1. The reference area
In offices the standard reference is gross usable area, sometimes called gross leasable area in international transactions. It is the total area of the floors let or sold, measured to the face of the façades, including circulation within the floors but excluding vertical common parts, stairs, lifts, risers, and plant rooms.
Gross usable area is always smaller than regulated floor area, the planning measure, in a ratio of 0.75 to 0.85 according to the design. A compact building with a concentrated central core has a favourable ratio; a slab building with generous perimeter circulation is less efficient.
Efficiency and the ratio between the two areas
The efficiency of an office building is measured by the ratio of usable to floor area. A ratio of 0.82 is standard; 0.87 is excellent, marking a well-optimised building; 0.70 signals an inefficient programme with generous circulation or an oversized core.
For the developer and the investor, every point of efficiency gained is additional lettable area at the same construction cost. The economist can price the effect of an architectural change on that ratio, and therefore on the potential rental income.
2. Delivery standards: from shell to turnkey
The office market has settled on standardised delivery levels that define precisely what the tenant receives at handover. They have a direct and major effect on construction cost: the spread from shell to turnkey is one to six.
| Delivery standard | €/m² gross usable | What is included | What is excluded |
|---|---|---|---|
| Shell and core | 900 – 1,400 | Structure, façade, roof, stairs, services capped off. Bare floor. | All finishing trades, internal services, cabling, partitioning, finishes |
| Category A, the market standard | 1,600 – 2,200 | Shell plus suspended ceilings, resin or floating floor, heating and cooling distribution, power and data cabling to the floors | Internal partitioning, final distribution cabling, high-end finishes, furniture |
| Enhanced category A | 2,000 – 2,600 | Plus basic partitioning, complete sanitary accommodation, integrated floor lighting, data to the workstation zones | Bespoke finishes, furniture, signage, IT infrastructure |
| Standard fitted out | 2,500 – 3,200 | Plus definitive partitioning, standard tenant finishes, raised access floor, final cabling, typical meeting room | IT equipment, furniture, decoration, brand signage |
| Premium fitted out | 3,200 – 4,500 | Plus high-end finishes, reinforced acoustics, staff restaurant, break-out space, concierge, wellbeing-compliant | Bespoke furniture, artwork, business-specific equipment |
| Turnkey | 4,000 – 6,000+ | Everything to the workstation: IT infrastructure, furniture, signage, the move itself. The tenant walks in and works. | Nothing; all included in the price |
Who pays for the fit-out: developer or tenant?
In France the standard practice is category A or enhanced category A delivery. The developer hands over the floor with services and ceilings; the tenant funds the fit-out of its own space, partitioning, finishes, final cabling, within a rent-free period or a landlord contribution.
The recent trend is a shift towards enhanced category A, or even standard fitted out, on premium new buildings, in order to shorten the tenant's installation time and secure the letting. That choice translates directly into a construction premium of 410 to 1,020 €/m² borne by the developer.
3. Cost structure by trade
The budget distribution of an office building differs fundamentally from housing. The weight of mechanical services and of data is markedly higher, reflecting the thermal comfort, air quality and connectivity expected in offices.
| Trade | Share, category A | Share, premium fitted out | What explains the difference |
|---|---|---|---|
| Structure | 25 – 30 % | 15 – 18 % | The relative share falls as the total rises; the finishing trades grow faster |
| Mechanical services | 18 – 24 % | 18 – 22 % | Remains dominant: thermal comfort and air quality are critical in offices |
| Electrics and data | 12 – 16 % | 14 – 18 % | Rising demands on data, smart building and vehicle charging |
| Façades and external joinery | 12 – 16 % | 8 – 12 % | The relative share stabilises; high-end curtain walling at premium level |
| Finishing trades and partitioning | 8 – 12 % | 14 – 18 % | The item that grows most with the level: materials, acoustics, demountable partitions |
| Finishes and coverings | 4 – 6 % | 10 – 15 % | Technical tiling against marble, raised floor against slab, active ceilings |
| Internal external works and landscaping | 5 – 8 % | 4 – 6 % | Relative share stable; shapes the image of the campus |
| Lifts and escalators | 2 – 4 % | 2 – 4 % | Little differentiation except premium cars |
Mechanical services are the structuring package in offices, and the one where trade-offs are most complex. A building cooled from a central chiller and boiler is cheaper to build than a variable refrigerant flow system or a water-source heat pump on boreholes, but its running costs over 20 years can be 30 to 50 % higher. An economist producing a whole-life analysis builds that dimension in, often decisive for a considered investor.
