3.3 Lessons for the Classification and Integration …
49
for a product system. From an LCA perspective, the WF class deals with the inventory
aspect of water use over the product’s life cycle, which could serve as a preparatory
step to advanced impact assessment. In other words, a subsequent step is to assess
the associated environmental impacts using one or more characterization models.
Water scarcity that the WF scarc describes is just one of the many environmental
consequences resulting from consumptive and degradative water use. Other impacts
at midpoint level may include eutrophication (Zonderland-Thomassen et al. 2014)
and human toxicity (Boulay et al. 2011), for instance. This is in contrast to endpoint
characterization where impacts refer to damage to several of the areas of protection,
like human health (Ridoutt and Pfister 2013a) and ecosystem quality (Hanafiah et al.
2011). All this goes beyond water quantity and thereby constitutes an expanding list
of impact/damage-oriented water footprints.
3.3.3 Lessons for the Integration of Footprints: A Three-Step
Framework
The variation in potential environmental impacts associated with a single stressor
(e.g., water use) brings our attention back to the weighting between footprints,
referred to as footprint weighting in this chapter. Though the two categories of footprints discussed above both have pros and cons, we argue below that only the IPOFs
have the capacity to be integrated into a single composite metric. After that, we
propose a three-step framework for the integration of IPOFs.
3.3.3.1 The Rationale of Choosing the IPOFs for Integration
There are two main reasons for choosing the IPOFs rather than choosing the IVOFs
when it comes to integrating different footprints into one single-score metric:
(a) Each IPOF characterized by science-based characterization factor is pinpointing
a well-defined impact category such as climate change and water scarcity.
Collectively, they are particularly suited to forming an overall picture of the
integrated environmental impacts of a product, organization, or nation, without
obvious overlapping. This is different from the IVOFs, for which double
counting may occur. The WF class , for instance, juxtaposes water use, depletion, and pollution. The pollution part may easily overlap with a chemical or
toxic footprint, and it appears difficult to attach a weight to such a heterogeneous
footprint.
(b) Footprint weighting in the integration of footprints is unavoidable, whereas
inventory weighting in shaping a single footprint can be avoided by making
use of characterization factors that bring together different inventory results
into an IPOF footprint with the best available scientific knowledge on natural
resources, human health, and environmental impacts. Compared with the IVOFs,
49
for a product system. From an LCA perspective, the WF class deals with the inventory
aspect of water use over the product’s life cycle, which could serve as a preparatory
step to advanced impact assessment. In other words, a subsequent step is to assess
the associated environmental impacts using one or more characterization models.
Water scarcity that the WF scarc describes is just one of the many environmental
consequences resulting from consumptive and degradative water use. Other impacts
at midpoint level may include eutrophication (Zonderland-Thomassen et al. 2014)
and human toxicity (Boulay et al. 2011), for instance. This is in contrast to endpoint
characterization where impacts refer to damage to several of the areas of protection,
like human health (Ridoutt and Pfister 2013a) and ecosystem quality (Hanafiah et al.
2011). All this goes beyond water quantity and thereby constitutes an expanding list
of impact/damage-oriented water footprints.
3.3.3 Lessons for the Integration of Footprints: A Three-Step
Framework
The variation in potential environmental impacts associated with a single stressor
(e.g., water use) brings our attention back to the weighting between footprints,
referred to as footprint weighting in this chapter. Though the two categories of footprints discussed above both have pros and cons, we argue below that only the IPOFs
have the capacity to be integrated into a single composite metric. After that, we
propose a three-step framework for the integration of IPOFs.
3.3.3.1 The Rationale of Choosing the IPOFs for Integration
There are two main reasons for choosing the IPOFs rather than choosing the IVOFs
when it comes to integrating different footprints into one single-score metric:
(a) Each IPOF characterized by science-based characterization factor is pinpointing
a well-defined impact category such as climate change and water scarcity.
Collectively, they are particularly suited to forming an overall picture of the
integrated environmental impacts of a product, organization, or nation, without
obvious overlapping. This is different from the IVOFs, for which double
counting may occur. The WF class , for instance, juxtaposes water use, depletion, and pollution. The pollution part may easily overlap with a chemical or
toxic footprint, and it appears difficult to attach a weight to such a heterogeneous
footprint.
(b) Footprint weighting in the integration of footprints is unavoidable, whereas
inventory weighting in shaping a single footprint can be avoided by making
use of characterization factors that bring together different inventory results
into an IPOF footprint with the best available scientific knowledge on natural
resources, human health, and environmental impacts. Compared with the IVOFs,