Sound pressure level

The sound pressure level is the volume that reaches a specific location, such as the property boundary. It decreases with distance from the heat pump.

The sound pressure level (Lp, in decibels) describes how loud it actually is at a certain point, such as at the neighbour's bedroom window. It depends on the sound source, but also on the distance and the surroundings. You can find the opposite term, the volume of the source itself, under Sound power level.

What affects the sound pressure level

• Distance: The further away, the quieter. The Beratungsservice der Stadt Wien (City of Vienna advisory service) calculates using the formula: sound pressure level = sound power level minus 20 × log(distance in m) plus surcharge minus 8.
• Reflections: If the device is placed against a house wall, according to Energieberatung NÖ (Energy Advisory Service Lower Austria), about 3 dB is added, and in a corner about 6 dB.
• Multiple devices: Two equally loud outdoor units next to each other increase the level by 3 dB.

A calculation example from Vienna

A device with 65 dB(A) sound power, freestanding 7 m from the property boundary, results in around 40 dB(A) there. If it is in a corner, it is around 46 dB(A).

Which values apply

The limit values depend on the federal state, zoning, and time of day. The klimaaktiv Wegweiser (guide) specifies a planning guideline value of a maximum of 30 dB(A) at night at the property boundary for residential areas (according to ÖNORM S 5021). You can find out what applies to you at your Gemeindeamt (municipal office).

With the sound calculator, you can estimate the level at the property boundary. Read more about permits under Permit.

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