4. The effect of environmental certification
Environmental certification is now the norm for any new office building aimed at institutional letting. It is no longer a differentiator but a condition of access to certain tenants and certain property funds. The question is no longer whether to certify but what level to aim for, for which market.
| Certification | Construction premium | Items affected | Rental and resale value |
|---|---|---|---|
| Entry-level national certification | + 2 to 4 % | Enhanced insulation, energy equipment | Little differentiation in the market |
| High national certification | + 5 to 8 % | High-performance services, water, waste, comfort | A rental premium of 5 to 10 % in major cities |
| BREEAM Very Good | + 4 to 7 % | Similar plus water management and biodiversity | An international reference, required by foreign funds |
| BREEAM Excellent or Outstanding | + 8 to 14 % | Advanced engineering, high-performance façade, smart building | A rental premium of 10 to 20 %, the prime standard |
| WELL Silver or Gold | + 6 to 10 % | Air quality, daylight, acoustics, thermal comfort | An HR differentiator for technology and finance occupiers |
| WELL Platinum with BREEAM Outstanding | + 15 to 25 % | The maximum level: integral engineering, certified materials, continuous monitoring | Ultra-prime positioning, a narrow market |
| The current French energy and carbon regulations | Built in on new build | Energy and carbon performance, mandatory since 2022 for offices | Required; a threshold rather than a differentiator |
The cost-benefit analysis of certification must take in not only the construction premium but also the rental premium expected, the greater liquidity at resale, and tenants' own environmental commitments. On the prime markets, the Paris central business district, La Défense, Lyon Part-Dieu, the absence of BREEAM Excellent or equivalent effectively excludes a building from the search area of large corporates.
5. Public and private offices: what differs
Public offices: procurement and regulatory constraints
A public office building, a prefecture, a court, a university, a local authority, falls under the public procurement code with its mandatory tender procedures. That has several economic effects. On one hand, greater competition on the works packages can produce more competitive prices when the market is slack. On the other, the longer procedure, three to six months more than in the private sector, creates an inflation risk during the tender period.
Public offices are also subject to specific requirements on durability, on universal accessibility, every space, not only the principal circulation, and sometimes on resilience: crisis rooms, redundant services. These translate into a premium of 5 to 12 % over an equivalent private programme.
Private offices: efficiency and return
Private offices are optimised for rental return. The efficiency ratio, the cost of parking, the level of certification and the standing of the common parts are all trade-off variables directly tied to the yield expected. The economist advises on those trade-offs: every technical decision affects the construction cost, the rent achieved and the resale value.
6. The key trade-offs
Raised access floor or concrete slab?
A raised access floor, 100 to 150 mm above the structural slab, lets power and data run beneath the floor, giving great flexibility for future partitioning. Its premium is 60 to 90 €/m², justified on large floorplates and buildings with high tenant turnover, less relevant on a single-occupier building with a stable brief.
Curtain walling or masonry façade?
Curtain walling, aluminium and floor-to-ceiling glass, is the image of premium offices, but it costs significantly more than a masonry façade with windows: 610 to 920 €/m² of façade against 360 to 560 €/m². On a medium-sized building with 1,500 m² of façade, the difference can reach 500,000 €. The economic justification rests on the rental premium generated and on the thermal performance of the latest curtain walling.
Central cooling or variable refrigerant flow?
A variable refrigerant flow system offers more zoning flexibility and better control zone by zone, a major advantage in multi-tenant buildings. It costs 15 to 25 % more than a central chilled and heated water system. The analysis must take in the ease of recharging each tenant through individual metering, and the maintenance costs over 15 years.
7. What the economist produces on an office project
At outline stage on an office project the economist produces an estimate distinguishing clearly the cost of the building, before tenant fit-out, and, if asked, the fit-out cost by target occupier profile. They price the variants of delivery standard and certification, and document the effect of each trade-off on the cost per square metre and on the rental return expected.
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In summary
The cost of building offices runs from 920 €/m² of usable area for a shell to more than 6,100 €/m² for an ultra-premium certified turnkey. The reference area, the delivery standard, the environmental certification and the type of façade are the four variables that structure the budget. Mechanical services are the dominant package and the most sensitive to technical and economic trade-offs. BREEAM Very Good or its national equivalent has become the standard for lettable new offices; building its premium into the budget from the outline stage is indispensable to an economically coherent result.
Reference basis of the figures
These bands are orders of magnitude for framing, and their reference market is the Paris region. They serve to place a budget at the earliest stages and to compare building types with one another. They replace neither a tender exercise nor an estimate prepared on drawings, and they are not a record of prices actually charged.
The ratios per square metre and per item on this page are stated in January 2026 values. They were updated from January 2025 values, the basis adopted for the whole cocoon, using the BT01 all-trades index published monthly by INSEE on its 2010 base: 132.0 in January 2025, 134.7 in January 2026, a rise of about 2 %.
The global amounts quoted as examples, and any rents, charges or receipts expressed per year or per night, remain on their own basis: a building cost index does not apply to them.
To bring the ratios forward, apply the usual revision formula: updated value = page value × (BT01 for the month in question / 134.7). The index has kept rising since: it stood at 138,3 in June 2026, the last value published when this page was checked, that is 2,7 % above the reference base. BT01 measures contractors' input costs, wages and social charges, materials, plant and energy, not the prices actually tendered.
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Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.