City-based Carbon Budgets for Buildings

The construction of buildings consumes about 50% of all materials produced globally measured by weight. Materials such as cement, ceramic tile and steel are among the most carbon intensive materials to manufacture, and come with a carbon footprint of their own. This is called embodied carbon. Accounting for embodied carbon is a different way of visualizing the emission effect of the consumer rather than the generator of emissions. Bringing the consumer, and the related production value chains, into play can engage powerful market drivers in the combat against GHG emissions. The building sector, with its vast resource consumption, is the ideal place to start. This working paper provides concrete
ideas on how to proceed. Currently, there is scant regulation addressing embodied carbon. Cities have great potential influence over the construction industry, as nearly all construction of buildings requires city government approval.
Energy efficiency is the usual focus, though recent policy development regarding embodied carbon emissions in buildings has been observed in a number of cities and countries. Moreover, industry has been pushing the development of standards for calculation and reporting of embodied carbon in buildings. Embodied carbon is also addressed by several green building certification schemes. The development, however, needs to speed up. The construction sector and cities together are ideally positioned to establish a local up-scalable regime that will curb greenhouse gas emissions from within. This working paper suggests concretely how to design and implement a model in which cities use existing construction approval processes to allocate a carbon budget that combines emissions from operational and embodied carbon - and make usage permits for buildings constructed under this restriction contingent upon documented compliance - leaving it up to the sector itself to document its carbon footprint. A parallel is drawn to the dissemination of ISO standards 9001 and 14001, where quality and environmental demands from decisive commercial actors spread through the supply chain. The paper explores principles and specific limits regarding e.g. calculation of the carbon budget over time and the method of budget allocation in order to repeat this experience with the purpose of emissions reduction. The working paper also reveals that cities have a firm ground to stand on and that in curbing emissions through carbon budgets for construction they would act in their own self-interest. Adopting the model they would and will
ultimately deliver a ground breaking initiative for cutting global emissions at scale – beyond that of the construction sector. If the ISO experience has any merit, it suggests less than a decade for the effects of carbon budgets to show themselves.