A New Estimate of Building Floor Space in North America.

Floor space is a key variable used to understand the energy and material demands of buildings. Using recent data sets of building footprints, we employ a random forest regression model to estimate the total floor space (conditioned and unconditioned) of the North American building stock. Our estimate for total floor space in 2016 is 88033 (+15907/-21861) million m2, which is 2.9 times higher than current estimates from national statistics offices. We also show how floor space per capita (m2 cap-1) is not constant across the North American region, highlighting the heterogeneous nature of building stocks. As a critical variable in integrated assessment models to project energy and material demands, this result suggests that there is much more unconditioned floor space than previously realized. Furthermore, when estimating material stocks, flows, and associated embodied carbon emissions, total floor space per-capita estimates, such as those presented in this study, offer a more comprehensive approach in comparison to national statistics that do not capture unconditioned floor space. This result also calls for an investigation as to why there is such a vast difference between estimates of conditioned and total floor space.

A Novel Method for Estimating Emissions Reductions Caused by the Restriction of Mobility: The Case of the COVID-19 Pandemic.

The COVID-19 pandemic is the single largest event in contemporary history in terms of the global restriction of mobility, with the majority of the world population experiencing various forms of "lockdown". This phenomenon incurred increased amounts of teleworking and time spent at home, fewer trips to shops, closure of retail outlets selling non-essential goods, and the near disappearance of leisure and recreational activities. This paper presents a novel method for an economy-wide estimate of the emissions reductions caused by the restriction of movement. Using a global multiregional macro-economic model complemented by Google Community Mobility Reports (CMRs) and national transport data, we cover 129 individual countries and quantify direct and indirect global emissions reductions of greenhouse gases (GHG; 1173 Mt), PM2.5 (0.23 Mt), SO2 (1.57 Mt), and NOx (3.69 Mt). A statistically significant correlation is observed between cross-country emission reductions and the stringency of mobility restriction policies. Due to the aggregated nature of the CMRs, we develop different scenarios linked to consumption, work, and lifestyle aspects. Global reductions are on the order of 1-3% (GHG), 1-2% (PM2.5), 0.5-2.8% (SO2), and 3-4% (NOx). Our results can help support crucial decision making in the post-COVID world, with quantified information about how direct and indirect consequences of mobility changes benefit the environment.

A compactness measure of sustainable building forms.

Global population growth and urbanization necessitate countless more buildings in this century, causing an unprecedented increase in energy consumption, greenhouse gas emissions, waste generation and resource use. It is imperative to achieve maximal efficiency in buildings quickly. The building envelope is a key element to address environmental concerns, as it is responsible for thermal transfers to the outdoors, causing energy demand and carbon emissions. It also requires cladding, thus consuming a significant amount of finite resources. This paper investigates the relationship between surface area and indoor space to unravel the sustainability of building forms. Firstly, we demonstrate what the optimal form is. Secondly, as a single definite form is of little use in practice, we develop a scale-independent metric to measure the degree of optimality of building forms and show its practical use. This newly developed metric can significantly help in early design stages, by quantifying how much a building form deviates from optimality and identifying the domain of alternative geometries to bring us closer to it. This compactness measure also represents a theoretical basis for further research, to explore how optimality changes when additional parameters are factored in. It therefore contributes to both theory and practice to support global efforts towards sustainable built environments.