Why Timber?

September 30, 2020by John Doe

Why Timber? In a word, energy.

The Problem

Our lives are founded on the ways that we manage energy, and our capacity to increase the quality of life we enjoy has always depended on energy consumption. As we know, our reliance on fossil fuels to generate this energy and the corresponding carbon emissions is causing more of the sun’s radiation to remain trapped in our atmosphere. In Australia in 2017, we emitted 54kg of CO2 per person per day1. Globally, the additional energy these emissions trap in our atmosphere is now equivalent to letting off six hiroshima-sized atom bombs - per second2. As we know, this is destabilising our climate, increasing the frequency of ‘freak’ natural events which threaten human and natural environments. With 93% of the energy production in Australia in 2017/18 derived from oil, coal, and gas3, there is plenty of work to be done. But while entrepreneurs and business leaders tackle renewable energy production and storage, what can we do about energy use?

The UN Global Status Report 2017 noted that buildings are responsible for 39% of energy-related carbon dioxide4. The Intergovernmental Panel on Climate Change (IPCC) in their special report Global Warming of 1.5°C outlines the need to limit global warming to 1.5°C of pre-industrial levels to significantly reduce the probability of destabilising climate change. It is also the global temperature limit committed to by the Paris Agreement, effective from 2016. The 1.5°C pathway requires new construction to be fossil-free and near-zero energy by 2020, and building emissions to be reduced by 80-90% by 20505. To make matters even more challenging, we need to make these changes amid the largest wave of urbanisation in history with the total number of buildings in the world expected to double by 20604 - equivalent to building a New York City every month, for the next forty years. This is also true in Australia, where it is projected that half of all buildings standing in the year 2050, will have been built after 20196.

It is clear that we aren’t meeting the IPCC goals as the end of 2020 draws near, and this fact paired with the rapidly increasing demand for construction paints an ugly picture. Is there a way we can reverse the ongoing trend and create a more sustainable construction industry?

Energy use in Construction

Energy use over the life of a building is divided between embodied energy and operational energy, with roughly one-third embodied, and two thirds operational. The precise ratio depends on the project.

Operational energy is accrued through the life of the building. This is all the energy used to keep the structure illuminated at night, serviced with modern appliances and hot water, and heated or cooled to a comfortable temperature. The greatest impact we can have on operational energy is through ensuring the construction of high-performance buildings that are suited to their environment. One of the best ways to do this is with the Passive House standard, where buildings can achieve energy savings of up to 90% compared with traditional buildings7. This amounts to significant savings for the operators over the life of the building.

Embodied energy is consumed by all the processes associated with the production of a building. While this accounts for ~30% of the total lifetime energy of a structure, embodied energy is accrued from day 1 of the building’s operation. Due to the time lag in operational energy, it can take between 10-20 years for the cumulative operational energy to become as significant as the upfront embodied energy. Indeed, Architecture 2030 estimates that between now and 2050, half of total global carbon emissions of new construction will be attributed to embodied carbon, and half to operational carbon8. No matter how you slice it, both operational and embodied energy are critical to the decarbonisation of construction.

Construction as a carbon sink

The building infrastructure we construct stands for many decades, and the sheer quantity of buildings we will need to produce between now and 2050 is a tremendous opportunity to trap carbon. Current construction methods favour steel and concrete, which require massive quantities of energy and resources to produce. Traditional lightweight timber systems cannot match steel and concrete in meeting the demands that modern society has for its structures. Massive timber is the only material that is both renewable and can meet the demands that modern society has of its structures. Massive timber, AKA mass timber or engineered timber, is an umbrella term encompassing a range of value-added timber products created in a factory setting by recompositing solid-sawn timber boards into arbitrary shapes - unrestricted by the dimensions of boards sourced from any individual tree. The collaboration of mass timber construction, which sequesters up to 1 tonne of carbon per cubic metre of material, and high-performance building standards such as Passive House, presents a real possibility of true zero energy buildings.

Beyond Environment - The added value of massive timber

There are more than just environmentally conscious reasons to use massive timber. Structurally, mass timber is very strong, robust, and light. Buildings of mass timber have 30% less dead load than comparable concrete structures, requiring lighter foundations and opening up the possibility for retrofits expanding existing structures. Construction sites that build using mass timber are quieter and more easily managed, improving safety. There are no wet or hot trades pouring concrete or welding connections. Architecturally, the material has a high aesthetic quality which can be expressed to leverage the biophilic response - the natural tendency for stress levels in occupants to reduce in the presence of nature, with a plethora of documented improvements in wellbeing9.

Mass Timber and Prefabrication - Scaling to the future

So how exactly will we build a New York City’s worth of massive timber, high performance buildings per month for the next 40 years?

Prefabrication.

The strongest economic case for building with mass timber is its disposition in favor of prefabrication and offsite manufacturing. Baked into its method of manufacture, individual boards, panels, beams and columns are composited to tight tolerances, cut to angle, fit with dowels, covered with insulation, fire protection, or finishes, and transported to site where they can be rapidly assembled into the final product. This change in building method challenges the current culture of construction: to be ready for manufacture, the design needs to be completely resolved. This requires a high level of coordination between project teams, and a rigorous approach to building information modelling. We are witnessing a shift in the construction industry with the uptake of these methods, and a cultural shift that is heralding a future of highly efficient, prefabricated, sustainable and high performing buildings.

The way we handle our energy remains the key to our prosperity. Over the coming decades it is clear that we will need to find ways of doing much, much more with much, much less. For the construction industry, this represents a grand opportunity to reinvent our infrastructure and scale to the future. By harnessing prefabrication and bringing low embodied energy materials in structures of low operational demand, we can build beautiful, net-zero energy buildings as a platform for our civilisation to thrive.

That is why we choose to design in timber.

About the author

John Doe

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September 30, 2020