Common

Generic calculation implementations

class greenlang.calculations.ghg.base.base.BaseCalculationMethod

This is the base class for all calculation methods. All lot of categories are using this class because they are using a predefined factor. In term of form, the user has to select a GHG emission factor, a GHG emission unit and a amount.

amount(collection_item)

Return the amount value of the related ghg emission factor.

Parameters:

collection_item – the collection item where the amount value is stored.

Returns:

The amount value, as float number, of the related ghg emission factor.

compute(collection_item)

Compute.

explain(collection_item)

Return calculation explanation in human readable format. Basically, it’s displaying the amount, the GHG emission factor value and the total co2 value. It’s also mentionning the data source and the data source year. :param collection_item: the collection item where informations are stored.

Returns:

Calculation explanation in human readable format.

property form_class

Return form class to use for this calculation method. The form is responsible both of the displayed inputs both of the validation and the saving, if so.

Returns:

The form class to use for this calculation method.

total_co2(collection_item)

The total co2 value for the given GHG emission factor value.

Parameters:

collection_item – the collection item where informations are stored.

Returns:

The total co2 value, as float number, for the given GHG emission factor value. If the GHG emission factor value is a goods or services, the total co2 value is updated with an inflation rate. For the moment, the inflation rate is hard-coded : 7% per year.

Generic forms

class greenlang.calculations.ghg.base.forms.PredefinedFactorCalculationMethodForm

This form provides the inputs for category using a predefined factor. It exposes the following fields:

• description_user: a description of the item

• ghg_factor: the GHG emission factor to use, prefilled with the factors related to selected calculation method

• value_float: the amount value

• ghg_unit: the GHG emission unit to use, prefilled with the units related to selected GHG emission factor

As hidden fields, the form exposes:

• method: the selected GHG emission source computation method

• collection: the selected collection

• item_type: the selected item type, must be ‘ghg’

• ghg_scope: the selected GHG scope

get_extra_fields()

Return extra fields to add to the form. This method is meant to be overriden by subclasses. :returns: A list of extra fields to add to the form. Empty list by default.

save(commit=True)

Save

class greenlang.calculations.ghg.base.forms.CustomFactorCalculationMethodForm

CustomFactorCalculationMethodForm

get_extra_fields()

Return extra fields to add to the form. This method is meant to be overriden by subclasses. :returns: A list of extra fields to add to the form. Empty list by default.

get_placeholder(field_name)

Get placeholder

get_value_float_columns()

Get value float columns

save(commit=True)

Save

class greenlang.calculations.ghg.base.forms.SupplierSpecificMethodForm

Supplier specific method

class greenlang.calculations.ghg.base.forms.CustomAverageDataMethodForm

Custom Average data method form