3. Le basculement "L'ilot ouvert de Christian de Portzamparc" - Jacques Lucan

Urban Planning Inflection Point (Post-1995)
📌 The major inflection point in urban planning is precisely situated around 1995, marked by the competition for the Masséna district.
🏙️ This competition sought an alternative to the existing urbanism prevalent in early French biotech zones, contrasting with the closed block (îlot fermé) concept.
🏗️ Christian de Portzamparc's winning project introduced a move away from continuous street alignment and ceiling heights, emphasizing open spaces and a more sculptural conception of development operations.
🌳 The shift involved designing the city more from architecture rather than defining public space first, a change deemed almost irreversible.

Architectural Concepts: Open Blocks and Islands
🏡 Portzamparc discussed the concept of "the third city," reconciling the historic closed block with modern open planning, realized through the open block (îlot ouvert).
🧩 The importance of the plot definition (fiche de lot) increased significantly in the Masséna district projects, as it determined the overall massing of each lot, unlike previous ZACs where it was merely a declination of the general regulations.
🏝️ Projects like Desjardins de la Lironde in Montpellier used the term "islands" (îles) instead of blocks, where buildings were separated and connected by a common podium, forming a single structure.

The Mandate for Diversity and Fragmentation
🚨 A central, near-obsessive theme became diversity, requiring every lot within an urban operation to differ architecturally, materially, and in color from its neighbors.
👻 The underlying driver is the "ghost of the large housing estate (grand ensemble)," leading to strategies to avoid linear or bar-like buildings, manifesting as fragmentation of volumes.
📏 This fragmentation is formalized through principles like the principle of multiple authors or variation in heights, often inscribed in regulatory documents, making design variation mandatory (e.g., breaking form every 15-30 meters).
📉 This led to an excessive fragmentation of operations, such as having 18 lots for only 180 housing units on Rue Ledru Rollin, utilizing nine architects for the small number of dwellings.

Architecture as Rule Following and Isolation
🏛️ Architecture became highly structural and regulatory, with architects strictly adhering to template rules (règles des gabarits), despite often claiming rules stifle creativity.
❓ This adherence results in projects that are excessively contextual based on boundary regulations but lack genetic relationship with surrounding buildings, creating urban "isolates."
🗣️ An isolate (like the Basque language) is defined as something with no genetic relationship to its neighbors, suggesting these developments become detached from the broader urban fabric.

Typologies of City Design
🤔 The speaker questions which city type is being constructed: the traditional compact block, the modern open planning city, the open block, or the varied city.
⚪ The "varied city" concept, exemplified by Lyon Confluence, risks becoming an open block where buildings are aesthetically too similar (homogeneous, calm architecture, few materials), contrasting with the French search for variety.

Key Points & Insights
➡️ The 1995 Masséna competition marked a critical shift toward developing open blocks as an alternative to established urban models.
➡️ The focus moved from defining public space to defining building massing (volumetry) via the plot definition (fiche de lot).
➡️ Architectural diversity became mandatory in new developments, driven by the fear of replicating the "large housing estate" aesthetic.
➡️ Modern regulatory constraints lead to architectural isolates—projects that adhere strictly to local rules but lack connection to the wider urban DNA.

📸 Video summarized with SummaryTube.com on Feb 03, 2026, 23:50 UTC