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

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Section II: Calculating product carbon footprints
over a defined time period, recognising variations in
geography, distance and materials.
In order to comply with the requirements of PAS 2050,
data quality should be judged according to the rules
described in PAS 2050 Section 7.2.
• How specific is it to the declared reporting period?
(Ideally the data would cover the exact time period)
• How specific is it to the product’s relevant geography?
• How specific is it to the product’s relevant
technologies and processes?
• How accurate is the information used (e.g. data,
models and assumptions)?
• How precise is the information? i.e. measure the
variability of the data values (see Step 5: Checking
uncertainty)
• How complete is it? i.e. is the sample size sufficiently
large and representative of all potential sub-categories
of the product? What percent of the data used
was actually measured vs. taken from a general
database?
• How consistent is it?
• How reproducible is it? i.e. what is the extent to
which an independent practitioner could reproduce
the results?
• What sources are used?
These rules are subjective; however, their application
will allow companies to identify the most appropriate
data for their circumstances.
Data types
Two types of data are necessary to calculate a carbon
footprint: activity data and emission factors. Activity
data refers to all the material and energy amounts
involved in the product’s life cycle (material inputs and
outputs, energy used, transport, etc.) – see below.
Emission factors provide the link that converts these
quantities into the resulting GHG emissions: the amount
of greenhouse gases emitted per ‘unit’ of activity data
(e.g. kg GHGs per kg input or per kWh energy used).
Activity data and emissions factors can come from
either primary or secondary sources:
• Primary data refers to direct measurements made
internally or by someone else in the supply chain
about the specific product’s life cycle
• Secondary data refers to external measurements
that are not specific to the product, but rather
represent an average or general measurement of
similar processes or materials (e.g. industry reports
or aggregated data from a trade association)
Inputs/outputs Energy used Direct gas
emissions
Distribution/
transport
] Type and quantity
] of all inputs and
] outputs
] For each process
] step:
] – Material inputs
] – Product output
] – Co-products
] – Waste
] Type, source and
] quantity of all
] energy used:
] – Electricity
] – Other fuels
] Type and quantity
] of direct GHG
] emissions
] Vehicle type,
] average distance
] for all transport
] legs
] % full or shared
] with other
] products
] % full on return
] journey (backhaul)
Per unit of finished product
Common activity data