Life Cycle Assessment of Biomaterials in Construction (Final)

8/18/2019 Life Cycle Assessment of Biomaterials in Construction (Final)

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Sustainability of Biomaterials inConstruction

understanding the issues for products using plant- and animal-based

materials

OverviewAs

pressure

on

resources

grows and

the

demand

for sustainability rises, muchattention is being given to the use of

materials from plants and animals as

the basis for a wide range of

products. However, it is extremely

dicult to get a clear picture of the

conseuences of using such

!biomaterials! as alternatives to

existing "typically non#biological$

options.

%his paper is aimed atmanufacturers interested in

manufacturing with these products

and those interested in selecting

them. &t is also of interest to those

producing policy relating to these

materials and researchers see'ing to assess them.

%he paper reviews the 'ey economic, social and environmental issues for

biomaterials and the approaches being ta'en to address them. &t highlights the

need to ensure that these materials are assessed in a way that is comparable to

approaches being used to assess existing materials that are performing the samefunction.

1 BackgroundBiomaterials have a long history of use as construction materials, such as timber for

framing, boarding and roo(ng, and reeds and straw for roo(ng and )ooring. *here

the use of these materials is well established and their performance 'nown then

by +r o -undy

with contributions from John Hutchinson, Dr Gary Newman and Mark

Lynn

Contentsverview................................................................................................../ Bac'ground..................................................................................../0 Commercial issues.........................................................................0

0./ 1roduction and procurement................................................00.0 Standards.............................................................................00.2 3conomic issues...................................................................20.4 1ractical issues.....................................................................2

2 Social issues..................................................................................44 3nvironmental performance issues...............................................4

4./ 3nvironmental problems related to agricultural systems....54.0 -ethodological problems for agricultural 6CAs...................5

5 Conclusions................................................................................../57 8eferences.................................................................................../5


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Sustainability of Biomaterials in Construction

they continue to be used for these applications. However, where such materials are

used in novel applications or novel combinations, or both, then there may be

resistance to their upta'e unless their performance in practical, economic and

environmental terms can be demonstrated.

Biomaterials present us with the opportunity to capture and exploit properties that

have evolved in nature to provide certain performance characteristics. Biomaterials

have the potential to provide construction materials with the following bene(ts9

• Capture and storage of carbon extracted from atmospheric C0 by recent

photosynthesis• Sustainable production as crops grown annually or as longer harvest#cycle

forest.• Biodegradability at end of life. "Controlled decay inside an anaerobic digester

would produce both organic fertiliser and bio#methane to supply energy$• 6ow or almost :ero linear coecients of thermal expansion

• %he property of controlling temperature and humidity in enclosed spaces by

phase changes of water in cells• High vapour di;usivity and !Should we wor' with a

biomaterial!s inherent properties or should we process it to produce a di;erent

structure and achieve a di;erent performance?> A 'ey criterion for @udging this

uestion!s answers is the reuirement for sustainable development. %his paper

explores the economic, social and environmental issues that should be assessed when

see'ing to evaluate the sustainability of biomaterial products.

2 Commercial issues

2.1 Production and procurement-any applications of bio#based materials in construction are relatively new and the

mar'et structure characterised by a low concentration of S-3s that are ma'ing the

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transition to a more mainstream model. %hese business models are currently

operating in the =9

a Direct manufacturei. Small scale running of high capacity euipment # operating plants sub#

optimally is li'ely to result in more inputs per unit of production and so

increase the environmental burden of associated with each unit of

production. However, when demand eventually meets capacity, reduced

unit impacts may be achieved via the e;ects of scale and specialised

production euipment.ii. Small scale production using low capacity euipment # this may o;er a

lower impact model particularly if local materials are sourced and sold

locally for products with relatively little processing or additional materials.

