Effects as ranges: why we do not calculate figures
Updated
It is tempting to put a precise figure on how much nitrogen or CO2 a project saves. But a figure without a methodology can undermine the credibility of the entire project.
Official calculations
In VLP projects (wetland and lowland projects), effects are calculated using the methods and spreadsheets provided by SGAV (the Danish Agency for Green Transition and Aquatic Environment), while MARS (a Danish land-use planning system) calculates nitrogen effects during planning. These are the figures used in applications and reporting.
Ranges from the literature
For early-stage discussions, ranges from specialist literature can give a sense of the order of magnitude, for example for shade from trees along watercourses. Always state the source and make clear that the values represent a range.
Keep measured, assessed and expected effects separate
- Measured: what has been recorded on site.
- Assessed: what a specialist has concluded.
- Expected: effects derived from calculations or literature.
Freyra's principle
Freyra presents effects only as ranges with source references, never as figures calculated by Freyra itself. The planting analysis is labelled as an outline requiring specialist validation.
Frequently asked questions
Where is a project's nitrogen effect calculated?
In MARS and using SGAV's methods and spreadsheets for VLP projects.