Office thermal comfort: diagnosis, air conditioning, heating and the commercial buildings decree. The Kytom 4-step method, with costs, ROI and field feedback.
"Too hot in summer, too cold in winter"
A poorly calibrated setpoint is expensive: 1 °C too high on the heating increases the bill by 7%. On an 850 m² floor, the annual drift quickly exceeds €6,000 excl. tax. The absence of precise zoning also makes it impossible to leverage the available energy savings certificates.
Above 28 °C, productivity drops by 10 to 30%, and short-term absenteeism rises by 20% on poorly regulated floors. Thermal discomfort ranks among the top three reasons for HR complaints, ahead of noise in recent buildings.
The French commercial buildings decree requires a reduction in final energy consumption of at least 50% by 2040 compared to 2010. The regulations also govern temperature and air renewal in professional premises. An oversized air conditioning system exposes you to an unfavourable audit and jeopardises the operating certifications targeted by real estate departments.
We treat thermal comfort as a coupled system of envelope, HVAC, occupancy and layout. Present since 2006 with 11 offices in France and Spain, Kytom works on 1,200+ projects with an average area of around 850 m². Our approach combines temperature readings over 2 to 4 weeks, occupancy counts and analysis of solar gains by façade. We then weigh up HVAC works, solar protection, acoustic and thermal partitioning, furniture choices and setpoint zoning. Technical departments receive a costed file room by room, ready to integrate into the multi-year plan; real estate departments have a rationale compatible with the regulatory obligations to reduce consumption in commercial buildings and with environmental performance certifications.
Measurement campaign over 2 to 4 weeks: temperature and humidity sensors, CO2 readings, façade thermography, analysis of BMS setpoints. Deliverable: thermal mapping of the floor, identification of the 3 to 5 critical zones and prioritisation by usage criticality and remediation cost.
Workshop with technical and real estate departments and user representatives. Definition of target setpoints (19 to 21 °C in winter, 24 to 26 °C in summer), the budget envelope and an operations-compatible schedule. Deliverable: costed framing note, prioritised scenarios, success indicators measurable over 12 months.
Coupled design of HVAC, partitioning, solar protection and furniture. Dynamic thermal modelling on sensitive zones, sizing of terminal units, choice of materials with controlled inertia. Deliverable: technical file compliant with the regulatory obligations applicable to workplaces, compatible with the environmental standards selected according to the real estate requirements defined in phase 2.
Works phased over 10 to 14 weeks, commissioning, training of facility teams on the BMS. Follow-up at 3, 6 and 12 months with setpoint adjustments based on user feedback. Deliverable: energy and thermal performance report, the basis for the annual regulatory reporting of commercial buildings.
"We had thermal complaints every week. After diagnosis and reworking of the HVAC zoning, the feedback dropped by half and our employee comfort score gained 18 points."
No strict numerical threshold is imposed by general labour regulations, but technical references converge towards 20 to 22 °C for sedentary activity and 24 to 26 °C with summer air conditioning. The 2022 energy sobriety decree confirmed the 19 °C setpoint in heated commercial buildings.
Zoning is almost always preferable. On 1,000 m², air conditioning only the south- and west-facing zones reduces the investment by 30 to 40% and consumption by 15 to 20%, while addressing 80% of the actual complaints raised to the facility team.
By combining an energy diagnosis, reworking of BMS setpoints and passive solar protection. This combination secures the -40% targeted in 2030 while improving perceived comfort. Field feedback documents gains of 20 to 30% without degrading usage.
Allow 2 to 4 weeks for instrumented diagnosis, 3 to 5 weeks for design and 6 to 10 weeks for phased works. That is 10 to 14 weeks in total, without relocation, on a typical 850 m² floor.
Three key indicators structure the follow-up: the gap between actual temperature and setpoint (target below 1.5 °C), the number of monthly complaints raised to facility management, and HVAC consumption expressed in kWh/m². Reviews at 3, 6 and 12 months make it possible to adjust setpoints and document the regulatory reporting applicable to the commercial building portfolio.
Yes in 90% of cases. HVAC works and solar protection are phased in the evening, at weekends or by half-floors. Across Kytom's 1,200+ projects, almost all were delivered on occupied sites, with a schedule validated by the technical department.