Urban Nature Platform

Assessing the impacts and benefits of Nature-Based Solutions in urban environments

Understand the HIBOU method

The HIBOU method (Hybrid method for assessing the Impacts and Benefits of Nature-based Solutions in Urban environments) offers a scientific, integrated, and operational approach to analyzing the effects of urban projects on nature and living systems.

It is based on:

  • Interdisciplinary research work
  • Theses, national and European projects
  • Multi-stakeholder working groups (e.g., CAP 2030 – GT7 Biodiversity)
  • Continuous exchanges with local authorities, developers, consultancy firms, and life‑science experts

Objective: to turn a qualitative ambition (“more nature in the city”) into measurable, comparable, and justifiable action.

The key principles of the HIBOU method

The HIBOU method turns measurement into a tool for decision-making
and ecological transition

Multi-criteria

All urban challenges are evaluated in a coherent way, without implicit hierarchy

Multi-scale

Building, plot, neighborhood, block, territory

Multi-solutions

Several nature-based solutions, but also their “grey” alternatives

Contextualized

Integration of local characteristics: climate, soils, density, heritage, urban pressure

Transparency

Each indicator is documented, accompanied by its assumptions and limits

Regulatory compatibility

With existing frameworks: RE 2020, CAP 2030, QEC method, etc.

Operational

The Urban Nature Platform is designed to be easy to use, even by non-experts

Challenges assessed by the HIBOU method

You can choose to calculate only certain HIBOU indicators or mobilize them all. The method is designed to be fully modular and adaptable to each situation.

In situ Biodiversity
Water management
Health and well-being
Harmonized Biotope Area Factor (CBSh), species richness, functional diversity, habitat quality, etc.
Retention, infiltration, runoff, hydraulic capacity of NBS, evapotranspiration, etc.
Access to nature, pollution, quality of environments, etc.
Environmental footprint
Heat
Economy
LCA indicators (carbon, pollution, resources, water), impacts on ex-situ biodiversity, etc.
Exposure to Urban Heat Islands, clay swelling/shrinkage, local climate vulnerability, etc.
Total cost, avoided costs, cost/benefit ratio of nature-based solutions, etc.

A method in service of stakeholders

HIBOU was developed in partnership with researchers, local authorities, urban planners, and consulting firms.

It allows:

  • Local authorities: to incorporate robust environmental criteria into their specifications.
  • Urban planners and developers: to showcase their projects and compare different scenarios.
  • Researchers: to experiment with and continuously improve evaluation methods.

A method in constant evolution

The HIBOU method is a living approach, developed progressively in response to scientific advances, feedback from experience, and opportunities for collaboration with field practitioners. Some components of the method are already operational, while others are still under development or in an exploratory phase. This gradual, dynamic process allows for the regular integration of new indicators, the refinement of existing models, and an ever-better response to the needs of local authorities, developers, and consulting firms. HIBOU is therefore a method of continuous improvement, designed to evolve and grow in step with urban challenges and environmental knowledge.

Context for the development of the HIBOU method

The HIBOU method is the result of a collective effort, built at the intersection of CSTB’s internal expertise and numerous external collaborations. Its development is grounded in a robust scientific foundation, supported by a wide range of professions and stakeholders involved in the ecological transition.

🔬 CSTB Expertise mobilized

HIBOU benefits from the wealth of internal competencies:

  • Hydrology
  • Climatology
  • Data science
  • Environmental health
  • Economic
  • Urban heat island
  • Ecology
  • Software development
  • Urban environment
  • Life cycle analysis

These areas of expertise are mobilized in a coordinated manner to build reliable indicators, robust models, and a truly integrated approach to urban issues. This multidisciplinary approach is one of the pillars of the HIBOU method.

🤝 Collaborations and partnerships

HIBOU is not built alone: it relies on an extensive network of scientific, institutional, operational, and industrial partners. This collaborative work allows to:

  • Co-develop recognized indicators
  • Cross-reference data and methodologies
  • Align tools with field practices
  • Ensure the relevance and operationality of the method

Within this ecosystem of actors, CSTB plays the role of integrator: it brings together contributions to create a harmonized, coherent, and evolving reference for evaluating urban nature.

In-situ Biodiversity

How does the HIBOU method assess biodiversity directly affected by the development project ?

