Refrigerant material balance methodology by DEFRA

This methodology enables the calculation of greenhouse gas emissions associated with the use of refrigerants. The methodology is sourced from the UK government department DEFRA, as published in their most recent greenhouse gas (GHG) conversion factors documentation, but ultimately follows the methodology publlished in association with the IPCC National Greenhouse Gas Inventory Programme.

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The methodology

Emissions model

This methodology estimates refrigerant emissions on the basis of material balance - that is, an accounting of refrigerant inputs, outputs and stores. The discrepancy between inputs and outputs is assumed to represent the quantity of refrigerant which was lost as emissions. This is more accurate than the 'emissions factor' approach (see below) in which assumptions regarding all of the emissions causing processes are incorporated into a single, generalized emissions rate.

Refrigerants differ in their specific physical (particularly thermal) properties and therefore exert a variable effect on atmospheric warming. As such, the absolute quantity of emissions for a given refrigerant type is converted into a standard measure of environmental impact - CO₂e: the equivalent quantity of carbon dioxide (CO₂) which would produce the same atmospheric warming effect. This conversion is made by multiplying the absolute emissions quantity by the 'global warming potential' (GWP) of the respective refrigerant - a value unique to the gas which represents its warming effect relative to CO₂.

Similar methodologies

DEFRA publishes an alternative methodology for accounting for greenhouse gases associated with refrigerants which uses generic emissions factors relating to the installation, operation and disposal of refrigeration and air conditioning units.

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Using this category

Specifying activity type

To use this category, simply create a profile item - there are no alternative drill choices.

Specifying activity data

Since the methodology is based on a material balance accounting of refrigerant quantities, each of the following quantities must be specified in order to make an emissions calculation:

• purchased: Purchases of refrigerant used to charge new equipment
• newCapacity: Total full capacity of the new equipment
• service: Quantity of refrigerant used to service equipment
• retiredCapacity: Total full capacity of retiring equipment
• recovered: Refrigerant recovered from retiring equipment

The refrigerant type can also be specified using the refrigerant profile item item value. The type of refrigerant must match one of the drill options found here - this category is used as a lookup resource for converting absolute emissions into the appropriate quantity of CO₂e for the respective refrigerant.

Results and calculation

Discover calculates the the absolute and CO₂e emissions of refrigerant using the material balance methodology. The following quantities are returned:

• absoluteEmissions: Absolute quantity of emissions based on specified input/output quantities
• CO2e: Emissions quantity expressed as CO₂e

These are expressed in terms of a mass (e.g. kg). The CO2e return value represents the conversion of absolute emissions into CO₂e and is enumerated only if the refrigerant type is specified (using the appropriate GWP). Otherwise this value is set to 0.