Carbon accounting practices need improvements, may misdirect efforts to reduce emissions
WINNIPEG, April 3, 2019 /CNW/ - Construction practices, policies, building and energy codes and other regulations need to change if Canada is to meaningfully reduce GHGs from the building sector, a new report finds.
Emission Omissions: Carbon accounting in the built environment, a new peer-reviewed study conducted by the International Institute for Sustainable Development (IISD), examines Life-cycle Assessments (LCA) – the primary analysis tool used by industry and researchers to account for GHGs and other impacts of building products at each phase of their "cradle-to-grave" lifespan (i.e., production, use, end of life).
The report finds while they are the best-available tool for evaluating GHG performance of alternative building products and designs, current LCAs have limits that may misdirect efforts to reduce GHGs from the built environment – one of Canada's largest sources of emissions. Major findings include:
1. LCAs may produce very different accounting of carbon for similar projects because data can be missing, while built-in assumptions and uncertainties are not disclosed.
2. LCAs do not track or account for "biogenic carbon" from the extraction and end-of-life stages of wood building products. For example, carbon losses related to soil disturbance in logging operations, variable regeneration rates of forests, and conversion of primary to secondary forests are not counted. This may represent up to 70 per cent of total lifecycle emissions.
These impacts challenge the prevailing assumption wood construction materials are less carbon intensive than steel or concrete and should be favoured.
3. Existing LCA models may misrepresent embodied emissions from materials, exaggerating their importance while ignoring embodied emissions from other building systems or the contribution of other significant lifecycle emissions, such as from a building's energy use.
4. Important regional factors are often overlooked. For example, while production intensities and related emissions can vary significantly from site to site, LCAs typically use average national, continental or global data.
According to the researchers, LCAs need to become more robust and transparent. They should include more data and full disclosure of research assumptions if they are to guide GHG reduction strategies and reduce other environmental harms from buildings and infrastructure. Building efficiency and longevity as well as optimizing material use should also be priorities for decarbonizing the built environment.
The study was commissioned by the Cement Association of Canada and conducted under the guidance of an advisory group comprised of university affiliated academics, notable environmental organizations and architects/designers from the green building community.
"LCA approaches are integral to understand how buildings and the materials they are made of will impact GHG emissions. However, there are still several uncertainties in the LCA process that building designers and policymakers need to be aware of and should be taking into consideration, especially with respect to the embodied biogenic carbon and biodiversity impacts of wood products."
Philip Gass, Senior Policy Advisor, IISD
"This study identifies serious gaps in the way we currently account for carbon emissions from building materials, particularly emissions from forestry products. Soil disturbance, conversion of old-growth primary forest and variable silvicultural success rates are potentially significant sources of carbon that current LCAs don't account for. We need to strengthen our metrics to make sure our strategies to reduce carbon from buildings hit their mark."
Dr. Jay Malcolm, Professor with University of Toronto Faculty of Forestry and member of the study's Advisory Committee
"It's clear that LCAs are an important tool, but they have their limitations as well. More work needs to be done to unpack some of the assumptions that go into them. The study has a clear message for the building industry and for policy makers. We have to get the carbon accounting right, get the evidence that we need and put it to work on reducing Canada's greenhouse gas emissions."
Keith Brooks, Programs Director, Environmental Defence and member of the study's Advisory Committee
"This study demonstrates the importance of applying the best life-cycle evidence to policy decisions related to how Canada's public forests and products interact with our atmosphere. Forests are complex systems that belie simple assumptions about renewability and carbon neutrality. When it comes reducing carbon in buildings and infrastructure, our policy frameworks and choices – including about how building materials are harvested, produced and used – need to reflect a more rigorous assessment of climate impacts, or they may be flawed and counterproductive."
Janet Sumner, Executive Director, CPAWS Wildlands League Advisor to Federal Minister of Environment and Climate Change
About the International Institute for Sustainable Development
The International Institute for Sustainable Development (IISD) is an independent think tank that delivers the knowledge to act. Our mission is to promote human development and environmental sustainability. Our big-picture view allows us to address the root causes of some of the greatest challenges facing our planet today – ecological destruction, social exclusion, unfair laws and economic and social rules, a changing climate. With offices in Winnipeg, Geneva, Ottawa, Toronto and Beijing, our work impacts lives in nearly 100 countries.
SOURCE International Institute for Sustainable Development
For further information: Matthew TenBruggencate, Communications and Media Officer, International Institute for Sustainable Development (IISD), www.iisd.org, email: [email protected], phone: 1 204 297 9779