Cité Vivante
Development
Spring 2026
Overview
Cité Vivante · Chilly-Mazarin, Essonne
Investment Case · USC RED 469 Field Project · Spring 2026
A redevelopment case for Sanofi’s former R&D campus in Chilly-Mazarin, south of Paris.
Sanofi vacated the 16.2-hectare R&D campus in 2024. The project studies retaining the wet-lab buildings and replacing obsolete offices with housing, services, and public space.
- 16.2 ha · 162,493 m² · 7 parcelsSite area
- Chilly-Mazarin and Longjumeau, EssonneLocation
- Market research · underwriting · investment committee presentationWork
- €178–240M development budget · 7–10-year holdUnderwriting
Project Background
The campus and the sponsor’s plan
The former Sanofi campus includes roughly 32,000 m² of wet-lab and vivarium infrastructure and about 50,000 m² of office space.
Arizona Asset Management’s Boost Campus program retains the lab platform and replaces the offices with industrial flex. The Cité Vivante team program studies retained labs with housing, services, and public space.
Disclosure: academic work. Cité Vivante is an independent USC RED 469 field-project thesis, studied against the sponsor’s real programme. It is not Arizona’s approved plan, not audited underwriting, and not a realized development.
Site & Parcels
Seven parcels behind one fence line
Behind one fence line the campus is a single operating asset. On title it is seven cadastral parcels straddling the Chilly-Mazarin / Longjumeau boundary, which is why the entitlement runs on two tracks, and why the programme sorts the way it does. Three parcels carry the deal; four carry infrastructure.
| Parcel | Commune · use | Area | Note |
|---|---|---|---|
| AC 705 | Chilly · residential | 64,034 m² | 6.3 ha |
| AC 092 | Longjumeau · mixed-use | 49,159 m² | B3 café · retail |
| AC 600 | Longjumeau · BSL-2 | 32,006 m² | B9 + B14 |
| AC 323 | Longjumeau · transit | 9,560 m² | rail frontage |
| AC 601 | Longjumeau · lab svc | 6,710 m² | support |
| AC 324 | Longjumeau · easement | 758 m² | servitude |
| AC 327 | Longjumeau · easement | 268 m² | servitude |
| Total unité foncière | 7 parcels · 2 communes | 162,493 m² | 16.2 ha |
Source: parcel geometry digitised from cadastre.gouv.fr; areas cross-checked against DRIEAT dossier F01125P0115.
AC 705 (6.3 ha in Chilly-Mazarin) is the residential play. AC 600 holds the BSL-2 platform that cannot be reproduced. AC 092 anchors mixed-use frontage on the transit corridor. The remaining four are servitudes, rail frontage and lab support.
Exhibit 02·A · Interactive Site Explorer
An interactive map of every geometry in the case. The same GeoJSON behind the exhibits, rendered as a six-layer Leaflet application I built for the field project: high-level zoning, the detailed PLU code mosaic, the Chilly-Mazarin / Longjumeau boundary, all seven cadastral parcels, on-site building footprints and the T12 · RER C · Métro 18 transit corridor. Parcels were digitised from cadastre.gouv.fr; buildings and rail geometry queried from OpenStreetMap through the Overpass API; Métro 18 is plotted through its ten future stations. Click any parcel, building or zone for its ID, surface and status.
Leaflet · 6 layers · OSM + cadastre + PLU — Zoning · PLU codes · Communes · Parcels · Buildings · Transit
Open full screen ↗Development Program
Three parts of the plan
The exhibits below show the market data behind each part.
- OfficesRemove the offices
Demolish ~50,000 m² of obsolete office rather than refurbish it speculatively. Greater Paris Q1 2026: take-up down 15% year-on-year, immediate supply up 9% to 6.33M m², average incentives at 30.4%. The inner southern suburbs ran 15.9% vacancy against a 17.9% ten-year high.
→ Exhibit 02 · office scissors - LaboratoriesLease the existing labs
Keep and re-lease 32,000 m² of BSL-2 wet lab and the vivarium as the Phase-1 income anchor, gated on an anchor-tenant LOI with only 5,000 m² of speculative new lab, because Île-de-France supply is growing from ~108,000 m² toward ~250,000 m² by late 2026.
→ Exhibit 03 · lab supply wave - Housing and servicesAdd homes, services, and a park
Introduce 350 to 500 homes (20 to 25% affordable), 3,000 to 5,000 m² of services and a 2 to 3 ha park. Chilly-Mazarin delivered ~32 net new homes a year from 2016 to 2022, while Boost Campus alone returns 1,300 to 1,500 jobs; new-build apartments trade near €4,000/m².
→ Exhibit 04 · the supply gap
Site Plan
From enclave to neighbourhood
Labs and industry to the north; homes and a park to the south.
