Life Cycle Assessment of Toca Madera Finalist Designs

Background

The eight finalist projects of the Toca Madera competition for young designers in Spain are due to be exhibited at the Madrid Design Festival 2020 in February. Participants were challenged to create “infinite objects” in red oak, an abundant renewable material, that would stand the test of time. The designers must also be able to justify that the product is “sustainable”. The project was born of the international collaboration between AIDI (Association of Engineering in Industrial Design) and AHEC (American Hardwood Export Council).

The Life Cycle Assessment (LCA) contributes to the key aim of the Toca Madera competition to provide a practical demonstration of sustainable design. It reveals the life cycle stages (from red oak harvest site through to completion of the finished design) which are most significant in determining the overall environmental footprint of each of the eight finalist designs. Insights into the specific environmental impacts of each design are facilitated by use of a common base material in red oak and by manufacturing at a single location, at Carpintería La Navarra in Madrid .

The assessment draws on data from a Life Cycle Assessment (LCA) study, commissioned by AHEC and undertaken by PE International (now Thinkstep) to determine environmental impacts linked to delivery of U.S. hardwood into world markets [1]. This data is combined with information on material and energy use gathered during manufacturing at La Navarra.

Environmental profile of red oak delivered to La Navarra

The red oak used to manufacture the Toca Madera designs is a large and expanding resource and harvesting does not threaten biodiversity or forest carbon storage. U.S. Forest Service FIA program data shows that U.S. red oak growing stock is 2.48 billion m3, 18.7% of total U.S. hardwood growing stock.  U.S. red oak is growing at a rate of 55.2 million m3 per year while the annual harvest is 33.9 million m3. The net volume (after harvest) is increasing 21.3 million m3 each year. It takes less than one second for the around one cubic meter of hardwood logs harvested to manufacture all eight designs to be replaced by new growth in the U.S. forest.

The carbon footprint of the red oak lumber delivered to the factory in Spain for the project is better than carbon neutral – in the sense that the carbon stored in the wood during growth (459 kg CO2 eq.) exceeds the carbon emissions during all stages of material extraction, processing and transport from the U.S. (294 kg CO2 eq.). Of these emissions, those associated with processing (53% – mostly kiln drying) exceeds those due to transport (43%) despite the lengthy shipping distances involved. Only 4% of carbon emissions to deliver the red oak to Spain occur during forestry operations.

Carbon footprint of finished designs

On a cradle-to-factory-gate basis, the total carbon footprint of all eight Toca Madera designs is 427 kilograms of carbon dioxide equivalent (kg CO2 eq.). That is similar to the carbon footprint of a single return economy class flight from Madrid to London [2] or driving 3,700 kilometres in an average Spanish car [3]. To put another way, it is about the same as emitted by the average Spaniard in a 26 day period [4].

Most of the carbon emissions and other environmental impacts associated with the designs occurred during the manufacturing stage in Madrid. Emissions due to use of grid electricity during manufacturing were 415 kg CO2 eq. This is largely due to the lengthy time required on machines (particularly a CNC machine) powered by electricity from the Spanish national grid, which is inevitable for such high-end bespoke products. 

The impact of electricity use during manufacturing in Spain is mitigated to some extent by the country’s relatively high dependence on renewable energy sources. Only 37% of electricity is generated using fossil fuels in Spain – a low proportion by international standards – with the majority derived from low carbon technologies, including nuclear (21%), wind (19%), hydro (13%), and solar (5%) [5].

A relatively large proportion of wood waste was generated during the project due to the complexity and quality demands of the designs involving production of large numbers of small and precisely engineered components. Of 303 kg of American hardwood used to produce the designs at the factory in Spain, 170 kg (56%) is incorporated in the final product, while 7 kg (2%) is lost as dust or shavings, and the remainder (42%) is collected by a specialist company which shreds wood for energy recovery. 

For American hardwood, the environmental implications of low conversion efficiency are less of a problem than they might be for other materials. This is because the wood itself is better than carbon neutral and is derived from a sustainable and renewable resource, while the wood waste can be readily converted into useful energy. Carbon emissions for the project are partially offset by 80 kg CO2 eq. resulting from substitution of fossil fuels through incineration of this wood waste.

The quantity of non-wood materials used for the designs is small relative to wood and therefore has only a minor effect on the overall carbon footprint. Non-wood components, principally steel fixings with a small quantity of brass, accessories (like the mirror, wicker bed and soft furnishing), glues and coatings which together made up 10.5% of the total mass of the finished designs, contribute 69 kg CO2 eq. (16%) to the total carbon footprint.

Overall the results of the LCA highlight that, from an environmental perspective, the issue of “product miles” – sometimes used to justify preference for local materials over imported products – is much less relevant when procuring wood products than the relative efficiency of processing operations and waste management and variations in the energy mix in the processing location.

This is not a cradle-to-grave assessment due to lack of data on product life and disposal. However, an explicit aim is to design “infinite objects” that will remain in use for many years. This is achieved by combining the skills of the designers and the craftsmanship of La Navarra with the beauty and durability of U.S. hardwoods. This longevity helps to maximise environmental benefits. There is less need for regular replacement and therefore less repetition of impacts. Long-lived wood products also supplement the carbon store in the forest and help to keep CO2 out of the atmosphere. Together the eight designs store the equivalent of 269 kg of CO2.

At end of life, since nearly 90% of the mass of the designs comprise wood which can be readily separated from non-wood components, the waste material may be incinerated and thereby offset use of fossil fuels (if these are still widely used at that time). These designs will therefore go a long way to fulfilling the requirements for “extended producer responsibility” whereby the manufacturer takes responsibility for the entire life cycle of the product, especially the recycling and final disposal.

Notes

  1. For more details see the AHEC publication,, Telling the Whole Story: The Environmental Life Cycle of American Hardwoods, February 2017
  2. Calculated using https://www.co2nsensus.com/carbon-offset-calculator which shows that a single return economy flight from Madrid to London Heathrow has a carbon footprint of 395 kg CO2 eq.
  3. Based on 115.4g CO2/km average emissions by new passenger cars sold in Spain in 2013. Source: European Environment Agency (EEA) Technical Report No 15/2018 “Monitoring CO2 emissions from passenger cars and vans in 2017”.
  4. Based on emissions of 5.94 tonnes CO2 per capita in Spain in 2016 as reported by California Green Innovation Index (International Edition) by “Next 10” which provides comparative data on the 50 countries that emit the most energy-related greenhouse gas emissions (www.next10.org).

5. Derived from Informe Preliminar de 2018 de la Red Eléctrica de España.