WarmtepompGeluid
Evening+Night
62
Day
67
dB(A) max LwA

Property

Residential zoning

Outdoor unit

Zb = 1.15 m · Q = 2 · On: Woning

Margin

3 dB

Sound power

Buildings

Garden walls

Left
Right

Receiver positions

No receiver positions. Click '+ Receiver position' on the map to add one.

Buitenunit staat op hoogte - controleer ook ramen/deuren van buurwoningen! Voeg ontvangposities toe op de hoogte van nabijgelegen ramen.

Result

Evening+Night
62
dB(A) max LwA
Day
67
dB(A) max LwA
Qbron = 2 · Margin = 3 dB
Max Lp at boundary: 42 dB(A)
(at LwA = 67)
Side cross-section
Side cross-section — Shows the height of buildings and the sight line from the outdoor unit to the loudest point on the property boundary. There is a clear line of sight between the outdoor unit and the measurement point.

Calculate heat pump noise: unit on the roof of the house

On the roof of the house the outdoor unit is far from every boundary. The classic boundary check therefore often comes out surprisingly well: distance is large and the roof edge screens the low assessment points. But that is not the whole story. At this height the unit has a clear view of bedroom windows of houses further away — and that is exactly where complaints arise in practice.

This preset starts with a unit at 7.3 metres on the roof of a terraced house. The warning in the results panel reminds you that upper windows of neighbouring homes need separate assessment.

How to use the tool for this situation

  1. 1
    Set up the house and roof

    Adjust the footprint and height of your house under “Buildings”. For a pitched roof, use the gutter height or the height of the mounting position.

  2. 2
    Position the unit on the roof

    Keep the unit at least a few metres from the roof edge so the edge screens all low points at the boundary.

  3. 3
    Add neighbours’ windows as receiver positions

    Use “+ Receiver position” to place points at bedroom windows of houses across the garden or street, at the real window height (z).

  4. 4
    Test your unit

    Enter the sound power of the unit you are considering under “Equipment specs”; the tool instantly checks it against both the boundary and the window positions.

The boundary check doesn’t tell the whole story on a roof

The legal assessment point at the boundary sits 1.5 metres above ground. For a source at 7 metres that point lies deep in the sound shadow of your own roof edge: the calculated value is low and the check passes easily. The real concern is higher up: windows and roof terraces of surrounding homes at comparable height, with a clear view of the unit.

The WPAC method therefore requires receiver positions at openable windows and doors of neighbouring dwellings, at their actual height, whenever the source is above 2.5 metres. In this tool you do that with the yellow P markers. The maximum allowable LwA is then set by the strictest point — often such a window, not the boundary.

Points of attention specific to roof installations

Place the unit as far as possible from the roof edge and from the side with the nearest bedroom windows. Every extra metre from the edge increases the screening angle. A position in the middle of the roof, possibly with a small parapet, performs best acoustically.

Two practical issues fall outside this airborne calculation but deserve attention: vibration transfer into the structure (a timber roof needs heavy-duty dampers and possibly a decoupled frame) and wind noise around the unit at height. When in doubt about the structure, consult an installer or structural engineer.

How does the calculation work?

The calculator is based on WPAC-geluid V2020, the official Dutch calculation tool for noise from outdoor heat pump and air-conditioning units, developed for the Ministry of the Interior. It computes the sound transmission loss (D) from the outdoor unit to each assessment point: the larger the transmission loss, the more sound power the unit is allowed to produce.

Distance is the dominant factor: every doubling of distance reduces the level by 6 dB. The directivity factor Q also matters — a unit within 2.5 metres of one wall (Q=1) is 3 dB louder than a free-standing unit (Q=2), and a corner between two walls (Q=0.5) adds another 3 dB. Reflections from building walls raise the level, while buildings between the unit and the assessment point screen the sound.

The transmission loss yields the maximum allowable sound power (LwA) of the unit: max LwA = limit + D − margin. The safety margin (default 3 dB, minimum 2 dB) covers design and measurement uncertainty. Compare the calculated maximum with the sound power on the unit’s energy label or product documentation.

The noise limits in brief

Since 1 January 2024 the noise requirements for heat pumps and air conditioners are set by the Besluit bouwwerken leefomgeving (Bbl), the successor to the Dutch Building Decree 2012. Article 4.107(2) Bbl states that an outdoor heat or cold generation installation may cause at most 40 dB at the boundary with a neighbouring residential plot. For situations on the same plot — such as apartment buildings — the same limit applies at openable windows and doors of another dwelling (article 4.108(3) Bbl).

The 40 dB limit applies in the evening and at night (19:00–07:00). If the unit has a low-noise setting (silent mode) active during that period, a limit of 45 dB applies during the day (07:00–19:00). Without silent mode the unit must meet 40 dB during the day as well. Read more on the heat pump noise limits page.

Frequently asked questions about this situation

Do the noise rules apply on the roof as well?

Yes. The 40 dB requirement at the boundary and at windows of other dwellings applies wherever the unit stands — ground, extension or roof. On a roof the critical point simply tends to shift from the boundary to upper windows of neighbours.

My boundary result passes comfortably. Am I done?

Not yet. With a roof-height source you must also assess windows and doors of surrounding homes at their actual height. Add them as receiver positions; the lowest maximum allowable LwA across all points governs.

How far from the roof edge should the unit stand?

The further the better: the roof edge screens lower points as soon as the sight line is broken. From roughly 2 metres in from the edge the effect becomes significant; the tool calculates the screening exactly from the geometry.

Are wind noise or vibrations included in the calculation?

No. The calculation covers the airborne sound of the unit itself (LwA). Structure-borne vibrations and wind effects are outside its scope but are important in practice on roofs — use vibration dampers and consult your installer.

Calculate other situations

In the garden On extension On outbuilding Apartment

Further reading

This calculator provides an indicative result based on WPAC-geluid V2020 and does not replace a formal acoustic study. When in doubt, consult an acoustic consultant or your municipality.