Reference year, applicable years and validity dates

A factor carries three kinds of date. reference_year is the publisher's year for the data. applies_from_year and applies_to_year are the accounting years the value is meant for. The publisher's own validity window, where one is printed, is kept for reference and never removes a value. To pick a factor for a reporting year, use the applicable years.

Reference year#

reference_year is the year the publisher attaches to the value. Its meaning depends on the publisher: the year the data describes, the year of the edition, or the vintage of the guideline it follows. Two libraries with the same reference year do not necessarily describe the same year of activity.

A newer edition of a factor gets a newer reference year. The data keeps the older editions, so you can reproduce an inventory you reported before. The edition is a different axis from the year: which edition you are reading, and what a newer one changes, is Editions and updates.

Applicable years#

applies_from_year and applies_to_year are ours. They turn a succession of editions into ranges of accounting years, so that every year has exactly one value:

• The earliest edition has no start (applies_from_year is empty): it also covers any year before it.
• Each edition runs until the year before the next edition's reference year.
• The newest edition has no end (applies_to_year is empty): it covers the current year and later years, until a newer edition arrives.
• A factor with one edition only has neither: it applies to any year.

An empty end means "open", not "unknown".

Worked example: ADEME butane#

ADEME has published two editions of its well-to-use factor for butane in Europe, per kWh:

For a 2016 inventory, use 0.26748. For 2019 or any later year, use 0.269. The row for the newest year is flagged is_latest_activity_year, and it is what a factor page shows by default. Search ADEME butane factors.

In factor search, year picks accounting years. It keeps the factors whose range covers at least one of the years you picked, and shows the value for the latest of them, for example factors for 2016.

Spend factors: one row per year#

A monetary factor works differently. A monetary factor works differently. Every accounting year from 2015 to 2025 gets its own row, with applies_from_year equal to applies_to_year and the value re-priced to that year's money. Where a publisher has issued several editions, each published value supplies only the years its edition is the current one for, so one value may cover a single year rather than all eleven. See Spend-based vs activity-based factors.

The publisher's validity window#

Some publishers print their own validity dates. ÖKOBAUDAT prints one on every value it serves: each EPD states a date until which the declaration is valid. Others print one on part of their data, and most print none at all. For example, the EPD for the product ALT 100 has reference year 2021 and is valid until 31 December 2026.

These dates are kept on the underlying value record, not on the rows factor search and the API serve by default, and they never shorten the applicable years. An EPD past its validity date is still the manufacturer's most recent declaration for that product, and removing it would leave you with nothing rather than something better. Read the window, and decide for your own use case whether an expired declaration is acceptable.

Watch out. currency_year is not a date of the data at all. It is the price level a spend factor is expressed in, and it exists only on monetary factors.

Which date to use#

Related#

• Use a value for a past year
• Glossary: year window
• Pin a release
• Cite a factor