Tallinn Green Factor (Rohefaktor)

Requiring green space in new development is easy to state and hard to enforce consistently — without a shared way to measure it, “green enough” means whatever each planner decides. Tallinn wanted a quantified, comparable tool it could actually apply and check.

Modelled on Berlin’s 1994 Biotopflächenfaktor and its adaptations in Malmö, Oslo, Stockholm, and — most directly — Helsinki’s Viherkerroin, developed with TalTech and overseen by a steering group drawn from across the city’s planning departments over four stages between April and November 2022.

Different land-cover types and green components on a site are weighted by ecological-value coefficients and summed against a required target — five base factors and up to seventeen stackable bonus factors at the design stage. The tool was tested by ten planning and design firms across roughly twenty real detailed plans and building projects across different Tallinn districts before being finalised.

Delivered as a full methodology report, an Excel calculation tool, and appendices covering international comparisons and tester feedback — followed by a dedicated training session for the city in January 2023.