Decentralised vs centralised MVHR: what makes sense, and when

Whether you are building or renovating today, one question is almost unavoidable: how do you bring fresh air into the house without letting precious heating warmth escape through a tilted-open window? Modern buildings are constructed so airtight that natural air exchange often no longer suffices. The result is stale indoor air, increased humidity and, in the worst case, mould. Controlled home ventilation with heat recovery provides the remedy – but should it be a centralised or a decentralised system? This comparison helps you decide.

💧 Why controlled home ventilation makes sense

In an average household, several litres of moisture are produced every day: through cooking, showering, drying laundry and simply breathing. If this moisture cannot escape, the risk of mould formation rises. Added to this are pollutants such as CO₂, VOCs (volatile organic compounds) and, in some regions, the radioactive soil gas radon.

The regulations take this into account: in England Approved Document F sets the minimum whole-dwelling and extract ventilation rates a home has to achieve, and PAS 2035 requires the existing ventilation to be assessed in any retrofit that reduces air leakage. In Ireland the equivalent is Part F of the Building Regulations (TGD F). What the rules fix is the airflow, not the type of system that delivers it. This is precisely where centralised MVHR and decentralised MVHR — the single-room heat recovery ventilators (SRHRV) named in Approved Document F, paragraph 3.26 — come in.

🏢 Centralised MVHR: one unit for the whole house

With a centralised ventilation system, a single ventilation unit supplies the entire flat or the whole house. From this central unit – usually located in the cellar or utility room – a network of air ducts runs to every room. Stale air is extracted from the kitchen, bathroom and WC, while fresh air is blown into living rooms and bedrooms. A central heat exchanger transfers the warmth of the extract air to the fresh incoming air.

The advantages of the centralised solution:

• ✓ A single unit supplies all rooms – centralised maintenance and filter changes
• ✓ With good design, a very even and comfortable air exchange throughout the building
• ✓ High heat recovery and optional extra functions such as central filtration or a post-heating coil

The disadvantages of the centralised solution:

• ✕ A complex duct network is essential – difficult to install after the fact
• ✕ Requires space for the unit and ducts, often suspended ceilings
• ✕ Higher investment and design costs
• ✕ The ducts must be cleaned regularly to remain perfectly hygienic

Centralised ventilation shows its strengths above all in new builds, where the duct network can be integrated cleanly into the design from the very start.

🔄 Decentralised MVHR (dMVHR): room by room, without ducts

A decentralised system does without a central unit and a widely branched duct network. Instead, a compact unit is installed directly in the exterior wall of each room – or each pair of rooms. In systems with heat recovery, a ceramic heat accumulator works in alternating cycles: in one phase, warm extract air flows outwards and charges the accumulator with heat; in the next phase, fresh outdoor air flows in and takes up this stored heat again.

The advantages of the dMVHR solution:

• ✓ No duct network required – ideal for retrofitting and renovating while the home stays occupied
• ✓ Minimal construction work, with installation often completed in a few hours per room
• ✓ Expandable room by room – you start where the need is greatest
• ✓ No long ducts that can become soiled
• ✓ Each unit can be controlled and adjusted individually

The disadvantages of the dMVHR solution:

• ✕ Each room with an exterior wall needs its own unit
• ✕ Interior rooms without an exterior wall cannot be ventilated directly
• ✕ Several units mean several filters to maintain

📊 Comparison table: dMVHR vs centralised MVHR at a glance

🧭 Which system suits your project?

In a new build, you have the freedom to plan each system from the ground up. A centralised installation can make sense here – but so can a decentralised system, if you want to keep construction work to a minimum and stay flexible.

When renovating existing buildings, decentralised ventilation unfolds its greatest strength: because no ducts need to be laid, there is no chiselling work, no suspended ceilings and no long construction phases. A single core hole in the exterior wall is usually enough.

For individual problem rooms – a damp bedroom or a bathroom without a window, for example – a single dMVHR solution is often the most pragmatic and most economical choice.

⭐ Ambientika’s dMVHR solution

Ambientika is manufactured by the South Tyrolean family business Südwind GmbH, which brings more than 55 years of experience in ventilation technology. The units work without ventilation ducts, achieve heat recovery of up to 93 % and are whisper-quiet with a sound pressure level from 20 dB. They are certified by IFT Rosenheim and TÜV, demonstrably reduce humidity, the risk of mould and radon exposure, and are eligible for funding through KfW and BAFA.

The range meets a variety of needs:

• → Ambientika solo+ (379 €) – the simple single-room solution for a quick start
• → advanced+ (519 €) – wired, with sensors, up to 15 units interconnectable and a Free Cooling function
• → wireless+ (579 €) – wireless and therefore particularly flexible in existing buildings
• → Ambientika smart (619 €) – with app control, VOC, temperature, light and humidity sensors, plus Home Assistant integration
• → advanced B+, the bathroom fan (439 €) – specially designed for damp rooms
• → Office (699 €) – for commercially used spaces

You will find an overview of all units and matching accessories in our product overview.