HVAC works for commercial spaces: turnkey air conditioning, ventilation, heating

Three regulations govern every commercial HVAC project in France, and Kytom has tested them on 1200+ projects since 2006.

The category 2 operation threshold is triggered from 20 employees present for more than 30 days, and imposes two aeraulic thresholds on the client during the design phase: 25 m³/h per occupant in an enclosed office without specific pollution, 30 m³/h per person in a meeting room or high-density space. These airflows are non-negotiable, they govern the handover report and the enforceability of the file in the event of a Labour Inspectorate check.

The Eco Energie Tertiaire scheme commits you to a trajectory of -40 % in final energy consumption by 2030, -50 % by 2040, -60 % by 2050, with annual reporting. RE2020 supplements the scheme for extensions and new builds. The average consumption of a French office stands at 270 kWh/m²/year, of which 45 to 55 % is attributable to HVAC: this is where your 2030 compliance is decided.

NF EN 16798-1 frames hygrothermal comfort at 24 °C +/- 1 °C during the summer period. On the acoustic side, environmental certification standards cap technical equipment at 38 dB(A) in an enclosed office, a constraint that directly guides the choice of air handling units and fan coil units.

In practice, most of the energy gain comes from hourly control and zonal CO2 sensors, far more than from replacing the thermal production. Replacing a VRF in good condition to gain 0.3 points of COP is rarely worthwhile before 2030.

The choice of thermal production depends on your floor area, the architectural grid and the occupancy scenario. The choice of system depends on floor area and partitioning: VRV/VRF adapts to flexible floor plates up to 2,000 m², the air-to-water heat pump becomes relevant beyond 1,500 m² in a multi-tenant building, and the centralised all-air air handling unit is essential for large volumes exceeding 2,500 m². Works budgets typically range from 220 to 400 € excl. tax/m² depending on the system selected and the complexity of the site.

VRV/VRF suits floor plates with variable partitioning and makes up the majority of our portfolio. The air-to-water heat pump supplies 4-pipe fan coil units or radiant ceilings in multi-tenant buildings. All-air meets premium IAQ requirements with CO2 < 800 ppm. A high-performance air-to-water heat pump achieves a seasonal COP above 4.2, a value tracked by AICVF in its technical guides.

Our design office decides after dynamic thermal simulation, with a focus on MEP coordination under raised flooring (height 100 to 300 mm, four parallel conduits: air, high-voltage electrical, data cabling, condensates). Beyond 2000 m² on a single floor plate, VRV/VRF loses its advantage: the length of refrigerant lines degrades the seasonal COP and the R32 charge exceeds practical F-Gas thresholds. Below 200 m² with fewer than 4 thermal zones, a standard multi-zone split is sufficient without the VRF premium.

Three constraints structure your HVAC works on an occupied site, and we anticipate them from the detailed design phase to avoid unplanned production stoppages.

Restricted working hours. Noisy operations (slab drilling, duct cutting, refrigerant brazing) shift to non-working hours: 7pm-7am on weekdays, weekends in critical areas. On our commercial projects delivered on occupied sites, 35 to 50 % of installation hours are scheduled outside employee presence.

Phasing by zones. The floor plate is divided into 3 to 6 zones of 100 to 200 m² delivered sequentially, with a gradual shift of occupancy. Indoor units are commissioned zone by zone, the main refrigerant network remains continuously supplied to preserve the zones still occupied.

Noise and air quality measurements during works. Sound level meters at the boundary of the occupied zone (55 dB(A) threshold maintained in the adjacent open-plan area), temporary filters on air handling unit returns, dust isolation via plastic airlocks at interfaces.

Measured results. On 850 m² delivered in 12 weeks on average, Kytom achieves the handover report with no major reservations on the vast majority of its occupied-site projects. The residual reservations mainly concern the fine balancing of vents in transition zones, lifted within 8 weeks.

Our full sequence is not always the right answer, and we prefer to tell you before the quote.

Floor plates below 200 m² with fewer than 15 workstations. Targeting a premium IAQ goal (CO2 < 800 ppm, advanced environmental certifications) is not economically justified: the additional cost of a high-efficiency dual-flow air handling unit with zonal CO2 sensors remains hard to recoup on such small areas. The R4214-2 threshold of 25 m³/h remains the relevant reference, without oversizing.

Like-for-like replacements of end-of-life VRF units. Our six-step sequence stops being worthwhile: the audit and dynamic thermal simulation phase represents a significant share of the works budget for a marginal sizing gain. A direct three-step approach (survey, costing, installation) is sufficient, and we apply it without overcharging for the service.

VRF in good condition before 2030. Replacing to gain 0.3 points of COP does not cover the investment: most of the gain comes from hourly control and zonal CO2 sensors. We systematically start by optimising the building management system and hourly scenarios before touching the production, and we say so in pre-sales when this is your case.

1. Audit of the existing setup
   Thermographic survey of the building, measurement of airflows at supply and return vents, analysis of energy consumption over the last 12 rolling months. This step reveals R4214-2 under-airflows, unidentified heat losses and the gap with the consumption reduction trajectory of the commercial property stock before any costing. Deliverable: audit report with hourly load curve and map of thermal gaps by zone.
2. Sizing
   Calculation of thermal loads compliant with the prevailing standardised methods, dynamic thermal simulation beyond 500 m², trade-off between VRV/VRF, reversible air-to-water heat pump or hybrid system based on floor area, target seasonal COP and acoustic constraints (38 dB(A) in an enclosed office). The Kytom design office produces the enforceable calculation note and the forecast scenario.
3. Detailed design and costing
   Detailed preliminary design with three scenarios submitted to the client: an economic R4214-2-strict scenario, a high environmental quality performance scenario, a premium scenario focused on usage quality and occupant health. Each variant includes works cost excl. tax/m², projected seasonal COP, impact and lead time. The detailed tender file serves as the contractual reference for subcontracting firms and for the handover report.
4. Works and installation
   Installation of outdoor units, connection of brazed copper refrigerant networks, routing of insulated supply ducts, installation of dual-flow ventilation with recovery above 75%. On an occupied site, phasing by zones of 100 to 200 m² and gradual shift of occupancy. Kytom site managers run 6 active projects per project manager.
5. Handover and balancing
   Aeraulic balancing on each vent, COPREC, IFG smoke extraction tests if applicable, CO2 and temperature measurements over 5 working days in real occupancy. Deliverables: enforceable balancing report, as-built file, populated file. Clearance of reservations within 8 weeks and optional 3 to 7-year maintenance contract during the warranty period.