iam-units 2020.4.6

Usage

>>> from iam_units import registry

>>> qty = registry('1.2 tce')
>>> qty
1.2 <Unit('tonne_of_coal_equivalent')>

>>> qty.to('GJ')
29.308 <Unit('gigajoule')>

To make the registry from this package the default:

>>> import pint
>>> pint.set_application_registry(registry)

# Now used by default for pint top-level classes and methods
>>> pint.Quantity('1.2 tce')
1.2 <Unit('tonne_of_coal_equivalent')>

Warnings

iam_units overwrites Pint’s default definitions in the following cases:

Technical details

Emissions and GWP

emissions.txt defines some greenhouse gases (GHGs) as Pint base units. Conversion of masses of these GHGs to CO₂ equivalents use selectable global warming potential (GWP) metrics, implemented as Pint contexts in the other files in the same directory. The contexts have names like gwp_<IPCC report>GWP<years>, where <years> is 100 and:

To use one of these contexts, give its name as the second argument to the pint.Quantity.to() method:

>>> qty = registry('3.5e3 t N20')
>>> qty
3500 <Unit('metric_ton * nitrous_oxide')>

>>> qty.to('Mt CO2', 'gwp_AR4GWP100')
0.9275 <Unit('carbon_dioxide * megametric_ton')>

# Using a different metric
>>> qty.to('Mt CO2', 'gwp_SARGWP100')
1.085 <Unit('carbon_dioxide * megametric_ton')>

Tests and development

Use pytest iam_units to check that the definitions can be loaded. Example unit expressions in checks.csv are also checked. See DEVELOPING.rst for further details.