THE LIFE CYCLE ASSESSMENTS OF NATURAL FIBRE INSULATION MATERIALS

Proceedings of the 11th International Conference on Non-conventional Materials and Technologies (NOCMAT 2009) 6-9 September 2009, Bath, UK THE LIFE CYCLE ASSESSMENTS OF NATURAL FIBRE INSULATION MATERIALS Andrew J Norton 1, Richard Murphy 2, Callum A S Hill 3, Gary Newman 4 1 Renuables, Llanllechid, Gwynedd, UK 2 Division of biology, Imperial College London, UK 3 Centre for Timber Engineering, Edinburgh Napier University, UK 4 Plant Fibre Technology Ltd, Bangor, Gwynedd, UK Abstract: The use of natural fibres in construction materials is generally perceived as a low environmental impact option. In many cases, the production of natural fibre products can require the consumption of less fossil fuel and other resources, generating fewer overall environmental impacts than alternatives. These assumptions however, need to be examined objectively and transparently on a case-by-case basis if the acceptance of biobased materials is to be successful. The results of an in depth LCA of Isonat, a hemp/recycled cotton based insulation material is presented here as a case study, with comparison to other insulation materials. Data was gathered from all aspects of the production including farming, transportation, processing and manufacture. End of life and potential scale up scenarios are also discussed. A marginal analysis of the products global warming potential revealed the environmental benefit of using natural fibres due to their sequestration of CO 2 as compared to the large impact derived from the polyester binder and binding process. The comparisons between LCAs was found to be problematic, especially when only comparing final figures, due to the potential scope for differences in system boundaries, datasets used, and the functional unit chosen. The inclusion of end-of-life scenarios was found to make a notable difference in results due to the potential release of the sequestered CO 2. It is advised however that such figures be used in the consideration of future disposal options rather than for comparison with other materials due to the theoretical nature of such figures. Large reductions in environmental impacts where also revealed through the assessment of potential scale up operations Keywords: Natural fibres, insulation, life cycle assessment 1 Introduction There is increasing interest in the use of natural fibre insulation (NFI) in buildings. In part, this interest derives from the perceived green credentials associated with such products. However, there are very few studies of the environmental impact associated with the use of NFI. The results shown in this summary are taken from a report by Murphy and 1 Consultant: a.norton@renuables.ac.uk 2 Reader: r.murphy@imperial.ac.uk 3 Professor: c.hill@napier.ac.uk 4 Director: gary@plantfibretechnology.com

Norton (2008). In the original report, the two natural fibre materials studied were; Isonat, a hemp/recycled cotton based material and Thermafleece which is produced mainly from waste sheep wool. These where compared to market-leading, BRE Green Guide to Specification A rated (now A+) insulation products, the aggregated data sets of which were kindly supplied by Knauf Insulation Ltd and Rockwool Ltd. Only the Isonat product is represented here in order to summarise the issues that arose from the previous study. Also, so as not to over complicate the results, this study will focus on the impact category of Global Warming Potential over a 100 years life span (GWP 100). Though there is reference to the embodied energy, the 9 different CML (2001) impact categories listed in the original study, as developed by the LCA Institute of Environmental Sciences (CML) of Leiden University, are not presented here. In order to calculate the environmental impact of the Isonat product data was gathered from all aspects of its production following the flow from farming thorough fibre production and then insulation production, including its transportation. Data and assumptions regarding its use and final disposal were also considered, thus providing a full picture of the cradle to grave life cycle. It is noted that a more efficient process is now in place than that studied in 2007 the effect of which is mentioned later. At each stage of production, the fuel and electricity used along with the production of additional materials (including packaging) was considered. In place of measuring individual emissions of CO 2 equivalents, secondary data provided by reputable sources was used. Namely that of the BUWAL 250 Library (written by Pre Consultants in the Netherlands) which has been used for transport and Disposal scenarios, and Ecoinvent data (written by the Swiss Centre for Life Cycle Inventories) that has been used for all other processes and materials. These data sets are provided with the SimaPro software that was used for the LCA calculations. Studies (such as Weidema et al. 1995) have shown that the production of farm machinery, e.g. a tractor, can have a similar impact on GWP to the quantity of fuel used in a given farm process, due to the relatively short life cycle of the example tractor and the large amount of fossil fuel based energy to produce it. As such, the Ecoinvent farm processes that take into account the impact arising from capital inputs (e.g. a proportion of the impact arising from production of tractors, ploughs, barns etc) was chosen. It was noted that many of the actual on farm practices associated with hemp growing in East Anglia, UK, where more efficient than the Swiss farm data used. In the absence of reliable correction factors however, the data was left un-adjusted as it was found to make little difference to the final figures. The quantity of CO 2 sequestered in the ligno-cellulosic plant fibres was also included, using the assumption that the carbon fraction of the plant would have originated as atmospheric CO 2, and so a negative value was awarded to the final fibre fraction. The proportion of this released during potential end of life scenarios was also considered. When hemp straw harvested from the farm is processed, approximately 29% of this, by weight is fibre (which in this case will go on to be used in insulation) 67% is Shive (spongy core of the stem sold as bedding) and 4% is dust. An issue of allocating the environmental burden from the previous farming thus arises. In this case a mass allocation was used, so the proportions by weight described previously assigned the proportion of the impact from farming to each by-product.

