Humanity needs to get its act together. To achieve the ambitious climate goals laid out by the Intergovernmental Panel on Climate Change (IPCC) in its Global Warming of 1.5°C report from 2019, we need to radically decarbonize our economy and seek new and increasingly more efficient technologies to better utilize resources.
Annually, we currently emit around 43GtCO2eq (the equivalent of 43 gigatons of CO2), and the IPCC stresses that global warming greater than 1.5°C above preindustrial levels would be catastrophic and that humanity as a whole should take every step possible to neither exceed nor approach the lowest estimated carbon budget of 420GtCO2eq. Without major changes to our industries, that gives us about 10 years.
"The literature and data reviewed demonstrated that these buildings can typically be built in the same cost range as their counterparts, or at minor cost premiums; sometimes even at lower costs."
Perhaps nowhere else is industrywide transformation more necessary than in the building sector. As many reading this already know, it is responsible for 36% of final energy use and 39% of process-related CO2 emissions globally (2018). Moreover, just to build the new urban infrastructure that will be necessary by midcentury using today’s average technologies will result in carbon emissions of 220 GtCO2eq. This does not include operational emissions.
In other words, before we even turn on the lights in any of these new builds, we may have already exceeded half of our carbon budget.
However, there is good news. In a landmark review released earlier this week in the Annual Review of Environment and Resources, members of the IPCC (including lead author Diana Ürge-Vorsatz, who we interviewed earlier this year) examined what steps the global building sector will need to take to transform into a green, mean, carbon footprint shrinking machine, and found that we already have the tools, technologies, and knowhow to significantly reduce embodied carbon in buildings, bring down operational energy, and decarbonize the remaining operational energy demand. This is true of both new builds and retrofits.
There is even evidence, the review’s authors claim, that new materials and building techniques, like Passive House, can be implemented without significant increases in costs in construction. “The literature and data reviewed demonstrated that these buildings can typically be built in the same cost range as their counterparts, or at minor cost premiums; sometimes even at lower costs,” the authors wrote. Given that high-performance buildings have yet to achieve market dominance, “their costs can still be expected to decrease,” the author concluded.
Though the overall tone of the paper is optimistic, there are still major hurdles that we face. The costs associated with making deep-energy retrofits on an unprecedented scale, for example, will be significant as many property owners have a limited investment horizon that makes financing the upgrades difficult. Policies that encourage governments to absorb some of these costs, which would theoretically be repaid by reductions in healthcare spending due to healthier occupants and other benefits, could help bring nationwide retrofit programs to scale. Challenges also remain in ensuring that buildings in warm and humid climates can be adequately cooled and that carbon-intensive construction materials can be replaced by bio-based materials that also present opportunities for carbon storage. Nevertheless, advances on both fronts appear to be promising.
What remains are two significant gaps. The first is between modeling and actual performance. The authors note that performance gaps of between 10–30% are common, while some small-scale studies have found performance gaps of up to 500%. Such gaps would seem to make true carbon neutrality impossible, but the authors do note that such disparities are significantly reduced in Passive House construction, as well as in retrofits that have taken part in the Energiesprong program in the Netherlands. Passive House design appears to offer one potential solution to this issue.
The other major challenge will be to eliminate the current gap (or lag, perhaps) between industry and policy innovation and scientific literature. What is recommended is more coordination and co-production between building scientists, designers, and policymakers. Given that the Passive House community is a growing nexus of exactly these kinds of professionals (plus tradespeople), it seems that Passive House may be part of the solution for this problem, too.
For the full paper, click here.
“Advances Toward a Net-Zero Global Building Sector”
Authors: Diana Ürge-Vorsatz, Department of Environmental Sciences and Policy, Central European University and Intergovernmental Panel on Climate Change (IPCC); Radhika Khosla, Senior Researcher, Smith School of Enterprise and the Environment, University of Oxford; Rob Bernhardt, Advisor, Projects & Policy, Passive House Canada; Yi Chieh Chan, Electrical & Electronic Manufacturing, Delta Electronics Foundation; David Vérez, GREiA Research Group, Universitat de Lleida; Shan Hu, Building Energy Research Center, Tsinghua University; and Luisa F. Cabeza, GREiA Research Group, Universitat de Lleida