Planning decentralised ventilation in a new build: eight early decisions

Plan decentralised ventilation before electrical installation, internal plaster and façade details are fixed. This allows unit numbers, pairing, wall openings, power and external hoods to work together and avoids later rework. Start with airflow needs and air paths, not one product per room.

Why plan early?

Airtight new buildings reduce uncontrolled heat loss but also incidental air exchange. Germany’s Umweltbundesamt recommends airtight construction combined with ventilation and heat recovery for efficient new homes. Mechanical ventilation provides continuous exchange without relying solely on occupants opening windows.

German DIN 1946-6:2019-12 addresses natural and fan-assisted residential ventilation, design, airflow, installation and maintenance. It is a German planning reference, not automatic evidence of compliance in other countries. This guide and the German-language JESSP planner do not replace project-specific design or applicable local requirements.

Eight decisions before fit-out

1. Record each room’s use and air demand. Include area, height, occupancy and duration: a two-person bedroom differs from a home office or occasional guest room. See unit numbers and the German-language planner. Complex layouts, internal wet rooms and combustion appliances need individual review.
2. Choose the ventilation principle. Heat recovery units alternate supply and extract. Arrange and coordinate pairs correctly. Use average fresh-air output in heat recovery mode rather than maximum one-direction fan output. See push-pull operation.
3. Select the unit for each room. Compare airflow, opening, filter and control; a small opening may mean insufficient quiet airflow in a large or heavily occupied room. Use the table below and model comparison.
4. Mark positions on plans and elevations. Keep air paths and filters accessible, clear of cupboards, curtains and later fittings. Consider window reveals, downpipes, canopies, balconies and façade appearance outside. Give all trades the same positions. For acoustics see the bedroom guide.
5. Specify wall build-up and core holes. Vario 160: recommended Ø170–180 mm; Vario 110: Ø120–130 mm. Do not transfer these to DZ/Easy+; follow the delivered model’s manual. Document total wall thickness, insulation, plaster and required slope. See installation mistakes.
6. Coordinate power and controls. Before plastering, establish supplies, controller positions and connecting cables. Easy+ uses a shared wall controller; DZ/Vario have different control/app concepts. An arbitrary socket is not an electrical plan. Determine which units are controlled together; electrical work must follow the manual and be performed by a qualified person. See app controls.
7. Plan any inter-room airflow. Closed, tight doors can obstruct intended transfer. Door undercuts or transfer elements must suit sound, fire and comfort requirements. Internal bathrooms, kitchens and rooms with combustion appliances require specific coordination with designers and trades. A same-room pair does not itself require an inter-room transfer assignment.
8. Prepare commissioning and maintenance. Check assignments, operating modes, air paths and controls. Record model, location and pair membership. Hand over manuals and instructions, keeping filter access unobstructed. See filter service.

Fresh-air planning values in heat recovery mode

Decisions by building stage

Concept: use, airflow, principle and special requirements. Detailed design: models, numbers, pairs, positions and transfer paths. Shell: openings, thickness, slope and façade positions. Electrics/plaster: supply, controller and wiring. Completion: installation, assignments, testing, records and user instruction.

Frequently asked questions

When start? During concept or early detailed design, before drilling, electrics and finishes. One unit per room? Not automatically: calculate room needs within the whole concept. Choose after plastering? Possible, but limits options and risks visible retrofit work. Is the online planner proof of compliance? No; it supports preliminary selection only.

Early coordination saves rework. Start with the rooms and air paths, then compare JESSP units.

Sources from the German original

• dinmedia.de
• umweltbundesamt.de