The plan keeps the B9 laboratory spine and the vivarium; reuse B3 for services; and remove the office crescent and central parking field. Labs and industry sit along the northern rail corridor. Homes, a park, and daily services sit to the south around a central commons. Parking moves below grade.
| Component | Quantum | Disposition |
|---|---|---|
| Life-science labs | 32,000 m² | Retain and reposition: BSL-2 wet lab, CDMO/CRO tenancy |
| Legacy office | ~50,000 m² | Demolish; no speculative office added |
| Residential | 350–500 units | New build, 5–7 storeys; 20–25% affordable |
| Retail & services | 3,000–5,000 m² | Ground floor: café, pharmacy, crèche, grocery, co-working |
| Public park | 2–3 ha | Converted from ~53,000 m² of existing green space |
| Cultural facility | ~2,000 m² | Maison de quartier, conceived as a concession to the commune |
Entitlements
Entitlement is the deal
The site’s industrial/activity zoning prohibits standalone housing outright. Nothing about the residential programme is possible without a land-use change, and the proposal treats that as a central risk.
The pathway is a Déclaration de Projet with Mise en compatibilité du PLU, coordinated across two communes on an 18-to-30-month runway, with no residential construction triggered before rezoning is final.
The mechanism has already worked three kilometres away. At Découflé, Nexity Héritage ran the identical process on a former industrial site, and the consultation record also set the political ceiling: the original 500-unit concept was judged too dense and advanced at roughly 300. Cité Vivante is deliberately sized below the precedent, at 35 to 50 units per hectare.
- 500+ units, rejected as too dense2019 concept
- ~300 homes + ~105 serviced roomsApproved revision, 2025
- 30% LLSSocial housing share
- ~82 units / haPrecedent density
- 35–50 units / ha · 20–25% affordableCité Vivante target
- 19 May 2025 → 30 Oct 2025MEC deliberation → consultation
Field Research
Eleven meetings, one week in Paris
March 15 to 21, 2026: the sponsor, capital markets, brokerage, municipal government and the regional agency, plus a site walkthrough with Arizona and a Paris typology tour with USC faculty.
- SYNAPTICA · Boost CampusJean Marc Bourez · President, SYNAPTICA; Dir. Executive, Boost CampusThe sponsor’s One Health positioning, tenant-fit discipline, and a development-return framework of 18 to 20% target IRR at 50/50 debt-equity.
- Eastdil SecuredArnaud de Sordi · Managing Director, FranceCapital-markets framing: suburban capital appetite, debt advisory backdrop, and how lenders read unsecured entitlements.
- BNP Paribas Real EstateResearch sessionEuropean CRE investment at €177bn in 2025 (+9%), rate trajectory, and the Paris CBD (5.4%) versus secondary (10.9%) vacancy spread.
- Chilly-Mazarin & LongjumeauMunicipal planning officialsTwo-commune PLU coordination, governance conventions, and the local political context any rezoning must survive.
- Paris-Saclay AgglomerationEconomic development officeCluster priorities across six target sectors, student-housing pressure, and support for a public-facing business facility in B3.
- Newmark & World BankDavid Bouita · Ellen HamiltonÎle-de-France industrial demand and comparable transactions; the suburban-redevelopment policy lens on campus conversions.
“A north-Paris office conversion absorbed €10 to 20M of structural reinforcement and then couldn’t find tenants. Wait for the right tenant; don’t spend conversion capital speculatively.”
Underwriting
Underwriting you can audit
In this deck, every figure traces to a source, and that check caught three errors before the committee saw them.
- Primary research. Eleven Paris meetings logged with dates, people and roles: the qualitative base for every assumption.
- Source-traceable warehouse. A 27-table Supabase/PostgreSQL database of INSEE, Sitadel, DVF, Immostat and broker data, every row carrying its source, pull date and a confidence rating.
- Exhibits from queries. Fifteen SVG charts render from warehouse queries rather than numbers retyped into slides, feeding the HTML/CSS deck and its PDF/PPTX exports.
- Verification pass. A source-check workflow caught a vacancy figure attached to the wrong geography, stale prior-year rents presented as current, and a mislabelled rent row.
Supabase / PostgreSQL · Python figure pipeline · HTML/CSS deck system · Inline SVG exhibits · Three.js massing viewer · Next.js 15 portfolio
Underwriting targets · academic exercise, not audited results
Project Status
Academic case; no deal closed
This USC RED 469 field project did not result in a financing or construction. The figures on this page are projections for an academic case, not realized operating results. The page documents the research, entitlement analysis, and underwriting behind the proposal.
Cité Vivante is an independent academic proposal studied against Arizona Asset Management’s actual Boost Campus programme; it does not represent the sponsor. All financial figures are academic underwriting targets from a Spring 2026 course exercise, and are not audited, realized, or sponsor-endorsed results. Market data as recorded in the project’s source-verified warehouse (Immostat, Institut Paris Region, INSEE, Sitadel, broker research), Q1 to Q2 2026.
Author
Kyle Tran
USC Price · Real Estate Development · KAT Development
I led the investment case, including market research, source checks, entitlement analysis, underwriting, and the investment committee presentation. I also built the 27-table Supabase market database, the source-linked presentation deck, and a Three.js massing model.
My RED 469 paper proposed a higher affordable-housing share and extended-stay and VEFA-condominium housing for people working in the Paris-Saclay biotech cluster.
© 2026 Kyle Tran · KAT Development
USC Sol Price School of Public Policy · RED 469, Spring 2026