Anne Carcelen | The URSSAF headquarters in Paris, an eight-story mass timber structure, is certified RT 2012 -30%, HQE Exceptionnel, BREEAM Excellent, and E+C-:E2C1. It received 3 awards in 2020/2021 and was elected to be part of “The 100 best projects of the year 2021 in France“ by Archistorm magazine.

A century ago, the Roaring Twenties marked an economic, social, and cultural renewal. Today climate crisis and eco-anxiety call for a new renewal. Timber, an ancient yet contemporary material with sustainability and versatility at its core, can pave the way to a sunny future. It is time for growing forests and optimism. Because as our children grow, they ask questions and… very soon they’ll hold us accountable. Let’s be honest, let’s not hide away, let’s answer their questions. “Why not timber? Timber is renewable, low-carbon and healthy. So… why not timber?”

Renewable? Yes. Timber is renewable because it is bio-sourced. Furthermore, although counter-intuitive, data shows that global regions with the highest levels of industrial timber harvest and forest product output are also regions with the lowest rates of deforestation, as revenue and policy incentives are provided to invest in reforestation and sustainable forest management rather than in other profitable uses such as agriculture. And since forests are the lungs of our planet, then using timber gives her breath. Plus, modern forestry standards in North America ensure a continuous cycle of growing, harvesting, and replanting. More than 90% of the world’s certified forests are in the northern hemisphere, almost half is in North America, and some 9% in the United States. So timber is available, though the manufacturing force is still lacking. It is time to invigorate the timber industry.

Low-carbon? Yes. Timber is low-carbon because forests are carbon sinks. Furthermore, timber stores more atmospheric carbon during its use stage than is released during its production stage, reducing global warming potential (GWP) by up to 200% compared with a steel-framed benchmark, thus allowing us to respect our carbon budget. As importantly, timber has a better strength-to-weight ratio than steel or concrete. This minimizes foundation work and allows, by use of a mobile crane and a dry construction process, light timber extensions within the existing building fabric. Because the future no longer lies in demolishing and rebuilding, as existing buildings offer the priceless advantage of having already amortized their carbon footprint. Because the future lies in restructuring and retrofitting existing structures through targeted interventions, we will carefully build the interstices, build within, above, in between… We will “inter-build” thanks to the lightness of timber. It is time to reach net zero.

Healthy? Yes. Timber is healthy because it is a key part of biophilia. A concept first enunciated in 1984 by biologist Edward O. Wilson, biophilia means incorporating into buildings natural elements such as wood, vegetation, daylight, water, fresh air, access to outdoor spaces, and views of nature. It can reduce blood pressure, heart rate, stress, activation of the sympathetic nervous system, volatile organic compounds, and virus spread. It improves calmness, cognition, learning, memory, emotion, sociability, creativity, productivity, performance, focus, and mood. While wood has been used as a building material from time immemorial, its benefits to people who live, work and gather in the built environment are only beginning to be understood. Yet, Americans spend about 90% of their time indoors. It is time to design healthy buildings.

Anne Carcelen and François Leclercq | The Nelson Mandela education complex in Nantes, biggest timber structure school in a seismic area in France, is certified HQE (high environmental quality) and BEPOS (positive energy building). It was awarded the Grand Prix National of Wood Construction in 2015.

Being renewable, low-carbon, and healthy are all compelling arguments. Then, which obstacles restrain us from using timber? Code and cost. We can consider the code obstacle as a thing of the past. As expertise, technology, and experience in mass timber advance, as its inherent fire rating through charring is being recognized, the International Building Code has evolved, and the IBC 2024 calls for more timber. The code’s building type IV-A permits mass timber structures up to 18 stories and 270 feet, though it does not allow any exposed timber… yet. Type IV-B permits timber buildings up to 12 stories and 180 feet with 100% exposed timber ceilings. Type IV-C permits timber buildings up to 8 stories and 85 feet with full timber exposure in the building’s interior. Thereby the code obstacle is overcome and in its wake, the public fear of timber’s hazard is progressively swept away. 

As for the cost obstacle, it is actually a misconception. As while timber construction still shows a higher capital cost compared with steel or concrete, it proves to be cost-competitive when we consider global cost. If we look further, we see the savings soon to come. First, timber construction shortens the schedule, limits waste, reduces foundation loads, minimizes site crew, and diminishes finishes (by use of exposed timber), thus saving construction costs. Second, timber construction’s energy efficiency will save fines that will soon come as coercive laws are around the corner. Third, the high thermal performance of timber buildings reduces energy consumption in HVAC systems, thus saving operating expenses. Fourth, timber’s cost will progressively lower as the timber industry and market-driven competitiveness kick in. Fifth, data shows that sustainable buildings are more marketable, and healthy interiors increase productivity, thus increasing profitability. In the long term, these benefits outweigh the higher capital cost.

Thereby, timber presents undeniable advantages and no valid obstacle. And yet, we ask our children for more patience, claiming we need some time to adapt. But their patience is over; Earth Overshoot Day is now in July. Rather than seeing the climate crisis as the end of the road, let’s see it as a door opening toward the essential values of our life on Earth. Timber is a live material that takes us back to the essentials and helps us hear when a child cries: “It is time for growing forests and optimism!” These are the Growing Twenties.

Anne Carcelen and François Leclercq | The France-Uruguay boarding school in Avon (FR) is a modular mass timber building completed in 2022. The 206 student homes were installed on site within only eight weeks.

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