However, energy and other environmental impacts may be greater for

certain materials when processing methods are applied on a very smallscale. %his appears to be the case for raw wool scouring for instance.

b$ !tilise e"isting !# capacity # the use of spare capacity in complimentary

industries within the = to produce bio#based materials for construction. %his

enables the biomaterial company to bene(t from scale economies and

associated environmental bene(ts from an earlier stage. &n the medium term,

sharing capacity may not be the most ecient way of minimising environmental

impacts or maximising the impact of specialisation. %his approach reduces the

impact of building new capacity in the short term and can allow for an ecient

transition from small to large scale dedicated production.

c$ $mport and distribute # the importing and distribution of biomaterials fromestablished overseas mar'ets such as ermany. %he biomaterial company can

bene(t from established scale economies and potentially better social and

environmental standards of production. Certain bio#based materials such as

hemp and )ax are not widely available in the = so sourcing these types of

material from overseas provides a way of utilising these crops from areas where

they are abundant. However, the energy#related impacts will depend on the

energy mix of the country of origin plus there are additional transport impacts,

particularly important for low density (nished goods.

2.2 Standards %he nascent state of the segment means there are few standards that embrace the

sector and the various product groups within. As such products can fail to meet the

expectations of speci(ers. %his can be addressed through technical approvals such as

British Board of Agrment "BBA$ certi(cation or the 3uropean %echnical Approval "3%A$

for established products such as insulation. However, it can prove more dicult for

newer or novel applications to gain standard recognition.

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%he di;erent inherent properties of bio#based materials can also ma'e standardised

tests derived for synthetic products dicult to apply and can a;ect the results.


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of free moisture. %his ability to ta'e up moisture also in)uences their potential

durability and service life.

%here are also practical issues to be addressed during the life of these materialsF their

performance in use is highly in)uenced by whether appropriate design decisions were

ta'en to incorporate them into the building to achieve their potential service life.

3 Social issues3nvironmental and social issues surrounding the supply of bio materials have been

well recognised in the (eld of forestry and sustainable forest management schemes,

such as the schemes of the


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• 3nergy consumption "contributing to climate change, acid rain, resource depletionetc.$

• %he use of nitrates and phosphates "causing pollution of surface# and groundwater$

•

Agri#chemical use "resulting in toxicity impacts$• 8educing soil uality "producing soil degradation, pollution, erosion etc.$

• *ater depletion

• +ecrease of biodiversity due to prevalence of mono#culture.

4.2 "et#odological prolems for agricultural $C%s %hese relate to9

/. -ethod choice0. oal de(nition and functional unit

2. &nventory analysisi. Boundariesii. 1rocesses included and capital goodsiii. Substance )ows to and from soiliv. Choice of data sources with respect to the studyGs goalv. 6ocation of nutrient emissions

vi. roundwater abstraction and lin' with desiccationvii. Allocationviii. Crop rotation

4. Classi(cation and Characterisation5. Sustainability indicators7. 3nd of life

4.2.1 "et#od c#oice

6CA was developed to be location-independent "*egener Sleeswi@' et al%, /EE7$%However, in agriculture, di;erences in local conditions, such as soil type and climate,may in)uence the environmental impacts resulting from a given emission. &nventorydata may be very dependent upon local conditionsF site#dependent aspects mighthave a greater in)uence on an agricultural 6CAGs results than activity#dependentaspects.

4.2.2 &oal de'nition and functional unit

-ost agricultural 6CAs are aimed at assessing the impacts of producing foodsFagricultural systems are typically multi#functional "Milà i Canals, 2003)F they can berelated to 'eeping the land to a de(nite appearance as well as to the production ofproducts.

%he functional unit for non#food crops "whether wholly non#food, e.g. hemp, or partiallyas the non#food part of a food crop, e.g. wheat straw$ can also be faced with the

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complication of multiple functions from the system. However, the purpose of the non#food product will guide the selection of the functional unit. A study may produce aJdelivered unitG rather than a functional unit, with the delivered unit being an amountof the non#food crop material typically from cradle#to#farm "or factory$ gate.

4.2.3 (nventor! %nal!sis

%he main 6ife Cycle &nventory Assessment "6C&A$ topic in reported agricultural 6CAstudies appears to be the need to develop new impact categories addressing theimpacts caused by agricultural systems. %he issues of land use, land uality andbiodiversity have received particular attention.

%hree aspects related to agricultural land use have been highlighted "Cowell and Clift,1997)9 actual or potential productivity of landF e;ects on biodiversity, and aestheticvalue of landscapes. Soil uality and generic land uality indicators have been studiedby many to assess the impacts on potential productivity of land. %he following havebeen suggested Mattsson et al. (2000) as useful indicators of long#term soil fertility andbiodiversity9 soil erosion, soil organic matter, soil structure, soil pH, phosphorus andpotassium status of the soil, and the impact on biodiversity. However, theyac'nowledge that these indicators are a mix of uantitative and ualitative anddicult to aggregate.

