Summary
• Architects and specifiers want to know wood’s environmental impacts.
• AHEC’s life cycle analysis for US hardwood, will be comprehensive.
• The study examines timber’s eco credentials from cradle to grave.
• Transport will be a key focus.
Not long ago architects just thought about their client’s needs and aspirations, designed a building, picked some nice materials and made sure the finished article stood up and didn’t leak.
Those days have long gone. While issues like disability access and health and safety have had a considerable effect on buildings, the most important new impact is the issue of sustainability. This feeds in to everything from the regulations that have to be followed to more in-depth concerns about the sourcing of materials. These include both the need for assurances that materials have been sourced sustainably and calculations about the embodied energy of the materials that are used in buildings. The latter becomes increasingly important as the energy that a building consumes in use decreases. So it is important to look at the ‘cradle to cradle’ impact of a building – from the first actions taken with the raw materials, all the way through to demolition and possible reuse.
The difficulty, of course, is that there are so many components in a building, and so many variables. As Jim Greaves of Hopkins Architects said at the recent American Hardwood Export Council (AHEC) European Convention, “I am talking about systems – looking at the impact of everything put together in a building.” As an architect, he doesn’t have the time or the skills to look at all the individual components in terms of their environmental impact.
So, in response to the needs of Mr Greaves and other specifiers and timber users AHEC is investing in a detailed life cycle assessment (LCA), produced by the independent consultancy PE International. This will provide detailed information on timber and veneers, and is being carried out in line with ISO 14040, the international standard on LCAs. When complete, it will be peer reviewed to make doubly sure it is an authoritative piece of work. But, given that architects and specifiers are already overloaded with information, is it worth it?
The answer is definitely yes. Architects who want to use wood in buildings need the ammunition that such a document can give them. AHEC’s is the first LCA that deals with hardwoods. Other industries such as steel and concrete have invested in them already and use them to push their materials. Without an LCA of its own, US hardwood, in fact all timber, is in a weakened market position.
Preliminary results
Rupert Oliver, of Forest Industries Intelligence, who has helped to provide much of the information about the timber industry that PE International used in order to set the parameters for its LCA, told the AHEC European Convention that preliminary results show that the global warming potential (GWP) of one tonne of 1in kiln-dried American white oak lumber delivered into the EU is -1 tonne. This means that: “Due to the carbon stored in the wood, every tonne of US hardwood lumber imported into the EU effectively offsets one tonne of carbon dioxide emissions.”
So, while it has often been said that timber is environmentally friendly because it is the only material that, overall, stores carbon rather than generates it, the figures are now there to prove it. These take into account all the processing that the timber has gone through, the energy consumed in drying it, and the energy used for transport.
Transport is a greatly misunderstood issue. While it is true that transporting any material consumes energy, not all transport is equal. American hardwoods are typically grown and processed relatively close to navigable water. This means that when used in Europe they may generate little more carbon on their 6,000km sea journey than European timber will do if it travels 500km by road.
It may be, of course, that an architect or a client will want to support a local producer, or use a particular locally-grown timber for aesthetic reasons or because of an association. The point is that the LCA allows them to make this decision on an informed basis, not because of an intelligent but wrong guess.
The other reason why an LCA is important is because of the increasing amount of documentation required now and in the future. These include Environmental Product Declarations (EPD), a coding method for showing how ‘green’ your product is. EPDs already exist, forming, for example, the basis of BREEAM’s guide to green building materials, but at the moment they are only voluntary. France, however, is looking at making them mandatory on all consumer goods, and we can expect others to follow. The information that can be extracted from an LCA can feed into these systems.
It is all still quite complicated but the information will be there if you need it. Almost every major project now has a sustainability consultant, and the LCA will provide them with vital information. It is a back-up for architects who love timber and want to use it wherever possible, and an incentive for those who are still considering whether to use it. Simply pronouncing timber is green is no longer enough. With an LCA you will have the information behind you to back up your argument if need be.
