Green movement

Of all the environmental benefits of American hardwoods, just one should make many users and specifiers of building materials take notice – that between 1953-2007, the volume of hardwood standing in US forests more than doubled from 5 billion m³ to 11.4 billion m³. This huge expansion – which actually coincides with a period of significant increase in US and international wood demand – is testament to a long-term commitment to good forest governance and sustainable hardwood production in the US.

Hardwoods represent 43% of the US’s forest growing stock and around 25% (60 million m³) of the total annual production of lumber, plywood and veneer (250 million m³).

The US hardwood resource is significant not only for its size, but also for its rich diversity. Hardwood forests comprise hundreds of species, of which at least 30 are of significant commercial value. In the eastern states, red and white oak species are the most prevalent hardwoods, followed by hard and soft maples, tulipwood, hickory, sweetgum and ash. Red alder is the main commercial hardwood produced in the north-western states.

Global trade

Backed by a diverse and expanding resource and with rising international concern for sustainability, US hardwoods are playing an increasingly important role in the supply of raw materials to the world’s building and furniture industries. The US contributes nearly one-fifth of the world’s hardwood saw and veneer logs. It is also the largest external supplier of hardwood to the EU, accounting for one quarter of all imports of hardwood lumber and veneer. Around 20% of all hardwood consumed in the UK derives from the US.

Despite its global significance, the US hardwood industry is very much a community affair. Four million individuals and other private entities own the 110 million ha of hardwood and mixed oak-pine forest types in the US. Of the private hardwood timber produced, only 17% derives from company-owned lands and the remainder comes from non-corporate, family forest owners. There are more than 14,000 hardwood businesses in the US, mainly small and family owned.

This ownership structure has major implications for forestry practices and environmental impacts. The main motivation for owning hardwood forests is usually the enjoyment of ownership, not timber production. Because timber production and economic return to shareholders are not primary objectives, owners tend to manage less aggressively and grow their forests on long rotations.

Harvesting operations

Selection harvesting rather than clear-felling is typical. The size of harvesting operations is limited by the size of forest holdings which rarely exceed 10ha. After harvesting, forest owners usually rely on natural regeneration and there is little need or incentive for the addition of chemical fertilisers and no non-native or genetically modified species are used.

Long-term management of the forests for sustainable timber production makes a significant contribution to carbon storage. Each year for the past 50 years the forests stored around the equivalent of 165 million tonnes of carbon dioxide (excluding all harvested material). That’s enough to offset about 14% of US annual residential emissions in 2006, or 9% of US annual transport emissions in the same year. This direct contribution to carbon sequestration excludes the carbon held in long-term storage as a component of American hardwood products.

American hardwoods are also energy efficient. The process of converting wood into building products requires considerably less energy than most other materials. Furthermore, much of the energy needed to produce American hardwood products is bio-energy. A 2007 study of 20 hardwood mills in the north-east revealed that 75% of the energy required to manufacture kiln-dried lumber derived from biomass.

Carbon footprint

A preliminary assessment by The American Hardwood Export Council (AHEC) of the carbon footprint of American hardwoods from forest to European distributor suggests that carbon sequestration during growth of the tree will more than offset the total carbon emissions resulting from harvesting, processing and transport. The AHEC assessment also suggests that transport is a relatively minor factor in the overall carbon footprint. This is particularly true of ocean transport. Shipping more than 6,000km across the Atlantic, requires little more energy than an overland journey of 500km. Even a complete circumnavigation of the world by sea (40,000km) is likely to be readily offset by the carbon sequestered in the wood product.

To increase the scrutiny of the environmental impacts of materials and the transparency of supply chains, in 2007 AHEC commissioned an independent assessment of the risk of illegal and unsustainable wood entering US hardwood supply chains. The report by consultants Seneca Creek Associates concluded that there can be high confidence regarding adherence to national and state laws in the hardwood sector and that stolen timber is likely to represent, at most, 1% of total US hardwood production.

The authors of the Seneca Creek study also have high confidence that US hardwood be considered low risk in all five “risk categories” of the FSC Controlled Wood standard.

Legal regulations

Building on the results of the Seneca Creek study, the American hardwood industry is a strong advocate of regulations which aim to eradicate illegal wood supplies from the international trade. In 2008, the US Hardwood Federation, the industry’s representative association, joined environmental groups in a successful effort to extend the US Lacey Act to include wood products. The amendment makes it an offence within the US to possess any wood product “taken, possessed, transported, or sold” in violation of any foreign or state law. Any US company that doesn’t take due care with respect to its wood supplies could face criminal sanctions.

AHEC has been advocating the introduction of similar legislation in other major wood-consuming regions, including the EU, and it welcomes the EU’s Illegal Timber Regulation (ITR) which comes in effect from March 2013. The ITR will make it a criminal offence to place timber illegally harvested under the laws of any country onto the internal EU market. It also requires European importers to implement due diligence procedures to minimise the risk of any wood coming from an illegal source.

For American hardwoods, the combination of the Seneca Creek study and existing shipping documents, such as exporters’ invoices, phytosanitary certificates, and US Shipper Export Declaration forms which identify species, product type, quantity and that the product is of US origin, should be sufficient to demonstrate negligible risk and meet the ITR requirements.

Life cycle assessment

AHEC is now encouraging a more science-centred approach to green specification and design using environmental life cycle assessment (LCA). Although there is some way to go before LCA becomes a deciding factor in material specification in the UK and wider European market, there are clear signs of movement in this direction. Green building rating systems like BREEAM in the UK, HQE in France, and DGNB in Germany are becoming more widely used and all draw on LCA for allocating credits for building materials.

In line with this market shift, in 2010 AHEC commissioned the largest LCA study ever carried out in the international hardwood sector. The independent assessment is being undertaken by PE International, in accordance with ISO 14040 standards for LCA. It will include, as a discrete component, independent assessment of the carbon footprint of American hardwoods in line with carbon footprint standards such as the UK’s PAS 2050 standard and the international Green House Gas Protocol.

The study involves the compilation of environmental life cycle inventory data on the main American hardwood species from point of extraction in the US through to delivery as kiln-dried sawn lumber or veneer in the EU and Asia. This will enable the industry to identify “hot spots” of higher environmental impact and to better target improvement measures. The study also includes a life cycle impact assessment for a number of high priority finished construction and furniture products manufactured from American hardwoods in the EU market.

Environmental Product Declarations

A major output of the study will be the preparation of Environmental Product Declarations (EPDs) for American hardwood products. EPDs are designed to allow fair comparison of the environmental performance of products through structured, science-based, and verified information. They provide information along the product’s entire supply chain, are designed to be neutral with no value-based judgements, and are required to be verified by an independent third party. ISO 14025 provides guidance on the structure and content of EPDs.

So is American hardwood the most environmentally friendly building material on the planet? We don’t know – yet. We’ll have to await the results of the PE International study and more widespread publication of EPDs. But American hardwoods must be a contender – given their unique ability to combine a vast and rapidly expanding resource, low intensity extraction, carbon sequestration properties, low emissions during processing, strong performance in use, and an industry with demonstrable commitment to transparency and improved environmental performance.