Biodiversity indicators have been researched by many and the Hemeroby conceptexplored "see Brentrup et al. (2002) for a review), which considers a classi(cation scheme forland based on its JnaturalnessG.

However, there is no single de(nition of land useF some researchers exclude landscapee;ects, others distinguish between the impacts of occupation and ecosystem impactsthat change the time needed for the ecosystem to return to its natural state. %here isgeneral consensus that land use covers any human activity reuiring land to carry itout.

4.2.4 Boundaries

Since there are no factory walls it can be dicult to answer the uestion, Kwhere doesthe agricultural system border the environment system?L

How the soil is regarded can have a considerable in)uence on the (nal results9 some

have argued for its exclusion but others regard it as an ancillary product that is

reuired by the system and altered by it, even though it does not remain part of the

(nal product. %he alteration of the soil by the agricultural system introduces a time

boundary consideration as it has implications for future activities # this is covered in

the section on crop rotation.

Cowell "/EEM$ raised the uestion of time boundaries and suggested that activities inthe past a;ecting actual productivity should also be included in the analysis. 3xamples

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of such activities are fertiliser use that is useful for more than one crop, hedgeestablishment and maintenance etc. %herefore, the system under study should includeall these relevant activities, and so comprise full crop rotations, whole forest rotations,etc.

Accounting for crop rotations is addressed in a subseuent section.

%a'ing time into account for forest#based products presents practical problems in that

a forest stand ready for harvest now in the = was planted ND to /DD years ago, and

little or no information is available on the practices applied to that stand to establish

and maintain it. &t is also true that a stand planted now will have 'nown establishment

practices but its future management, whilst planned now, is li'ely to vary over its ND#

to /DD#year life time. Conseuently, time#dependency is usually addressed by

assuming that past and future practices are the same as those used currently.

4.2.4.1Processes to be assessed and capital goods %his presents a particular challenge # it is not practical to assess all activities relatingto a product!s production and the process tree must be cut o; at various points.+eciding what processes to assess and what to exclude reuires an understanding ofthe system and the li'ely impactsF many state that the only processes that can beomitted are those that contribute scarcely if at all to the environmental interventionsassociated with the functional unit O though this reuires experience to assessbecause it is dicult to determine how important a process is until its contribution tothe whole has been assessed.

%he following list sets out the agricultural processes that should typically be includedin an 6CA for agricultural products "Wegener leeswi!" et al., 199#)9

/. crop cultivationa. fertiliser use "materials and application fuels$b. crop protection "materials and application fuels$c. soil tillage "application fuels$d. irrigation "extraction and application fuels$e. sowing "materials and application fuels$f. harvesting "application fuels and organic waste disposal$g. capital goods9 production and maintenance of machinery, farm trac's and

roads and buildings.0. livestoc' breeding

a. feeding "materials and application fuels$b. care "materials and application fuels$c. manure#related activities "materials , treatment and application fuels, and

waste manure disposal$d. shed maintenance "materials, application fuels, and waste disposal$e. mil'ing "materials and machinery fuel use$

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for agricultural products. Similarly, the contribution of infrastructure should not simplybe ignored. However, farm buildings can generally be omitted from the study, exceptin the case of greenhouse horticulture and in studies where farm buildings are themain source of di;erences between systems.

4.2.4.2Substance fows to and rom soil

&f the soil is included in the 6CA then all inputs to the soil such as fertiliser and manureshould in principle be classi(ed as causing 3utrophication "i.e. nutrifying$. Besidesemissions of minerals and other substances to the soil, agriculture also involvesextraction of these substances from the soil. &n the inventory phase of an 6CA, theuantity of a substance extracted from the soil should be subtracted from the uantityemitted to the soil, because the extracted substance held in the crop has noenvironmental impact. %his is particularly relevant for substances present in fertiliser

dressings.&t has been proposed that a soil mineral balance should be used to determine whatfraction of the applied mineral supplements end up in the environment "Wegenerleeswi!" et al., 199#). %his balance can be used to calculate the emission, by subtractingall outputs from all inputs.


