🚪 The Corridor as "Tunnel"
The narrow hallway becomes the main trunk duct. A false ceiling there drops it to 2.30 m - nobody notices in a passageway. Branch ducts punch through the wall and blow into the rooms.
Ducted Air Conditioning in Old Buildings: Invisible Comfort Without Lowering Your Ceilings
In luxury hotels you feel cool air but see no plastic air conditioner on the wall. That's Ducted Central AC - and you can bring it to your home during renovation.
The fear: the engineer will drop the entire ceiling. The truth: smart solutions exist that hide the AC without sacrificing precious headroom!
1. The Corridor Trick (Trunk & Branch)
This is the golden rule of renovation: never lower the ceiling in the main rooms. Place the unit and ducts in secondary spaces only.
🛁 Bathroom Loft Spaces
Bathrooms already have lower ceilings (due to plumbing). The loft above the bathroom is ideal for concealing the indoor unit. Insulation + acoustic lining = zero noise in the adjacent bedroom.
🚿 Above Wardrobes
Built-in wardrobes reach 2.20 m. The space above them (20-40 cm) can host a concealed duct run with no visible point. Supply grilles emerge in the adjacent bulkhead.
📐 The Result
Your living room stays untouched at 2.80 m! False ceiling exists only in "hidden" spots. No visitor realises ductwork runs behind the wall - they see only an elegant slot diffuser.
2. Perimeter Soffits (Plasterboard Steps)
If the home is open-plan (huge living-kitchen with no corridors), the solution is an architectural soffit - a false ceiling only around the perimeter.
📏 How It Works
Instead of dropping the entire ceiling, we build an architectural box around the walls only, 40-50 cm wide and 20-25 cm deep. Ducts run inside. The centre of the living room remains high and open.
💡 Bonus: Concealed Lighting
The underside of the soffit is perfect for LED strip lighting (indirect cove lighting) or recessed downlights. A mechanical "obstacle" becomes an architectural masterpiece.
🔇 Acoustic Lining
Inside the soffit, acoustic insulation (typically 25 mm mineral wool) wraps the ducts. This eliminates airflow noise - critical especially in bedrooms.
🎨 Seamless Integration
The soffit is painted the same colour as the ceiling. Grilles are integrated into the shadow gap. The finished room looks like a designer interior - no one guesses a full HVAC system hides behind it.
3. Low-Silhouette (Slim) Ducted Units
Manufacturers know the old-building challenge. That's why they created slim ducted units that fit even in very tight loft spaces.
📏 Just 18-20 cm Tall
While a standard commercial unit needs 40-50 cm of height, slim units are just 18-20 cm. This means you need a false ceiling of only 25 cm instead of 55 cm.
🔊 Ultra-Quiet
Modern slim units operate at 23-28 dB(A) - virtually silent. Ideal for placement above bedrooms. They pair with flexible ducts for easier routing through tight spots.
❄️ System Types
Multi-split ducted: 1 outdoor unit + multiple slim indoor units. VRV/VRF: For larger homes (150+ m²) with independent zone control. Both deliver heating + cooling from the same ductwork.
💶 Cost
Ducted AC in a renovation costs €150-250/m² (mechanical + plasterboard). In a 100 m² home that's €15,000-25,000. More expensive than splits, but delivers silent, invisible, uniform temperature.
4. Linear Grilles: The Finishing Touch
Concealed AC needs visible points only at the grilles: where air enters and exits. In modern renovations, forget those square aluminium louvres!
✨ What They Are
Ultra-thin, elegant "slots" (slot diffusers) painted to match the wall or in matt black. They integrate so seamlessly into the plasterboard they look like a decorative shadow gap.
🌀 Types
Supply: Grilles that blow cool/warm air. Return: Grilles that draw air back to the unit. You need both - without a return, air doesn't circulate properly and performance drops.
📐 Placement
Supply grilles go near windows (to counter cold drafts). Return grilles go on the opposite wall or in the centre. This layout creates uniform circulation with no "dead zones".
✅ Summary
Ducted AC is not off-limits in old buildings. It requires close collaboration between the mechanical engineer and architect. With strategic placement in secondary spaces, slim units and linear grilles, you enjoy silent, invisible, hotel-grade comfort without losing a single centimetre of ceiling height in your living room.
🔑 Key: The mechanical engineer must be involved BEFORE the plasterer. If ducts are designed after the plasterboard, you lose 90% of the "hidden" options.
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