emissions can be diminished by reusing the materials, shortening transportation distances, and using biofuels and green electricity. The other advantage of conversion projects or updating the existing building is improvements in energy efficiency and savings in energy consumption.

Energy sources, energy use at the site, and logistics are hot topics now. Shortening the project time and reducing the lost time by optimization and JOT delivery systems is relevant, especially in wintertime due to extreme weather conditions and heating at the site. In addition, it is possible to diminish energy-related emissions by up to 80% in construction and maintenance. For example, in Helsinki, Finland, up to 70 000 square meters of heated office space without relevant use produce approximately 1,8 million CO2kg emissions per year. Superfluous emissions are avoided by modifying existing buildings for more relevant use.

Whether the project is a modification or a new building, the emissions can be diminished by choosing wisely construction materials and the place from which the materials and construction elements shall transport to the site. The EU green transition supports the reuse, recovery, and circulation of construction materials. Hitherto, the national legislation has not been flexible enough for dismantled products and materials in Finland. The overall problem is in the acceptability and eligibility of reusable products: the process needs time, patience, and resources. However, there are great examples of new construction designs which have used dismantled products.

In addition to circularity, choosing materials having a significantly lower carbon footprint can diminish the carbon footprint of a whole project by up to 40%. Carbon footprints exist in verified LCA calculations, like CO2 databases, Environmental Product Declarations (EPD), and other verified sources. I dare to say that most of the construction product manufacturers that have not compiled EPDs have only a hint of the actual emissions of the value chain. The sad truth is that under one per cent of the product lines have gone through the examination globally. Therefore, accurate data is hard to get. In addition to carbon footprint, the EPD provides reliable information on other environmental indicators, which is important for a holistic perspective. EPD information should be required in every construction project!

All the emission sources and improvement possibilities must be recognized along the value chain to gain emission reduction targets. This needs changes in processes, measurement accuracy, and attitudes. Automation in processing and producing data will be needed to get constant information. Finally, all the environmental information and data should be constantly and wisely exploited alongside economic information in strategic and operational decision-making. Think bold and brave, require up-to-date data!

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