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%o investigate the environmental impacts associated with mil' sold insupermar'ets, average data on mil' production is appropriate

%o compare current mil'#production methods, average data on the companiesapplying the various production methods can be used

%o understand which elements of an individual product "system$ have thegreatest bearing on the environmental impacts, data speci(c to that product"system$ are needed.

&f the government wishes to use 6CA to bac' up a policy to encourage ordiscourage a given production method, normative data speci(c to companiesapplying the production method in uestion are appropriate.

4.2.4.4ocation o nutrient emissions

&t has been proposed that, contrary to conventional 6CA, nutrient accumulation in thesoil reuires a distinction between problem areas O where nitri(cation constitutes a

problem, e.g. in large parts of *estern 3urope O and non-problem areas O wherenitri(cation does not form a problem "virtually the entire 2 rd *orld, where soilexhaustion is the problem$ is needed "Wegener leeswi!" et al,. 199#).

&n areas where 3utrophication "nutri(cation$ is not a problem, then the accumulationof minerals in the soil should not be classi(ed as a nutrifying emission. %his meansthat in the inventory phase a distinction must already be made, on the basis of thelocation of the emission, between areas where nutri(cation is a problem and areaswhere it is not. 3missions of soil#supplement minerals to other environmental media,via run#o;, leaching and volatilisation, are classi(ed as nutrifying, because theseemissions can lead to 3utrophication of surface waters or of areas in the vicinity of thenon#problem area. &f it is un'nown whether 3utrophication constitutes a problem in agiven area, all nutrifying emissions should be regarded as causing 3utrophication.

4.2.4.!"roundwater abstraction and lin# with desiccation

6CA currently gives no consideration to desiccation, because this is considered to be alocal problem. &n agriculture, however, desiccation does constitute a ma@orenvironmental problem. ey determining factors in the problem of desiccation aredrainage, watertable management and groundwater abstraction. +rainage andwatertable management are highly location#speci(c and are dicult to relate to afunctional unit of product and therefore cannot currently be included in an 6CA.+esiccation should conseuently only be included if it is governed largely by the director indirect withdrawal of groundwater in the area in uestion.

&t has been advocated that, as for 3utrophication, allowance should be made for thedi;erence between problem and non#problem areas. roundwater abstraction shouldnot be classi(ed as desiccating in areas where there is no desiccation problem, or inareas where groundwater abstraction does not contribute to this problem "forexample, where surface water levels are being 'ept arti(cially low thus determiningthe degree of desiccation$. &f it is un'nown whether a groundwater#abstraction processcontributes to desiccation, groundwater abstraction should be classi(ed asdesiccating.

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&S is currently wor'ing on the production of a water footprint standard "&S /4D47$

that is based on 6CA.

4.2.4.$%llocation

Allocation is the sharing of environmental burdens between the products of a multi#output process. &S /4D4/ "/EEM$ recommends that 6CA studies should9

• Avoid allocation wherever possible by dividing the shared unit process into sub#processes

• Allocate on any underlying physical relationship

• Allocate on a relevant relationship.

3 /5MD4 also advocates the avoidance of allocation wherever possible giving priorityto a physical relationship where processes can be subdivided and to a value

"economic$ approach when subdivision is not possible.

As noted earlier, co-production is common in agriculture. %he various parts of animalsand plants produced are often used for di;erent applications. Before allocation isunderta'en, it must therefore be clear that multi#output processes have as far aspossible been divided into single#output processes. nly for those processes thatcannot be further subdivided should allocation be carried out, and this should be doneon the basis of economic value.

&f manure is used in arable farming, recycling is ta'ing place and the environmentalinterventions associated with the processes involved "storage, transport, processing$should be allocated to the product system that pays for these processes. &f payment is

collective, e.g. in the case of storage in a manure centre, interventions should beallocate on the basis of the ratio between the cost paid by the arable farmer and thecost paid by the cattle farmer. Again, these rules are based on economic value.

%he inclusion of complete rotation schemes can also present allocation issues. &t hasbeen suggested that the inclusion of soil uality and uantity into the 6C&A greatlyreduces the allocation problem for crops but this reuires the development of aconvenient impact indicator.

