Version 1.2 – unchanged for 2016 Edition

Introduction to

Water Assessment

in GaBi

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Contents

Contents .................................................................................................................................. 1

1 Introduction ..................................................................................................................... 2

2 Terminology ..................................................................................................................... 2

3 Water assessment in GaBi Software ............................................................................. 3

4 Quantities of water use, degradative water use and fresh-water consumption ....... 5

4.1 Water use 5

4.2 Degradative use 6

4.3 Consumptive use of freshwater (freshwater consumption) 7

5 Assessment of environmental impacts – water footprinting .................................... 10

6 References ..................................................................................................................... 12

Authors

Dr. Annette Koehler annette.koehler@thinkstep.com

Daniel Thylmann daniel.thylmann@thinkstep.com

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1 Introduction

Freshwater scarcity is recognized as one of the most pressing environmental issues today and

in the future. There is increasing interest in using the GaBi software to assess water use from

an LCA perspective. With the yearly upgrades, GaBi Software always contains complete and

consistent water inventory data. Since 2012 (GaBi 6 upgrade) GaBi provides additional

quantities to allow for easy assessment of water data that are the fundamentals for water

footprint calculations. It is therefore important to have a correct understanding of the terminology

for the GaBi quantities applied. This document provides an introduction to the latest GaBi water

assessment terminology and details on how water use and water consumption can be assessed

using GaBi Software.

2 Terminology

Water use:

Water use is understood as an umbrella term for all types of anthropogenic water uses. On an

inventory level, water use equals the measured water input into a product system or process. In

most cases water use is determined by total water withdrawal (water abstraction).

Consumptive and degradative use:

Freshwater use is generally differentiated into consumptive water use (= water consumption)

and degradative water use, the latter denoting water pollution:

Freshwater consumption (consumptive freshwater use) describes all freshwater losses on a

watershed level which are caused by evaporation, evapotranspiration from plants1, freshwater

integration into products, and release of freshwater into sea (e.g. from wastewater treatment

plants located on the coast line). Therefore, freshwater consumption is defined in a hydrological

context and should not be interpreted from an economic perspective, so it does not equal the

total water use (total water withdrawal), but rather the associated losses during water use. Note

1 Note: Typically, only water from irrigation is considered in the assessment of agricultural processes and the consumption of rain

water is neglected. The rationale behind this approach is the assumption that there is no environmental impact of green water (i.e. rain water) consumption. Such an effect would only exist if crop cultivation results in alterations in water evapotranspiration, runoff and infiltration compared to natural vegetation. Additionally it remains arguable whether or not such changes (if they occur) should be covered by assessment of land use changes rather than in water inventories. However, rain water use is sometimes assessed in different methodological approaches or can be used for specific analyses. The GaBi software allows assessment of both water use including rain water (“Total fresh water use”, “total freshwater consumption”) and without rainwater (“Blue water use” and “blue water consumption”), see Chapter 4.

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that only the consumptive use of freshwater, not sea water, is relevant from an impact

assessment perspective because freshwater is a limited natural resource.

Degradative water use, in contrast, denotes the use of water with associated quality alterations

and describes the pollution of water (e.g. if tap water is transformed to wastewater during use).

These alterations in quality are not considered to be water consumption.

Note that the watershed level is regarded as the appropriate geographical resolution to define

freshwater consumption (hydrological perspective). If groundwater is withdrawn for drinking

water supply and the treated wastewater is released back to a surface water body (river or lake),

then this is not considered freshwater consumption if the release takes place within the same

watershed; it is degradative water use.

The difference between freshwater use and freshwater consumption is highly crucial to correctly

quantify freshwater consumption, in order to interpret the meaning of the resulting values and

for calculating water footprints (see ISO 14046).

Summary:

Freshwater Use = consumptive use + degradative use of freshwater = water input of freshwater

or total freshwater withdrawal on inventory level

Degradative use of freshwater = freshwater released back to watershed, with possible alteration

in quality

Freshwater consumption = freshwater lost to the watershed (water vapor to air2,

evapotranspiration, water incorporated into products, water release to sea)

Freshwater inputs – degradative freshwater outputs (outputs to freshwater and soil environment)

= Freshwater consumption

3 Water assessment in GaBi Software

All water flows necessary for calculating water use and freshwater consumption can be found

in the GaBi balance view.

2 Note that evaporated water is denoted water vapor (elementary flow) in the GaBi inventory system while steam is considered

a technical flow (as product output from e.g. steam generation, i.e. valuable substance).

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The water input flows can be found under Resources Material resources Renewable

resources Water (see also Figure 3-1).

