• Central system (usually D/WTW).: one unit, ducts to all rooms. Everything goes through a central unit with heat recovery.
• Decentralized system (WTW per room).: one compact unit per room (surface mounted/constructed) with heat recovery. No ductwork throughout the building.

• Renovation-friendly: decentralized requires no ductwork → less breaking work, finished faster, occupied renovation can.
• Energy & comfort: WTW keeps heat inside; supply is pre-heated → less draft, windows stay closed → less noise and dust.
• Control per room: night mode in bedrooms, boost when cooking/showering, automatic control on CO₂/VOC/moisture. That level of precision is usually extra and more expensive in central.
• Monitoring: decentralized units log easily per room → insight, reporting and customized maintenance.
• Hygiene: no long ductwork that can foul; filters are at the source and easily accessible.

Renovation / apartments

• You don't want no ducts in ceilings or shafts.
• You want to phases: today living space, tomorrow bedrooms.
• You want individual control per room and clear data per room.

New construction with a focus on flexibility

• You want to easily adjust rooms later without interventions in a duct network.
• Acoustics are critical (silence in bedrooms) and you want short airways.

• Large new building with adequate engineering space and a well-developed duct plan.
• Projects where few wall penetrations are desired or building physics demands it.
• When you provide top duct design, silencers and duct cleaning early in the design.

Fair is fair: centralized can work perfectly - if it is well designed, installed, adjusted and maintained and maintained. In renovation, this is often the stumbling block.

• Central: channel networks require space, design, fire/noise attention and cleaning. Without maintenance, dust, moisture and biofilm can develop.
• Decentralized: source-filters and short airways. Units are quickly accessible for filter changes. No scattered contamination in hidden ducts.

• In renovation decentralized is often more cost-effective: fewer working hours, no duct finishing, quick installation.
• In new construction are the material costs sometimes closer together; the real difference is in arrangement and finishing. Per-chamber control is a decentralized standard; for centralized systems often surcharge.
• TCO (Total Cost of Ownership): WTW savings, less duct maintenance, and less rework often fall in favor of decentralized.

• Per room comfort: quiet night mode in bedrooms, powerful but short boosts in kitchen/bath.
• Better focus: CO₂-/VOC-controlled ventilation feels noticeably fresher, especially in work or study areas.
• Closed windows: less traffic noise, pollen and fine dust inside.

Either system can suffice. The difference is made with sizing, commissioning, documentation and maintenance. In Belgium/Lux always coordinate with your EPB reporter: they process the device dates and flow rates in the file.

The "central reflex" is understandable, but no longer self-evident. If you renovate or per room control wants, offers decentralized today offers a quiet, efficient and scalable solution with excellent monitoring and hygiene. In well-designed new construction, central is still possible, but in daily practice decentralized WTW often wins out on comfort, flexibility and total cost.