%he carbon cycle also presents an allocation problem in agricultural systems. Someconsider it a negative climate change impact and account for it whereas others regardthe storage as happening over too brief a period with the C0 released again when the

material degrades. %his is sensible for food crops where the lifetime of the product isvery short but it is not the case for non#food crops used in construction products, forexample, the reen uide uses a 7D#year study period for assessing building elementspeci(cations. Conseuently, C0 seuestration is ta'en into account along with end#of#life scenarios that include disposal in land(ll where part of the seuestered carbonwill be emitted as methaneF the lobal *arming 1otential of methane is more than 0Dtimes that of C0 over a /DD#year period/.

/

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4.2.4.&Crop rotation

Agricultural crops are typically cultivated in a system of crop rotation, with di;erentcrops being cultivated in succession on a given plot of land. &f a comparison is beingmade between di;erent crop#rotation schemes, this will cause no extra allocationproblems. &n practice though, such a comparison will not often be useful, because 6CAis a tool designed for comparing the environmental impacts of various di;erentproducts. *hat will usually be compared is a product from one crop#rotation schemewith one from another rotation scheme. %his gives rise to diculties, because thevarious crops and the activities performed in cultivating these crops often also haveconseuences for the crops grown later in the rotation scheme. 3xamples include9

Soil fumigation carried out for potatoes but also bene(ting other crops Application of organic fertilisers in a given crop, with some fraction of the

minerals only being ta'en up after the following crop has been sown.

%hese allocation problems cannot simply be ignored in an 6CA. %he uestion '(hy is agi&en acti&ity performed)* can be used to guide decisions.


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iven the importance of the crop#rotation scheme for further choices within an 6CA, itis of ma@or importance that the crop#rotation scheme being used to cultivate theproducts in uestion already be indicated in the goal de+nition.

4.2.) Classi'cation and C#aracterisation

6CAGs current method for the characterisation of toxic substances does not allow forenvironmental transport and degradation of these substances, but for variousagricultural pesticides, these processes may be highly in)uential on the degree towhich the toxic potential of these substances leads to potential environmentalimpacts. *egener Sleeswi@' et al% "/EE7$ derived new euivalency factors,incorporating intermedia transport and degradation, for the most commonly usedagricultural pesticides for the toxicity themes of C-6Gs 6CA method. %hese euivalencyfactors were calculated with the aid of the =S3S "=niform System for the 3valuation of

Substances$ model "8&P-, P8, *PC, /EE4$. However, the new euivalency factorscannot be compared with the factors in the 6CA uide, and the scores calculated forpesticides using these factors can only be listed separately.

%he &nstitute for 3nvironmental 8esearch and 3ducation "&383$ has derived a list of&mpact Categories for agricultural product 6CAs9

Climate ChangeStratospheric :one +epletion3utrophication1hotochemical SmogAcidi(cationAirborne %oxicity*aterborne %oxicity*ater 8esource +epletion-ineral 8esource +epletion6and =seQBiodiversitySoil ConservationHormone =seAntibiotic =seene -odi(ed rganisms

f these, 6and =seQBiodiversity, Soil Conservation, Hormone =se, Antibiotic =se, and

ene -odi(ed rganisms are directly applicable to agricultural systems. But it isdicult to see how these impact categories can be applied to non#agricultural systemsto achieve a fair comparison of non#food crop products used in construction.

4.2.* Sustainailit! indicators

Sustainability indicators may provide a suitable alternative to the development ofspeci(c impact categories for agricultural issues.

