Residential Ventilation (HRV) in Berlin

In refurbished buildings with good insulation and new windows KWL is very beneficial – heat recovery pays for itself within 8–12 years through heating energy savings. In unrefurbished old-build properties with leaky windows and poor insulation, decentralised ventilation may be the better solution, since central KWL cannot achieve its full efficiency potential. Especially after renovation (new windows, external insulation), KWL suddenly becomes attractive – before that it's hard to justify the investment. We advise individually and calculate the payback period based on your specific situation.

Modern KWL units operate at 20–30 dB(A) on normal setting (level 2 of 4) – quieter than a refrigerator and barely perceptible during sleep. On minimum setting (level 1) often only 15–20 dB(A). On highest setting (level 4) can reach up to 40 dB(A), but this isn't necessary for continuous operation. The biggest noise risk is poorly routed ducts with air turbulence – with our anti-vibration accessories and optimised routing we avoid this from the start.

For an apartment (70–100 m²) total costs including duct network, routing and installation range from €6,250–15,000, depending on: unit class (standard KWL €6,250–8,750 vs. premium units with humidity sensors €10,000–15,000), duct routing (simple straight ducts cheaper than complex routing over ceilings and through walls), and filter configuration (standard filters €250–500, HEPA filters for allergies €1,000–1,500). Add annual maintenance (€190–315) and filter replacement (€125–375/year).

Ventilation ducts (typically flexible plastic pipes DN 125–160 mm) are routed over ceilings or behind suspended ceilings, possibly hidden in cable ducts. Half-timbered buildings often have cavities we can use – this saves considerable costs. Solid old-build properties with solid ceilings often need a suspended ceiling (about 8–10 cm room height loss) or surface-routed ducts (less attractive but cheaper). Before we start planning, we do a site survey for €375–625 and create a custom routing concept – that's included at no extra cost and prevents surprises later.

Yes – modern KWL units have optional humidity and CO2 sensors that automatically adjust ventilation capacity. In high humidity (e.g. after showering) units automatically ramp up; at normal levels they ramp down – saving energy and noise. These sensors cost about €500–875 extra and pay for themselves through energy savings, but more importantly they dramatically improve room comfort. Common scenario: humid rooms in old buildings → mould risk → open windows despite KWL. With humidity control the KWL runs exactly when needed.

Yes – KfW and BAFA subsidise KWL systems as part of energy-efficiency house standards (KfW 55, 40, 40+) or as individual measures under BEG. Typically 25–40 % subsidy for new builds and 15–30 % for renovations. Subsidies are tiered: smaller units without heating supplement receive less than larger systems with heat exchanger. Important: application MUST be submitted BEFORE contract signature. We help with applications and file directly with BAFA – saving you wait times.

No. The airflow of a ventilation system is designed for air quality and moisture protection, not for cooling loads. Even with a cooling coil, a flat only gets a few hundred watts of cooling, while a split air conditioner delivers many times that per room. The summer bypass helps on cool nights, not on hot days.

Yes. Ventilation systems with heat recovery count as system technology in the federal funding for efficient buildings: a 15 percent grant. Since 21 July 2026 the bonus for an individual renovation roadmap is only added from 30,000 euros of eligible costs and only for the amount above that. The application is filed before the order is placed and confirmed by a listed energy efficiency expert; we take care of this step.