2 Results of Lifecycle Assessment (Impact Assessment Phase) The total impact for the Isonat product was found to be 0.345 kg of CO 2 e / kg of product delivered to Coventry UK (following production in France). A break down, or marginal analysis, of the contributions by input to this figure is given in Figure 1. Figure 1: Marginal analysis of the Isonat system shown as kg of CO 2 e / kg of product shown on a total and per input basis There is a large net benefit derived from the use of recycled cotton and virgin hemp fibre due to the incorporation of atmospheric CO 2 in the materials. However, there are negative impacts associated with the use of gas for heating, the use of polyester as binder and from transportation. This production system requires heat (from gas) to partially melt the fibres to allow them to bind with the natural fibres. The bi-component polyester fibres themselves require a large amount of fossil based energy and materials to produce. The relatively high impact from transport is associated with the current (at time of study) transporting of hemp fibre from the UK to France and the return journey of the finished product. There is only a small contribution to GWP from electricity here as only the final production is shown, the primary processing electricity usage is hidden by the sequestered CO 2 in the fibres (in the hemp fibre production category).

1 kg B Isonat production at Buitex, France inc transport for MA 0.345 0.35 kg Hemcore Hemp f ibre production -0.486 0.35 kg Cotton fibres recycled inc -ve CO2-0.511 0.15 kg Bi component Polyester 0.455 8.35 MJ Heat gas B250 0.506 1 kg Transport total 0.263 0.35 kg Hemcore Farming hemp straw production hemcor -0.553 0.075 kg Polyethylene terephthalate, granulate, 0.174 0.075 kg Polyethylene terephthalate, granulate, bottle 0.186 0.095 0.225 kg Extrusion I 0.127 p Transport - Isonat to Coventry 0.157 1.47 tkm Truck 28t B250 0.23 2.82 MJ Heat diesel B250 0.23 Figure 2: A flow chart to show the process and material contribution the overall product impact in terms of GWP. Impacts of less than 8% of the total have been omitted from the flow chart for clarity Figure 2 shows the origin of all the major impacts and stores of carbon in the Isonat product. The display as a flow shows the combined impact that 2 different grades of polyethylene and their extrusion, used to approximate the bi-component polyester binder, have on the final product. 3 Comparison to Other Products Data from other insulation materials studied by Ecoinvent (Kellenberger et al, 2007) was used to give an idea of how the Isonat product studied here compares to alternatives. As can be seen in Figure 3 the Isonat product compares favourably with other insulation materials on a per kg basis at factory gate (i.e. less the original UK delivery transport). It is notable that the lowest impacting of the materials, of those studied by ecoinvent, are also derived from natural resources. Though the Isonat product was studied here using secondary data from Ecoinvent where possible, it is not possible to tell exactly how comparable the figures provided are due to a limit in documentation regarding the system boundaries. It is also considered that

