EVRF2007: European Vertical Reference Frame

Technical guide to EVRF2007 (EPSG:5621) — the European Vertical Reference Frame. Covers the geoid-based transformation H = h - N, ETRS89 compatibility, country-specific guidance for Poland, Germany, and the Netherlands.

EVRF2007 height (EPSG:5621) ⇄ ETRS89 / WGS84

EVRF2007 Ellipsoidal → Orthometric Height

Conversion formula: H_EVRF2007 = h_ETRS89 − N_geoid

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Professional Risk Notice

Using the wrong datum or applying coordinates without grid-to-ground correction can cause 1–400 metre positional errors — a leading cause of surveying negligence claims and contract disputes.

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Technical Background: EVRF2007

EVRF2007 (European Vertical Reference Frame 2007 — EPSG:5621) defines a unified European height system based on normal heights (Helmert heights). It is the authoritative vertical reference for trans-national infrastructure, flood modeling, and geodetic work across the EU.

The Core Formula

The fundamental relationship between GNSS-derived ellipsoidal heights and EVRF2007 orthometric heights is:

H_EVRF2007 = h_ETRS89 − N_EVRF2007

Where: H = orthometric height (what engineers use), h = ellipsoidal height from GNSS, N = geoid undulation from the EVRF2007 national geoid model.

Country-Specific Geoid Models

Legal and Infrastructure Implications

EU national laws and construction standards often mandate EVRF2007 for cross-border projects. Germany, Poland, and the Netherlands require EVRF2007-compliant heights for flood defense design, levee certification, and transnational rail/road projects. Using a pre-EVRF2007 national datum without proper transformation can produce decimeter-level height biases — critical for sea-level flood modeling.

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Technical FAQ

What is EVRF2007?

EVRF2007 is the European Vertical Reference Frame 2007 (EPSG:5621). It provides a unified height system using normal heights across Europe, replacing EVRF2000. It is the official vertical reference for transnational EU infrastructure and geodetic projects.

How is EVRF2007 different from national height datums?

National systems (e.g., Germany's DHHN2016, Netherlands NAP) are connected to EVRF2007 via country-specific geoid grids. Small but legally significant biases exist between national systems and EVRF2007, making the transformation mandatory for cross-border work.

What does 'H = h − N' mean in practice?

h is what your GNSS receiver reports (ellipsoidal height). N is the geoid model value at your location. H is the physically meaningful orthometric height — what a level measures. For FEMA-style flood work, H is what matters because it relates to sea level and water flow.