Biodiversity is complex, multifaceted, and cannot be captured by a single indicator. It depends on:

  • Habitat diversity
  • Species richness
  • The ecological functions performed by species
  • Local land-use dynamics

For this reason, the Urban Nature Platform uses a set of complementary indicators that cover the different aspects of local biodiversity.

At this stage, only the calculation engine for the Harmonized Biotope Aera Factor (BAFh) is available on the Platform.

HIBOU Flash

Harmonized Aera Factor (BAFh) - CAP 2030 Flash
Calculate the BAFh of my project

HIBOU Mid-level

Habitat quality/functionality indicator - CAP 2030

Direct land-use change indicator (LUCd)
Species richness indicator

HIBOU Expert

Fonctional Attribute biodiversity indicator (FAD)
Permeability indicator
Dynamic species richness indicator
Invasive exotic species

Harmonized Biotope Aera Factor (BAFh)

Presentation of the BAFh

The BAFh (Harmonized Biotope Aera Factor) is the reference indicator of CAP 2030’s GT 7 Biodiversity, led by CSTB. It measures a site’s capacity to support biodiversity and answers a simple question: what proportion of my project is truly favorable to biodiversity?

It is based on a detailed classification of 41 land-use types, each associated with a biodiversity support coefficient.

It takes into account vegetated areas according to their substrate thickness and the combination of vegetated layers they support.

The calculation follows a straightforward logic:

  • Identify the project’s surfaces (buildings, outdoor spaces, roofs, soils, gardens, water bodies, etc.)
  • Assign each surface to a BAFh classification type
  • Apply the corresponding coefficient: 0 for an unfavorable surface, 1 for a highly favorable surface
  • Calculate the weighted total ratio: the final result ranges from 0 to 1 and represents the site’s overall biodiversity support capacity.

The BAFh is calculated at two key stages: before and after the project. This dual assessment allows determining whether the project has:

  • Degraded the site’s biodiversity capacity
  • Maintained the initial ecological level
  • Or Improved the site’s ability to support biodiversity

This dynamic interpretation of the BAFh is essential to objectify choices, guide trade-offs, and demonstrate the benefits of nature-based development.

The Urban Nature Platform integrates a BAFh calculation engine fully compliant with the rules defined by GT7 Biodiversity.

Calculate the BAFh of my project

Development Context of the BAFh – CAP 2030

CAP2030

The CAP 2030 project is led by the Ecological Interest Group (GIE), formed by three associations (Alliance HQE-GBC, Collectif des Démarches Quartiers Bâtiments Durables, and Collectif Effinergie), with the support of DGALN and ADEME, and the assistance of CSTB and the Plan Bâtiment Durable.

The objective of this project is to establish a common reference framework shared by all stakeholders, in order to go beyond the requirements of RE2020.

It is composed of nine working groups, including the one on Biodiversity.

Presentation of the Work of GT 7 Biodiversity

The loss and transformation of habitats resulting from human activities remain the main drivers of biodiversity decline and the associated ecosystem services (e.g., regulation of urban heat islands, stormwater management, provision of food and raw materials, and strengthening of social connections). Therefore, when planning an urban project, construction and development stakeholders must take care to minimize their impacts on biodiversity. A range of measures is available to them, such as greening, de-paving, and the integration of bird or bat boxes.

To achieve this goal, stakeholders can use various approaches, including greening, de-paving, or installing nesting boxes. To ensure that these measures adequately address the specific situations they face, it is essential to assess and quantify the impacts—positive or negative—that these actions have on local biodiversity.

It is within this context that the work of GT 7 Biodiversity takes place, structured around two complementary actions:

  • Measuring the biodiversity support capacity of projects: calculating the Harmonized Biotope Aera Factor (BAFh) before and after the project.
  • Assessing habitat quality and functionality to ensure that:
    • Stakeholders are aware of the biodiversity issues of the initial site and incorporate them into the project design phase.
    • Project developments effectively support species’ life cycles (e.g., installation of nesting boxes, flowering or berry-producing plants, etc.).

Since 2021, GT 7 Biodiversity has been coordinated by CSTB (Aline BRACHET) and brings together over 180 participants (ecologists, planners, local authorities, certification bodies, consulting firms, etc.), ensuring the ecological relevance and operational applicability of the proposed indicators.

At this stage, the Urban Nature Platform enables the calculation of the BAFh.
Ongoing IT developments aim to automate the calculation of the habitat quality/functionality indicator. In the meantime, you can use the Excel tool: Habitat Quality/Functionality Indicator Calculation Grid – July 2025 Version.