The effect of procurement and construction site decisions on the embodied carbon emissions of buildings: a Finnish perspective

Abstract

As regulation starts to introduce carbon emission limit values for new buildings, the importance of variations between the as-designed and the as-built building increases when aiming for actual decrease of emissions. This study quantitatively evaluates possible emissions variations between high-, average-, and low-carbon product alternatives in the Finnish context and finds that the difference between average products and high carbon product alternatives may reach up to 30% of the buildings A1-A3 emissions. On the other hand, there is similarly about 20% possibility to decrease emissions when using low carbon product alternatives compared to average products. The study also reveals a significant emissions variation potential for modules A4 and A5, implying that is worthwhile to carefully plan transportation and site operations to limit emissions. Combined, these findings suggest that as-designed carbon calculations for new buildings that are below the legal carbon limit values, might in practice be above the limit value post-construction due to unfavourable final material choices and site operation methods. Therefore, it is recommended to enhance the data collection and visibility to be able to steer the final carbon footprint of the building and that emissions safety margins are applied when designing new buildings.