Figure 3-1: Water input flows in GaBi Software

The water output flows are depicted in Figure 3-2:

Figure 3-2: Water output flows in GaBi Software

Note that for the output flows, the first term in brackets refers to the receiving water body, and

the second term to the water type released from the technosphere. E.g., “river water from

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technosphere, cooling water” refers to cooling water that is released into a river after use. With

the 2014 update a set of new flows was introduced:

lake water from technosphere, rain water,

river water from technosphere, rain water, and

sea water from technosphere, rain water.

These flows can be used to account for collected rainwater that is released back into the

environment (after use and/or treatment if applicable) in order to set up closed water balances.

Please also note that only flows that are used in the respective data set/ LCA model will appear

in your balance view, i.e. not all listed flows will be visible in all datasets.

4 Quantities of water use, degradative water use and fresh-

water consumption

With the 2012 update, the GaBi software contains quantities for water use and water

consumption, as defined and described below.

4.1 Water use

The water input flows in GaBi refer to total water use. In order to quantify total freshwater use,

all freshwater input flows are summed up. As stated above, rain water is important for a complete

inventory and thus part of the total water use and total freshwater use. However, for impact

assessments, in general only blue water (surface and groundwater) is considered, excluding

rain water (see above footnote 1). Normally, the focus lies in freshwater use and consumption.

Sea water is also excluded in this aggregation. Thus, the flow based equations are:

Total freshwater use = total freshwater withdrawal/abstraction

= water (river water) + water (lake water) + water (ground water)

+ water (rain water) + water (fossil groundwater)

Blue water use = Water (ground water) + Water (lake water) + Water (river water) + Water

(fossil ground water)

Accordingly the provided GaBi quantities are defined as in Figure 4-1 and Figure 4-2:

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Figure 4-1: Fresh water use in GaBi Software

Figure 4-2: Blue water use in GaBi Software

4.2 Degradative use

Degradative water output: As mentioned above, degradative use takes place when the water

used remains in the same watershed (potentially with altered quality). Water emissions to

freshwater are assumed to remain in the same watershed, so this is the degradative use

category (see Figure 4-3).

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Figure 4-3: Degradative water outputs in GaBi Software

The water flows that leave waste water treatment plants (river water from technosphere, waste

water) can be found among the outputs. “River water from technosphere, turbined” refers to

water use in hydroenergy generation. Corresponding flows “lake water from technosphere”

exist. Please note that river/lake/sea water in the output refers to the destination of the water

released, not to the source (see above).

Degradative use (water pollution, release of contaminants or heat into water bodies) describes

changes in quality which are covered by specific impact categories of LCA (e.g. eutrophication,

acidification, ecotoxicity, assessment of thermal emissions). Methods to assess effects of

reduced water availability due to deterioration in water quality are still in development and in

their very infancy. Please contact thinkstep in case further information is needed.

4.3 Consumptive use of freshwater (freshwater consumption)

As mentioned above, freshwater that leaves the watershed is considered consumed. This is the

fraction that is most interesting as this water is lost to the ecosystem and for downstream users.

Total freshwater consumption is defined as:

degradative water

outputs

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Total freshwater consumption = total freshwater use (water input) – total

freshwater

release from technosphere (water outputs)

= water vapor (including water evaporated from

input products and including evapotranspiration of

rain water from plants)

+ water incorporated in product outputs + water

(freshwater, incl. rainwater released to sea,)

Please note that in general only blue water (surface and ground water) is considered. Therefore,

rain water is typically excluded from freshwater consumption and the focus is only on blue water

consumption (see above, footnote 1). In detail, the flow based calculation is:

Blue water consumption = Water (ground water) + Water (lake water) + Water (river water)

– Water (river water from technosphere, cooling water) – Water (river water from

technosphere, turbined) – Water (river water from technosphere, waste water) – Water

(lake water from technosphere, cooling water) – Water (lake water from technosphere,

turbined) – Water (lake water from technosphere, waste water)

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The corresponding GaBi quantities are defined as follows in Figure 4-4:

Figure 4-4: Total freshwater consumption in GaBi Software

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Figure 4-5: Blue water consumption in GaBi Software

5 Assessment of environmental impacts – water

footprinting

The water footprint of a product system is a set of different calculations (see ISO 14046) and

should be used as an umbrella term rather than to communicate a single number. Only results

on the level of environmental impact (e.g. after consideration of regional water availability)

should be labeled as a water footprint. The simple aggregation of water on an inventory level

represents water accounting and should be expressed as such and not as a water footprint.

Please contact thinkstep for further information on how further evaluations, including impact

assessment of your GaBi water inventories, can be performed.

