Although the need to reduce greenhouse gas emissions is widely understood and agreed upon, less widely appreciated is the need to reduce resource consumption in tandem. This is due to several factors, from the energy and carbon embedded within resources and their extraction to the pollution caused by waste resources and the reduced capacity of the environment to absorb emissions due to changes in land use.
Pursuing emission-free construction sites is just one part of transitioning the construction industry to more sustainable practices. Consequently, construction activities must be related to the broad scope of sustainability.
7.1 The pace of emission cuts in construction
Current policies to reduce the emission of greenhouse gases are unlikely to keep global warming within safe levels (IPCC 2023; UNEP 2023). The time frame for reaching near-zero emissions is only a few decades away. Keeping global warming below 1.5°C requires net-zero emissions in the energy sector by 2050 (IEA 2021). The construction sector also has to reduce emissions at a similar pace, requiring significant emissions cuts every year from now on. At the same time, the demand for new housing is growing with the floor area of buildings expected to increase by 75% globally between 2020 and 2050 (IEA 2021).
The Nordic countries are implementing limit values for the climate impact of buildings as the primary legislative climate action (Boverket 2023; VCBK 2023). General carbon taxes, such as those on fossil fuels, also affect construction. In time, the limit values will also apply to construction sites. The first proposed limits are based on current construction materials and practices and will not result in any significant reduction in emissions per built square metre within the next few years. The recent and soon-to-be implemented limit value in the Nordics stipulates no limit on the number of new square metres built, so this regulation and other actions may fail to reduce emissions from construction.
At the same time, private entities state that faster emissions cuts in construction are needed. The “Reduction Roadmap” is a Danish initiative that aims to serve as a practical tool for the construction industry. Its purpose is to translate the planetary boundary for climate change into a reduction target for new residential construction in Denmark. The Reduction Roadmap aims to create a tool and establish a target to facilitate the transition towards construction practices that adhere to the planetary boundaries. However, discussions are and should remain ongoing regarding the prerequisites and methods required to translate the planetary boundaries into specific reduction targets (Reduction Roadmap 2022; Steffen et al. 2015).
The Reduction Roadmap presents reduction pathways, based on the CO2 budget for limiting global warming to 1.5°C. The most effective pathway is to simultaneously reduce the carbon footprint for an area and total build area.
The Science Based Targets initiative (SBTi) is another tool, which provides companies with a path to reducing emissions in line with the goals of the Paris Agreement (`Science Based Targets Initiative’ 2023). The achievement of the goals of the Paris Agreement has been calculated on the basis of everyone taking responsibility for their share and setting goals. However, without universal participation in goal-setting and regular updates, achieving the goals of the Paris Agreement appears unlikely.
Total emissions from construction activities, including construction sites, need to be systematically monitored as proposed in Chapter 3. This allows for the possibility of adjusting actions and legislation to the climate ambitions of the construction industry and governments. The expected emissions gap should then be addressed by exploring more rapid emission cuts based on existing knowledge related to construction and construction sites. Carbon pricing is considered to be an effective way of incentivising the market to cut emissions (Boyce 2018). Circular economy methods are already being explored in the construction sector
(Hossain et al. 2020). Perhaps the most effective means of achieving the goal is degrowth thinking and respecting planetary boundaries (Birgisdóttir, H. et al. 2023). Although degrowth is a concept that is currently not salient in mainstream economics or the political arena, it still deserves further attention.
7.2 Clean energy and its side effects
Clean energy is a limited resource in the same way as the ability of the ecosystem to absorb carbon dioxide is a limited resource. The overconsumption of fossil fuels can easily be replaced by overconsumption of other natural resources. The demand for energy seems to be insatiable and may never be fulfilled sustainably.
Replacing fossil fuels with renewable energy sources is no simple task and is bound to have all kinds of adverse consequences. These concerns are widely discussed and nicely summed up by Seibert and Rees (2021), for interested readers.
The shift towards more sustainable construction practices must not only take into account clean energy and direct emissions but also sustainability in a broader and longer-term context (Kanafani et al. 2023; Johnsson et al. 2020).
The energy and material resources needed to achieve emission-free construction sites include huge quantities of biomass and renewable energy. Sustainable biofuels are a limited resource as organic waste and by-products are limited, as is the land available for the cultivation of energy crops (Karlsson, Rootzén, and Johnsson 2020). In addition, replacing fossil fuels with biofuels or electricity on the construction site can add to the environmental impact in other areas. In the case of electric cars, the embedded carbon in their production is greater than for conventional combustion engine cars (Dillman et al. 2020). The same is expected to apply to trucks and machinery.
These are only examples of the possible side effects of the energy transition in construction. Work in the field of emission-free construction sites should always consider the possibility of negative consequences of transitioning to clean energy.