Environmental co-benefits and trade-offs of climate mitigation strategies applied to net-zero-emission neighbourhoods

Abstract

Main purposeTo limit global warming at a safe level of 1.5 °C, deep emission reductions in all sectors combined with rapid, far-reaching, and unprecedented changes in all aspects of society are required. The ongoing climate urgency has led to greenhouse gas (GHG) emissions to be the most often inventoried life-cycle indicators. But, to draw comprehensive climate mitigation strategies (CMS), adverse potential environmental side-effects and trade-offs should be assessed as well.MethodsLCA is used to assess the potential environmental co-benefits and trade-offs of a net-zero-emission neighbourhood (nZEN) in the early planning stages. CMS are designed to test for the effect of (1) mobility patterns less based on the use of passenger cars, (2) a better material use by decreasing the size of the dwellings and increasing the passenger loads, (3) increased lifetimes of buildings and passenger cars, and (4) their combination.ResultsAcross the impact categories, environmental benefits of 5–20% are shown for single CMS and of 22–42% when combined. Interestingly, the highest environmental co-benefits are found for Metal Depletion, highlighting the close interconnection of CMS and decreased pressure on resource use.The use of several climate metrics has shed light on the use of fossil fuels in the production value chains of the materials used to provide the mobility services and shelters to the inhabitants of the nZEN under study. A combination of climate metrics with short- and long-time horizon should be used to give the importance that short-lived GHG such as methane deserve in the climate debate.ConclusionTo best mitigate climate change along with environmental co-benefits on a nZEN level, measures should be taken at different points in time. At the early planning stages, incentives should be in place that promote dwellings of reasonable sizes (measured per inhabitant) along with incentives to decarbonize the materials value chains, in- and out-land. Over time, a culture of car- and ride-sharing will have positive environmental benefits. When renovating, incentives that promote the reshaping of dwellings into dwellings of smaller sizes will help to shift the sole focus on nZEB standards to multi-layers strategies.