ISO 14046:2014 specifies principles, requirements and guidelines related to water footprint

assessment of products, processes and organizations based on life cycle assessment (LCA).

ISO 14046:2014 provides principles, requirements and guidelines for conducting and reporting

a water footprint assessment as a stand-alone assessment, or as part of a more comprehensive

environmental assessment. Only air and soil emissions that impact water quality are included in

the assessment, and not all air and soil emissions are included. The result of a water footprint

assessment is a single value or a profile of impact indicator results. Whereas reporting is within

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the scope of ISO 14046:2014, communication of water footprint results, for example in the form

of labels or declarations, is outside the scope of ISO 14046:2014 [ISO 14026:2014].

The most demanding aspect of the new standard is the need to limit the aggregation of

information on the life cycle impact assessment part of the modelling. This means that principally

any LCI value of any water related intervention of any step in the life cycle must be reported

separately in the inventory phase. Even if several thousand processes are involved it is

theoretically not allowed to aggregate on LCI level. Aggregation is only allowed in the

subsequent step in the impact assessment.

A sister standard “Environmental management — Water Footprint — Examples” is still in work

and practical guidance how to apply this standard on process chains of several thousand

processes still missing.

However, the GaBi database enables the user to fully comply with the new standard in the

foreground system. Any related and necessary water flow is defined in the GaBi database and

may be used in the own foreground system of the user and in the specific data collection process

of each individual user.

Concerning background data and data on pre-calculated systems (of several thousand unit

processes) in GaBi as well as data of other re-published third party or industry data sources (like

certain association data, certain company data) within the GaBi databases may show different

water results than (theoretically) calculated on basis of the new ISO 14046 standard.

Depending of the specific case of water quality and location of use the difference might be more

or less relevant.

Due to the relative premature nature of the water footprint results, we recommend to carefully

interpret water footprint results. In case of any significant difference between existing water

footprint results and newly ISO 14046 calculated results we recommend scenarios and the

sensitivity analysis.

Concerning our own background data and the data provided by industry and associations we

will stepwise update the information towards full ISO 14046 conformity, considering relevancy

and feasibility of the update.

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6 References

BAYART ET AL.

2010

BAYART, J.; BULLE, C.; DESCHÊNES, L.; MARGNI, M; PFISTER, S.; VINCE, F.; KOEHLER, A. (2010): A FRAMEWORK FOR ASSESSING OFF-STREAM FRESHWATER USE IN LCA. INT J

LIFE CYCLE ASSESS 17(3), PP 304-313

BERGER, FINKBEINER

2010

BERGER, M.; FINKBEINER, M. (2010): WATER FOOTPRINTING: HOW TO ADDRESS WATER

USE IN LIFE CYCLE ASSESSMENT?. SUSTAINABILITY 2 (4), 919-944

ISO 14046 ISO/CD LIFE CYCLE ASSESSMENT -- WATER FOOTPRINT -- REQUIREMENTS AND

GUIDELINES. INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.

KOEHLER

2008

KOEHLER, A. (2008): WATER USE IN LCA: MANAGING THE PLANET’S FRESHWATER

RESOURCES. INT J LIFE CYCLE ASSESS 13 (6), PP 451-455

PFISTER ET AL.

2009

PFISTER, S.; KOEHLER, A.; HELLWEG, S. (2009): ASSESSING THE ENVIRONMENTAL

IMPACT OF FRESHWATER CONSUMPTION IN LCA. ENVIRON SCI TECHNOL 43(11), 4098–4104.

PFISTER, HELLWEG

2009

PFISTER, S.; HELLWEG, S. (2009): THE WATER “SHOESIZE” VS. FOOTPRINT OF

BIOENERGY. PNAS 106(35), E93-E94

RIDOUTT, PFISTER

2010

RIDOUTT, B.; PFISTER, S. (2010): A REVISED APPROACH TO WATER FOOTPRINTING TO

MAKE TRANSPARENT THE IMPACTS OF CONSUMPTION AND PRODUCTION ON GLOBAL

FRESHWATER SCARCITY. GLOBAL ENVIRONMENTAL CHANGE 20 (2010), 113–120

RIDOUTT, PFISTER

2012

RIDOUTT, B.; PFISTER, S. (2012): A NEW WATER FOOTPRINT CALCULATION METHOD

INTEGRATING CONSUMPTIVE AND DEGRADATIVE WATER USE INTO A SINGLE STAND-ALONE

WEIGHTED INDICATOR. INTERNATIONAL JOURNAL OF LIFE CYCLE ASSESSMENT, ONLINE

FIRST (2012)