Sound power level
The sound power level indicates how much noise the heat pump itself emits, regardless of the location. It is listed in the data sheet and is suitable for comparison.
- Device with 55 dB(A) sound power level on a house wall.
- The same device in a corner of a building: around 3 dB louder.
- Night-time guideline value in residential areas on the outskirts: 40 dB; for individual heat pumps, authorities often set values of 30–35 dB.
The sound power level (LW, in decibels) describes the total sound energy emitted by a device. It is a characteristic of the heat pump itself and does not depend on where you are standing. This makes it ideal for comparing devices. How loud it actually is at the neighbour's is described by the sound pressure level.
Where you can find it
According to the Energieberatung NÖ (Energy Advisory Service of Lower Austria), information on the sound power level is usually found in the manufacturer's data sheets. Pay attention to which operating state the value applies to, for example full load or night operation.
Guide values
- The Energieberatung NÖ (Energy Advisory Service of Lower Austria) recommends choosing a device with a maximum sound power level of 52 dB. This corresponds to the Gold rating on topprodukte.at, a service by klimaaktiv.
- Look out for a silent or night mode that allows the device to run more quietly during the night.
- The Energieberatung NÖ (Energy Advisory Service of Lower Austria) advises choosing a quieter device right from the start, rather than retrofitting expensive acoustic hoods later.
Where the noise comes from
In air source heat pumps, the fan is the main source of noise. The compressor can also cause vibrations that are transmitted into the house as structure-borne noise via the foundation and walls. The klimaaktiv Wegweiser (guide) therefore requires a vibration-isolated installation and advises against locations next to or below bedrooms.
With the sound calculator, you can see what a certain sound power level means at your property boundary.
Sources
- Energie- und Umweltagentur NÖ: Infoblatt Aufstellort Luft-Wasser-Wärmepumpe (Energy and Environment Agency of Lower Austria: Information Sheet on Installation Sites for Air-to-Water Heat Pumps, 2025) (accessed on 4 October 2026)
- Stadt Wien, Beratungsservice erneuerbare Energie: Wärmepumpe & Schallschutz (City of Vienna, Renewable Energy Advisory Service: Heat Pump & Noise Protection - Webinar on the Noise Protection Guide) (accessed on 4 October 2026)
- klimaaktiv Wegweiser zur guten Installation von Wärmepumpen (klimaaktiv Guide to Good Installation of Heat Pumps, BMK, 2020) (accessed on 4 October 2026)