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http://www.iere.org/sustain/LifeCycle.htm#climate%23climatehttp://www.iere.org/sustain/LifeCycle.htm#strato%23stratohttp://www.iere.org/sustain/LifeCycle.htm#eutroph%23eutrophhttp://www.iere.org/sustain/LifeCycle.htm#smog%23smoghttp://www.iere.org/sustain/LifeCycle.htm#acid%23acidhttp://www.iere.org/sustain/LifeCycle.htm#airtox%23airtoxhttp://www.iere.org/sustain/LifeCycle.htm#watertox%23watertoxhttp://www.iere.org/sustain/LifeCycle.htm#waterres%23waterreshttp://www.iere.org/sustain/LifeCycle.htm#mineral%23mineralhttp://www.iere.org/sustain/LifeCycle.htm#landuse%23landusehttp://www.iere.org/sustain/LifeCycle.htm#soil%23soilhttp://www.iere.org/sustain/LifeCycle.htm#hormone%23hormonehttp://www.iere.org/sustain/LifeCycle.htm#antibiotic%23antibiotichttp://www.iere.org/sustain/LifeCycle.htm#gmo%23gmohttp://www.iere.org/sustain/LifeCycle.htm#climate%23climatehttp://www.iere.org/sustain/LifeCycle.htm#strato%23stratohttp://www.iere.org/sustain/LifeCycle.htm#eutroph%23eutrophhttp://www.iere.org/sustain/LifeCycle.htm#smog%23smoghttp://www.iere.org/sustain/LifeCycle.htm#acid%23acidhttp://www.iere.org/sustain/LifeCycle.htm#airtox%23airtoxhttp://www.iere.org/sustain/LifeCycle.htm#watertox%23watertoxhttp://www.iere.org/sustain/LifeCycle.htm#waterres%23waterreshttp://www.iere.org/sustain/LifeCycle.htm#mineral%23mineralhttp://www.iere.org/sustain/LifeCycle.htm#landuse%23landusehttp://www.iere.org/sustain/LifeCycle.htm#soil%23soilhttp://www.iere.org/sustain/LifeCycle.htm#hormone%23hormonehttp://www.iere.org/sustain/LifeCycle.htm#antibiotic%23antibiotichttp://www.iere.org/sustain/LifeCycle.htm#gmo%23gmo


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+efra has developed a suite of sustainability indicators "+efra JSustainabledevelopment indicators in your poc'et 0DD7G http9QQwww.sustainable#development.gov.u'QpublicationsQindex.htmR0DD7 $, with the following relatingdirectly to agricultural systems9

00. Agricultural sector O fertiliser input, farmland bird population, and ammoniaand methane emissions.

02.


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that understand the conseuences associated with them and how to ma'e the bestuse of their properties. gricultural Ls reuire attention to the following issues9

• Correct de(nition of the studyGs functional unit.

• Appropriate setting of study boundaries and choice of allocation method, which isparticularly important for carbon seuestration.

• Assessment of machinery and infrastructure impacts

• An understanding of what environmental impacts are occurring "particularly for theuse of pesticides and fertilisers$ and whether where they are occurring contributesto environmental impacts.

• Consideration of all relevant environmental impacts including aspects such as landuse, landscape, soil uality and biodiversity.

• Calculation of carbon seuestration and conseuences of end#of#life for whole lifecarbon balance and climate change impact.

• Assessment of service life and end#of#life scenarios "re#use, recycling, disposal

"incineration with or without energy recovery, land(ll$$.

) Conclusions

%here are many factors to consider when assessing the sustainability of biomaterialsany of which could present limiting factors for the successful upta'e of constructionproducts using these materials.

%he assessment of their environmental impact presents some complex issues toaddress O it is crucial that they are assessed in a manner compatible with theassessment methods applied to alternative materials that are used to perform thesame function.

* -eferencesBrentrup,


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Gallagher , / (Cair)' 200' %e allager eview of te indiret effets of .iofuels prodution' enewa.le

4uels gen*'

"attsson, BF Cederberg, C, and Blix, 6% 0DDD. Agricultural land use in life cycle

assessment "6CA$9 case studies of three vegetable oil crops. . Cleaner 1roduction, ,,0M2#0E0.

"il i Canals/ 6. 0DD2. Contributions to 6CA methodology for agricultural systems.

Site#dependency and soil degradation impact assessment. =niversity of Barcelona O

1h+ thesis.

0egener Sleeswik/ AF -eeusen#van nna, -F van Tei@ts, HF lei@n, 8F 6eneman, HF

8eus, A*A, and Sengers, HH*-. /EE7. Application of 6CA to agricultural products. /.

Core methodological issuesF 0. Supplement to the J6CA uideGF 2. -ethodological

bac'ground. 6eiden, Centre of 3nvironmental Science 6eiden =niversity "C-6$, Centre

of Agriculture and 3nvironment "C-6$, Agricultural#3conomic &nstitute "63+6$, &SB

ED#5/E/#/D4#/. C-6 8eport /2D.

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Documents

Life Cycle Assessment of Biomaterials in Construction (Final)