The built environment already is responsible for almost 40 percent of global carbon emissions, according to the UN Environment Programme, and the problem grows larger every day—in fact, the world adds buildings equivalent to the size of Paris every five days.
Making a meaningful move toward sustainability requires addressing the whole-life carbon emissions of both new and renovated buildings. Whole-life carbon considers emissions from operating buildings (such as lighting and heating) as well as the emissions embodied in producing building materials and the construction and renovation processes. Sustainable materials—including mass timber—can reduce whole-life carbon emissions, but adoption isn’t as rapid as it could be.
Rebalancing Operational and Embodied Carbon
First, the good news: there has been tremendous progress in addressing the emissions of buildings in operation. Few people now will be surprised to see solar panels on roofs or heat-pump compressors on walls, and the benefits of LEDs over incandescent light bulbs is well established.
This is excellent, but it represents only one side of the coin. The other is the embodied carbon: the emissions caused by manufacturing the materials that comprise the building as well as the emissions released in the process of building it. In this regard, progress has been much slower. The go-to “modern” materials for architects and designers are steel and glass built on a concrete structure. In fact, concrete, steel and aluminium production worldwide account for 23 percent of global carbon emissions today.
Unlike operational emissions, which can be reduced over time, these emissions are effectively locked-in from the design table onward. That makes it even more time-critical to address, yet we’re only just beginning to.
Rethinking Materials
There are concerted efforts from the concrete, steel and aluminium industries to lessen their footprint, including by investing in new technologies such as electric arc furnaces and carbon capture. However, these trends are in their infancy and remain expensive—we remain a way off from widespread adoption. For many applications, however, including structural ones, we can look to other materials instead.
Mass timber—or engineered timber—refers to specifically manufactured wooden elements that replicate many of the structural advantages of concrete and steel. However, if sourced from sustainably harvested forests, timber can be not only lower in carbon than these materials, it
can be carbon negative; carbon captured from the air during a tree’s growth remains in the wood for the duration of the material’s lifecycle and is only released if the timber is allowed to rot or be burned. Timber can be recycled and reused for purposes such as furniture, packaging and paper after its initial use as a building material, thereby prolonging the period before the carbon is released.
Whole-Life Thinking
A building may stand for 50 to 100 years. Therefore, it’s tempting to leave the question of dismantling and disposal to future generations; tempting, but unjustifiable. Every day, old materials find their way to landfill, with only minimal reuse. It doesn’t have to be that way—elements can be designed for reuse, either in new buildings or in other sectors.
The move toward circularity backed by lifecycle assessments (LCAs) seeks to address this, calculating the environmental impact of products throughout their lifecycle, from cradle to grave. Producers are therefore incentivised to extend that lifecycle to attain better performance, whether through extended longevity or designed-for reuse.
Shifts in Action
Fortunately, we’re not starting from square one. There are pockets of progress where these mindset shifts are already well underway. For example, in 2020 the French government introduced a law known as RE2020, which came into effect in 2022. These rules mandate the use of LCAs and put an explicit focus on embodied carbon in addition to energy use. RE2020 is explicitly focused “on three pillars: low-energy design, use of low-emission materials and reuse,” says Laurent Petit, director of engineering at real-estate developer WO2.
In France, these mindset shifts are well underway. In some of the Nordic and German-speaking countries, they also have been underway for some time. However, progress must be made on a global scale to keep whole-life carbon in focus and make important progress in reducing the built environment’s contribution to global emissions.
About Johanna Pirinen
Johanna Pirinen is senior vice president of Sustainability and People & Culture, Wood Products Division, Stora Enso; email: sustainability.wp@storaenso.com.
The post Future Forward: Raise the Roof with More-Sustainable Materials to Bring Down Carbon Emissions first appeared on Informed Infrastructure.