Considering the timber lifecycle

Camp Glenorchy Eco Retreat

At Camp Glenorchy, all design decisions were guided by the following question: What if every single act of design and construction could make this world a better place? This principle led the project’s design team to rethink the traditional approach to using timber and to make design decisions aimed at transforming its typically linear lifecycle into one that was more sustainable.

The traditional timber lifecycle

There are many good reasons to use timber for buildings at Camp Glenorchy. Not only does it come from a renewable resource (unlike quarried materials), it also continues to store carbon for the duration of its life. Timber reduces build times, has better thermal insulating qualities than competing products³, and adds character and warmth to interior spaces.

New Zealand is considered one of the world’s top timber producers. The industry generates around 4 million cubic metres of timber every year, using mainly Radiata Pine and Douglas Fir (both introduced plant species) that come from renewable plantation forests⁴.

However, there are also some negative aspects related to the timber industry and to the way timber is most often used in New Zealand:

  • Forest diversity - Pine or Douglas Fir plantations are not as diverse as natural mixed forests, which means that native animal species relying on food from different sources can’t live in these habitats. Despite this, some species do live in these forests, and they lose their habitats when the forest is cleared for felling.
  • Modern milling - Transforming a log into standardised timber sections is a process that generates great amounts of waste. On average only half of a log ends up as timber, the rest is transformed into chips, shavings or pulp.
  • Chemical treatment - The most common way to demonstrate compliance with the New Zealand Building Code clause for timber durability is to use treated pine. The treatment usually involves chemicals that can potentially be harmful to the environment and to people. Commonly used chemicals include boron (highly toxic to plants), copper, chromium and arsenic.
  • Embodied energy - While timber is a natural product and requires less energy for manufacturing, there is still the energy used in the drying and milling process, which has associated carbon emissions. There’s also energy associated with transportation from forests to mills and from mills to stores. 

Timber use during construction

Timber is the primary building material in New Zealand and the environmental impacts of the timber industry are therefore large in scale. Timber is responsible for 24% of the waste generated by new residential construction, second only to plasterboard. Most of this timber has been previously treated and is hard to recycle because of the chemicals used. It, therefore, ends up in landfills or is chipped or ground up to be used as boiler fuel. Treated timber offcuts can’t be burned for space heating or for cooking food; nor are the shavings suitable to be used as garden mulch.

Disposing of timber in landfills during construction and at the end of a building’s life is costly and represents the final stage of the linear model that the life cycles of most man-made products and materials follow. Finding alternatives to transform this model into a more cyclical and sustainable one is essential.

Towards a more sustainable timber lifecycle

Camp Glenorchy’s use of timber was done in full awareness of its traditional life cycle and significant efforts were made efforts towards transforming this material’s typically linear process into a cyclical one. To do this, efforts were focused two main areas: using salvaged timber wherever possible and using certified timber that was responsibly sourced. The project was also committed to reducing waste, both during construction and at the end of the buildings’ life.

Salvaged timber

The Winton Woolshed was one of many sources of reused timber for Camp Glenorchy

Salvaged timber is mostly used for furniture and interiors, where it adds character and texture to rooms and common areas. This timber has been recovered from local sources, including a 100-year-old woolshed carefully dismantled by the project’s team, who sorted and quantified the material before storing it under cover on-site so it could be reused in various buildings.

There are multiple benefits associated with the use of this salvaged timber:

  • ‍The woolshed was bought just before it was burned by its previous owners to make space for a new one. Dismantling the building enabled more than 500 linear metres of usable timber to be re-purposed.
  • ‍Most of the timber used in the woolshed was rimu, a strong and durable native timber commonly used in old buildings and rarely found in modern ones. This beautiful timber is a valuable addition to Camp Glenorchy.
  • Using salvaged materials has helped Camp Glenorchy reduce its demand for new raw materials, including virgin timber. This has helped to minimise its environmental footprint and, most importantly, preserve nearby forests and natural resources.

Certified timber

Wherever salvaged timber couldn’t be used, timber certified by the Forest Stewardship Council (FSC) was sourced. This international not-for-profit organisation promotes responsible forestry practices worldwide and advocates for the economic and social sustainability of the communities affected by the timber industry. FSC certified forests work to maintain biodiversity and a healthy ecology, provide education to nearby communities and prevent exploitation or illegal forestry.

By using FSC certified timber, Camp Glenorchy helped minimise the impact of the project on the ecosystems where the timber came from through best practice management and sourcing. As a result, all new timber onsite can be traced back to its origin.

Other efforts

Awareness of the traditional timber life cycle has also led Camp Glenorchy to use Strandboard for interior cladding, a material made of wood flakes and resin that is resistant to moisture and is fully reusable at the end of its life. It has low volatile organic compounds (VOCs) and holds a Declare label from the International Living Future Institute.

Additionally, the use of chromium and arsenic to treat timber was avoided, and a copper-based alternative was chosen instead. Camp Glenorchy also implemented an Environmental Management Plan to ensure quantities of waste during construction were minimised. Strategies to reduce the amount of timber waste included a preference for offsite prefabricated elements, avoiding offcuts and separation of waste streams to facilitate recycling.

Further steps

Timber is a renewable building material that has many benefits when compared to other alternatives. It is durable and full of character. However, there is a long way to go before its use can be truly sustainable. Increasing awareness about the traditional linear model of the timber life cycle is the first step towards transforming that model into a more sustainable, cyclical one that mimics Nature.

Additional steps for design and construction teams to explore include finding new and creative ways to salvage and recycle timber, using alternative treatment methods that enable the reuse of offcuts and chips, and design that reduces waste during construction. Together these strategies should considerably reduce the amount of timber sent to landfill and have the potential to bring about positive change in the life cycle of timber.

Camp Glenorchy wants to encourage this shift by using salvaged and certified timber, and through educational resources that aim to inspire visitors. Reused timber tells a story and gives character to interior spaces while reducing the demand for virgin timber. The use of certified timber guarantees that impacts on the place the timber comes from are minimal, further helping Camp Glenorchy to reduce its environmental footprint.

Footnotes
  1. BRANZ, Housing life cycle and sustainability
  2. Based on 2006 data. Ministry for the Environment. Solid waste composition environmental report card
  3. New Zealand Timber Industry Federation, Timber, your building choice
  4. New Zealand Timber Industry Federation, Industry Information
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