HVAC (Heating, Ventilation, and Air Conditioning)

HVAC (Heating, Ventilation, and Air Conditioning) encompasses all the systems and controls that ensure thermal comfort, indoor air quality (IAQ), and hygiene in a building, while managing energy consumption. It covers production (boilers, heat pumps, chillers), distribution (hydraulic/air distribution systems), emission (radiators, underfloor heating, fan coil units, air handling units/mechanical ventilation), control/building management systems (BMS), as well as maintenance and commissioning. A well-designed and properly adjusted HVAC system delivers comfortable, quiet, and energy-efficient spaces.

HVAC: Operational definition and components

An HVAC system is organized into four links:

- Production : air/water heat pumps, water/water heat pumps, boilers (gas/biomass), chillers, recovery systems (free-cooling, heat recovery), tanks and heat exchangers.

- Distribution : hydraulic networks (VFD pumps, 2/3 way valves, balancing, thermal insulation) and aerodynamic networks (AHU/MVHR, ducts, filtration, acoustic attenuation).

- Emission : low temperature radiators, underfloor heating/cooling, fan convectors, cassettes, chilled beams, diffusers.

- Regulation & control : water law, external/ambient/CO₂ probes, BMS/EMS (times, scenarios, alarms), remote reading and dashboards.

The entire process relies on data (heating/cooling/electricity metering), measurable criteria (ΔT, flow rates, COP/EER/SCOP/SEER, fan SFP) , and a quality assurance approach (completion, sludge removal, filters, seasonal reviews). In the RE2020 regulations, HVAC systems are combined with architectural features (Ubat, g/TL, solar shading, thermal inertia) to meet Bbio, Cep/Cep,nr, DH, and Ic requirements.

HVAC: Benefits, limitations, and points to consider

Benefits

• Controlled comfort: stable temperatures, filtered IAQ, humidity under control.
• Energy: variable flow rate (VFD), fine regulation, recoveries → kWh and OPEX down.
• Resilience: redundant/sequenced equipment, anti-peak BMS scenarios.
• Traceability: measurement, remote reading, indicators (COP/ΔT/SFP) for control.

Boundaries

• High CAPEX and multi-lot coordination (HVAC/electrical/architectural).
• Complexity: without commission, the calculated performance does not translate into reality.
• Essential maintenance (filters, balancing, adjustments, water testing).

Points to consider

• Logical order: sobriety & envelope → system efficiency → RES.
• Hydraulics: balancing, PICV, ΔP controlled, ΔT targets respected.
• Aerodynamics: adapted filtration, high recovery, bypass for free/night-cooling.
• Regulation: water law correctly calibrated, sensors well placed, pressure/setpoints reset via BMS.
• Water quality: descaling, inhibitors, purging/degassing, monitored conductivity.
• Commissioning: functional tests, in-situ measurements, live DOE + seasonal reviews.

Anecdote — “A CVC brought back to life with music in Montpellier”

In Montpellier, an office building was experiencing alternating periods of extreme heat and chilly office temperatures. The audit revealed oversized valves, fixed-speed pumps, excessive pressure drop at peak times, an air handling unit (AHU) without CO₂ control, and an overly steep heating curve. The solution was implemented in three steps (without replacing everything): VFDs on the pumps with pressure reset, PICV and balancing, and conversion of the AHU to variable flow controlled by CO₂ with a bypass for night cooling. The result over one season: a 32% reduction in fan/pump usage, maintained temperature drop, and a dramatic decrease in complaints. The manager smiled: "Even the air conditioning is working smoothly now."