Wood use on construction sites increasing

Media release from the Southern Wood Council
December 16, 2008

Wood use on construction sites increasing

More wood is being used on construction sites around New Zealand, and Otago and Southland is no exception.

There’s been growth in wood used for new house framing, flooring, and new house floor joists, as more home builders make conscious choices for sustainable building options.

According to the latest BRANZ report on market share of timber and timber consumption in new building work for the first six months of 2008 in New Zealand, there was a 3.1 percent increase in timber share, which was offset by decreases in concrete masonry and panels, light steel framing, and other framing.

The new house framing market share was up by five percent, as was flooring.

Southern Wood Council chairman Grant Dodson welcomes the growth in wood use, and points out the increase is having a positive environmental impact as wood, of all the construction materials, is the only one that removes carbon from the air.

“An average house can therefore make a significant contribution to reducing carbon simply on the basis of the materials it has been built from,” he said.

This is backed by information from a new carbon calculator for houses just released by NZ Wood, which shows choosing timber options for an average house can take nearly 20 tonnes net of carbon out of the atmosphere.

This saves carbon to the equivalent of over 110 trips from Picton to Bluff, 7.1 years of car use, or flying around the world five times.

Building, particularly residential construction has an increasingly important part to play in carbon absorption, and the Otago and Southland region is certainly contributing.

116 building consents worth $35 million were issued for new dwellings in October 2008 in Otago and Southland (according to Statistics NZ). Timber house construction from these structures would therefore easily store 2320 tonnes of carbon from the atmosphere from just one month’s building in the southern regions.

Better still the replanted trees in the forest will continue to absorb even more carbon for the next generation of buildings to come. If other materials such as steel or concrete were used instead of timber, this building activity would be a carbon emission,” Mr Dodson said.

The carbon calculator on the NZ Wood website www.nzwood.co.nz works out the carbon emissions or savings that can be attributed to the building materials used for a new home, making it straight forward for potential new home owners and their builders to see their carbon impact.

Mr Dodson sees the calculator’s launch as a simple but dramatic demonstration of the amount of difference construction materials can make to the environment. It also demonstrates the clear environmental benefits that the forest industry brings to New Zealand.

“The 215,662 hectares of plantation forests in Otago and Southland are increasingly valued as a precious regional resource because of their carbon-absorbing ability as well as their economic contribution.”

“Now data is coming through that shows how easy it is to build a ‘carbon-neutral’ house using wood, which is more recognition that growing and harvesting wood is good for the environment,” Mr Dodson said.

The data is based on what is known as “embodied CO2”. This represents the amount of CO2 either emitted or absorbed by the building materials in their production.

In the case of wood, for example, Pinus radiata has absorbed a net 1.7 tonnes of CO2 for every tonne of wood used in the house. That’s over and above all the energy used (and subsequent CO2 released) in its growing, harvesting and processing – right up until it leaves the sawmill door.

This compares with a material such as aluminium, which has released over nine tonnes of CO2 into the atmosphere for every tonne of final product. Steel releases 1.2 tonnes of CO2 for every tonne of final product. Concrete releases around 160 kilos of CO2 per tonne of final product.

And all New Zealand-grown wood is grown sustainably – usually from a forest plantation. This means new trees will be grown to replace those harvested - removing still further carbon.

“I can see the carbon calculator being a useful tool for home builders here in Otago and Southland as they weigh up their sustainability options in home design and construction,” Mr Dodson said.

According to the carbon calculator, using a wooden frame and a wooden floor makes a difference. If you choose a weatherboard rather than brick cladding, then use wooden window frames instead of aluminium, you’re making a huge difference, and end up with a carbon footprint of minus 20-25 tonnes. That’s 20-25 tonnes of carbon removed from the atmosphere.

The calculator was developed with the help of researchers and engineers at Victoria and Canterbury universities and quantity surveyors Davis Langdon.

The Southern Wood Council Inc was set up in 2001 to promote, encourage and coordinate the sustainable economic development of the forest products industry in Otago and Southland. One of a few truly independent groups of its type in New Zealand, i_t includes all the major forest owners within the region (ownership or management of over 140,000 hectares of production forests with an annual harvest of over 1.2 million m³ of wood), the larger wood processing and manufacturing companies, the port authorities, and each of the three economic development agencies from local councils.

ENDS

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