The construction, operation and decommissioning of our buildings and infrastructure account for approximately 40% of all man-made greenhouse gas emissions. For those involved in climate policy, it is self-evident that building practices need to change – our buildings must become lower carbon and more resilient to our changing climate.
Governments and many in the building sector are in hot pursuit of solutions. And, on the face of it, we’re doing a lot of things right.
First, it is generally understood that retrofitting our existing stock of relatively inefficient buildings is priority number one.
Second, building code processes are focused on pushing new construction toward net-zero carbon as quickly as possible – through measures such as extreme operational energy efficiency, electrifying our buildings with non-emitting electricity sources, and by decarbonizing construction materials.
Third, there is an emerging consensus among academics, governments, procurement professionals and environmental groups that lifecycle assessment (LCA) is the best, and perhaps only tool that can objectively and transparently address the complexity of designing for low carbon and climate resilience.
For all this great work, governments across the country are nevertheless placing big bets on one particular strategy: building with more wood.
“Wood First” in British Columbia. La Charte du bois in Quebec. A Private Member’s Bill, C-354, which would see wood favoured in federal procurement. These are but a few examples of policies that proclaim wood’s climate benefits and they have been accompanied by $100s of millions in subsidies.
History has taught us that Governments “picking winners” is bad policy – it’s bad for the economy, it’s fiscally inefficient and, when it comes to transformative challenges like climate change, it disrupts natural innovation cycles that are constantly pushing competing industries to do better. In the case of favouring wood, the underlying environmental rationale also turns out to be deeply flawed.
Flawed assumptions are misdirecting efforts to reduce GHGs
Decades ago, the 1990s to be exact, when the models currently used by the Federal Ministry of Natural Resources to account for forest carbon cycles were developed, the prevailing wisdom was that robust reforestation requirements on the forest sector would ensure that carbon losses from logging would be fully offset by regrowth.
Fast-forward to 2019 and our understanding of real-world silvicultural success rates, carbon releases from soil disturbance and changes in carbon productivity between old growth and replanted forests has evolved, but the models that underpin how we account for a wood product’s carbon footprint have not kept pace.
A new report by Canada’s renowned International Institute for Sustainable Development (IISD), titled “Emission Omissions: Carbon accounting gaps in the built environment,” should now give policy makers and building professionals reason for pause.
Among its most significant findings is that current lifecycle assessment models do not account for biogenic carbon losses from logging and that, even taking into consideration relatively high forest management standards and sustainability certifications in Canada, these carbon releases could represent up to 72% of a wood product’s carbon footprint. In this scenario, a wood building is in fact more carbon intensive than a concrete building (before even accounting for significant low carbon advances in the cement and concrete sector or the emerging evidence that concrete, over its life, re-absorbs a significant portion of the carbon emitted in its production).
The unchallenged orthodox assumption that ‘wood sequesters carbon’ is enormously favorable to the wood industry and to Canada’s internationally reported carbon footprint, where our suppositions about the relationships between carbon and Land Use Changes (LUC) make an outsized contribution to our Intended Nationally Determined Contributions (INDC) obligations.
To be fair, the forest carbon cycle is complex, with massive variability across different forest systems. In an age where climate change was not yet understood to be the crisis it is today, it made sense to explain away most of that complexity with simple assumptions.
Today this complexity matters more than ever, and we are better equipped to manage it. The atmosphere doesn’t care about our assumptions, and with growing evidence that up to three-quarters of wood’s carbon footprint is missing from our ledger, we need to do better.
The cement industry in Canada, and globally, accepts that new wood products, such as Cross Laminated Timber (CLT), are expanding the role wood can play in the building sector. But just like concrete (with a carbon footprint that can vary widely across, for example, different mix designs) and steel (with a carbon footprint that varies by orders of magnitude based on technology and energy sources), the carbon footprint of wood also spans a wide range of values and, as the IISD study suggests, offers no guaranteed outperformance on carbon compared to other materials.
The way forward: what governments can do
Rather than promote one building material over others, governments must get the best from all building materials. Low carbon building policies should secure a level but competitive playing field where material manufacturers and the building industry are driven toward low carbon solutions (including the most essential but often overlooked strategy of simply using materials more efficiently).
As home to the world’s largest remaining intact forest resources, not to mention as a country warming at twice the rate of the rest of the world, Canada must also drive greater accountability and transparency on accounting for biogenic carbon and other LUC based GHG emissions. We must ensure that our material choices are truly carbon positive. If we don’t, others eventually will, and Canada may find itself on the wrong side of the science and with a larger carbon deficit than it once believed.