The built environment and construction sector have been known to consume exorbitant amounts of energy and environmentally strenuous materials, such as concrete, plastic, glass, and steel.
With 1 billion additional people projected to be living in African cities by 2050,[1] demanding decent housing, schools, and places to work, it is guaranteed that if we continue building with current mainstream methods, more solid waste will be produced, more carbon will be emitted, and more natural resources will be depleted. Therefore, rethinking how we build to meet future housing demands may be one of the most crucial steps toward increasing sustainability and tackling the Climate Change Emergency.
Many architects and construction companies worldwide have positively responded to the call to minimize the industry’s environmental impact. They are increasingly adopting more environmentally responsible and resource-efficient design and construction practices. This shift toward less climate-intensive practices is commonly referred to as green or sustainable building.
In its basic form, green building focuses on energy, land and water efficiency, environmental protection, reducing pollution, and optimizing human comforts. A more complex look at green buildings encompasses the entire building’s climate impact from its construction, operation, maintenance, and renovation, to demolition. The goal of green building is not just to contribute less greenhouse gas emissions into the atmosphere but also to anticipate, absorb and adapt to climate shocks. This more expansive sustainability goal has led to a resurgence of mass timber[2] use in construction.
Making the case for timber
The material cost of mass timber is slightly higher than that of reinforced concrete, which begs the question, why would anyone choose a more expensive building material? Well, wood, even when engineered into mass timber, maintains its lightweight quality, allowing material costs to be offset by other construction costs such as design modality, project timelines, and labor charges. Mass timber projects can be fabricated off-site and easily transported to construction sites, lowering project timelines by 20% to 60%[3], requiring significantly fewer people to build and producing less material waste. Despite the higher material cost, a mass timber construction projects can actually be less expensive than current traditional construction projects.
Moreover, while embodied carbon from traditional construction materials contributes to about 11% of global carbon emission[4], building with timber can decarbonize the built environment. Growing trees removes carbon dioxide from the atmosphere and store it as carbon compounds in their wood. The carbon dioxide stored in the tree remains in place throughout its lifetime, even after turning it into a wood product.
So, when we sustainably harvest grown trees for long-life products such as mass timber to use in buildings, substituting for carbon-intensive products like plastic, concrete, or steel, we contribute to a positive climate outcome. A recent study suggests that housing 90% of the world’s growing urban population in mid-rise wooden buildings could prevent 106 billion tons of carbon emissions by 2100.[5]
Wood’s regenerative quality, leveraging techniques such as ‘group harvesting’[6][7], also gives us confidence that we can meet the supply and demand of the impending construction boom while continuing to decarbonize construction if we continue to manage our forests sustainably. Which means harvesting trees at a rate that allows the forests to renew themselves by planting tree seedlings as soon as possible after harvest.
Once built, wooden houses are natural thermal insulators and sound absorbent, making them more energy efficient and echo-proof than masonry, concrete, and steel-framed buildings.
But how safe is wood?
Wood is commonly understood to be eco-friendly, healthy, and aesthetically pleasing but is often disregarded as a durable construction material able to withstand the tests of time, and protect us from the elements, and infestations. But with hundred-year-old wooden structures still standing in Europe and Asia, we have proof that wood is in fact long-lasting. Mass timber buildings are made from mature trees, joined together in thick layers, forming durable and tensile structures that have been proven to outperform even steel and aluminum.
Another common concern about building with timber is fire. Wood is undeniably combustible, but the risk of fire developing is not tied to how flammable any construction material is. Like any other buildings, wood-framed buildings are made to meet fire code requirements, with fire-protective cladding and sprinklers making them equally safe. In the event of a fire, mass timber’s large mass provides inherent resistance to fire because it chars on the outside while retaining strength on the inside, slowing the combustion rate, and allowing ample time for evacuation.
Nature’s response to the climate crisis
As we plan to meet the future housing demands of East Africa’s rapidly urbanizing landscape, we must think wood!
Despite the current nascency of the mass timber construction industry, the industry can play a central role in meeting the regions housing demands. The region has a looming 65% rise in affordable housing demand by 2050,[8] a new generation of climate-conscious home buyers demanding green buildings and abundant forest covers, ready to supply timber to East Africa’s built environment for years to come. According to the East Africa Sustainable Timber Construction Supply/Demand Study, systemic changes are needed to fill supply chain, policy, and regulation gaps to allow a full-scale and sustainable adoption of mass timber in construction in the region.
Yet, using Kenya as a case study, if the country can create the necessary enabling environment and the regional supply chain is strengthened, the study projects that by 2040, the market share for green buildings could rise up to 70%, with mass timber and mass timber hybrid buildings constituting up to 42% of all new green residential and commercial developments. In this scenario, the country could save up to 2.97M tCO2e of embodied carbon within the mid-rise residential buildings landscape by 2040.[9] So, early adopters of this innovative building material stand to gain a first-to-market advantage, establishing themselves as not only timber build experts but also climate heroes.
Paving the way to a full-scale wooden revolution and offering affordable housing solutions in East Africa are BuildX Studio and Easy Housing.
BuildX Studio operates in Kenya, pioneering green construction while offering a framework for a forest-to-frame value chain suited to respond to Kenya’s housing demands. According to a World Bank Group study, Kenya needs to build about 200,000 new housing units yearly in its cities just to keep pace with population growth and rocketing demand.[10] In addition, BuildX is developing a multi-story mass timber building to demonstrate the feasibility of the material in the East Africa context. Easy Housing has focused on building prefabricated timber homes to offer comfortable, safe, and affordable housing for low to middle income urban families. The organization has completed successful demonstration projects in Mozambique and Uganda and is looking to scale operations further in these countries.
BuildX and Easy Housing are among the organisations laying the groundwork to unlock the full climate potential of engineered timber construction in East Africa. The discoveries and knowledge generated through these model projects are making a case for a wood-based construction industry in the region and highlighting the opportunities yet to be grabbed by industry players. As the industry grows in the region, design and construction companies must leverage the opportunity to build East Africa’s future homes using a timesaving, cost-effective, aesthetically pleasing, and climate-smart building material such as mass timber, or get left behind.
[1] ARUP, East Africa Sustainable Timber Construction Supply/Demand Study, 2022 [2] Mass timber, also called structural or massive timber, is an engineered wood product category composed of multiple solid wood panels joined together to provide exceptional strength and stability. Mass timber comes in different shapes, sizes, and functions, with the most popular kinds being Glue-Laminated Timber (glulam) and Cross Laminated Timber (CLT). [3] Climate Smart Forest Economy Program, Building a technical and finance facility to support impact oriented businesses, 2022 [4] See note 1 [5] See note 1 [6] Grebner PHD, et al., Introduction to Forestry and Natural Resources (Second Edition), 2022 [7] For example, some coniferous forests in northern Italy are managed with group selection harvests that attempt to achieve timber production, ecological (e.g., soil protection), recreational, and aesthetic objectives. In this system, the typical cutting cycle ranges from 10 to 20 years and the intensity of harvest is about 20% (or one-fifth) of the standing tree volume [8] See note 1 [9] See note 1 [10] See note 1