Decentralised vs Centralised ERV: The Complete Comparison

The choice between decentralised and centralised energy recovery ventilation (ERV) is one of the most consequential decisions in modern building design. Both approaches recover heat from exhaust air and transfer it to incoming fresh air, but they differ fundamentally in architecture, installation, cost, and suitability. This guide provides an exhaustive comparison to help architects, engineers, building owners, and installers make the right choice.

What Is Centralised ERV?

A centralised energy recovery ventilation system uses a single large air handling unit (AHU) — typically installed in a plant room, roof space, or basement — connected to every room in the building via a network of supply and extract ductwork. The AHU contains one or more heat exchangers (usually counter-flow plate or rotary wheel) that transfer heat between the outgoing stale air and the incoming fresh air.

Centralised systems have been the default choice for commercial buildings, hospitals, and large residential developments for decades. They offer precise airflow balancing, centralised filtration, and the ability to integrate heating, cooling, and humidity control into a single system.

However, they require significant ductwork — often hundreds of metres of rigid or semi-rigid ducting routed through ceiling voids, risers, and wall cavities. This makes them most practical in new-build projects where the duct routes can be designed into the building from the outset.

What Is Decentralised ERV?

A decentralised ERV system places individual ventilation units directly in (or on) the wall of each room. Each unit handles its own supply and extract through a single core-drilled penetration in the external wall. There is no ductwork between rooms — each unit operates independently.

Modern decentralised units like the Din Ventilation AirPro V2.0 use ceramic regenerative heat exchangers that achieve up to 97% heat recovery efficiency. They alternate between supply and extract cycles every 60–70 seconds, storing heat in the ceramic core during the extract phase and releasing it to incoming air during the supply phase.

Units are typically paired (one supplies while the other extracts) to maintain balanced ventilation across the building. Built-in WiFi, humidity sensors, and CO2 sensors enable smart, demand-controlled ventilation without any central controller.

Side-by-Side Comparison

Installation Differences

Centralised systems require careful planning from the earliest design stage. Duct routes must be coordinated with structural engineers, fire engineers (for fire dampers at compartment boundaries), and other building services. Ceiling void depths of 300–500mm are typical, and acoustic attenuators are often needed to prevent fan noise transmitting through the ductwork. Commissioning involves balancing airflow across every terminal device — a process that can take days for a large building.

Decentralised systems require a single 160mm (or 110mm for the Air Nano) core drill through the external wall per unit. The unit is mounted on the inside face of the wall, connected to mains power, and paired wirelessly with its partner unit. No ceiling void, no risers, no fire dampers, no duct cleaning. A trained installer can fit an AirPro V2.0 in under two hours.

Cost Comparison

For a typical 10-classroom school, a centralised MVHR system might cost EUR 40,000–60,000 installed (AHU, ductwork, terminals, controls, commissioning). The same school fitted with decentralised AirSchool units — two per classroom — might cost EUR 25,000–35,000 installed, with far less disruption.

For residential retrofits, the difference is even starker. Installing centralised ventilation in an existing home often requires extensive building work to create duct routes, which can cost more than the ventilation system itself. A pair of AirPro V2.0 units per room avoids all of this.

Operating costs are also lower for decentralised systems. The AirPro V2.0 consumes just 1.5–7W, compared to 200–500W for a typical residential centralised unit. Over a 15-year lifecycle, the energy savings alone can exceed the initial investment.

Maintenance

Centralised systems require periodic duct cleaning (every 3–5 years), filter replacement in the AHU, and inspection of fire dampers. If a fan motor fails, the entire building loses ventilation until it is repaired — which may require a specialist contractor and lead times for parts.

Decentralised units have washable ceramic cores and filters that can be cleaned by any building occupant. If one unit fails, only that room is affected, and the unit can be swapped out in minutes. This is particularly valuable in schools and care homes where continuous ventilation is critical.

When Centralised Still Makes Sense

Centralised ERV remains the better choice in certain scenarios:

• Large new-build commercial buildings where ductwork is already planned and the building has dedicated plant rooms.
• Hospitals and laboratories requiring HEPA filtration, strict pressure hierarchies, and 100% fresh air.
• Buildings requiring integrated heating/cooling where the AHU also serves as the primary HVAC system with heating coils and DX cooling.
• Very high airflow requirements (above 5,000 m3/h) where a single large AHU is more practical than dozens of individual units.

Why Decentralised Is Taking Over

The trend across Europe is unmistakable: decentralised ventilation is growing rapidly, driven by several converging factors.

• Retrofit demand: The EU Renovation Wave strategy aims to double the annual energy renovation rate. Most existing buildings cannot accommodate centralised ductwork, making decentralised the only practical option.
• Higher heat recovery: Ceramic regenerative exchangers now achieve 97%, surpassing the 75–90% typical of centralised plate or rotary exchangers.
• IoT and smart controls: Modern decentralised units include WiFi, CO2 sensors, and humidity sensors, enabling demand-controlled ventilation that was previously only possible with expensive BMS-integrated centralised systems.
• Reduced construction risk: No duct clashes, no coordination delays, no commissioning balancing. Installation is faster, more predictable, and less dependent on specialist trades.
• Resilience: No single point of failure. Each room maintains its own air supply independently.

Conclusion

For the vast majority of residential, educational, and light commercial buildings — especially retrofits — decentralised ERV is now the superior choice. It delivers higher heat recovery, lower installation and running costs, faster installation, room-by-room control, and built-in resilience. Centralised systems remain relevant for large new-build commercial and healthcare applications, but their dominance is waning as decentralised technology improves year on year.