depaving In new real estate projects: incorporate CBS from the design phase to meet RE2020 and ZAN requirements

Désimperméabilisation et projets neufs : un enjeu désormais central

What the ZAN actually means for developers

Tout projet sur un terrain naturel ou agricole contribue au «budget d'artificialisation» de la collectivité. Les collectivités favorisent les projets qui minimisent l'imperméabilisation et maximisent les surfaces végétalisées. Un projet à faible empreinte imperméabilisante est plus attractif dans les appels d'offres de cession foncière publique.

Les PLU et CBS imposés par les collectivités

Paris mandates a green space ratio of 0.3 in certain densely populated areas. Lyon, Bordeaux, and Nantes have followed suit with similar regulations. A green space ratio of 0.3 per 5,000 square meters means that 1,500 square meters must consist of permeable or vegetated surfaces.

CBS: Understanding and Optimizing the Indicator

How is the CBS calculated?

The thresholds typically imposed

• Dense urban area: 0.2 to 0.3
• Residential area: 0.3 to 0.5
• Special zones: up to 0.6

The trend is on the rise.

The types of surfaces that matter

To optimize the CBS without sacrificing leasable space:

• Green roofs (coefficient 0.7): do not encroach on the footprint
• Roof gardens over underground parking (coefficient 0.7)
• Swales and rain gardens (weighting factor 1.0)
• Green facades (coefficient 0.5)

Intégrer la désimperméabilisation dès le programme

Underground vs. Above-Ground Parking Garages: Implications for the CBS

Asphalt-covered surface parking lot = coefficient 0. Underground parking lot with a green roof = coefficient 0.7. The cost difference (underground parking: +€15,000 to €25,000 per space) must be weighed against the regulatory and commercial benefits.

Green spaces, landscaped swales, and permeable roadways

The site plan design must incorporate the following from the outset: green spaces with optimized coverage ratios, landscaped swales for stormwater management, and permeable pathways rather than paved ones.

Green roofs and terraces

An extensive green roof costs €50 to €80 per square meter and contributes 0.7 CBS units. For a tower with 1,000 square meters of roof area: a contribution of 700 CBS units.

Simulation: Quantifying the Impact Before Submitting a Building Permit Application

Ce que Netcarbon modélise sur un projet neuf

À partir du plan masse et du programme de végétalisation, Netcarbon simule l'état environnemental du projet à horizon 25 ans : température de surface attendue, stock carbone supplémentaire, CBSh et superficie effective désimperméabilisée.

Example: Housing project + nature park

For a project comprising 80 housing units with a nature park (3,000 m²), involving the planting of over 691 trees and over 1,151 shrubs:

• -5,4°C de réduction de la température de surface locale
• CBSh +0.4
• +52 tCO2 stored

These figures were included directly in the technical proposal submitted in response to the request for proposals.

Valoriser la désimperméabilisation dans les RAO et les mémoires techniques

Ce que les collectivités attendent

Environmental criteria account for 20% to 40% of the overall score in many major cities. The most commonly requested indicators include: overall CBS score, green space area, number of trees, permeability rate, and impact on urban heat islands.

Quantitative data vs. qualitative commitments

«Nous planterons de nombreux arbres» n'a pas la même portée que «la plantation de 691 arbres génère une réduction de -5,4°C et +52 tCO2 à 25 ans, simulés par Netcarbon».

Generate carbon credits upon delivery

Le Label Bas Carbone (méthode Ville Arborée) permet de certifier et monétiser le stockage carbone lié aux plantations. Les crédits se valorisent selon les bénéfices apportés par le projet et peuvent représenter un financement significatif du projet.