Guide to PAS 2050 How to assess the carbon ... - Aggie Horticulture

10
Section II: Calculating product carbon footprints
1
2
Process map
Boundaries and
prioritisation
] Build process map of product’s life cycle, from raw
] materials to disposal, including all material, energy
] and waste flows
] Confirm boundaries and perform high-level
] footprint calculation to help prioritise efforts
Update process map
with new information
3
Data
] Collect data on material amounts, activities and
] emission factors across all life cycle stages
4
Calculation
] Calculate the product carbon footprint
5
Uncertainty
] Assess precision of the footprint analysis
Five steps to calculating the carbon footprint
Step 1: Building a process
map
The goal of this step is to identify all materials,
activities and processes that contribute to the chosen
product’s life cycle. Initial brainstorming helps to build
a high-level process map that can then be refined
through desktop research and supply chain interviews.
The process map serves as a valuable tool throughout
the footprinting exercise, providing a starting point for
interviews and a graphical reference to guide both
data collection and the footprint calculation.
To develop a product process map, start by breaking
down the selected product’s functional unit into its
constituent parts (e.g. raw materials, packaging) by
mass using internal expertise and available data or
desktop research. A product specification or bill-ofmaterials
is a good starting point. Focus on the most
significant inputs first, and identify their respective
inputs, manufacturing processes, storage conditions
and transport requirements.
In practice there are considerable benefits to repeating
the process map step (Step 1 above) as understanding
of the life cycle improves, allowing greater prioritisation
and focus. For example, in Step 2 a high-level footprint
can be calculated with estimates and readily available
data before fully investing in data collection. This
approach enables prioritisation based on highest
impact emission sources rather than spending time on
small or ‘immaterial’ (less than 1% of overall life cycle
emissions) contributors.
Process map steps
Business-to-consumer (B2C)
When calculating the carbon footprint of B2C goods,
typical process map steps include those illustrated
opposite. From raw materials, through manufacture,
distribution and retail, to consumer use and finally
disposal and/or recycling.
Business-to-business (B2B)
Business-to-business carbon footprints stop at the
point at which the product is delivered to another
manufacturer, consistent with the ‘cradle-to-gate’
approach described in BS EN ISO 14040 3) . The B2B
3)
BS EN ISO 14040, Environmental mamagement — Life cycle
assessment — Principles and framework.