GHG: it is better to recommend wood to reduce the carbon footprint
The conclusions of the last two reports of the Intergovernmental Panel on Climate Change (IPCC) are unequivocal; the recent increase in greenhouse gas (GHG) emissions is the largest in human history. And they continue to increase. In this context, when it comes time to construct buildings, how can we limit the energy-intensive production of cement and steel? By betting on wood!
ANALYSIS – Buildings play a crucial role in the transition to a decarbonized economy, in particular towards energy sources using little or no fossil fuels. The construction and renovation sector was responsible for approximately 37% of global energy-related anthropogenic carbon dioxide (CO2) emissions in 2020, of which 27% was caused by building operations and 10% attributable to the manufacture of building materials.
Emissions related to the operation of buildings come in particular from energy consumption related to thermal needs (heating and/or air conditioning and hot water supply). As for the manufacture of building materials, emissions are mainly linked to the very energy-intensive production of cement and steel. Together, these two materials were responsible for more than half of the global CO₂ emissions related to the manufacture of all building materials in 2019.
Therefore, it is necessary to use low-emission building materials to reduce the carbon footprint of building construction and renovation.
My colleagues and I are working on the evaluation of potential barriers to the use of wood in public buildings in Quebec. Knowing that the carbon benefit of the construction of wooden buildings is not a topic frequently treated in the media, we present here some of the results of our research.
Impacts of buildings in Quebec
In Quebec, a drastic reduction in the carbon footprint of residential and non-residential buildings is a primary objective. In fact, in 2019, by transportation and industry sectors, CO2 emissions from residential, commercial and institutional buildings were responsible for 10% of the province's total emissions.
These imposing impacts associated with the construction sector are causing concern within the industry and various government entities. We therefore observe a growing awareness on the part of these players, linked to the reduction of the carbon footprint of a key sector for the Quebec economy.
What strategies to reduce the carbon footprint of buildings?
In order to reduce the carbon footprint of buildings, the provincial government is deploying three strategies in particular: the use of renewable energy sources for heating systems (solar heating, biogas), energy efficiency (ventilation strategies that reduce the demand for thermal energy, insulation of facades) as well as the substitution of highly carbon-containing construction materials, such as cement and steel.
The use of wood would reduce the carbon emissions of a building. (Shutterstock)
Because of the significant heating needs, efforts have been mainly concentrated, in recent years, on the first two strategies. So, in the future, the emissions associated with the manufacture, transport and installation of building materials will become proportionately more important than the energy consumption of buildings. Buildings are becoming more and more energy efficient and source more low-carbon energy.
It is important to place increasing importance on the substitution of highly to achieve the province's carbon neutral ambitions.
In the rest of the text, we want to highlight the potential carbon reduction that could result from the use of wood.
Wooden buildings among the potential solutions?
Most studies agree that building wooden buildings would reduce GHG emissions from the construction sector. However, it is important to assess how much GHG could be avoided in this way.
The carbon benefits from using wood change depending on the choice of structural systems. When we talk about replacing conventional materials with wood, it does not mean that there will be no steel or concrete in a building at all. Rather, we speak of buildings in which wood is:
- the only structural material used;
- used in combination with other materials in a hybrid construction (the structural system is made up of two or more materials);
- used in a mixed construction (two or more structural systems overlap).
It is important to note that the benefits of using wood also vary according to the methodological choices and the data used in the studies. For example, a recent meta-analysis showed that wood buildings, when used as a replacement for conventional building materials, would reduce, on average, 216 kg eq. CO2 m-2 (-69%).
Typologies of buildings in which wood prevails in proportion over other construction materials (wood (timber), steel (steel), concrete (concrete)). Eduardo Wiegand & Michael Ramage (2022), study published in the journal Building Research & Information, Provided by the author
What about wooden buildings in Quebec?
Quebec finds itself in a favorable position for the construction of wooden buildings. Indeed,
- the province is a world-class forest state, where forests are managed according to rigorous scientific criteria that aim for sustainability (mandatory condition for wooden constructions to be considered) ;
- sawmills as well as secondary and tertiary processing plants use some of the least carbon-intensive electricity in the world to run their plants; and
- unlike cement and steel, wood production does not emit any GHGs from chemical reactions.
When we look at the studies that have compared wood buildings with conventional materials in Quebec, the use of wood is a consensus. For example, a recent study showed that if 80% of non-residential structures in Quebec were built of wood by 2050, it would save, on average, 2.6 Mt eq. CO2. This amount is equivalent to 3.5% of Quebec's CO2 emissions reduction target for 2050 compared to 1990.
Carbon benefits of using wood in several types of buildings in Quebec. (Luciano Rodrigues Viana), provided by the author
In general, the carbon performance of wood buildings is attributable to several particularities, including less use of fossil energy during the production of engineered wood; avoidance of carbon emissions from high-carbon industrial processes, such as steel and cement; the use of by-products from wood production to replace fossil fuels; biogenic carbon storage in wood; lower energy consumption during the construction and demolition phase of a building; less material needed for the structure as well as for the finishing of the buildings.
It is important to note that we find several examples of world-class wood construction in Quebec, such as the Arbora project, which is the largest residential complex built in solid engineered wood in the world, and the Origine project, a 13-storey building, 12 of which are made of solid wood. The completion of these large-scale projects demonstrates the desire of players in the wood industry and the provincial government to promote the construction of wood buildings.
The construction of wooden buildings is not a panacea. The exploitation of this resource generates significant pressure on forest ecosystems, hence the importance of developing strategies that optimize both the storage of carbon in the forest and the protection of biodiversity.
The greenest building remains the one that is not yet built.
But in terms of carbon emissions, wood seems to be the preferred material in Quebec during the construction and renovation of buildings.
An analysis by: Luciano Rodrigues Viana, doctoral student in environmental sciences, department of basic sciences at the University of Quebec at Chicoutimi (UQAC), Alejandra Zaga Mendez, postdoctoral fellow in geography at the’ Laval University, Jean-François Bissonnette, assistant professor in geography at Laval University, and Jean-François Boucher, professor at the University of Quebec at Chicoutimi (UQAC).
This article is republished from by The Conversation under a Creative Commons license. Read the original article.