Building for Zero, The Grand Challenge of Architecture without Carbon

Abstract

Almost 40% of global carbon emissions can be attributed to the building sector (Global Alliance for Buildings and Construction 2019). This makes the built environment both a challenge and an opportunity in terms of mitigating climate change. To further understand the implications of global carbon budgets on buildings, housing policy and development, we present an interactive model for carbon emissions from buildings between 2020 and 2050. In our simulation, the user initially chooses one of the Intergovernmental Panel on Climate Change’s (IPCC) Shared Socioeconomical Pathways (SSP) to define a global carbon budget until 2050. Based on this choice, our model presents three alternative scenarios. The “Business as usual” scenario assumes a constant 1% renovation rate for existing buildings and usage of current building standards for new construction. The “Net Zero Operational Carbon” scenario assumes that all new buildings will become net zero in their operation after a user-defined transition period. Finally, the “Net Zero Operational Carbon and Embodied Carbon” scenario assumes that new buildings will become Net Zero Energy Buildings (NZEB) in terms of both, operational and embodied carbon from construction also following a user-defined transition period. For all three scenarios, the model assumes a linear decarbonization of the electric grid until 2050 and current annual emissions of 14.8 GtCO2 for buildings. Global floor areas and operational emissions are based on projections by the International Energy Agency (IEA) (Wörsdörfer et al. 2019). In our research, we find that the retrofit rate must be increased substantially from today’s 1% to around 4-5% and new buildings must be built in a net zero standard by 2040 to meet the climate goals for any SSP. Next to operational carbon emissions, we show how the embodied carbon of buildings has a significant impact on the carbon budget, contributing between 14-46% to building-related carbon emissions by 2050, and is therefore key in achieving net zero building stock.

Keywords: Climate change, carbon, construction, mitigation, embodied, net zero, sustainability, architecture