G-34 (Buildings) / G-32 (Products) Water consumption as a new impact category

Aspect G-34 (Buildings) / G-32 (Products) Water consumption as a new impact category
The water consumed during the life cycle of a product or a building can have an impact on the environment. This impact actually depends on the geographical location. For example, in some regions of the world, the same amount of consumed water may have different environmental impacts, depending on the available water resources. The current practice in LCA is that water flows are classified only according to their type (ocean, river, groundwater etc.). In this context, should a factor for regional availability be included? Should the scarcity of water be considered? What type of water (e.g. drinking water) should be considered? How should water demand be classified regarding its origin?

Related study objective

stand-alone LCA comparative assertion

Related study phase

goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

Relevant for

new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions As there is no commonly agreed method for assessing the impact related to water consumption, scarcity of water is not considered at present. The provisions of EN 15804 and EN 15978 should be used, i.e. use of the indicator ‘net fresh water’. Yet, if the goal and scope of the study mention the use of an LCIA indicator for water consumption, the indicator that is used for the assessment needs to be described.
Rules from:
EN 15978:
11 Calculation of the environmental indicators

EN 15804:

7.2.3 Parameters describing environmental impacts

8 Life cycle impact assessment – calculating LCIA results
Provisions: 8.2 Calculation of LCIA results
Provisions: Resource elementary flows 

1) Practical guidance for the use of EN 15804 indicator
Two cases can be differentiated for guidance: practical calculation of the LCI indicator (currently provided in the CEN TC 350 standards) or available references for the use of a new impact category indicator for water consumption.– If the ‘net fresh water’ indicator is used according to EN 15804 and EN 978, it should be calculated as the difference between the water input and water output from a product system. Thus cooling and turbine-use inventory flows are not to be accounted for in the indicator. Salted water is also excluded, as this category deals only with ‘fresh’ water.

2) Practical guidance for the use of a water indicator as a new impact category

If a water indicator is to be considered as an optional impact category, it has to be documented separately. For more information, please consult the following sources. Results from the UNEP/ SETAC working group ‘Assessment of Freshwater Use within LCA’ (WULCA) should be considered, and are especially relevant. Scientific papers on the latest developments of the water impact category can be also be consulted.

At the standardization level, the ISO is also working on a new standard on water footprint: ISO/CD 14046 Life cycle assessment – Water footprint – Requirements and guidelines.

Revision of this aspect is required if a generally accepted method is available – and used by the EN 15804/15978 standards.

Please also note that some of the EPD programmes consider the inclusion of water in one way or another. Additional information on methodologies can be found in such EPD programmes. However, the various data sources could refer to different methodologies for the calculation of a water indicator.

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