the per kg presentation here does not take into account the thermal efficiency of the products shown here. Figure 3: Presentation of the Isonat product presented alongside ecoinvent data on other insulation materials presented in kg of CO 2 e / kg of product shown at factory gate As outlined in the ISO 14040 guidelines on LCAs (BSI, 1997), comparisons should be made by the consideration of a functional unit. The above per kg basis is one such functional unit, but is simplistic. A fairer functional unit is described in the original study which takes into account an in-use scenario. This was taken as the insulation of one square meter within the cold roof space of a given dwelling described as: The manufacture, installation, use and disposal of an insulation material for one square meter of the central part of a first floor plasterboard/timber ceiling in a UK domestic house to a U- value of 0.16 W/m²K for a period of 60 years service (Building Regulations Part L). An example product described as Mineral wool was chosen from the previous selection (Figure 3) for its similar usage. The product chosen is produced by a company in Switzerland (Flumroc AG).The properties and quantities required to fulfil the FU for each unit of the Isonat and Rock wool product is presented below in Table 1. Table 1: The details for each insulation material required to meet the same functional unit of 1 m 2 of loft insulation to achieve 0.16 W/m²K Product name K value (W/mK) Density kg/m 3 Thickness (mm) to achieve U- value Functional Unit (kg) Isonat 0.039 35 225 7.875 Mineral wool 0.037 32 200 6.4

GWP impacts in general stem from the use of carbon emitting fuel sources and are thus linked to the energy consumption of most products. It is however noted that although the GWP reported for the natural fibre products is far lower than that of the conventional material, the energy requirements are actually higher (presented in Table 2 and Figure 4). Table 2: The total energy requirement (calculated using the Ecopoints 97 V2.1 method) and the GWP (calculated using the CML 2 baseline 2000) for the studied products on a functional unit basis Impact category Unit Isonat Mineral Wool Energy MJ LHV 263 150 Global Warming (GWP100) kg CO 2 eq 2.72 8.72 Figure 4: The total energy requirement (calculated using the Ecopoints 97 V2.1 method) and the GWP (calculated using the CML 2 baseline 2000) for the studied products on a functional unit basis For the natural fibres, the lack of a simple coupling between the energy consumption to make the product and its Global Warming Potential is a result of the removal of CO 2 from the atmosphere via photosynthesis. Thus, the sequestration of atmospheric CO 2 into the basic raw material in the natural fibre products exerts a strong negative GWP effect (removal of CO 2 from the atmosphere). The potential of reducing the embodied energy through scaling up production is discussed below in section 5. Two critical components in assessing the overall GWP balance over the life cycle of natural fibre materials and products is 1) their longevity in use (in this case assumed to be 60 years in a building) and 2) the end-of-life disposal method. It is in the disposal phase of the life cycle that some, or all, of the carbon sequestered into the product may be returned to the atmosphere, this being highly dependent upon the specific disposal route followed. This is reported in the end of life section that follows. 4 End of Life Scenarios There are many potential end of life scenarios for natural fibre insulation products, after the assumed 60 year in-use period. During this theoretical in-use period it is highly likely that legislation and practice surrounding the disposal of construction waste will change and as such it is very difficult to assume any one particular scenario will be used. A range of potential scenarios for NFIs are displayed in Figure 5. Those studied are shown in blue. These were to chosen primarily to indicate the effect that a range of different options might

