Perspectives on Zero Emission Construction

An IPCC (The Intergovernmental Panel on Climate Change) special report on the impacts of global warming shows that a 2°C temperature rise, compared to 1,5°C, will have severe consequences for ecosystems, humans and society (IPCC, 2018). According to IPCC, global greenhouse gas emission must be reduced by about 45 % from 2010 level by 2030 to avoid global warming above 1.5°C. In 2018 the member cities of the C40 network emitted 2.4 Gt of CO2e (C40 Cities, 2018). In the decades ahead, the global population living in urban areas is expected to grow by approximately 1.5 million people every week. A rapid low-carbon transformation of the industry that produce urban infrastructure is thus among the critical steps necessary to fulfil the Paris ambitions.

This paper focuses on emissions at the construction site. Emissions at construction sites is mainly related energy use from construction machinery. Today, machinery used at construction sites are mainly dieselbased. There is a great potential for reducing greenhouse gas emissions, local air pollution and noise from construction sites by switching to zero emission alternatives such as electricity or hydrogen. Based on an assumption that emissions from construction sites represent between 5-10 % of total emissions in cities as well as greenhouse gas emissions from the C40 cities, the total annual greenhouse gas emissions from construction sites in the C40 cities is estimated to be in the range of 120 to 240 Mt of CO2e. The demand for such alternatives today is however small and the alternatives therefore few.

The main reason for the low demand is additional costs related to zero emission alternatives. While electric construction machinery usually provides lower operating costs, as electric engines are more efficient than conventional diesel engines, immature markets and high battery prices lead to high investment costs. The costs of electric machinery can be reduced by connecting the machine to the grid during some of its operations and hence reduce the battery size. The profitability of switching to electric machines varies between countries, depending on local diesel and electricity prices. In some countries, electric machinery can be profitable already today. With expected reduction in battery price and more mature markets for zero emission construction machinery, it is likely that electric machinery will become more economically attractive in the years ahead.

While electric construction machinery is a zero-emission solution at the construction site, the effect on total CO2 emissions depends on the country’s energy mix. Electric and other zero emission alternatives will however remove local air pollution and noise. Local air pollution contributes to severe health problems in many large cities. As cities with the highest construction activity often have the largest challenges with local air pollution, zero emission construction machinery can be an effective measure to increase the welfare of its citizens.

To meet the Paris targets and to realise the benefits zero emission alternatives provide, cities need to find ways to limit the use of fossil fuels, and fossil-free and zero emission solutions must be available and economically feasible. The demand for zero emission construction machinery is today small and the alternatives are therefore few. An increased demand for zero emission construction machinery will contribute to the development of such alternatives. In force of being important proprietors, the C40 cities can promote low-carbon alternatives and thereby contribute to development of a competitive market for zero emission construction machinery.