Timber - Our Sustainable Future
15-02-2008 - Building Contractor - January - February 2008
Timber in its most basic form continues to be one of the truly renewable building materials available to the Australian construction industry. As it can be harvested and replanted for future generations to continue this cycle. Timber remains one of the most commonly used as Hardwood and Softwood are readily available for purchase in any hardware store. What impact is it having on our environment? Is it sustainable?
Sustainability is a word that is being bounced around everywhere at the moment as the federal and local governments push for more environmentally friendly building practices. Designers and builders have the task creating a house that meets all the requirements set out whilst delivering a home that the property owner will want to live in. Timber offers great benefits to the environment as it is a natural carbon sink. Trees absorb green house gases (including carbon dioxide) that get stored in the wood fibre whilst releasing oxygen via photosynthesis. This is unique when compared to other building materials as the majority arc drawn from the excavation of earth. Steel and Aluminium are mined, brick mortar is extracted from a quarry and most plastics are petroleum based (which is a fossil fuel drawn from deep below the-earth's surface). When mining is used to extract a metal bi-product, tonnes of dust are pushed up into the atmosphere damaging the ozone layer we live beneath. Fossil fuel is used to drive the machinery to cart it around and removed from the site. Once the extracted material leaves the mine site all that is left is a large hole which more than likely never be filled in. Most metal producing companies plant trees to attempt to offset the carbon release during and once extraction is complete. But docs this balance the damage done?
The harvesting and processing of timber does use energy (power) or fuel to run machines therefore carbon dioxide docs get released into the atmosphere but it is mostly off set due to the carbon being stored in the wood fibre. Once a tree is harvested another tree can be replanted in its place to continue to absorb carbon making timber a truly renewable resource. The circle of life for trees can continue into the unforeseeable future. Carbon held in trees is stored until the timber is either burnt or naturally decomposes. Thus if timber is used in the construction of a house the carbon is secure for life.
Designers must now attempt to make the houses as carbon neutral as possible and timber offers a carbon reducing option. The smaller the carbon foot print left behind when construction of a house is complete the better it is for our environment.
Is the limner you use sustainable?
Timber in Australia is very diverse as the natural geography of the country requires trees to grow in a range of conditions. For example wet lands in Tasmania, dry arid land in the desert and tropical rain forests to the north. Each forest carries its own characteristics and own unique collection of species adapted to those conditions. The common volume of timber in the market for everyday construction of Aussie Homes is faster growing Hardwoods, and Softwoods.
Hardwood
Hardwood in the broadest term is a strong, rigid timber that may be drawn from either local and off shore forests with a vast range of species giving birth to almost endless array of colours and textures for builders and designers to utilise in home design. Some species are more readily available than others, this is commonly the faster growing species. Applications may vary around the standard house for example decking, framing, flooring, bench tops and more.
Breaking it down further the forests may be plantation or old growth, responsibly managed or not. A managed forest utilises a silvicultural system which ensures that every tree is replaced with a seedling for the future generation to harvest. If not managed the trees are cut down and bare land is left to erode and be non productive. This practice is regularly seen off shore for example the Amazon jungle and Indonesia. Old growth forests are harvested in Australia but are managed by the way of selective logging (where only a set quantity of trees are can be harvested leaving the seed baring trees to regenerate for the future) or they may be clear felled and a seeding program is applied (basically seeds collected from the local area are spread over the harvested area to regenerate). When old growth is clear felled the areas harvested are small and on long rotation cycles to ensure the surrounding ecosystem are not effected by the harvest operation. These regeneration methods ensure localised species of trees remain in the area as they would have adapted to grow to the conditions. More volume of plantation grown hardwood timbers is available to the building industry today but also a lot of old growth harvesting continues to be available. Where does your hardwood come from?
Softwood
Softwood on the other hand is a lot clearer, as pine is not native to Australian or New Zealand shores. Therefore areas of existing forest had to be clear felled to make space to this new type of tree to be planted. A few different species were introduced but the most commonly used and referred to is Radiala Pine. Since its introduction silvicultural systems have been modified to suit this fast growing tree for example - pruning to give clear wood, thinning to increase tree size and the number of trees per hectare. Also tree breeding and research now has pine growing faster than ever therefore with these developments it has been able to be grown successfully in plantations in Australia and New Zealand. Some forests in New Zealand are into their third generation.
Plantation forests have a range of management principles applied to them, for example they must manage water run off, road and track positions and removal, tree waste distribution, and protection of waterways. Therefore managed plantation forests are the way of the future. Therefore when considering timber options note that the useable volume of timber drawn from 1 hectare of plantation grown pine equates to approximately 40 hectare of harvested Amazon jungle.
Conclusion
Timber has many environmental advantages over alternate building materials so be sure you choose wisely when you start your next project. No matter if you prefer hardwood or softwood there are sustainable options available. Therefore consider the future generations when choosing building products to ensure our kids of today has something to utilise in the future.
How can you be sure where your timber is coming from? Simple, ask your timber merchant. Any timber supplier should be able to prove where their timber is drawn from, or if they do not know off hand they should be able to put you in contact with some one who does.
Building Contractor - January - February 2008