have on the LCA outcome as a whole rather than as a prediction of those most likely to be adopted in the future. Natural Fibre Insulation Product Landfill Installed in Roof Use and maintenance of insulation Demolition / Refurbishment Application to Land Incineration Incineration with Energy Recovery Home Composting Fertilizer replaced Transport Energy Replaced Peat Replaced Municipal Composting Peat Replaced Recycling Product Replaced Figure 5: Potential end of life Scenarios for the NFI Materials with individual scenarios selected for further study highlighted with grey fill As can be seen from Figure 5, there are many potential options with regard to the disposal of a NFI product. The calculation of the impacts can thus be of limited use without knowing which options are likely. The chosen examples did provide some insight into which options may be favourable. However, using the assumption that the fibres would degrade in a similar way and over a similar time scale to that of news print, showed that the lowest emission of green house gasses would come from the option of landfilling the NFI. Which is 1) the least likely option given the phasing in of landfill reduction legislation and 2) dependant on the NFI degrading in the same way. In both cases the fibres are ligno-cellulosic (hence the assumption) but the structure is very different and it is simply not known how such products will degrade. It is however thought that the current addition of ammonium phosphate (as a fire retardant on the product) will possibly accelerate certain types of nitrogen sensitive decay. The assumption of in-use service length can also potentially alter the outcome of the LCA. If for example the product actually lasted 100 years then no end of life scenario would be considered when calculation the GWP 100. The original study assumed a 60 year life span and so the emission of all the carbon from the product during the incineration scenario meant that no benefit from the sequestration of CO 2 would be realised. Since the original study the publicly available carbon labelling scheme PAS 2050 was released. In this standard the issue of sequestered carbon (or carbon storage) is dealt with in such circumstances, by the calculation of a weighted average. Using this method

60% of the carbon would remain accounted for in the final GWP 100 figure, purely from the in-use phase. 5 Scale up Natural fibre insulation materials, like many other new products, have yet to realise efficiencies derived from increased production scale. These efficiencies will lead to reduced environmental impact. As shown here, in figure 4, the Isonat product had a higher embodied energy figure than that reported for an example mineral wool fibre. The Flumroc AG product was noted as being representative of large scale production and so considered to be highly efficient. Thus, the large quantities of energy associated with melting and spinning mineral components into fibres is in effect disbursed over the large quantities of product produced. In the original study the effect of a number of potential scale up scenarios was considered, covering larger scale (more efficient) production, UK production of the product, density reduction, as well as the use of bio-derived binders (PLA and starch). Each of these scenarios where based on industry data to give the most representative figures possible and large reductions in both GWP and embodied energy (as well as other environmental impacts) where revealed. Even limited and potentially near future scale up scenarios, similar to recently formulated products, revealed a negative GWP at factory gate. 6 Conclusions In this abbreviated study, Isonat was shown to benefit in the GWP 100 due to the use of natural fibres and their sequestration of CO 2, however a large impact in GWP is derived from the polyester binder and binding process. The inclusion of potential end of life scenarios was found to make a notable difference in results due to the potential release of a portion of the sequestered CO 2. It is advised however that such figures be used in the consideration of future disposal options rather than for comparison with other materials due to the theoretical nature of end of life studies. Natural fibre insulation materials have potential to benefit greatly from the economies of scale, not only in terms of reducing production costs and price, but also reduced environmental impact through more efficient production. 7 References BSI, 1997, Environmental Management - Life Cycle Assessment - Principals and Framework, BS EN ISO 14040:1997, European Committee for Standardization, Brussels. CML, 2001, LCA: An Operational Guide to ISO Standards, CML and TNO, Brussels. KELLENBERGER D., ALTHAUS H.-J., JUNGBLUTH N., KÜNNINGER T., 2007. Life Cycle Inventories of Building Products. Final report ecoinvent data v2.0. Volume: 7. Swiss Centre for LCI, Empa TSL. Dübendorf, CH MURPHY R, NORTON AJ, 2008. Life Cycle Assessments of Natural Fibre Insulation Materials, NNFCC Publications [available from: www.nnfcc.co.uk/metadot/index.pl?id=5968;isa=dbrow;op=show;dbview_id=2457] WEIDEMA BP, PEDERSEN RL, DRIVSHOLM T.S., 1995. Life Cycle screening of Food Products. Danish Academy of Technical Sciences