Tall Timbers – wood is the fastest sustainable way to build

On this page:

1. Energy efficient design first
2. Protect old growth and biodiversity hotspots
3. Wood is strong and survives fire and earthquake better than steel and concrete!
4. Faster builds, less labour costs
5. House 3 billion people in record time!
6. Forests can be harvested sustainably
7. Katerra went bankrupt. But the building codes have adopted wood and the industry WILL change!

1. Energy efficient design first

We cannot sacrifice energy efficiency just to use some trendy new material. The videos on my Energy Efficient page have helped me conclude that while the energy embodied in the materials is important, operational energy efficiency over the building’s lifespan is more important. That is, if it takes more energy in the materials up front (like building out of concrete) to generate energy efficiency for a longer period of time over the building’s lifespan – then do that!

Fortunately, with wood as a building material, we may find we can have both!

2. Protect old growth forests and biodiversity hotspots

While timber is a great renewable material, we must first protect biodiversity hotspots and old growth forests. Some forests and tropical jungles have threatened bugs and plants and insects and mammals and birds. We must protect these at all costs. Personally I would ban logging from all remaining old growth forests and encourage fast growing bamboo and hemp and other wood alternatives to meet any gaps in the paper fibre markets. Then we should establish a vast new tree farm industry to meet the growing populations’ need for future housing. Tree-farms should not be monoculture, but diverse and encourage a true ecosystem – and even be logged sequentially over time so the ecosystem survives! 

3. Wood is strong and survives fire and earthquake better than steel and concrete!

This TED talk explains

CLT or Cross Laminated Timber can take stress from both directions so is great for panels that make floors or ceilings. GLULAM is Glue Laminated Timber which is used for load bearing columns.

By gluing these timber products together, they are stronger than steel with less weight, and even resist fire damage at a predictable rate sometimes safer than steel and concrete.

Tomorrow’s Build channel also looks at strength, fire, supply chains and the pre-fab factories.

4. Faster means less labour costs

The Vox youtube above claimed a traditional steel and concrete construction site might have 100 workers carrying in all sorts of materials to make custom pieces on site. This creates a lot of extra work on site, and work managing dust and waste. But with wood, the digital design process is even more important because all that is being prefabricated in the factory before the panel gets there. Once the prefab parts are on site – it might only take 30 workers to do the same job – with far less mess.

Fire engineer Robert Gerard from ARUP says:

From a financial perspective, developers are starting to acknowledge the benefits of tall wood construction using prefabricated elements because it reduces construction times and costs. So that’s ultimately what’s driving the push. And I think that as governments continue to quantify sustainability costs through credits, rebates, and upholding energy and carbon standards, it makes the business case to support timber as the primary structural material even stronger. And architects are driven to wood by the sustainability benefits and increased design flexibility.

Gizmodo says:

At London’s Stadthaus, a team of four put the first eight floors of structure together in less than a month. The entire building was finished in less than a year.

 

5. House 3 billion people in record time

This is the famous Michael Green TED talk from March 2011 that inspired America to build their first tall buildings from CLT.

• Summary: 3 billion people will require new housing in the next 20 years! This is 100,000 new homes each and every day.
• A first world (average Canadian) home built out of wood stores 28 tonnes of carbon for about 60 years, rather than emitting as much carbon from concrete and steel. New Urban ecocity apartments might be more efficient than suburban homes with the wood per person, but you can still see the potential for storing carbon is enormous. Divide 100 thousand people per day into the average of 2 people living in a family home (from memory – don’t quote me on that) and you get 50,000 homes per day, or 1.4 million tonnes per day, or 511 million tonnes per year. Over 20 years for the 3 billion people that’s 10.2 gigatonnes of carbon sequestered. Not CO2 – carbon – which is 37.5 gigatonnes of CO2 equivalent. Stored for 60 years!
• Michael claims that rammed earth and adobe projects are mainly rural or suburban solutions, not the high density, fast to deploy pre-fab construction we so urgently need.
• 15% of the world lives like the ‘first world’ and builds the majority of floor space today, but 85% are living in sub standard accommodation.
• Buildings use:
  • 20% of our water,
  • 25% to 40% of our energy,
  • 30 to 40% of greenhouse gases,
  • 24% to 40% of solid waste generation,
  • we make 3 tons of concrete per person on earth each year,
  • airlines emit 1% of world carbon, shipping does 3%, all transportation is 15%, but 5-8% of all our carbon emissions comes from concrete alone!

This ABC podcast architect Michael also unpacks some other building statistics.

• He uses Aspen and Birch trees that are shredded and the fibres glued together
• Trees are only 10 to 15 years old when harvested
• Apart from the foundations, wood can replace the use of steel and concrete in buildings and becomes the new structural backbone of the skyscraper!
• CLT beams are now 20 m long by 2.5 m wide by 8.5 cm thick
• Wood weighs half as much as concrete which improves the strength of the building in an earthquake. Wood buildings have survived earthquakes better than heavy steel and concrete buildings
• Can lead to an enormous reforesting business worldwide, and an enormous sequestration of Co2!
• As a material the wood is more expensive but it drastically reduces the labour costs associated with buildings as it can go up so much faster.
• Once the growers and millers are in the supply chain, CLT creates an assembly line for housing. It’s the equivalent of Henry Ford inventing the assembly line for cars! If not convinced, rewatch the videos above.

6. Forests can be harvested sustainably

There’s enough trees. The 2014 study in the Journal of Sustainable Forestry concluded:-

“Globally, both enough extra wood can be harvested sustainably and enough infrastructure of buildings and bridges needs to be built to reduce annual CO2 emissions by 14 to 31% and FF consumption by 12 to 19% if part of this infrastructure were made of wood.”

The biggest drop in CO2 emissions came, it said, from “avoiding the excess [fossil fuel] energy used to make steel and concrete structures.”

7. Katerra went bankrupt. But the building codes have adopted wood and the industry WILL change!

Sadly it seems Michael Green’s company was bought by Katerra and then Katerra went bankrupt. The youtube below explores what went wrong in basically not just building from wood, but trying to reorganise the entire supply chain and building sector from growers and millers to the prefab factories and builders. Rather than each construction project being bespoke custom designed and built, with pretty much customized sizes of components etc, they were trying to put housing into an assembly line much like the car industry. It seems they failed.

But the good news is the International Building Codes have accepted up to 18 storey structures. Prefabricated CLT panels manufactured in a factory are intrinsic to building with wood. Standards have to emerge. The assembly line process will evolve and mature. Standards will emerge for parts and processes. Individual architectural designs and homes and apartments can still be built, but will draw on an easier modular system for their custom requirements. This industry as an assembly line system should reform despite the bankruptcy of Katerra!